Warsaw University of Life Sciences

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1 Annals Warsaw University of Life Sciences Forestry and Wood Technology No 73 Warsaw 2011 Contents: SMARDZEWSKI JERZY, KŁOS ROBERT Modeling of joint substitutive rigidity of board elements... 7 ALTUN SUAT, YAPICI FATIH, KORKMAZ ZEHRA. Effects of vacuum drying with infrared heating on some properties of wood BARBOUTIS IOANNIS, MELISSIDES THEODOSIOS Influence of the time between machining and assembly of mortise and tenon joints on tension strength of T-type joints GAWROŃSKI TOMASZ Optimization of furniture technology at design stage HAVIAROVA EVA Approach to furniture design education at Purdue University

2 KAMPERIDOU VASILIKI, BARBOUTIS IOANNIS, VASSILIOU VASSILIOS Correlation between bending and tension strength of corner and middle joints constructed with beech and poplar wood KOŘENÝ ADAM, ŠIMEK MILAN Experimental testing of cam fittings PREKRAT SILVANA, PERVAN STJEPAN, SMARDZEWSKI JERZY Optimization of furniture testing SMARDZEWSKI JERZY, MAJEWSKI ADAM Auxetic spring elements for elastically supporting a sitting or lying TANKUT NURGUL The influence of pilot hole on the moment resistance of screwed T-Type furniture joints TAUBER JIŘÍ, SVOBODA JAROSLAV Ergonomic authentication for dimensions furniture ANDRES BOGUSŁAW Basidiomycetes growing on sleepers reused in small garden architecture ANDRES BOGUSŁAW, MAŃKOWSKI PIOTR Resistance of lime wood (Tilia sp.) impregnated with Paraloid B-72 resin against cellar fungus Coniophora puteana (Schum., Fr.) Karst ANTCZAK ANDRZEJ, MAŃKOWSKI PIOTR, BORUSZEWSKI PIOTR Chemical studies of ozone impact on pinewood (Pinus sylvestris L.) degradation BAJKOWSKI BOGUSŁAW Application of artificial intelligence in the wood industry BAJKOWSKI BOGUSŁAW Computer techniques in automatized wood industrial company BARBU SIMONA-MARIA, BADESCU LOREDANA ANNE-MARIE, JAVOREK LUBOMIR Studies regarding the influence of forces and torques on the quality of surfaces obtained at wood drilling BIERNACKA JUSTYNA The analysis of selected parameters characterizing economic condition of furniture manufacturer - Forte SA BIERNACKA JUSTYNA The analysis of selected parameters characterizing economic condition of Paged SA BIERNACKA JUSTYNA The analysis of selected parameters characterizing economic condition of Grajewo SA

3 BODNÁR FERDINAND, JABŁOŃSKI MAREK Stress distribution along the contour of a circular opening in wooden plate loaded by inplane bending moment BORUSZEWSKI PIOTR, BORYSIUK PIOTR, JASKÓŁOWSKI WALDEMAR, FAJKOWSKA KAROLINA, MAMIŃSKI MARIUSZ, JENCZYK-TOŁŁOCZKO IZABELLA Characteristics of selected fireproof properties of particleboard made from particles impregnated with salt agent BORUSZEWSKI PIOTR, BORYSIUK PIOTR, JASKÓŁOWSKI WALDEMAR, ŚWIĘCKI ANTONI, MAMIŃSKI MARIUSZ, JENCZYK-TOŁŁOCZKO IZABELLA Influence of flakes impregnation with salt flame retardants on selected physical and mechanical properties of OSB BORUSZEWSKI PIOTR, BORYSIUK PIOTR, MAMIŃSKI MARIUSZ Screw holding ability of the lignin-bonded biocomposites BORYSIUK PIOTR, KRAJEWSKI KRZYSZTOF, BORUSZEWSKI PIOTR, JENCZYK-TOŁŁOCZKO IZABELLA, JABŁOŃSKI MAREK Bonding quality of veneers protected with fireproofing preservation based on diammonium hydrogen phosphate, citric acid and sodium benzoate BORYSIUK PIOTR, JABŁOŃSKI MAREK, POLICIŃSKA-SERWA ANNA, RUŽINSKÁ EVA Mechanical properties of glue bonds in black locust wood treated with ammonia BORYSIUK PIOTR, JASKÓŁOWSKI WALDEMAR, BORUSZEWSKI PIOTR, JENCZYK-TOŁŁOCZKO IZABELLA, JABŁOŃSKI MAREK, BYLIŃSKI DAWID Flammability of plywood made from veneers protected with flame retardant based on diammonium hydrogen phosphate, citric acid and sodium benzoate BORYSIUK PIOTR, ZBIEĆ MARCIN, BORUSZEWSKI PIOTR, MAMIŃSKI MARIUSZ, MAZUREK ANDRZEJ Possibilities of single-stage pressing of veneered particleboards BORYSIUK PIOTR, DANIHELOVA ANNA, JABŁOŃSKI MAREK, POLICIŃSKA-SERWA ANNA, RUŽINSKÁ EVA The impact of wood staining with specific synthetic dyes on pine wood gluability BORYSIUK PIOTR, JASKÓŁOWSKI WALDEMAR, BORUSZEWSKI PIOTR, JENCZYK-TOŁŁOCZKO IZABELLA, JABŁOŃSKI MAREK, BYLIŃSKI DAWID Ignitability of wood impregnated with fireproof agent based on diammonium hydrogen phosphate, citric acid and sodium benzoate BURAWSKA IZABELA, TOMUSIAK ANDRZEJ, BEER PIOTR Influence of the length of CFRP tape reinforcement adhered to the bottom part of the bent element on the distribution of normal stresses and on the elastic curve) 186 3

4 BURAWSKA IZABELA, TOMUSIAK ANDRZEJ, TURSKI MICHAŁ, BEER PIOTR Local concentration of stresses as a result of the notch in different positions to the bottom surface of bending solid timber beam based on numerical analysis in Solidworks Simulation environment CHUCHAŁA DANIEL, ORŁOWSKI KAZIMIERZ, KRZOSEK SŁAWOMIR The preparation method of experimental studies of the wood sawing process CYRANKOWSKI MARIUSZ, OSIPIUK JAN, BAREJ PAWEŁ Straw briquette as an energy source CYRANKOWSKI MARIUSZ, KORZEMSKI MICHAŁ Implementation issues in visual systems for wood quality testing CYRANKOWSKI MARIUSZ, OSIPIUK JAN, ADAMCZYK DAWID Plants as an alternative source of energy CZECHOWSKI JACEK, BLUS KAZIMIERZ Eco-friendly method for paper dyeing with reactive dyes ДЕЛИЙСКИ НЕНЧО Система модельно базированного автоматического управления процессом конвективной сушки пиломатериалов ДЕЛИЙСКИ НЕНЧО, ДЗУРЕНДА ЛАДИСЛАВ Вычисление удельной теплоемкости мерзлой древесины во время оттаивания льда в ней от адсорбционно связанной воды DIETZ HANS, KRZOSEK SŁAWOMIR Die Zukunft von Bandsägeanlagen mit Magnetführungen im Sägewerk

5 Board of reviewers: Bogusław Bajkowski Piotr Beer Ewa Dobrowolska Jarosław Górski Adam Krajewski Krzysztof Krajewski Donata Krutul Sławomir Krzosek Hanna Pachelska Jerzy Smardzewski Wacław Szymanowski Piotr Witomski Janusz Zawadzki Scientific council : Arnold Wilczyński (Poland) Kazimierz Orłowski (Poland) Ladislav Dzurenda (Slovakia) Miroslav Rousek (Czech Republic) Nencho Deliiski (Bulgaria) Olena Pinchewska (Ukraine) Włodzimierz Prądzyński (Poland) Dofinansowano ze środków Ministra Nauki i Szkolnictwa Wyższego Polska Akademia Nauk Komitet Technologii Drewna Warsaw University of Life Sciences Press [email protected] SERIES EDITOR Ewa Dobrowolska ISSN Marcin Zbieć PRINT: ZPW POZKAL 5

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7 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: 7-15 (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Modeling of joint substitutive rigidity of board elements JERZY SMARDZEWSKI, ROBERT KŁOS Department of Furniture Design, Faculty of Wood Technology, Poznan University of Life Sciences Abstract: Modeling of joint substitutive rigidity of board elements. The study presents alternative methods of numerical modeling of dowel joint rigidity of board elements using for this purpose nodes of substitute linear elasticity modulus. Values of joint deflections obtained by way of laboratory experiments and numerical calculations differed by 3 to 4%. Keywords: dowel joint, substitute linear elasticity modulus, numerical calculations INTRODUCTION Virtual furniture design requires verification of their quality from the point of view of their rigidity and strength of the applied construction solutions. This, in turn, is associated with the development of appropriate mesh models of furniture joints in the environment of programs calculating with the assistance of the finite elements method (FEM). Realistic representation of the examined structure in the FEM environment is very labour-consuming, requires numerous corrections of network geometry and meticulous determination of linear elastic properties of the applied materials (Dzięgielewski, Smardzewski, (1996), Kasal (2008), Kasal et al., (2008a,b), Smardzewski (2004a,b), Smardzewski (2005)). However, it is more practical but equally effective to replace joints with semirigid joints (Kłos, Smardzewski (2004), Nicholls, Crisan (2002), Smardzewski, Kłos (2004), Smardzewski, Ożarska (2005), Smardzewski, Prekrat (2002, 2005)). In this paper, an attempt was made to present alternative methods of numerical rigidity modeling of cabinet furniture dowel joints using nodes of substitute linear elasticity modulus. RESEARCH OBJECTIVE The aim of this research project was to determine values of the substitute linear elasticity modulus of a spatial dowel joint subjected to closing and opening, to ascertain deflections of this joint, to develop alternative mesh models, to compare the obtained results and to select the model most favourable for the virtual prototyping of furniture. MATERIAL AND METHODS Investigations were carried out on angle joints with three 8x32 mm dowel pins of beech wood (Fig.1). Arms of the connections were made of 16 mm thick chipboards and were supported and loaded in accordance with the diagrams presented in Figure 2, measuring values of force P with 0.01 N accuracy and displacements δ ip of point i along the direction of action of force P with 0.01 mm accuracy. For diagrams presented in Figure 2, function equations of the joint arm deflection were determined in the following form: w' ' x for x P l x, it was obtained, w x M y 2 2 M y, where EJ 2P l x ip dx dx Cx D EJ. 2 7

8 Taking into consideration kinematic boundary conditions and rigidity of joint elements, calculating integration constants and converting the above equation in relation to δ ip, the following equations were obtained: a) substitute elasticity model in a closing test: 2 Z Plz 3l1 3l1l z l E z 3 Pl1 3 ip J1 E1 b) substitute elasticity model in an opening test: 2 2 R Plz 3l1 3l1l z lz E z, 3 Pl1 12 ip J1 E1 where: l z length of the near-node section (for the board, it was assumed as l z =2h), l 1 length of the joint arm, b cross-section width of the joint arm, h thickness of the joint arm 16 mm, ip joint total deflection, 3 b h J 1 moment of inertia of joint arm cross-section, J, E 1 Young modulus of the joint arm - chipboard, P load (0.4P max 0.1P max ). 1 2 z 12, Fig. 1. Dowel joint 8

9 a) b) Fig. 2. Diagram of loading of the angle joint in: a) closing, b) opening tests Table 1 collates mechanical properties of beech wood, chipboard and glue bond used for the experimental joints, whereas in Table 2, calculation results of substitute modulus of linear elasticity are presented. Table 1. Mechanical properties of materials used to make joints Material Property Mean value Standard deviation Coefficient of variance [%] Chipboard Linear elasticity modulus [MPa] Bending strength [MPa] Beech wood Linear elasticity modulus [MPa] Bending strength [MPa] Glue bond Linear elasticity modulus [MPa] Table 2. Values of the joint substitute linear elasticity modulus Kind of research Mean value [MPa] Standard deviation [MPa] Coefficient of variance [%] Closing test Opening test When preparing models for numerical calculations, all attempts were made to make sure that geometry and elastic properties attributed to the materials corresponded to real objects as closely as possible. At the same time, issues associated with time necessary for the elaboration of models as well as cost-efficiency of the calculation process were also taken into consideration. For the above reasons, as well as for utilitarian motives, two mesh models were developed for each joint. One of the models constituted a faithful replica of the real joint, while the other, instead of profile and profile-adhesive joints, contained an element of previously determined substitute linear elasticity modulus (Fig.3). 9

10 a) b) Fig. 3. Network of finite elements for a solid body model of angle joint containing: a) dowel pegs, b) element of a substitute modulus of rigidity E z Brick type, eight-node elements were used to model the experimental dowel joints (Fig.3a). Joint arms were attributed earlier determined elastic properties of chipboards, while fasteners elastic properties of beech wood. The glue bond was modeled as an 0.1 mm thick layer of E s =460 MPa linear elasticity modulus. A contact surface was defined between joint elements differentiating the density of the master and slave networks in such a way that the former was at least two times denser at the place of contact than the slave network. The substitute model of the same joint (Fig.3b) was made using an element of determined substitute linear rigidity. In accordance with the diagram in Figure 2, the substitute element included the near-node sections and arms 2h long (two thicknesses of arms) measuring from the inside part of the connection. The remaining sections of the arms of the joint were attributed elastic properties as in the model from Figure 3a. Taking into consideration calculated mean values of the linear elasticity substitute modulus of the examined joints (Tab.2) as well as their non-linear rigidity characteristics, the following parameters were used for numerical calculations (Tab.3): External load P of the values corresponding to 40% of the joint mean breaking load determined for the linear-elastic range, Deflection δ ip corresponding to the determined external load, Linear elasticity substitute modulus: E Z z for the joint closing test and E R z for the opening test calculated for the determined P and δ ip. Table 3. Values of loads, deflections and linear elasticity substitute modulus of the experimental joints Joint Closing test Opening test P [N] δ 1P [mm] E Z z [MPa] P [N] δ 2P [mm] E R z [MPa] Dowel Numerical calculations for closing and opening patterns of the joints were conducted in the environment of Algor software which realises algorithms of the finite element method. Models from Figure 2 and load values from Table 3 were employed as schemes of static support and loading of the examined systems. The results of calculations comprised illustrations of the distribution of reduced stresses (Mises) in elements of joints, values of these stresses, illustrations of deflections of joints in the direction of action of the external force as well as values of these deflections. 10

11 RESEARCH RESULTS When dowel joints were subjected to closing with force constituting 40% of the breaking load value, it was found that the highest reduced stresses concentrated around fasteners and seats (Fig. 4). The value of these stresses did not exceed 3 MPa which means that the only critical condition deciding about the strength of this construction node was the resistance of the chipboard to delamination (k r =<1.0MPa). Fig. 4. Distribution of reduced stresses according to Mises in a dowel joint subjected to closing, σ max 3 MPa a) b) Fig. 5. Distribution of reduced stresses according to Mises in a dowel joint subjected to closing at the point of: a) board mutual pressure, b) pressure of fasteners on boards, σ max 3 MPa The forms of joint deformations presented in Fig.5 indicate strong loading of the front edge of the joint element and a lack of contact (formation of a gap) between elements on external surfaces (Fig.5b). Because the external chipboard surfaces from which elements of joints were made consist of microchips, contact stresses developed on the edge caused by pressures did not exceed 3 MPa and were not dangerous for this joint. 11

12 Fig. 6. Distribution of reduced strains according to Mises on the surface of seats in a dowel joint subjected to closing, σ max 3 MPa The most dangerous stresses for the load bearing capacity of the joint were those concentrating on the surface of seats (Fig.6). Their value was higher than 3 MPa significantly exceeding the strength of chipboards for stratification. Such concentration of stresses first caused damage of seat surfaces made in the loosest and the weakest zone of the chipboard and then resulted in the delamination of the element in which fasteners were mounted longitudinally to wide planes of the board. Fig. 7. Size of gap between boards pressing against each other in the joint subjected to closing, δ max 0,08 mm It is also interesting that within the discussed range of loads, the joint was characterised by distinct rigidity. The size of the gap formed between board elements of the joint did not exceed 0.08 mm in the course of its closing (Fig.7). 12

13 Fig. 8. Deflection value δ 1P of the dowel joint subjected to closing, δ 1P(max) =0.75 mm. The quality of the elaborated model was assessed by comparing the calculation results of deflections determined on the direction of load action with the results of laboratory measurements. In the case of numerical calculations, the obtained deflection value amounted to 0.75 mm (Fig. 8). For the adequate substitute model (Fig. 9a), the value of the deflection was 1.42 mm, whereas in the case of the realisation of the pattern causing opening of the joint, the deflection in the direction of force action amounted to 1.62 mm (Fig. 9b). The comparison of the obtained results with measurements obtained experimentally revealed that the results of numerical calculations conducted on models with substitute modulus of linear elasticity were closer to these values. a) b) Fig. 9. Size of deflection: a) δ 1P of the joint with the element of substitute rigidity (E Z Z) subjected to closing, δ 1P(max) =1.42 mm, b) δ 2P of the joint with the element of substitute rigidity (E R Z) subjected to opening, δ 2P(max) =1.62 mm 13

14 Table 4 collates values of deflections obtained from calculations and laboratory experiments after the comparison of the quality of numerical models elaborated for the examined joints. Values of numerical calculations obtained from models faithfully representing the shape of the examined joints were distinctly lower in relation to the results of laboratory measurements. On the other hand, the comparison of the calculation results obtained from models containing nodes with substitute modulus of linear elasticity with empirical results indicates that, in their majority, they were slightly higher. In the case of the wall angle dowel joint, the difference in deflections during closing amounted to 4,1% and during opening 3,8%. Table 4. Deflections of the examined joints determined experimentally. Joint Closing test δ 1P [mm] Opening test δ 2P [mm] Experiment Brick model Experiment Brick model True Substitute True Substitute Wall CONCLUSIONS Taking into consideration the performed analysis of the obtained research results it should be emphasised that for virtual (numerical) construction modeling of cabinet furniture dowel joints it is recommended to apply cuboid, six- and eight-node networks of finite elements which should be assigned substitute modulus of linear elasticity determined empirically. REFERENCES 1. DZIĘGIELEWSKI ST.; SMARDZEWSKI J. 1996: Moduł sprężystości połączeń a sztywność mebli skrzyniowych - analiza numeryczna. Materiały VIII sesji naukowej Badania dla meblarstwa. Wydawnictwo Akademii Rolniczej im. A.Cieszkowskiego w Poznaniu. Poznań KASAL A. 2008: Effect of the number of screws and screw size on moment capacity of furniture corner joints in case construction. Forest Prod. J. 58(6): KASAL A., ZHANG J., YUKSEL M., ERDIL Y.Z. 2008a: Effects of screw sizes on load bearing capacity and stiffness of five-sided furniture cases constructed of particleboard and medium density fiberboard. ForestProd. J. 58{10}: KASAL A., ERDIL Y.Z., ZHANG J., EFE H., AVCI E. 2008b: Estimation equations for moment resistances of L-type screw corner joints in case goods furniture. Forest Prod. J.58(9): KŁOS R., SMARDZEWSKI J. 2004: Wielokryterialna optymalizacja mebli skrzyniowych metodą algorytmów genetycznych. Roczniki Akademii Rolniczej w Poznaniu 39: NICHOLLS T., CRISAN R. 2002: Study of the stress-strain state in corner joints and box-type furniture using Finite Elements Analysis (FEA). Holz als Roh- und Werkstoff, 60(2002) SMARDZEWSKI J., KŁOS R. 2004: Możliwości polioptymalizacji mebli skrzyniowych z wykorzystaniem metody gradientowej, Przemysł Drzewny 4(LV): SMARDZEWSKI J., OŻARSKA B. 2005: Rigidity of cabinet furniture with semirigid joints of the confirmat type. Electronic Journal of Polish Agricultural Universities Wood Technology 8(2), # SMARDZEWSKI J., PREKRAT S. 2002: Stress distribution in disconnected furniture joints. Electronic Journal of Polish Agricultural Universities, Wood Technology, Volume 5, Issue 2. 14

15 10. SMARDZEWSKI J., PREKRAT S. 2005: Nonlinear strength model of an eccentric joint mandrel. Drvna Industrija 55(2): SMARDZEWSKI J. 2004a: Modeling of semi-rigid joints of the confirmat type. Annals of Warsaw Agricultural university, Forest and Wood Technology 55: SMARDZEWSKI J. 2004b: Modelowanie półsztywnych węzłów konstrukcyjnych mebli. Monografia pod redakcją B.Branowskiego, P.Pohla. Wydawnictwo AR w Poznaniu , SMARDZEWSKI J. 2005: Nieliniowe modele połączeń zaczepowych. Polioptymalizacja i komputerowe wspomaganie projektowania. Wydawnictwo Uczelniane Politechniki Koszalińskiej. Mielno Streszczenie: Modeling of joint substitutive rigidity of board elements. W pracy przedstawiono alternatywne sposoby numerycznego modelownia sztywności połączeń kołkowych elementów płytowych z wykorzystaniem węzłów o zastępczym module sprężystości liniowej. Wartości ugięć połączeń, uzyskane w drodze badań laboratoryjnych oraz obliczeń różniły się o 3-4%. Corresponding authors: Jerzy Smardzewski, Robert Kłos Uniwersytet Przyrodniczy w Poznaniu, Wydział Technologii Drewna Wojska Polskiego 38/ Poznań, [email protected] 15

16 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Effects of Vacuum Drying with Infrared Heating on Some Properties of Wood SUAT ALTUN, FATIH YAPICI, ZEHRA KORKMAZ Karabuk University, Technical Education Faculty, Department of Furniture and Decoration Education Abstract: Effects of vacuum drying with infrared heating on some properties of wood. Drying of wood is one of the most important industrial processes in wood manufacturing. Mechanical properties of wood are affected from drying process. Heating method of the drying process is the most effective factor on the properties of end product. The aim of this study was to determine the effect of infrared heating in vacuum drying on the drying quality and mechanical properties of wood. For this purpose Oriental beech (Fagus orientalis L.) and Scots pine (Pinus Sylvestris L.) samples were dried by vacuum drying with infrared heating at º C temperatures and at mbar ambient pressure for 48 hours. Final moisture content (MC) distributions, case hardening, modulus of elasticity (MOE), modulus of rupture (MOR) and compression strength (CS) of dried samples were determined. According to the results of the test, although average MC of the pieces met the requirements of the standard drying class, distribution of the individual MC did not meet the requirements in both pine and beech. Vacuum drying with infrared heating increased the MOE, MOR and CS of Scots pine and only CS of beech. MOE and MOR of beech were not affected from drying with infrared heating. Keywords: vacuum drying, infrared heating, drying quality, Scots pine, beech, mechanical properties INTRODUCTION Drying of wood is one of the most important industrial processes in wood manufacturing. There are many methods, which are widespread used to drying lumber such as air drying, shed air drying, forced-air shed drying, warehouse pre-drying, low temperature kiln drying, conventional electric dehumidification kiln drying and conventional steam-heated kiln drying (Denig et.al., 2000). Drying is the most energy-intensive and time-consuming component of the lumber manufacturing process. Currently, over 80% of the produced lumber has been dried in conventional and vent kilns. Although this operation is simple and inexpensive, the product quality is often low and the drying time is very long, especially for hardwoods (Li et al., 2008). An incorrect drying process generates cracking problems, rupture of the cellular structure of the wood, folding in the piece, and in general an inadequate drying stage. These alterations devalue the final product and important losses for the wood industry take place. Drying influences the mechanical properties of wood in three ways, namely through the direct effect of moisture loss, the internal drying stresses and strains. (Taskini 2007) Many studies have been carried out on vacuum drying of wood. Water in wood at the sub-atmospheric pressure can be vaporized and moved at a temperature below C as rapidly as for high temperature drying at the atmospheric pressure. Therefore, vacuum drying has the benefits of high temperature drying without the danger of developing defects with some susceptible species. (Jung et al. 2004) Generally, there are two basic processes (continuous or discontinuous) and three type of heating (by convection, heating plates or microwave) in vacuum drying. In discontinuous vacuum drying the wood undergoes repeated changes, first being heated at atmospheric pressure then demoisturised at low pressure without any heat. There is considerable risk of discoloration owing to the presence of a high oxygen component during heating phase. In continuous vacuum drying there is simultaneous heating and demoisturising most of the time, at reduced pressure; external air is excluded. With convection heating the air speed must be 16

17 suitably high owing to the low density of the drying agent. With direct heating no fans at all required but there are serious problems: heating plates are only used individually and only for small useful volumes owing to their limited size and the very laborious, time consuming job of stacking and removing from the stack. The other direct heating method is the use of microwaves. Apart from the comparatively high capital cost and greater likelihood of malfunctioning it is very difficult to obtain homogenous intensity distribution over the whole stack. (Brunner 1993) Jomaa and Baixeras (1997), Chen (1997), Audebart et al. (1997) and many other researchers studied on vacuum drying with heating by convection or heating plates. Recently, researchers have focused on vacuum drying of wood with radio frequency and microwaves. Koumoutsakos (2001) investigated the energy dissipation coupled with heat and moisture mechanisms in wood during radio frquency/vacuum drying. Li et al. (2008) established a onedimensional mathematical model to describe the process of wood microwave-vacuum drying based on the mechanism of moisture and heat transfer in wood. Hansmann et al. (2008) used the high-frequency energy assisted vacuum drying to improve drying quality of fresh Eucalyptus globulus. Abubakari (2010) studied on the effect of RF heating as preconventional kiln treatment on the drying characteristics and quality of sub-alpine fir lumber. Jung et al. (2004) compared the vacuum drying characteristic of radiate pine using contact heating, radio frequency heating and the combination of both. Möttönen (2006) compared the conventional low temperature drying with vacuum drying in terms of variation in drying behavior and final moisture content. Unlike these studies Perre et al. (2004) used infrared (IR) heating in vacuum drying of wood. They noted that IR heating could be used successfully in the vacuum drying. In most of these studies drying rate and moisture distributions were reported. Very little studies included the effect of drying specifications on the drying quality and mechanical properties of wood. Taskini (2007) made a comparison between microwave, infrared, and convectional drying effects on wood strength and reported that drying time of the microwave heating is significantly reduced, while the strength stays higher than that obtained in convectional and infrared drying. RESEARCH OBJECTIVE The aim of this study was to determine the effect of infrared heating in vacuum drying on the drying quality and mechanical properties of wood. For this purpose Oriental beech (Fagus orientalis L.) and Scots pine (Pinus Sylvestris L.) samples were dried by vacuum drying with infrared heating and final moisture content (MC) distributions, case hardening, modulus of elasticity (MOE), modulus of rupture (MOR) and compression strength (CS) of dried samples were determined. MATERIAL AND METHODS In this study Oriental beech (Fagus orientalis L.) and Scots pine (Pinus Sylvestris L.) were used as a wood material. Samples were sawn with a thickness of 25 mm, a width of 100 mm and a length of approximately 3000 mm. The samples were of best quality without any cracks, cell collapse, warp, or obvious discoloration. Then they were divided into two parts and one part of each sample was dried in a conventional kiln by a commercial lumber supplier according to their professional experience. These samples were used as the control group to determine the mechanical properties. Other parts of samples were dried with vacuum drying with infrared heating in a laboratory scale vacuum chamber. Before drying, 200 mm were cut off on both ends of the boards in order to remove any pre-dried wood and due to manipulation damaged material. A sample with a width of 50 mm was cut of at the middle of each board for determining the initial moisture content (MC) by oven drying at 103 º C and for determining 17

18 the density. Because of smallness of the pilot vacuum drying chamber, samples were cut into a length of 500 mm before drying. Oven dry densities, initial and final MC and drying rate of the samples were given in Table 1. Samples were dried in a sealed vacuum chamber. Heating for drying were supplied by 4 ceramic infrared heaters having 2-10 µm wavelength and 16 kw/m 2 surface ratings and were placed at the two sides of the stack. Ambient temperature of the chamber was measured at the top of the stack, and core temperature of the wood was measured from samples in the middle of the stack. Measuring probe was inserted into half of the thickness of the sample. It was measured 10 º C difference between chamber and core temperature of samples during drying. Vacuum was supplied by an oil vacuum pump. Table 1. Oven dry densities, initial and final MC and drying rate of the samples Wood Oven dry density Initial MC Final MC Drying time Drying rate (g/cm 3 ) % % h %/day Beech 0, Scots pine 0, Stack was placed in the chamber and dried at mbar absolute pressure and º C (core temperature of wood) temperature for 48 hours. After drying, each wood sample was weighed and inspected for occurrence of any drying defects in the form of surface checking. Drying quality of the process was assessed according to TS EN (2006) standard. Samples were marked and cut into wood sections to determine the average final moisture content, the MC distribution, for internal checking and case hardening. Wood sections were quickly weighed with a digital balance having sensitivity 0.01 g to determine the individual MC. Case hardening of the samples was determined according to TS ENV (2005) standard. Effects of vacuum drying with infrared heating on the mechanical properties of wood were investigated. Modulus of elasticity (MOE), modulus of rupture (MOR) and compression strength were determined according to TS 2478 (1976), TS 2474 (1976) and TS 2595 (1977), respectively. RESEARCH RESULTS Beech and Scots pine wood were dried by using vacuum drying with infrared heating for 48 hours. No visual defects were detected on the surface of the dried samples. After sectioning of the samples, each section was inspected and there was no internal check. For beech and pine, the average final MC values were measured as 12% and 10% and drying rate were calculated as 17 %/day and 18 %/day, respectively. The individual MC distribution was between 7.2% and 12.9% in pine samples and between 6.5% and 18.5% in beech samples. The MC distribution across the length and width of the vacuum dried samples are given in Figure 1. According to TS EN standard, allowable range of average MC around the target MC (12%) is ±1.5% and 93.5% of the pieces should have individual moisture content between 15.6% and 8.4%. According to measurements 87.5% of the pine pieces and 75% of the beech pieces had individual MC between this ranges. Although average MC of the pieces met the requirements of the standard drying class, distribution of the individual MC did not meet the requirements in both pine and beech. As can be seen in Figure 1, average MC at the middle of the beech samples was much higher than that of at the end of and outer side of the samples. That is why the distribution of the individual MC exceeded the allowable range for 18

19 the standard drying class. Although the MC difference between inner and outer side of pine samples was relatively low, it was also out of allowable rage Scots pine Beech 15 Average MC (%) end middle outer side middle Across the Length Across the Width Figure 1. MC distribution across the length and width of the vacuum dried samples Case-hardening gap (mm) Beech Scots pine 0 h 24 h 48 h Measurement time (hour) Figure 2. Casehardening gap values of vacuum dried wood samples Casehardening gap values of vacuum dried samples with infrared heating are illustrated in Figure 2. Casehardening gap of beech was higher than that of pine. The gap increased with time. According to Abubakari (2010) casehardening is a condition of stress and set in wood in which the outer fibers are under compressive stress and the inner fibers under tensile stress, after drying. Casehardening is caused by too rapid or uneven drying as a result of too high temperature or too low relative humidity or large fluctuation of both. According to these results it can be said that vacuum drying of Scots pine and beech with infrared heating is not proper enough in terms of drying quality assessment. Mechanical properties of wood are affected from drying process. Because of this, the selection of drying process is very important. The most important mechanical properties of wood are modulus of elasticity (MOE), modulus of rupture (MOR), and compression strength (CS) in the many applications. According to the test results, mean and standard deviation values of these mechanical properties are given in Figure 3. It has been seen that the drying process used in this study affected the MOE, MOR and CS values. It has been found that the MOE, MOR and CS values of the test samples varied between N/mm 2, N/mm 2, and N/mm 2, respectively. The variance analysis was applied on data belonging to these mechanical properties of samples, and the results were shown in Table 2. 19

20 (241.09) ( ) (491.91) 9559 (818.06) 1000 (N/mm 2 ) (2.69) (19.05) (6.08) (7.99) (3.15) (4.82) (4.42) (3.43) 10 1 Control VD Control VD Control VD Control VD Control VD Control VD Scots pine Becch Scots pine Becch Scots pine Becch Modulus of Elasticity Modulus of Rupture Compression Strength Figure 3. Mechanical properties of Scots pine and Beech wood (VD indicates Vacuum Drying and Values in the parenthesis indicate standard deviation) Table 2. The results of variance analysis MOE (N/mm 2 ) MOR (N/mm 2 ) CS (N/mm 2 ) Source F P<0,05 F P<0,05 F P<0,05 Corrected Model , , ,000 Intercept , , ,000 A: Wood species , ,000 B: Drying types , ,000 AxB , ,000 According to the variance analysis, it has been seen that while the effects of drying types, wood species and interaction of them on both modulus of rupture and compressive strength properties of wood were found statically significant at 95% significance level. However, just only the effect of wood species used in this study on the modulus of elasticity value of test sample was not found at 95% significant level. To comparisons of these means were done by employing a Duncan test and the results are given in Table 3. Table 3.The results of Duncan Test MOE (N/mm 2 ) MOR (N/mm 2 ) CS (N/mm 2 ) Experimental Experimental Experimental design Mean HG design Mean HG design Mean HG Scots pinecontrol A Beech-control A Scots pinecontrol A Beech-vacuum drying A Scots pine-control A Beech-vacuum drying B Beech-control A Beech-vacuum drying B Beech-control B Scots pinevacuum drying B Scots pine-vacuum drying C Scots pinevacuum drying C It was shown that vacuum drying with infrared heating did not affect the MOE of beech wood. According to the Duncan test there was no statistical difference between MOE values 20

21 of vacuum dried and control of beech specimens. Because of the fact that MOE values determined from Scots pine-control, Beech-Vacuum drying, and Beech-Control was seen much closer to each other; they were given the same homogenous groups. Vacuum drying with IR heating increased the MOE of Scots pine, statistically. It can be said that according to the result of Duncan test, vacuum drying with IR heating increased the MOR values in both Scots pine and beech specimens. Although MOR values, which were obtained from both Beech-control and Scots pine-control were given at the same homogenous group, the others were shown at different homogenous groups. It can be seen that CS values of beech were not affected from vacuum drying with IR heating. However, CS of Scots pine had dried with IR was much higher than that of control. Vacuum drying with IR increased the CS of Scots pine significantly. Contrary to these findings, Taskini (2007) reported that the infrared drying can reduce the strength of the spruce woods significantly. This contradiction may be explained by the ambient pressure. Drying under vacuum might eliminate the decreasing effect of IR heating. CONCLUSIONS Drying of wood is one of the most important industrial processes in wood manufacturing. Drying conditions influence the properties of wood. Effects of vacuum drying with IR heating on drying quality and mechanical properties of Scots pine and beech wood were investigated. 1) Vacuum drying with infrared heating can be used to dry Scots pine and beech, successfully. Vacuum drying decreased the drying time significantly compared to conventional drying. 2) Average MC of the Scots pine and beech after vacuum drying with IR heating for 48 hours was acceptable according to standard drying quality class. But distribution of the individual MC did not meet the requirements of the standard drying class in both Scots pine and beech. 3) Casehardening of beech was much higher than that of Scots pine after vacuum drying with IR heating. 4) Vacuum drying with IR heating increased the MOR value of beech while the MOE and CS values of beech were unaffected. It increased the MOE, MOR and CS values of the Scots pine, significantly. REFERENCES 1. ABUBAKARI A. 2010: Radio frequency heating pre-treatment of sub-alpine fir to improve kiln drying. MSc Thesis, The University of British Columbia, Vancouver. 2. AUDEBART P., TEMMAR A., HAMMOUM F., BASILICO C. 1997: Vacuum drying of oakwood :moisture, strains and drying process. Drying Technology 15(9): BRUNNER R., 1993: The choice fort he future: Timber drying by vacuum or by conventional methods. Central Timber Journal 58: CHEN Z. 1997: Primary driving force in wood vacuum drying. Ph.D. Dissertation, Virginia Polytechnic Institute and State University, Virginia. 5. DENIG J., WENGERT E.M., SIMPSON W.T. 2000: Drying hardwood lumber. Gen. Tech. Rep. FPL GTR 118. Department of Agriculture, Forest Service, Forest Products Laboratory Madison, WI: U.S. 21

22 6. HANSMANN C., STINGL R., PRIETO O.G., LOPEZ C.B., RESCH R. 2008: Highfrequency energy assisted vacuum drying of fresh eucalyptus globulus. Drying Technology 26: JOMAA W., BAIXERAS O. 1997: Discontinuous vacuum drying of oak wood: modelling and experimental investigations. Drying Technology 15(9): JUNG H.S, EOM C.D, SO B.J. 2004: Comparison of vacuum drying characteristics of Radiata pine timber using different heating methods. Drying Technology 22(5): KOUMOUTSAKOS A. 2001: Modelling radio frequency/vacuum drying of wood. Ph.D. Dissertation, The University of British Columbia, Vancouver, Canada. 10. LI X.J., ZHANG B.G., LI W.J. 2008: Microwave-vacuum drying of wood: Model formulation and verification. Drying Technology 26: MÖTTÖNEN V. 2006: Variation in drying behavior and final moisture content of wood during conventional low temperature drying and vacuum drying of betula pendula timber. Drying Technology 24: PERRE P., MOSNIER S., TURNER I.W. 2004: Vacuum drying of wood with radiative heating: I. Experimental procedure. AIChE Journal 50(1): TASKINI A. 2007: Effect of drying methods on wood strength: A comparison between microwave, infrared, and convectional drying. Mech. & Aerospace Eng. J. 3(1): TS 2474, 1976: Wood - Determination of Ultimate Strength in Static Bending. Turkish Standards Institution, Ankara. 15. TS 2478, 1976: Wood-Determination of Modulus of Elasticity in Static Bending. Turkish Standards Institution, Ankara. 16. TS 2595, 1977: Wood-Determination of Ultimate Stress In Compression Parallel to Grain. Turkish Standards Institution, Ankara. 17. TS EN, 14298, 2006: Sawn timber Assessment of drying quality. Turkish Standards Institution, Ankara. 18. TS ENV, 14464, 2005: Sawn timber Method for assessment of case hardening. Turkish Standards Institution, Ankara. Streszczenie: Wpływ suszenia próżniowego z ogrzewaniem za pomocą podczerwieni na niektóre właściwości drewna. Metoda ogrzewania w procesie suszenia drewna ma duże znaczenie dla właściwości uzyskanego produktu. Celem pracy było określenie wpływu suszenia próżniowego z ogrzewaniem za pomocą podczerwieni na niektóre właściwości drewna. Stwierdzono między innymi, że ogrzewanie za pomocą podczerwieni powoduje wzrost modułu Younga, wytrzymałości na zginanie oraz ściskanie drewna sosny oraz wytrzymałości na ściskanie drewna buka. Corresponding authors: Asst. Prof. Dr. Suat ALTUN, Asst. Prof. Dr. Fatih YAPICI, Zehra KORKMAZ Karabuk University, Technical Education Faculty 100. Yıl Karabük / TURKEY [email protected] [email protected] [email protected] 22

23 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Influence of the time between machining and assembly of mortise and tenon joints on tension strength of T-type joints IOANNIS BARBOUTIS, THEODOSIOS MELISSIDES Aristotle University of Thessaloniki, Faculty of Forestry and Natural Environment Abstract: The strength of mortise and tenon joints depends on a variety of factors. In this study, we examined the influence of the delay of the joints assembly, from the machining time of the mortise and the tenon, for months 1, 3 and 12, to the tension strength of the T-type mortise and tenon joints. We proved that the increase of assembly delay contributes to the decrease of the tension strength of the joints. The way of storage of the joints members, open in air and closed in plastic bags, also seemed to affect strength significantly. Finally, the use of D3 durability class PVAc adhesive showed higher strength values compared with the respective D1 durability class PVAc adhesive. Keywords: mortise and tenon, tension strength, T-type, middle joint, delay of assembly, PVAc. INTRODUCTION People s everyday life is intimately related to the utilization of furniture. Consequently, furniture has to satisfy functional needs in such ways as to offer safety and comfort through quality of structure and long life duration. The strength and stability of furniture highly depend on the way joints are made, i.e the way wooden parts are connected to each other. A fundamental way of connection is the mortise and tenon joint which has been widely used for centuries and continues to be used despite the development of a considerable number of variations of the basic joint (Wilczynski 2003). Regarding the mortise and tenon joint type, parts of wooden frames are joined together by the insertion of a suitably constructed wooden edge (mortise) into the respective opening of another frame piece (tenon) usually by means of an adhesive (Efe, 2005). There are various forms of this joint type such as the occult form in which the mortise ends up in the inner part of the wooden frame, the visible form where mortise continues up to the external part of the wooden frame, the double mortise and tenon joint and many others (Hill and Eckelman 1973). The manufacturer takes into consideration the dimensions of the wooden elements to be joined together, the density of the wooden material, the loadings that the construction is under and chooses the mortise and tenon joint type accordingly. A lot of investigations on mortise and tenon joints that have been conducted so far contributed considerably in the definition of factors affecting joints bending moment capacity and firmness. In 1973, Hill and Eckelman examined the bending moment capacity and firmness of the mortise-tenon joint and they evaluated the importance of the mortise length ranging from 0.5 to 2 inches with a standard 2 inches width. They also conducted experiments using different types of wood and adhesives aiming to access bending moment capacity and they found out an increase in joint stability based on shoulders formation in the mortise. In a similar study Erdil et al. (2005) concluded that the larger the dimensions (length, width, depth) of the mortise are, the higher the joint bending moment capacity gets. They also confirmed the increase in joint strength by applying adhesives on the surface of the mortise and also inside the tenon. Kamenicky (1975) studied the elasticity of this specific joint while Smardewski (2002) analyzed the loadings exerted on different parts of the mortise and tenon joint assays. 23

24 Dupont (1963) concluded that the optimum joint strength is achieved when the adhesive is applied both in the mortise and the sides of the tenon. Additionally, he found that the wooden elements about to be joined together would better be at a humidity level of 7-9%. Sparkes (1968) concluded that square-end mortise and tenons are stronger than round-end mortise and tenons although square-end joints inserted in a round-end tenon are weaker by 15%. Willard (1966) manufactured and then tested mortise and tenon joints showing that joints with compressed mortise before insertion in the tenon are not superior in firmness than the conventional mortise and tenon joints. Mihailescu (2001) used finite element methods (FEM) to obtain additional information about the bending moment capacity of mortise and tenon joints. The purpose of that study was to develop a predictive expression for mortise and tenon joints that would take into account wood species, adhesives, and joint geometry specifically, tenon depth, tenon shoulder width, and tenon length. Yang and Lin (1986a, b) found that maximum bending moment capacities were obtained with tenon/mortise fits of to inches. Tankut and Tankut (2005) also studied square and round mortise and tenon joints and they concluded that by increasing the mortise dimensions the bending moment capacity is consequently increased due to an increase of the adhesive area. An increase in bending moment capacity has been also observed after increasing the width of the wooden elements participating in the joint construction. Aman et al (2008) as well as Efe et al. (2005) proved the superiority of the traditional mortise and tenon joint against other types of this joint. The assembly of mortise and tenon joints in previous studies, following the guidelines of the European and International standards that referred to wood bonding, were made as soon as possible and not later than 24 hours after joint members cutting. In actual production conditions sometimes a significant time delay from the time of machinng of joint members to the time of bonding is detected. Researches regarding the influence of the delay of assembly to the strength of mortise and tenon joints have not been found in the literature. In the present research it was studied how time, from the moment of machining the mortise and the tenon, up to the moment of assembly them to each other, affects the tension strength of the T-type mortise and tenon joints. MATERIALS AND METHODS Experiments were carried out with unsteamed beech (Fagus sylvatica L.) solid wood originated from Greece. The material was placed in a conditioning room at 20±2 o C and 65±5% relative humidity and allowed to reach a nominal equilibrium moisture content (EMC) of 10-12%. Afterwards, in a frames factory for upholstered furniture, wood pieces were produced with a cross section 24 x 48 mm and the machining of mortise and tenon for the T- type (middle) joints samples were done. Totally, 210 couple samples of mortise and tenon were prepared and they were divided in 14 groups. The samples of 6 groups that were put into plastic bags with other 6 groups that were without any protection (open in air) remained at the factory until to assembly the T- type joints. Each T-type specimen consisted of two (2) structural members, a horizontal (the mortise) and a vertical member (the tenon). Holes of 18 mm in diameter were drilled in the vertical member of each specimen. The details of configuration and dimensions of the specimens used in the study are shown in Figure 1. The assembly of specimens were done in four different periods after machining of mortise and tenon, as follow: 1) two groups of specimens direct after machining, 2) four groups of specimens, two from open in air and two from closed in bags, one month after machining, 3) four groups of specimens, as previous, three months after machining and 4) four groups of specimens, as previous, one year after machining. 24

25 Figure 1. Configuration of the T-type specimens used to determine middle joint strength in tension Before assembling all the samples were cleaned with compressed air to remove dust and 6 ml PVAc adhesive D1 (solids 51.3%) or D3 (solids 43.2%) durability class (according to EN 204:2001 standard) were applied in every couple of mortise and tenon under cold conditions. The prepared bonded joints (15 samples for each parameter) were remained at 20 ± 2 o C and 65 ± 5 % relative humidity conditions for seven days. After that, the tensile shear strength test was carried out on a Shimadzu testing machine with a constant speed of 6 mm/min. The way of loading the samples in tension is given in Figure 2. Figure 2. Method of loading in tension the T-type joints Before assembling of the T-type joints and also after the test, samples were cut from the specimens and the density and moisture content (MC) were determined. The mean density of the beech wood was measured as g/cm 3 (s.d ) for % (s.d ) mean moisture content. In all cases the percentage of moisture content did not differ significantly. The tensile shear strength was expressed as the maximum load applied in Newtons (N). 25

26 RESULTS AND DISCUSSION Mean values of the tension strength of the tested T-type mortise and tenon joints are shown in the following Table 1 Storage Table 1. Tension strength (N) of T-type mortise and tenon joints Time from machining to assembly 0 days 1 month 3 months 1 year D1 D3 D1 D3 D1 D3 D1 D3 Open in air * (1227.2) (1240.2) (821.8) Closed in bag (1098.9) (1208.4) (722.0) (1328.2) (932.3) * Mean values of 15 samples and standard deviation in parenthesis (1078.0) (787.9) (688.8) (730.0) (860.1) (904.8) According to these results, the highest mean value of tension strength ( N) of the joints was recorded by the specimens which were assembled directly after the machining of the joint parts and the PVAc adhesive used was of D3 class, while the lowest mean value ( N) was measured in the specimens assembled one year after the machining of the joint parts and all that period had remained exposed in air conditions (open in air) and the adhesive used was that of D1 class. Obviously, the main factors that greatly affected the strength of the middle joints were the time between the machining and the assembly of the joint specimens, the durability class of the adhesive used and finally, the way that the T-type joint parts were kept (open in air/closed in bags). The increase of the storage time of the specimen parts, from the machining time of the mortise and tenon forms, up to the assembly time of the joint parts, was proved to gradually decrease the tension strength of the T-type joint. The lowest percentage of tension strength decrease (0.3%) was demonstrated by the specimens that were assembled one month after the machining of their parts, using D3 class adhesive and during this month the joint parts have been maintained closed in plastic bags. On the contrary, the highest percentage of tension strength decrease (70%) was marked by the specimens, which were assembled one year after the machining of the joint parts, using D1 class adhesive and the wooden joint parts have been maintained open in air conditions till the assembly time. In all cases, the joint specimens that were assembled one month after the machining of the parts presented lower mean tension strength values compared to the respective values of the specimens assembled directly after the machining procedure, but that difference did not seem to be statistically significant. Contrarily, the mean strength value of the specimens that were assembled one year after the parts manufacturing recorded statistically significant difference from the respective values of the specimens assembled one month after the machining and also the specimens assembled directly after the machining procedure, as well. This is attributed to the aging and inactivation of the wood surfaces that start to occur through different mechanisms immediately after their preparation (Custódio et al. 2009). Furthermore, in all cases, the joint specimens that were assembled with wooden parts that have been kept in closed plastic bags (Figure 3) resulted in higher mean strength values, than the respective values of the specimens assembled with the wooden parts that have been remained exposed in open air conditions (open in air). Although, only the specimens assembled one year after the machining procedure showed statistically significant difference from all the other joint cases. The aging of surfaces seemed to deteriorate in the presence of dust, which was difficult to be totally removed. 26

27 10000 Closed Open Closed Open N N D1 0 0 days 1 month 3 months 1 year D3 0 0 days 1 month 3 months 1 year Figure 3. Effect of method of storage the samples before gluing with PVAc class D1 and D3 on tension strength The use of D3 durability class adhesive contributed to the construction of powerful joints and specifically, showed in all cases higher mean strength values (Figure 4), than the values of the respective specimens, where D1 durability class adhesive was used. Statistically significant difference appeared only in the case of the specimens, assembled with wooden parts that have been maintained in closed bags D1 D D1 D N N A 0 0 days 1 month 3 months 1 year B 0 0 days 1 month 3 months 1 year Figure 4. Effect of glue on tension strength (N) of the (A) open in air and (B) closed in bag samples CONCLUSIONS The mortise and tenon joint is widely used in the furniture construction, in order to connect the solid wooden parts. The main conclusion, which can be drawn from the completion of this research, is that the tension strength of T-type mortise and tenon joints is strongly affected by the time that mediates from the machining of the parts, till their assembly in a stable joint, after the adhesive application. Any increase in the delay of assembly contributed to the further decrease of the tension strength of the joints. Not only time, but also the way of storage of the machined members of T-type joints till their assembly time affects the tension strength of the joints. The results of this research showed that the joints that were assembled with members kept into plastic bags, recorded higher tension strength than the joints assembled with members which had remained open in air without any protection. The tension strength of T-type joints was also affected by the durability class of the PVAc adhesive used in the assembly of the joints. The use of D3 durability class adhesive resulted in stronger joints in tension strength than the use of D1 durability class adhesive. According to these results, it could be maintained that the assembly of joints must be done directly after the machining of the joint parts. If this is not possible to happen, the 27

28 machined members of the joints must be kept clean into plastic bags, but not longer than 1 month. Finally, the use of D3 durability class adhesive seems to improve the tension strength of the joints. REFERENCES 1. AMAN R.L., WEST H.A., CORMIER D.R. 2008: An evaluation of loose tenon joint strength. Forest Products Journal. Vol. 58, No 3: CUSTÓDIO J., BROUGHTON J., CRUZ H. 2009: A review of factors influencing the durability of structural bonded joints. International Journal of Adhesion & Adhesives 29: DUPONT W. 1963: Rationalization of glued joints in the woodworking industry. Modern Holzverarbeitung. No EFE H., ZHANG J., ERDIL Y.Z., KASAL A. 2005: Moment capacity of traditional and alternative T-type end-to-side-grain furniture joints. Forest Products Journal 55(5) ERDILY.Z., KASAL A., ECKELMAN C.A. 2005: Bending moment capacity of rectangular mortise and tenon furniture joints. Forest Products Journal Vol. 55, No HILL M.D., ECKELMAN, C.A. 1973: Mortise and Tenon Joints: Flexibility and Bending Strength of Mortise and Tenon Joints. Furniture Design and Manufacturing 45(1): KAMENICKY J., 1975: The rigidity of mortise joints in furniture constructions. Drevarsky Vyskum. 20(4): MIHAILESCU T. 2001: An investigation of the performance of mortise and tenon joints using the finite element method. J. of the Institute of Wood Sci. Vol. 15, No. 5 (issue 89). 9. SMARDZEWSKI J. 2002: Strength of profile-adhesive joints. Wood Science and Technology 36: SPARKES A.J. 1968: The strength of mortise and tenon joints. Furniture Industry Res. Assoc., Maxwell Road Stevenage Hertfordshire, Great Britain. 11. TANKUT A.N., Tankut N. 2005: The Effects of Joint Forms (Shape) and Dimensions on the Strengths of Mortise and Tenon Joints. Turk J. Agric For. 29: WILCZYŃSKI A., WARMBIER K. 2003: Effect of Joint Dimensions on Strength and Stiffness of Tenon Joints. Folia Forestalia Polonica, Seria B, Zeszyt 34: WILLARD R. 1966: Compressed tenons I. Furniture Design and Manufacturing 38 (11). 14. YANG M-J., LIN T-Y. 1986a: Studies on the strength of mortise and tenon joints (I). For. Prod. Ind. 5(2): YANG M-J., LIN T-Y. 1986b. Studies on the strength of mortise and tenon joints (II). For. Prod. Ind. 5(3):

29 Streszczenie: Wpływ czasu pomiędzy obróbką a montażem na wytrzymałość na rozciąganie połączeń półkrzyżowych o złączach czopowych. Wytrzymałość połączeń czopowych zależy od wielu czynników. Celem niniejszej pracy było określenie wpływu czasu pomiędzy obróbką a montażem na wytrzymałość na rozciąganie połączeń półkrzyżowych o złączach czopowych. Wykazano, że wzrost czasu pomiędzy obróbką a montażem tych połączeń powoduje obniżenie ich wytrzymałości na rozciąganie. Corresponding authors: Associate Professor, Ioannis Barboutis Aristotle University of Thessaloniki, Faculty of Forestry and Natural Environment, Laboratory of Wood Products and Furniture Technology, Thessaloniki [email protected] Civil Engineer Frame maker, Theodosios Melissides, Thessaloniki [email protected] 29

30 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Optimization of furniture technology at design stage TOMASZ GAWROŃSKI Poznań University of Life Sciences, Department of Furniture Design Abstract: The aim of this paper is to present a conception of optimization of furniture technology that can be performed at design stage. The proposed solution allow for assessment and optimization of machining cost of a design alternative during design process. Moreover, it is possible to perform simulations of production flow to check how the introduction of new products affects the performance of the whole production system. Keywords: design to cost, furniture, optimization, technology INTRODUCTION The growing competition on globalized market make furniture companies frequently update their offer, to follow the design and technological trends and changing style of life. The new promising ideas should be quickly introduced to the market and the design stage of new products should be relatively short. Moreover, to compete with cheap mass-produced goods many companies offer make-to-order furniture that can be customized according to customer specification. This, in turn, results in high variety of parts within production plant. On the other hand, even in the case of high quality products, the price of them cannot be neglected. Unfortunately, the design to cost methodology may require much time to determine all cost drivers and to prepare the sufficient number of design alternatives before the target cost is achieved. Numerical methods may support the design to cost approach. Virtual prototypes may be tested for strength, rigidity, stability and even ergonomics using specialized computer software (Dzięgielewski and Smardzewski 1995, Smardzewski and Matwiej 2005, Smardzewski and Papuga 2004). Moreover the numerical optimization allow for automatic comparison of generated design alternatives in computer memory until the minimum of cost function is reached. There is a significant number of solution for optimization of material volume within a piece of furniture with strength and rigidity constraints (Gawroński 2005a, Kłos 2006, Smardzewski 1992). Numerical methods allow for the reduction of material cost without violation of normalized safety requirements and without affecting functionality. However, there is a lack of similar, numerical solutions dedicated for furniture industry that focus on machining cost. AIM OF PAPER The aim of this paper is to present a conception of optimization of furniture technology that can be performed at design stage. DESIGN TO COST WITH NUMERICAL METHODS The proposed cycle of preparation and assessment of a design alternative with the use of numerical optimization is presented in figure 1. Particular steps are explained below: CAD (computer aided design) preparation of 3D model of a design alternative; CAE (computer aided engineering) analysis of strength, rigidity, stability and ergonomics; optimization of material volume; 30

31 CAM (computer aided manufacturing) preparation of programs for CNC machines; OPTIMISATION optimization of technological parameters and unit times of operations; generation of optimized technological routes; ERP (enterprise resources planning) importing of optimized technological routes into computer integrated system; preliminary calculation of labor cost using ERP functionality; SIMULATION simulation of production flow based on predicted demand for existing and new products; determination of the best scheduling policy and analysis of possible tardiness; COST analysis of final cost based on simulation results, including setup cost, tardiness cost and external resources cost; MODIFICATION modification of design alternative if the target cost is not met. CAD MODIFI CATION CAE COST CAM SIMULA TION OPTIMI SATION ERP Figure 1. Proposed cycle of preparation and assessment of a design alternative with the use of numerical optimization Traditionally unit times are determined through chronometrical observation of real manufacturing process. Therefore, it is difficult to assess the labor cost at the design stage. In the optimization of technological routes unit times are determined based on optimized feed rates and tool paths (or workpiece lengths). In case of CNC machines the data on tool path is extracted form control program prepared with the use of CAM software. Then the new optimized control program is generated. The proposed decision variables, limiting conditions and objective functions of the optimization are presented in figure 2. The technological routes are generated based on optimization results and inference rules. The conception of expert system for building of technological routes in furniture industry is presented in Gawroński (2007). Simulation step is very important because it provides more information on how the introduction of new products affects the performance of the whole production system. Simulations of production flow are used in scientific research to prove the effectiveness of particular scheduling policies (Kim and Bobrowski 1994, Vinod and Sridharan 2008). The use of production flow simulation in real factory may help choose the best scheduling policy based on the expected demand. The introduction of new products usually increases the variety of manufactured parts and, therefore, it may significantly increase setup times. The use of simulation at design stage should identify such situations and determine the expected setup 31

32 cost. Moreover such simulation identifies the risk of tardiness. The simulation step provides the following metrics for performance of a whole production plant or department: Optimisation of technological routes of furniture parts Decision variables Limiting conditions Objective functions Presence of operations Machine feed capabilities Unit time Numbers of passes Motor power Energy cost Feed rates Surface quality Tool capability Figure 2. Proposed decision variables, limiting conditions and objective functions of the optimization START Generation of random orders (production plan) Generation of suborders Scheduling of orders Simulation of order flow Termination condition No Yes STOP Figure 3. Proposed simulation procedure mean flow time, mean tardiness, 32

33 maximum tardiness, percentage of tardy orders, setup time per operation, load of particular machines. Since most technological factors are optimized for particular design alternative, then, if the assumed target cost is still not reached, the redesign of product s construction should be considered. It is worth noticing that in literature the scheduling problem is considered either to be static (Artigues and Feillet 2008, Balas et al. 2008, Chen 2007) or dynamic (Kim and Bobrowski 1994, Vinod and Sridharan 2008). In static scheduling problem all jobs are known at the beginning of schedule and no more jobs arrive to the production system, until the whole schedule is finished. In dynamic scheduling job arrive to the production system continuously over time, so not all job are known at the beginning of schedule. Scheduling system in most furniture companies in neither fully static nor fully dynamic. Customers orders are collected over specified period of time and then are aggregated to form a production plan. Due to the rational resource use, the time windows of subsequent production plans do overlap. Therefore, new jobs arrive to the production system, until the schedule is finished. That is why the simulation of furniture production process requires special attention and algorithms. The simulation algorithm should iterate over significant number of overlapping production plans, first to overcome unstable condition resulting from initially empty production system and second to acquire suitable amount of data for statistical analysis. The proposed simulation procedure is presented in figure 3. EXAMPLE RESULTS The research on optimization of furniture technology are performed in the Department of Furniture Design for many years (Gawroński 2005b, 2009). The significant reduction of unit time was observed after optimization of feed rate for some operation for production of solid wood frame and panel furniture doors and drawer faces (table 1). Although these result of numerical calculation have to be verified experimentally, they look promising enough for practical applications. Table 3. Example results of optimization Operation Mean reduction of unit time [%] Rip sawing 34 4-side planing 60 CNC milling 48 The above applies also to the simulation results (figure 4). The results marked as before optimization apply to non-optimised unit times and scheduling policy that does not consider setup time. In turn after optmisation result are for optimized unit times with scheduling policy designed for reduction of setup times. The reduction of mean flow time may enable shorter completion time of orders. In turn the significant decrease of machines load make possibility for a factory to accept more customers orders without further investments and without use of external resources. 33

34 Mean flow time Before optimisation After optimisation CNC machine load Before optimisation After optimisation Figure 3. Example simulation results CONCLUSIONS 1. The numerical optimization of furniture technology at design stage can lead to the significant minimization of operation unit times, order mean flow times and machines load. 2. The efficient optimization of technology at the design stage requires seamless data exchange between optimization software and CAD/CAM/MRP systems. REFERENCES 1. ARTIGUES C., FEILLET D. 2008: A branch and bound method for the job-shop problem with sequence dependent setup times. Annals of Operations Research 159: BALAS E., SIMONETTI N., VAZACOPOULOS A. 2008: Job shop scheduling with setup times, deadlines and precedence constraints. Journal of Scheduling 11: CHEN W-J. 2007: Sequencing heuristic for scheduling jobs with dependent setups in a manufacturing system. The International Journal of Advanced Manufacturing Technology 38: DZİĘGİELEWSKI S., SMARDZEWSKI J. 1995: Komputerowa ocena i modelowanie formatek sprężynowych mebli tapicerowanych. Przemysł Drzewny 4: GAWROŃSKI T. 2005a: Multiobjective optimisation of a skeleton furniture construction. Roczniki Akademii Rolniczej w Poznaniu. Rozprawy Naukowe GAWROŃSKI T. 2005b: The concept of technological optimization of preliminary processing of furniture elements, Annals of Warsaw Agricultural University, Forestry and Wood Technology 56: GAWROŃSKI T. 2007: An expert system for building technological pathways of initial processing of furniture elements. Studies and Proceedings, Polish Association for Knowledge Management 11: GAWROŃSKI T. 2009: Technological process optimization for the pretreatment of solid wood furniture elements. Forest Products Journal 59(5): KIM S. C., BOBROWSKI P. M. 1994: Impact of sequence-dependent setup time on job shop scheduling performance. International Journal of Production Research 32(7), KŁOS R. 2006: Polioptymalizacja konstrukcji mebla skrzyniowego. Praca doktorska. Akademia Rolnicza im. Augusta Cieszkowskiego w Poznaniu. Wydział Technologii Drewna. 34

35 11. SMARDZEWSKI J., MATWIEJ Ł. 2005: Numerical models of upholstered furniture. Annals of Warsaw Agricultural University, Forest and Wood Technology 57: SMARDZEWSKI J. 1992: Numeryczna optymalizacja konstrukcji krzeseł. Przemysł Drzewny SMARDZEWSKI J., PAPUGA T. 2004: Stress distribution in angle joints of skeleton furniture. EJPAU 7(1): #05. Available Online: issue1/wood/art-05.html. 14. VINOD V., SRIDHARAN R. 2008: Dynamic job-shop scheduling with sequencedependent setup times: simulation modeling and analysis. The International Journal of Advanced Manufacturing Technology 36: Streszczenie: Optymalizacja technologii mebli na etapie projektowana. Celem pracy było przedstawienie koncepcji optymalizacji technologii mebli, która może być prowadzona na etapie projektowania. Proponowane rozwiązane pozwala na ocenę i optymalizację kosztów obróbki maszynowej poszczególnych alternatywnych wersji projektu. Ponadto, możliwe jest przeprowadzenie symulacji przepływu produkcji celem weryfikacji, w jaki sposób wprowadzenie nowych wyrobów wpłynie na funkcjonowanie systemu produkcyjnego. Corresponding author: Dr. eng. Tomasz Gawroński Poznan University of Life Sciences, Faculty of Wood Technology, Department of Furniture Design Wojska Polskiego 38/ Poznań [email protected] 35

36 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Approach to furniture design education at Purdue University EVA HAVIAROVA Purdue University, Department of Forestry and Natural Resources Abstract: This article contains a brief description of furniture design educational approach at Purdue University, Wood Research Laboratory. Aesthetic design, strength design, and design for manufacturing are presented and emphasized to student as equal components of a good design. Students are trained to understand these components and use them in synergy. Product engineering, strength design, and performance testing of furniture are essential parts of the furniture design curriculum. Performance testing is a common tool used to improve the durability and safety of furniture products and to predict failure or unexpected problems associated with the proposed construction. Students are trained that product testing and evaluation are needed to obtain safe and reliable furniture products and should provide pertinent information to designers, manufacturers and customers. Encouraged hands-on experience and rapid prototyping by CNC equipment are essential components of furniture design education, and the overall teaching method leads to meritorious student designs. Keywords: furniture design, education, strength design, performance testing, product engineering. INTRODUCTION The Wood Research Laboratory (WRL), in the Department of Forestry and Natural Resources (FNR), is responsible for teaching, research and extension in the area of wood products. WRL s mission is to: assist wood products manufacturers, develop new knowledge for wood products industry, add value to wood raw materials, develop new uses for wood residues and by-products, encourage innovation in wood and wood-based products, improve wood products engineering and processing technologies, also train experts for wood products field. Among others, WRL has pioneering contributions to wood science in product engineering, quality improvement, strength design of furniture and its performance. FNR department is offering undergraduate and graduate programs in Wood Products Manufacturing Technology and Wood Science, and a minor in Furniture Design. WRL is supporting this program with courses: Wood Products and Processing course provides insight into the many products and processes which are used to help convert round timber into industrial products and provides student with an adequate background in order to be employable by the hardwood industry. Wood Structure, Identification, and Properties students study cellular structure of native woody species, learning the identifying characteristics of commercially important wood species (color, odor, cellular arrangement, grain pattern, character marks, etc.) through laboratory exercises and field trips and study the manufacturing characteristics and uses of various species. Properties of Wood Related to Manufacturing course familiarizes the student with the basic physical, mechanical and working properties of wood and wood composites. Secondary Wood Products Manufacturing course familiarizes the student with basics of secondary hardwood products manufacturing (organization, raw materials, machinery, plant layout, production methods, machining, finishing, and industrial engineering techniques). Furniture and Cabinet Design and Manufacturing course familiarizes the student with qualitative and quantitative principles of furniture construction, performance testing of 36

37 furniture, and computer-based application and solutions. Course also features laboratory evaluation of fasteners, furniture joints and furniture. Furniture Design for CNC Manufacturing - course familiarizes the student with computer Aided Design (CAD), Computer Aided Manufacturing (CAM), CNC router operation, rapid prototyping and basics of secondary wood products manufacturing. APPROACH TO FURNITURE DESIGN Aesthetic design, strength design and design for manufacturing are presented and emphasized to the student as equal components of a good design and students are trained to understand them and use them in synergy (Fig.1). Figure 1. Approach to furniture design Furniture is often considered as a work of art while the engineering aspects of furniture, such as structural integrity, is often considered to be of secondary importance. The most important aspect of product engineering of furniture is structural design. However, aesthetic needs are often favored over the structural requirements of the products. Even though, in general, fashion sells furniture, a methodical design approach should be applied that generates structurally sound, safe, and durable furniture. Design for manufacturing is also an important aspect, especially for production of economically feasible furniture. PRODUCT ENGINEETING Product engineering is presented to student as an application of a systematic, disciplined, quantifiable approach to design of furniture structures. Attributes the designer should emphasized in the process of product creation include: strive to create furniture pieces which are fashionable, esthetically pleasing, economically feasible, functional, ergonomically correct, easy to produce with short lead time, and should apply feasible materials and joinery in order to create structurally sound product providing safe and reliable service. Product designer should know: properties of materials used for product, loads applied in service, rational design of joints in order to carry the service loads, how to determine the most suitable fasteners, joints connecting systems and their allowable stresses. A Seven-step Product Engineering Design Process (Fig. 2) by Carl A. Eckelman (2003) is applied to the product development process. Steps are: determine service loads; evaluate the material properties and determine the member and joint parameters; analyze the structure by finite element analysis tools; repeat steps 2&3 if any members or joints are under or over stressed; construct 1/1 prototypes; conduct performance tests to simulate service action; redesign if necessary; perform joint strength tests on joint extracted from prototypes. 37

38 Figure 2. Seven-step product engineering design process Strength testing of newly developed products (Fig. 3). This method has history and is based on accumulative damage theory (Fig. 4); it best simulates user service actions, has consistently accurate range, and sensitivity and number of cycles can be controlled. This type of testing is not for sale purpose, but it is testing for product engineering and research. Load (lbs) strength First Crossing Cycles (thousands) Figure 3. First-crossing concept of failure Load (lbs) strength Cycles (thousands) Figure 4. Cyclic stepped increasing load method WRL performance testing laboratory with its modular equipment allows students to observe, learn and develop structurally sound prototypes (Fig. 5). 38

39 Figure 5. WRL performance testing laboratory Student hands-on experience is encouraged though the laboratory exercises, club work and work on individual furniture projects (Fig. 6). Figure 6. Students are involved on variety of projects 39

40 Students are encouraged to submit their work for student exhibits and contests. The program has been recognized by numerous meritorious students design projects. Examples are presented in Fig. 7a-d. Figure 7a - d. Meritorious students designs 40

41 SYNERGY BETWEEN TEACHING AND RESEARCH Students are also involved in ongoing research projects conducted in WRL. Best example is the product development and investigation of manufacturing capabilities for Emerging Furniture Design Challenges: Plus-size Furniture, Adjustable Furniture, Customized Furniture, Sustainable Concepts and LCA Analysis (Fig. 8a-d). Figure 8a-d. Research projects 41

42 School furniture for the underprivileged children is a special project where involvement of graduate student was demonstrated in areas of product development and manufacturing system analysis. Undergraduate students were involved in a pilot project where they helped with building of school furniture manufacturing facility and conducted the production feasibility study (Fig. 9a-d). Figure 9a-d. School Furniture for developing countries project CONCLUSIONS In conclusion, an integration of aesthetic design, strength design, and design for manufacturing as an educational approach for furniture design education at Purdue is a challenging yet successful approach for training design students. Product engineering, strength design, and performance testing of furniture are essential parts of the furniture design curriculum. Performance testing is a useful learning tool which provides the last feedback in the furniture engineering process before furniture goes into service, and therefore, provides the last opportunity for increasing the quality and reliability of furniture. Students are trained that product testing and evaluation are needed to obtain safe and reliable furniture products and should provide pertinent information to designers, manufacturers and customers. Hands on experience approach is attracting young designers, rapid prototyping by CNC equipment is essential, and is leading to meritorious student designs. 42

43 REFERENCES 1. ECKELMANN, C. A. 1988: Performance Testing of Furniture. Part 1. Underlying Concepts. Forest Products Journal 38(3): ECKELMAN, C. A. 1968: Furniture Frame Analysis and Design. Ph.D. Thesis, Purdue University, West Lafayette, Indiana. 231 pp. 3. ECKELMAN, C.A. 1985: Performance test method for intensive use task chairs. FNEW D. Washington, D. C. 4. General Services of Administration, 1981: Upholstered Furniture Test Method. FNAE Washington, D. C Strzeszczenie: Podejście do edukacji w zakresie projektowania na Purdue University. Artykuł stanowi krótki opis stosowanego przez Wood Research Laboratory, Purdue University podejścia odnośnie edukacji w zakresie projektowania mebli. Równocennymi komponenty dobrego projektu, na które pokłada się nacisk w nauczaniu studentów są estetyka, wytrzymałość i technologiczność konstrukcji. Ważnym czynnikiem jest również szybkie prototypowanie projektowanych konstrukcji przy użyciu obrabiarek CNC. Corresponding author: Dr. Eva Haviarova 175 Marsteller Str. West Lafayette, IN U.S. 43

44 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Correlation between bending and tension strength of corner and middle joints constructed with beech and poplar wood VASILIKI KAMPERIDOU, IOANNIS BARBOUTIS AND VASSILIOS VASSILIOU Aristotle University of Thessaloniki, Faculty of Forestry and Natural Environment Abstract: This study was carried out to evaluate the strength of the three most frequent joints in the upholstered furniture frames, made of beech and poplar solid wood. The research included the following joints: Mortise and Tenon, double Dowel and double Gusset Plates, which were constructed and tested both in corner and middle joints. In the corner joints we examined the compression strength of the joints and in the middle joints the tension strength was thoroughly investigated. The results of the bending (compression) test indicated that bending strength values of the four different joints were strongly correlated to tension strength values of the corresponding joints, whether they were constructed with beech or poplar wood. Also, a correlation was noticed between the bending strength values of the joints constructed with beech and the bending strength values of the respective joints made of poplar wood. Relative to tension strength values, a strong relationship was also recorded between the beech wood joints and the poplar ones. Based on these results, it is concluded that the tension strength value of these joints could be sufficiently estimated by the measured bending strength value of the corresponding joints. Furthermore, the calculation of bending or tension strength of each of these three joints constructed with poplar wood gives the opportunity to calculate automatically and quite precisely, the corresponding strength value of the same joint constructed with beech wood. Keywords: Bending strength, corner joint, Dowel, middle joint, Gusset, Mortise and Tenon, tension strength INTRODUCTION The upholstered furniture contributes greatly to the human needs and also represents an integral part of the human every-day life. The strength and stability of this type of furniture depend mainly on the strength and stability of its joints (Eckelman 2003). There is a high interest in the research of the strength of the wooden frame and particularly the strength of the joints of this furniture. This study deals with the investigation of the strength of the three most substantial and frequent corner and middle joints of the upholstered furniture, which are: Mortise and Tenon joint, double Dowel joint and the double Gusset Plates joint. The Mortise and Tenon joint and the double Dowel joint represent two main and traditional types of joints of upholstered and other sorts of furniture, which have been studied by many researchers, while the strength and the mechanical behavior of the double Gusset Plates joint have not been thoroughly studied so far and is relatively innovative type of connection in furniture. Previous research refer mainly to bending strength of these joints (Hill and Eckelman 1973, Paulenkova 1984, Smardzewski 2002, Tankut 2007, Zhang and Eckelman 1993 etc.) and tension strength (Zhang et al. 2003, Eckelman et al etc.). Wood species used in previous studies referring to the investigation of these specific joints strength were mainly poplar (Hill and Eckelman 1973, Erdil et al etc.) and, in less extent, beech wood (Kamenicky 1975 etc.). The present research aims to provide information concerning the correlation between the bending strength of the three different corner joints and the tension strength of the respective middle joints, in cases when the joints were constructed either with beech or poplar wood. Additionally, the correlation of bending or tension strength values of beech wood joints to the respective values of poplar ones is investigated. 44

45 MATERIALS AND METHODS Experiments were carried out with beech wood (Fagus sylvatica) and poplar wood (Populus sp.), both of Greek origin and naturally desiccated for one year. Half of the samples were constructed in corner form (L-shape), and the rest in middle form (T-shape). The corner joint samples were tested in compression (Bending Capacity), and the middle joint samples were tested in tension (Tension strength). The configuration of the tested joints is shown in the following Figures (Fig.1-2). Figure 1. Dowel corner joint (A), Mortise - Tenon corner joint (B), Gusset Plates corner joint (C) Figure 2. Dowel middle joint (A), Mortise - Tenon middle joint (B), Gusset Plates middle joint (C) All the specimens consisted of two wooden parts, the horizontal and the vertical one. The samples for the bending strength were constructed in dimensions as follow: 150 mm length x 50mm width x 25mm thickness for the horizontal parts, while the dimensions of the vertical parts were 125mm length x 50mm width x 25mm thickness. These dimensions refer to corner and also middle forms of specimen and are based on the pre-existent research, because of lack of particular international standards on the method of the examination of strength of corner and middle joints. Concerning the double Dowel joint, it must be mentioned that the dimensions of the dowel were: 40mm length x 12mm in diameter and the space between the two dowels was 13mm. In the construction of the Mortise and Tenon joint it was determined to maintain the contact between the mortise and tenon only in the two surfaces of the mortise, because the mortise cut is semi-cylindrical, whereas the tenon has square cut. On the part of the construction of the double Gusset Plates joint, two wooden gusset plates were used alongside the connection place and each gusset plate was stabilized with the help of two staples. For every joint 10 specimens were tested. By using two forms of joints (corner and middle joint), three different types of joints (double dowel, mortise and tenon, double gusset plates) and two different wood species (beech and poplar wood), a total of 120 specimens were prepared. After their construction, the specimens were placed into a conditioned room at 20±2 o C temperature and 65±5% relative humidity and were allowed to reach a nominal equilibrium moisture content (EMC) of 10%. At the moment of the tests, the mean density of the beech 45

46 wood was measured as g/cm 3 and of the poplar wood g/cm 3, for 9.55 % mean moisture content for the beech wood and 9.29 % for the poplar wood. All the tests were carried out on a Universal Testing Machine (SHIMADZU UH- 300kNA), and the rate of crosshead-movement was adjusted at 8 mm/min, so that the maximum load was reached within 1.5±0.5 min throughout the test. The loading continued until a break of the joint occurred (Figures 4 and 5). The Maximum bending and tension rupture load was measured and expressed in Newton (N). Figure 3. Loading in compression of the corner joint specimens (A), Loading in tension of the middle joint specimens (B) RESULTS AND DISCUSSION The results of the bending strength tested are indicated in the table 1. Joint Type Table 1 Mean values of Bending and Tension strength of the joints Wood Species Maximum bending rupture load (Ν) Stand. Deviation s Maximum tension rupture load (Ν) Stand. Deviation s Double Dowel Beech Poplar Mortise and Beech Tenon Poplar Double Gusset Beech Plates Poplar As can easily be noticed, all the joints constructed with poplar wood resulted in lower strength values, compared to the respective joints constructed with beech wood, whether in bending or tension strength test. Additionally, there is an obvious relationship between the bending strength values of corner joints and the tension strength values of the respective middle joints, in both of the cases of beech and poplar wood. Statistical analysis of the covariance between the two strength properties values showed that these two are strongly correlated each other (table 2). That means that the bending strength (Y) of corner joints could be sufficiently estimated by 46

47 the corresponding measured tension strength (X) values of the respective middle joints whether they were constructed with beech or poplar wood. Table 2 Equations of covariance between bending strength (Y) and tension strength values of joints (X) Joint Type Wood Species Equation Correlation coefficient (r 2 ) Double Dowel Mortise and Tenon Double Gusset Plates Beech Y= X Poplar Y= X Beech Y= X Poplar Y= X Beech Y= X Poplar Y= X All joints Both species Y= X There is also a correlation between the bending strength values of beech wood and the respective values of poplar wood joints (table 3). That means that the bending strength values (Y) of these three different joints constructed with beech wood, could be sufficiently estimated by the corresponding measured bending strength values of the same joints constructed with poplar wood. Table 3 Equations of covariance between bending strength of beech wood joints (Y) and bending strength of poplar wood joints (X) Joint Type Equation Correlation coefficient (r 2 ) Double Dowel Y= X Mortise and Tenon Y= X Double Gusset Plates Y= X The corresponding correlation coefficient (r 2 ) ranged from up to 0.906, so the accuracy of the estimation appeared to be quite high. In figure 4(A), where the equations of covariance between the bending strength values of beech wood joints and the respective values of poplar wood joints are pictured, it is quite remarkable the fact that the straight lines are almost parallel, which means that all the equations can be represented by only one equation, the following one: Y = A X where Y is the bending strength value of beech wood joint, X is the bending strength value of the poplar wood joint, is the mean value of the three respective values of the three individual equations, corresponding to the slope of the equation, and finally, A is a value that varies for each joint and specifically, as it concerns the bending strength, A proved to be 334 for the double Dowel joint, 672 for the Mortise and Tenon joint and finally, 57 for the Gusset Plates joint. This general equation and the known for each joint variable A, as well, give the opportunity to accurately estimate the bending strength of each of these three beech wood joints from the respective value of the corresponding poplar wood joint and vice versa. Table 4 Equations of covariance between tension strength of beech wood joints (Y) and tension strength of poplar wood joints (X) Joint Type Equation Correlation coefficient (r 2 ) Double Dowel Y= X Mortise and Tenon Y= X Double Gusset Plates Y= X

48 According to the table 4, a strong correlation was also detected between the tension strength values of beech wood and the respective values of poplar wood joints. Therefore, the tension strength values (Y) of these three different joints constructed with beech wood, could be sufficiently estimated by the corresponding measured tension strength values of the same joints constructed with poplar wood. The corresponding correlation coefficient (r 2 ) ranged from up to 0.950, so the accuracy of the estimation appeared to be quite high. Figure 4. Equations of covariance between values of beech wood joints and values of poplar wood joints in bending (A) and tension (B) strength Similarly to bending strength, the equations of covariance between the tension strength values of beech wood joints and the respective values of poplar wood joints also, tend to be parallel (figure 4B), which means that all the equations can be represented by only one equation, the following one: Y = A X where Y is the tension strength value of beech wood joint, X is the tension strength value of the poplar wood joint, is the mean value of the respective values of the three individual equations, and A value, referring to tension strength, proved to be 1083 for the double Dowel joint, 2699 for the Mortise and Tenon joint and finally, 119 for the Gusset Plates joint. Therefore, this equation provides the opportunity to accurately estimate the tension strength of each of these three beech wood joints from the respective value of the corresponding poplar wood joint. The equations of covariance between values of beech wood joints and the respective poplar wood joints in bending and tension strength that were previously presented, as can easily be noticed, are almost similar, so one equation would be sufficient to cover both cases of bending and tension strength. Additionally, the A values used in the equations of each of the three joints tension strength, taking into account the standard deviation of mean strength values, proved to be almost threefold to the respective A values used in the bending strength equations and therefore, this relation can be sufficiently used for accurate estimations concerning either of them. CONCLUSIONS The investigation of the strength of three substantial and most frequent corner and middle joints of the upholstered furniture (Mortise and Tenon joint, double Dowel joint and double Gusset Plates joint) was accomplished in this research. Based on the results of this current project, it is concluded that the tension strength value of these three middle joints could be sufficiently estimated by the measured bending strength value of the corresponding corner joints. Furthermore, the calculation of bending or tension strength of each of these three joints 48

49 constructed with poplar wood gives one the opportunity to calculate easily and quite precisely, the corresponding strength value of the same joint constructed with beech wood. In this study, a general equation which provides the opportunity to calculate automatically the bending or the tension strength of beech wood joints, independently of the joint form, from the respective values of poplar wood joints and vice versa, was also discovered. All in all, the structure and the physical properties of wood species, used in the joints construction were proved to be the most significant factors that affect the correlation extent between the joint strength values and the general behavior of them, independently of the joint type and the kind of load. According to the results, it could be claimed that there might also be a correlation between the bending strength and tension strength value in the cases of the above studied joints, even if these joints were constructed with several other wood species, apart from beech and poplar. So, it would be very interesting and helpful, mainly for manufacturers, to expand and deepen the research on the strength properties correlation of these and several other joints, constructed with different wood species, so that they would be able to comprehend and calculate accurately the joints strength and behavior and therefore, to construct even stronger joints and wooden structures. REFERENCES 1. Eckelman C.A. 2003: Textbook of Product Engineering and Strength Design of Furniture. Chapter I. Introduction to Engineering Design. Pardue University. 2. ECKELMAN C., HAVIAROVA E., TANKUT A., DENIZLI N., AKCAY H., ERDIL Y Withdrawal capacity of pinned and unpinned round mortise and tenon furniture Joints. Forest Prod. J. 54(12): Erdil Y.Z., Kasal A., Eckelman C.A. 2005: Bending moment capacity of rectangular mortise and tenon furniture joints. Forest Products Journal 55(12): Hill M.D., eckelman C.A. 1973: Furniture Engineering Flexibility and bending strength of mortise and tenon joints. Furniture Design and Manufacturing 45(1): Kamenicky J. 1975: The rigidity of mortise joints in furniture constructions. Drevarsky Vyskum. 20(4): (in German). 6. Paulenkova M. 1984: Evaluation of the strength properties of mortise and tenon and dowel joints on cabinet bottom frames. Drevarsky Vyskum 29(2): (in Slovak). 7. Smardzewski J. 2002: Strength of profile-adhesive joints. Wood Science and Technology 36: Tankut N. 2007: The effect of adhesive type and bond line thickness on the strength of mortise and tenon joints. Elsevier, International Journal of Adhesion & Adhesives 27(6): Zhang J.L., Eckelman C.A. 1993: The bending moment resistance of single-dowel corner joints in case construction. Forest Products Journal. 43(6) Zhang J.L., Li G., Sellers T.J. 2003: Withdrawal and bending performance of dowel joints in furniture-grade pine plywood. Forest Products Journal. 53(7-8):

50 Streszczenie: Korelacja pomiędzy wytrzymałością na zginanie i rozciąganie połączeń kątowych i półkrzyżowych ściennych z drewna buka i topoli. Praca miała na celu określenie wytrzymałości 3 najbardziej popularnych złączy w stelażach mebli tapicerowanych z drewna litego buka i topoli. Do tych złączy zaliczono złącze czopowe, dwukołkowe oraz złącze z podwójnymi nakładkami (Gusset Plates). Wykazano, że niektóre badane połączenia charakteryzują się wysoką korelacją pomiędzy wytrzymałością na zginanie a wytrzymałością na rozciąganie. Corresponding authors: PhD Candidate Vasiliki Kamperidou, Associate Professor, Ioannis Barboutis, Professor, Vassilios Vassileiou Aristotle University of Thessaloniki, Faculty of Forestry and Natural Environment, Laboratory of Wood Products and Furniture Technology Thessaloniki [email protected] [email protected] [email protected] 50

51 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Experimental testing of cam fittings ADAM KOŘENÝ, MILAN ŠIMEK Mendel University in Brno, Faculty of Forestry and Wood Technology, Department of Furniture Design and Habitation Abstract: The experimental testing of knock down fittings in furniture corner joints is the objective of this paper. Combination of cam fitting and non glued dowels has been used in a joint. Therefore this work deals with the effect of different joint type and different dowel spacing. A testing jig was developed for an experiment. The jig is useable for L type joint bending test in compression and tension. Bending strength of corner joints was tested on specimens 380 mm long which were manufactured out of laminated particle board. Tested fittings were Häfele Minifix and Rondorfix eccentric cams. These were combined with non-glued wooden dowels (always 2 pieces). As a result a comparison of influence of dowel spacing and joint type on corner joints strength is described. Keywords: Cam fitting, knock down furniture, mechanical properties, bending strength, joints, testing INTRODUCTION Dismountable joints are widely used in many furniture applications. Those insert fittings are commonly used in dismountable furniture, mainly for its quick assembly on site at the end customer. Even lot of joints tests were made, by many researchers and limited information from manufacturers is available problem of joint strength is still actual. (Barboutis et al. 2006) According to Eckelman (1993) and Joscak (1999), joint is the weakest point of a carcass construction. Except of an influence on construction strength and stiffness there is also economic reason. In a joint should be used sufficient amount of a fitting to make furniture reliable and safe. On the other hand, there is no reason to use more joints than necessary. Key to sufficient mechanical and economical properties is usually combination of expensive knock down fitting with cheap wooden dowels. Important studies which gave overview about area of joint testing and possible testing methods were made by authors Eckelman, Smardzewski and Joscak. Related work by Eckelman was an experimental testing of a dowel joints spacing in a particle board. One of result of given paper is, that maximum bending moment is increasing with number of dowels in the joint. On the other hand with increasing number of dowels their failure zones become to overlap each other and moment per dowel is decreasing. He states, that maximum dowel joint strength is available, when spacing between dowels is at least 76.2 mm (3 inches). There is the lowest risk of failure zones overlapping. He also found a difference in material influence for compression and tension test. Compression has higher importance internal bonding strength of the board. For tension is more important surface tensile strength of the board (Eckelman, 1993). According to Joscak (1999) with increasing distance of dowels a joint strength increases. This dependence was tested up to a distance 96 mm. He also describes a failure area around the dowel similar to the Eckelman. He states, that failure zone width for 8 mm dowel 14 mm deep in the face member has width of the failure zone 57 mm. Smardzewski described joints by finite element analysis. He analyzed furniture joint combined of wooden dowel and eccentric fitting. He found out, that loads are transferred primarily by wooden dowel. In case of connector which use screw than has this one higher importance. (Smardzewski, 2002). Our study was focused only on fittings strength. According 51

52 to Tankut 2009 edgebanding is incerasing joint strength. In this study edgebanding wasn t point of interest, even this construction element could rainforce the construction. RESEARCH OBJECTIVE Objective of research was experimental testing of corner joints with focus on dependences of joints positioning and fitting type. Dismountable joints are used for knock down furniture, usually in combination with non-glued dowels. The experiment was segmented in two main parts. Initial experiments were quite widespread. This approach allowed determination of a risk group of joints for second part of an experiment. Area of our interest was strength of joints with different spacing of dowels. Initial hypotheses were confirmed: compression load is more dangerous than tension and that influence of fitting spacing is crucial. MATERIAL In first part were tested more groups of joints, but in each group were only 3 specimens. Those reference groups were evaluated and following tests were focused on most important groups. In the second part, main focus was on a compression load and specimens connected with cam and dowel. For determination of specimen load is used terminology compression and tension. There is no standard for given test, so method of testing is made in way that is commonly used by other researchers. Our approach is inspired by Eckelman and Joscak. When furniture carcass is stressed by bending moment, either tension and/or compression occurs (Figure 4). General name for given loads is bending in angle plane. Testing equipment For testing it has been developed a jig which is able to cope with both compression and tension loads. Main parts are: base plate with a groove, 2 pieces of carrier for specimen length 150 mm, 2 pieces of carrier for specimen length 380 mm, push beam with mortise mm long. All parts are made out of steel class In the middle of plates and beam is always a groove 1 mm deep with 120 inner angle. Each specimen consists of two main parts. Length of the inset arm is 132 mm, length of the onset arm is 150 mm. Total length of both sides is 150 mm. Specimens were tested in length 150 mm and 380 mm. Eight specimen types were used in the 1 st part of the experiment. Those were used for confirmation of jig functionaliy. It was also necessary to determinate differences between joint legth, joint type and load type. Eight specimen types were used in 2 nd part were 380 mm long and differences were in fitting type and dowel position. Fittings Selected fittings are cam type. Häfele Minifix 15 (Figure 1) and Häfele Rondorfix (Figure 2). Those two types represent most common cam fittings for knock down furniture. Häfele Minifix connector housing new desingn for 18mm thickness type. Combined with thread in dowel Minifix connecting bolt bolt head 7 mm, screw length 11 mm. Häfele Rondorfix universal for board thickness from 16 mm. Combined with Rondorfix connecting bold for pre-drilled hole ø 5 mm. 52

53 Figure 1. Minifix cam fitting and dowel Figure 2. Rondorfix cam fitting and dowel As an aditional connector to both cam fittings was used beech dowel ø 8 x 35 mm with straight roughing. Specimen types and construction In the major part of the experiment were used 380 mm long specimens (figure 3) of 8 different types, loaded only in compression. Each type of specimen was manufactured in 22 pieces. All of the pieces were manufactured on CNC machine. All parts were formated on its outline and than drilled. For tightening of cam fitting was used torsion moment of 6 Nm for Minifix and 5 Nm for Rondorfix. Tightening for screw-in bolt was set on 4 Nm for booth. Specimen types are specified in the table I. Figure 3. Specimen construction and dowel spacing. S dowel spacing [mm] Table I. Specimens by drilling type Length 380, Compression Minifix [pcs] Rondorfix [pcs] Dowel spacing 310 mm (155 mm from specimen center) Dowel spacing 240 mm (120 mm from specimen centre) Dowel spacing 160 mm (80 mm from specimen centre) Dowel spacing 80 mm (40 mm from specimen centre)

54 METHODS Principle of experiment Determination of maximum joint bending strength which cause its failure in angular plane. This type of load could be classified as a compression or tension. For testing was used universal testing machine Zwick. Setup of testing machine Preload 10 N; preload speed 10 mm/min; pressure speed 10 mm/min; data sampling: 0,1s (approximately samples per specimen) Compression speed has been set to time of filure 90 s ± 30 s. Tension in the specimen is not able to balance, but it is possible to determinate deformation smoothly. Testing has started by 10N force for preload of the specimen. Due to this we are able to figure out position of measurement tools. After preload and measuring setup test is started. After maximum load is test finished. Raw data from testing machine were recalculated to the from of bending moment. : Figure 4. Compression and tension in carcass construction Figure 5. Calculation schema Bending moment was calculated according to this expression: Where M bending moment [N m], r arm of loading force [m], R reaction force [N] RESEARCH RESULTS In the figures 6 11 are available test results of all specimen types which we are focusing on. Graphs in figures 6 and 7 were created by regress analysis with function High precision polynomical order 20 and shows values of displacement (X axis) on moment (Y axis). Moment was calculated from force multiplied by arm distance (Formula 1). Calculation has been done with dynamic change of arm length during sample displacement by the schema in figure 5. Best results by regression analysis for Minifix are reached by the spacing 160 mm and 240 mm. Dowel which are too close or too far don t give enough support to the cam fitting. Minifix specimens with dowel spacing 320 mm, 240 mm and 160 mm are very close up to the value of 8 N m. In figures 6 and 7 only small difference is visible and order of regression (1) 54

55 curves is 320 mm, 240 mm and 160 mm. On the edge of 8 N m occurs influence of dowel spacing and best results at the end of a test are given by distances 240 mm and 160 mm. Worst result in connection with booth fittings have got spacing of 80 mm. Dowels were to close and failure zones were overlapped. Main failure was visible in a face member joint, where board failed in the middle layer. This crack was visible around all connector positions. Worse result of 320 mm spacing is probably caused by too high distance of members which are than acting as separate dowels which is decreasing final stiffness. At Rondorfix fitting are results similar to the Minifix. Differences between different spacing aren t so crucial as for Minifix, but also here has spacing 80 mm worst result. Important is an influence of a fitting on a joint stiffness which reaches better values in comparison with Minifix. In a box plots we can see that Rondorfix fitting (Figure 9) cause more equalized values for all types of specimens, even dispersion of specimens values is higher than in case of Minifix (Figure 8). By ANOVA analysis is statistically significant only difference between dowel spacing 80 mm and 160 mm with Minifix (Figure 10). For Rondorfix, there are no statistically important differences (Figure 11). This could be caused by sturdy construction of fitting and larger diameter of the eccentric part. T-test also showed, that important is difference between 80 mm spacing with use of Minifix and Rondorfix. This could confirm that Rondorfix construction has higher influence on the joint than Minifix. Figure 6. Regression analysis graph of fitting Minifix in combination with different dowel spacing 55

56 Figure 7. Regression analysis graph of fitting Rondorfix in combination with different dowel spacing Figure 8. Boxplot graph of fitting Minifix with different dowel spacing 56

57 Figure 9. Boxplot graph of fitting Rondorfix with different dowel spacing Figure 10. ANOVA graph of fitting Minifix with different dowel spacing 57

58 Figure 11. ANOVA graph of fitting Rondorfix with different dowel spacing CONCLUSIONS Lower load compression capacity of tested joints was confirmed in the first part of the study. Tested specimens were ordered as follows glued dowels, non-glued dowels with cam fitting, non-glued dowels. Given ordering confirmed initial hypothesis which deals with basic order of joint stiffnes. From initial study was clear, that testing in the compression will be more important. Major part of experiment was focused on Minifix and Rondorfix fitting combined with different dowel spacing. Main results of a study are: - statistically tight difference is only between spacing 80 mm and 160 mm; - Minifix joint combination demontrates slightly lower stiffness than Rondorfix; - between specimens with use of Rondorfix are no statistically important differences; - dowels that are placed too close to the conector cause lower stiffness of the joint; - optimal dowel spacing is 160 mm 240 mm; Acknowledgement: Authors of this paper would like to thank to the research project Information system for support research, innovation, product development and furniture quality - MPO ČR FR- TI1/050 for a provided support. REFERENCES 1. BARBOUTIS I., Vassiliou v. 2006: Expression Problems of Screw Withdrawal Capacity Used in Furniture Eccentric joints, International Conference of Nábytok ECKELMAN C. A. 2003: Textbook of Product Engineering and Strength Design of Furniture, Purdue University Press, West Lafayette. 3. HÄFELE 2010: Der Grose Häfele, Häfele GmbH & Co KG, Nagold. 4. JOŠČÁK P. 1999: Pevnostné navrhovanie nábytku. DF, TU vo Zvolene, 246 pp. 58

59 5. SMARDZEWSKI J., PREKRAT S. 2002: Stress Distribution In Disconnected Furniture Joints, Electronic Journal of Polish Agricultural Universities, Wood Technology, 5(2). 6. TANKUT A. N., TANKUT N. 2010: Evaluation the effects of edge banding type and thickness on the strength of corner joints in case-type furniture, Materials and Design 31: ZHANG J., ECKELMAN C. A. 1993: Rational design of multi-dowel corner joints in case furniture. Forest Product Journal 43 (11/12): Streszczenie: Badania eksperymentalne złączy mimośrodowych. Celem pracy były badania eksperymentalne połączeń kątowych ściennych o złączach mimośrodowych. Rozpatrywano wpływ typu łącznika oraz odległości kołków ustalających na wytrzymałość na zginanie połączenia. Wykazano, że zbyt bliskie położenie kołka ustalającego w stosunku do głównego łącznika powoduje niską sztywność połączenia. Corresponding authors: Adam Koreny, Milan Simek Ph.D., Mendel University in Brno, Faculty of Forestry and Wood Technology, Department of Furniture Design and Habitation Zemedelska 3, Brno [email protected] [email protected] 59

60 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Optimization of furniture testing SILVANA PREKRAT 1, STJEPAN PERVAN 1, JERZY SMARDZEWSKI 2 1) Faculty of Forestry, Department of Wood Technology, University of Zagreb, Zagreb, Croatia 2) Faculty of Wood technology, Department of Furniture Design, Poznan University of Life Sciences, Poznan, Poland Abstract: In the area of sitting furniture testing there are different standards existing that define minimal quality range. These kind of testing are long lasting and expensive. The intention is optimisation and shortening of testing time (and decrease of expenses) for standard chairs in production. Research object in this paper was standard joint consisting of round tenon and mortise. Also there were two modified tenon joints made. Joints were statically and dynamically tested. Results of static and dynamic testing are given in form of load momentum. High coefficient of correlation of all sample groups shows strong dependence between static and dynamic testing of samples. From results of three samples testing it can be concluded that there is possibility for decreasing expenses for quality determination especially those related to durability of construction (replacement of dynamic testing with static testing). Keywords: Optimisation, wooden joints, furniture quality, furniture testing INTRODUCTION Until the second part of last century scientific approach to construction were not known. Construction method choice depended on a skill and experience of the craftsman. With mass production of furniture, need for scientific approach in design appeared, which enabled a production with extensive use of machines and constant technological improvement of process. Further development has been achieved with introduction of new wooden based and non-wooden based materials with previously unknown characteristics. At beginning, the scientific approach was introduced very often in construction industry and construction of buildings. After that, number of research studies on constructions of furniture, its parts or joints showed an significant increase in the use of this approach in that area. New trends in design have implemented the use of new materials and technologies that have been constantly developed. This development encouraged constructors for introducing of new construction solutions. Suitable choice of construction assembly is very complex and its final choice depend on various influencing factors. At the beginning selection is determined by formative and functional solution set by a designer. Following step is developing of constructional solution. Choosing quality range possibility of results in various range of product diverting in price classes. Those classes determine material choice for furniture production, also taking in consideration conformation of chosen wooden and non-wooden material to the standards defining furniture quality. Standards include functionality, durability, surface resistance and quality of the material, as well as precision range in production. The classification of products in price classes enables choice of different materials for products intended for same purposes. This choice will depend on a price of a final product intended for certain market. Technology chosen for the production of a design defines the choice of constructional solution. Construction development highlights differences between almost same constructional solutions from the time of manufacture production process compared to nowadays production. At the same time new technologies of production offer a possibility of multiply repeated high quality production of both joinery and whole product. 60

61 Besides different studies of types of joints and their geometry, some authors, Dziegielewski and Zenkteler (1975), Korzenniowski (1984), Biniek and Smardzewski (1987), Dziegielewski (1991,), Wang and Juang (1994), also observed different criteria that influenced the quality of constructions. Mostly the criteria have been related to the joint material properties, the way and precision of its production, conditions during production, types and properties of adhesives and bindings used. RESEARCH OBJECTIVE In the area of sitting furniture testing there are different standards existing that define minimal quality range. In Croatia exist standards for classification of furniture quality, and for adequate construction, dynamic durability is especially important and it is described in standard HRN D.E According to this standard three equal samples from regular production must be tested. Quality level is classified depending of number of achieved cycles in three classes: 5000, and of cycles. These kind of testing are long lasting and expensive. The intention is optimisation and shortening of testing time (and decrease of expenses) for standard chairs in production. Critical area is connection between chair leg and frame (figure 1). Durability testing is performed until dowel pulling out or connection rupture (figure 2). Figure 1 Chair, leg and frame connection Figure 2 Pulling out and rupture caused by load 61

62 MATERIAL AND METHODS Research object in this paper was standard joint consisting of round tenon and mortise. Also there were two modified tenon joints made. Samples were grouped in three groups: A, B and C. Croatian seating furniture testing method HRN D.E2.201 for determination of strength and durability was evaluated in this paper. According to previous work of Prekrat at al. (2004) joint elements were chair leg (cross section 42 x 28 mm) and chair frame (cross section 50 x 20 mm). Joints were statically and dynamically tested. Dynamic tested was performed in eight stages, according to force in cylinder and air pressure. Force is calculated by measurement at certain air pressure (table 1). Table 1 Stages for dynamic testing, air pressure and cylinder force Air pressure (bar) Cylinder force (N) Eckelman and Hiencz (1977), Dziegielewski et al (1983), Zhang and Eckelman (1993), Warmbier (1997) and Prekrat (2000) evaluated different methods of static and dynamic testing, compared them and proved dependence between methods of static and dynamic testing. Dziegielewski and Giemza (1983) researched dependence of static and dynamic coefficient where forces were at 80%, 60% and 40% level of static testing. The result is shown at figure 3. Number of cycles Figure 3 Relation between dynamic load coefficient and number of dynamic loads cycles according to Dziegielewski RESEARCH RESULTS Results of static and dynamic testing are given in form of load momentum. Range evaluation was done at figure 4. Statically tested samples were statistically tested according Kruskall-Wallis test, and it showed difference between different sample groups results (table 2). 62

63 Figure 4 Static MOR for all sample groups Table 2 Results of Kruskall Wallis test Pairs of tested groups P B C A C A B Equally, the results were confirmed for all tested sample groups in dynamic testing. Relationship is presented with coefficient, which is quotient between static and dynamic momentum (table 3). Table 3 Relationship between static and dynamic momentum coefficient for all tested groups Coefficient Md/Ms Dynamic momentum A B C (Nm) High coefficient of correlation of all sample groups shows strong dependence between static and dynamic testing of samples (table 4). Table 4 Coefficient of correlation for sample groups Coefficient of correlation A B C

64 CONCLUSIONS 1) There is strong relationship between coefficient of static and dynamic testing number of cycles. 2) From results of three samples testing it can be concluded that there is possibility for decreasing expenses for quality determination especially those related to durability of construction (replacement of dynamic testing with static testing). 3) Replacement of whole product testing with testing of critical assembly only (decrease of overall expenses). 4) Testing of assembly makes quality determination possible early in planning and design phase. REFERENCES 1. Biniek P., Smardzewski J. 1987: Effect of simultaneous changes in several factors on the strength of fork-tenoned joints, Przemysl - Drzewny, 38(11) : Dzigielewski S., Zenkteler M. 1975: Badania nad polaczeniami szkieletowych konstrukcji mebli z drewna cz.ii. Folia Forestalia Polonica, seria B, 12: Dziegielewski S. 1991: Sposoby nanosenia klejuna powierzchine zlaczy a jakosc polaczenia. Przemysl Drzewny 7: Dziegielewski S., Giemza I. 1983: Istraživanje statičke i dinamičke čvrstoće stolica kao parametra njihove kvalitete, Drvna industrija 34, (1 2): Eckelman C.A., Hincz T.W. 1977: Strength and stiffness of dowel joints in flatwise bending, Forest Products Journal. 1: Korzeniowsky A. 1984: The influence of fit on the mechanical properties of glued mortice and tenon joints. Ann. Warsaw Agricult. Univ. SGGW AR. Forest and Wood Technology 31: Prekrat S. 2000: Kriteriji čvrstoće spojeva u konstrukcijama stolica. Doctoral Thesis. Šumarski fakultet Sveučilišta u Zagrebu. 8. Prekrat S, Jazbec A, Pervan S. 2004: Analysis of bending momentum of innovative corner joints during static testing, Wood research 49 (1): Wang S.Y., Yuang H.B. 1994: Structural Behavior of Various Joints in Furniture Components Made of Softwood Laminated Vener Lumber, Mokuzai Gakkaishi, 40 (9) Zhang J.L., Eckelman C.A. 1993: Rational design of multidowel corner joints in case construction, Forest Products Journal, 43(11-12):

65 Streszczenie: Optymalizacja badań mebli. Celem pracy była optymalizacja polegająca na skróceniu czasu i redukcji kosztów badań typowych krzeseł. Przedmiotem badań były połączenia o złączach czopowych. Wysokie współczynniki korelacji wskazują na silną zależność pomiędzy wynikami statycznych i dynamicznych badań próbek. Wskazuje to na możliwość ograniczenia kosztów badań, poprzez zastąpienie badań dynamicznych testami statycznymi. Corresponding authors: Assis. prof. Silvana Prekrat Department of Wood technology, Faculty of Forestry, University of Zagreb Zagreb, Croatia [email protected] prof. Jerzy Smardzewski Department of Furniture Design, Faculty of Wood Technology, Poznań University of Life Sciences Wojska Polskiego 28, Poznań, Poland [email protected] 65

66 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Auxetic spring elements for elastically supporting a sitting or lying JERZY SMARDZEWSKI, ADAM MAJEWSKI Department of Furniture Design, Faculty of Wood Technology, Poznan University of Life Sciences Abstract: The paper presents a model of an auxetic push spring to be used in mattresses and seats of upholstered furniture. Grid models were subjected to numerical calculations assuming that springs are manufactured from silicone with the Shore hardness of 70 o ±5 o, and design load of 4 kpa. On the basis of calculations it was shown that the structure has a strongly negative Poisson s ratio of and that it is perfectly fitted to being combined in parallel systems. Keywords: push spring, auxetics, numerical calculations INTRODUCTION Quality of upholstered furniture to be used as seating and resting furniture is defined by the comfort of their use (Smardzewski and Matwiej 2009, Smardzewski and Wiaderek 2009). It is usually expressed by the level of pressures, contact stresses at the contact of the user s body and the seat or mattress (Smardzewski 2009, Smardzewski and Prekrat 2010). A significant element limiting this comfort is connected with the stiffness of the cushion or mattress. These in turn depend on the rigidity of used foams or springs. Water beds are models for high comfort. They provide uniform body support over a large area. Unfortunately, their use is connected with numerous drawbacks connected with their considerable weight, required heating and exchange of water, significant mobility of their surface and problems with maintenance of cleanliness around this piece of furniture. It is possible to provide uniform body support for the user thanks to the application of an appropriate spring design exhibiting auxetic properties. RESEARCH OBJECTIVE The of the study was to develop the design of an auxetic push spring, to determine deflections and stresses in a novel design of springs and to calculate values of Poisson s ratio for the new design. MATERIAL AND METHODS Auxetics are materials which are characterised by negative Poisson s ratios (Lakes 1987, Wojciechowski 2003, Wei 2005, Alderson and Alderson 2007). During uniaxial tension the dimensions of the cross-section increase (Fig.1b), while in conventional materials during this test their cross-sections are reduced (Fig.1a). Figure 1. Uniaxial tension test of: a) conventional, and b) auxetic materials. 66

67 a) b) Figure 2. A diagram for the action of a rigid body on: a) conventional, and b) auxetic foundations. Auxetic characteristics may pertain both to the material and the frame of a structure. In case of contact of a rigid body with a conventional material or frame internal forces cause tensioning of the material (Fig.2a), and thus a disadvantageous distribution of pressures and tangential forces on the contact surface with the body of the user (Fig.3). The parabolic concentrations of reactions of the foundation around ischiatic tubers and the tensioning of the body and clothing by forces of shearing stresses are particularly undesirable. The application of an auxetic material for the foundation (Fig.2b) results in a situation when internal forces in the mattress act inwards and do not strain the body of the user. Figure 3. A diagram for the distribution of pressures and friction forces on the body of the user when sitting The model of a spring as presented in Fig. 4 is a shape exhibiting auxetic properties. It is composed of two rigid sliders of 4 mm in thickness and an elastic foot with wall thickness of 1 mm (Fig.5). Figure 4. A model of a push spring with auxetic properties 67

68 Figure 5. A spring foot Figure 6. A computational model for the length of foot rockers Dimensions of sliders resulted from the dimensions of foot rockers and these were determined on the basis of a suboptimization process of the design from Fig. 6, constituting a symmetrical half of the foot from Fig. 5. At the same time it was assumed that width a of the spacing of foot rockers of the spring should be, angle φ between the upper and lower foot rockers should assume the values,, the length of the lower foot and the length of the skew rocker should be of identical dimensions e=d, the length of the upper rocker should be a multiple of the length of the skew rocket while: Thus equations were obtained, making it possible to establish the lengths of rockers b and c, where:,. 68

69 Table 1 lists dimensions b and c established for different values of parameters: a,n,φ, while Fig. 7 presents the effect of these parameters on the overall geometry of the spring. It may be observed in this figure that for parameter n=2 springs are higher than springs with parameter n=3. In turn, the width of the pressure area is greater when n=3 and angle φ decreases. On this basis the design with the following dimensions and parameters: a=60 mm, n=3, φ=60 o, c=45mm, b=26mm, was selected for further analyses. Table 1. A list of dimensions of foot rockers a (mm) n φ( o ) c=f(a,n,φ) (mm) b=f(a,n,φ) (mm) ,1 18, ,2 23, ,0 26, ,7 26, ,7 25, ,9 26, ,4 32, ,0 34, ,2 34, ,9 32,4 a) b) Figure 7. Examples of different foot geometries: a) tall and narrow, b) low and wide. It was decided to support and load the selected structure as presented in Fig. 8. Due to the proposed use of the modelled spring and its probable application in cushions of seating furniture, the value of load was assumed on the basis of tested contact stresses between the body of the user 50C, at the weight of 75 kg and height of 180 cm, and the seat made of polyurethane foam T3543 of 40 mm in thickness. Tests were conducted using a sensor mat and are presented in Fig. 9 in the form of a stress map. It results from that figure that contact stresses range from 0.28 kpa to 4 kpa. Maximum loads of 4 kpa were assumed for the purpose of numerical calculations. 69

70 Figure 8. A diagram of loading for a single spring Figure 9. Distribution of pressures on the seat caused by user 50C It was assumed in the brief foredesign that the modelled spring foot would be made from a hyperelastic material, resistant to temperature changes within the range from -40C o to +40C o and of Shore hardness of 70 o ±5 o. Silicone was considered most suitable for this purpose, being a non-linear - hyperelastic body (Fig.10). Figure 10. Characteristics of rigidity of silicon as a hyperelastic body Since silicone is a gum, it was decided for numerical calculations to use the Mooney- Rivlin model, describing energy of elastic deformations of this body in the form: W C 1 d 10 I 1 3 C01 I 2 3 el 1 J 2, 70

71 Where: I , I I , V V J el C10 C01 2 d., For the selected silicone with Shore hardness of 70 o ±5 o the respective coefficients are C 10 =0.47 and C 01 =0.12, while the modulus of volume elasticity was k=3.56. It was decided to manufacture the spring slider from hard polyamide with the modulus of rigidity of 12 GPa and Poisson s ratio ν=0.3. Figure 11. A mesh model of the spring Numerical calculations were performed in the Algor system realizing the algorithm of the finite element method. The grid model of the spring is presented in Fig. 11. In its construction 20-node solid finite elements were used. For each pair of surfaces, which may be in contact at compression, contacts were defined by the indication of the master and slave surfaces according to the schema as in Fig. 8. At the same time it was assumed that this contact will be frictionless and the surfaces will have identical rigidity as the material of the spring foot. RESEARCH RESULTS Figure 12 presents an image of spring deflection caused by uniaxial compression. As it may be observed from this figure under the load of 2.75 kpa the spring deflects by 15.4 mm and its rockers move backwards inside and press on each other and on the slider. Maximum horizontal displacement towards axes X and Z amounts to 11.2 mm. As it may be observed from Fig. 13 the process of spring settlement is not linear. It results both from the loss of stability of spring rockers as well as contact of individual rocker surfaces at the stage of bifurcation. For a load of approx. 0.8 kpa rockers of the foot frame lose stability and at a 71

72 slight increment of loads they cause a considerable increment in vertical and horizontal displacements. At the next stage walls of the frame structure press on one another and gradually result in a slight increase in spring rigidity. Figure 12. Deflection of a spring in the state of uniaxial compression Figure 13. Deflection along the Y axis and displacements along the X, Z axes On the basis of the shape of the deformed spring it may be concluded that it is an auxetic frame. Figure 14 presents a schema for calculations of Poisson s ratio for such a structure. The value of this coefficient was calculated from the dependence: Figure 14. Sketch for calucation of spring Poisson ratio 72

73 where: As it may be seen, it is a structure with a strongly negative Poisson s ratio, which in a parallel arrangement with other similar structures may provide considerable horizontal displacements. In order to verify the correctness of the design solution it was also decided to estimate the distribution of von Mises reduced stresses caused by design load (Fig.15). The greatest among them appear at sites of rocker contraflexure (point G). However, they are not crippling stresses and they do not exceed 0.7 MPa. As it results from Fig., 16 the course of these stresses changes with the process of loss of rocker stability, described above. Until that moment stresses increase rapidly and almost proportionally. From the moment of the loss of stability and mutual contact of rockers stresses increase slightly. Figure 15. The distribution of von Mises reduced stresses Figure 16. A change in von Mises reduced stresses at point G 73

74 CONCLUSIONS On the basis of the conducted analyses of results of numerical calculations the following conclusions may be formulated: 1. The presented spring model is an auxetic structure with a strongly negative Poisson s ratio, 2. Considerable vertical and horizontal displacements of spring rockers guarantee its applicability in parallel connections, 3. The developed design applied in seat structures should guarantee high comfort of their use. REFERENCES 1. ALDERSON A.; ALDERSON K.L. (2007): Auxetic materials. Proc IME G.J. Aero.Eng., 221: LAKES R.S. (1987): Foam Structures with a Negative Poisson's Ratio. Science, 235: SMARDZEWSKI J.; MATWIEJ Ł. (2009): Stiffness modelling of hyperelastic polyurethane foams of standard type. Annals of Warsaw University of Life Sciences, Forestry and Wood Technology, No 67: SMARDZEWSKI J.; PREKRAT S. (2010): Research of contact stresses between seat cushion and human body. Drvna Industrija 61 (2) SMARDZEWSKI J.; WIADEREK K. (2009): Non-linear stiffness characteristics of hyperelastic polyurethane foams. Annals of Warsaw University of Life Sciences, Forestry and Wood Technology, No 67: SMARDZEWSKI J. (2009): Antropotechnical aspects of furniture design. Drvna Industrija 60 (1) WEI G.Y. (2005): Design of auxetic polymer self-assemblies. Phys. Stat. Sol., 242: WOJCIECHOWSKI K.W. (2003): Non-chiral, molecular model of negative Poisson ratio in two dimensions. J. Phys. A: Math. Gen., 36: Streszczenie: Auksetyczne elementy sprężyste dla elastycznego podparcia siedzenia i leżenia. W pracy przedstawiono model naciskowej, auksetycznej sprężyny przeznaczonej do leżysk i siedzisk mebli tapicerowanych. Modele siatkowe poddano obliczeniom numerycznym przyjmując wykonanie sprężyn z silikonu o stopniu twardości 70 o ±5 o Shor a, oraz obciążenie użytkowe 4 kpa. Na podstawie obliczeń wykazano, że konstrukcja ma silnie ujemny współczynnik Poissona równy -0,41 oraz, że doskonale nadaje się do łączenia w układy równoległe. Corresponding authors: prof. Jerzy Smardzewski, Adam Majewski Department of Furniture Design, Faculty of Wood Technology, Poznań University of Life Sciences Wojska Polskiego 28, Poznań, Poland [email protected] 74

75 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) The influence of pilot hole on the moment resistance of screwed T-Type furniture joints NURGUL TANKUT Bartin University, Faculty of Forestry, Department of Forest Industrial Engineering. Abstract: This study was carried out to determine the effects of pilot hole, screw diameter, and wood composite panel type on the diagonal compression and tension strength properties of particleboard surfaced with synthetic resin sheet (LamPb) and MDF surfaced with synthetic resin sheet (LamMDF). Two different diameter of screws (3,5 and 4 mm) and three types of pilot holes (either 70 or 85 % of the root diameter of the screws, and without pilot hole) were utilized for constructing the test specimens. Samples with pilot hole gave higher strength values than control samples of all T-type corner joints. Namely, the use of pilot holes of the proper diameter significantly increases the bending and tension strength of the screws in the material. Pilot hole diamater was found to have a larger influence on bending moment resistance than screw diameter and panel type. Results of means separations of moment resistances indicated that in general the joints loaded in bending have greater moment resistance than those loaded in tension. LamMDF corner joints were stronger than LamPb corner joints. As case furniture constructions are under bending forces, in LamPB using 3.5 x 50 screws with a pilot hole of 70 % of the root diameter of the screws, in LamMDF using 4 x 50 screws with 85 % of the root diameter of the screws can be recommended as the most robust corner joint type for case furniture. As case furniture constructions are under tension forces, in LamPB using 4 x 50 screws with a pilot hole of 85 % of the root diameter of the screws, in LamMDF using 3.5 x 50 screws with 85 % of the root diameter of the screws can be recommended. Keywords: screws, pilot hole, wood composite material, case furniture INTRODUCTION For an efficient design of the case furniture constructed using screws requires specific design information on the the moment resistances of fasteners in LamMDF and LamPB. Several investigations have been made on the screwed corner joints that have yielded data on this design. Published information is mostly related to direct withdrawal resistances of screw-type joints (Eckelman 1974, 1975a, 1975b, 1978, Rajak and Eckelman 1993, Eckelman and Martin 1980, Erdil et al. 2002, Tankut 2007). Efe and Kasal (2000) stated screwed joints gave better strength than the glued joints with a fiberboard. Research has been carried out to determine strength properties of comer joints connected with screws and dowels (Rajak 1989, Rajak and Eckelman 1996, Liu and Eckelman 1998, Ho and Eckelman 1994). It was stated that withdrawal strength for each size of screw was affected by the diameter ratio of pilot hole for screw (Fujimoto and Mori 1983). Johnson (1967) noted that no significant difference was found in strength values obtained with pilot holes that were either 40 or 70 % of the root diameter of the screws. Withdrawal strengths were about 13 % higher when optimum pilot holes were used than when pilot holes were not used (Eckelman 1988, 1990). It is stated that the glue applied in pilot hole increased the withdrawal strength for screws (Ors et al 1998). Doganay et al. (1997) observed that the covered panels having gluedpilot hole showed the highest holding strength. Tankut (2004) stated that joint strength was strongly influenced by the type of particleboard used. 75

76 RESEARCH OBJECTIVE The objectives were to: 1. Compare moment resistance of the screwed corner joints constructed of different panel materials, namely LamPB and LamMDF. 2. Determine the effects of pilot holes used in the joints on moment resistance of screwed corner joints. 3. Determine the effects of screw diameter utilized for connecting the specimens on bending moment resistance of the screwed corner joints. MATERIAL AND METHODS Material properties Eighteen mm thick LamPb and LamMDF were selected for this study because of their common use by the Turkish cabinet manufacturers. In preparing specimens, 188 by 366 cm full-sized board sheets were first cut into face and butt member strips. These strips were subsequently cut into the desired member lengths. Members for joints were randomly selected from this common supply. The stiffness and modulus of rupture of the materials were determined following the procedures given in ASTM standard D Specific gravity values of LamPb and LamMDF were calculated following ASTM Standard D Method A. Moisture contents were calculated on the same specimens and followed ASTM Standard D Method A, oven-drying method. IB (internal bond strength) tests of LamPb and LamMDF were performed following the procedure given in ASTM Standard D a. Screws A total of two pan head, slotted, zinc plated, chipboard screws (3.5 x 50 and 4.0 x 50), having Turkish Standards TS 431 were used in this study. These screws were selected not only they are low-cost fasteners because they are readily available for the furniture industry, but also they have excellent holding strength in wood and woodbased materials. Properties of screws are given in Figure 1. Root diameter, outside diameter, and thread per mm were 2.4±0.25 mm. 4.0 ±0.3 mm, and 1.8 mm. respectively for 4-mm screws; and 3.0 ± 0.3 mm; 5.0 ± 0.35 mm, and 2.2 mm, respectively for 5-mm screws. Specification of screws used in this study is shown in Table 1. Table 1.Specification of screws Thread size 3,5 4 Major Dia D min Minor Dia d min Head height A min Head height H Recess width M Drive Size PH 2 2 Torque min Recess depth Q min Material C1018-C1022 Core hardness HV Surface hardness min. 450HV Surface hardness mm mm. Figure 1. Chipboard screw 76

77 Joint configuration The general configuration and detail of specimens is shown in Fig. 2. Zhang and Eckelman s (1993) work was used for the preparation of samples and testing. Each T-shaped specimen consisted of two principal structural members (A member and B member) jointed together. Before the tests, specimens were kept in an environment chamber at 20± 2 C temperature and 65±5 % relative humidity until their weight became constant. (a) Figure 2. General configuration of the specimens for bending (a) and tension (b) tests in mm By using two different types of panels (LamPb and LamMDF), two different types of screw diameter (3.5 and 4 mm), three types of pilot holes (either 70 or 85 % of the root diameter of the screws, and without pilot hole) and two different types of forces as parameters, for both test methods (bending and tension), a total of 120 samples were prepared using 5 samples for each parameter. Screws were drilled to the center of the thickness of rail members (Fig.3). When attaching screws, pilot holes were bored into the post side and end of the rail followed Eckelman s (1990, 2003) work. The diameters of the pilot holes were equal to approximately either 70 or 85 % of the root diameter of the screws, and depths of the pilot holes were equal to approximately 75 % of the penetration of the screws. (b) (a) (b) Figure 3. The distance between center of screw holes for bending (a) and tension (b) tests (in mm) 77

78 Test methods T joints were tested in a universal testing machine having 10 ton capacity fitted with a cast aluminum alloy angle plate to support the leg section while the rail section was loaded by means of a stirrup attached to the machine cross head. Universal test machine was equipped with jigs to hold the specimens and applying 1.5 mm/min loading time. A concentrated load was applied to the rail of each specimen at a point 21 cm from the front edge of the post as shown in Fig. 4. The maximum bending and tensile strength were determined as the force applied to each experimental sample at the time of failure. Ultimate failure load values and joint failure modes were recorded. The loading was continued until a failure or full separation occurred in the specimens. The strength of joints was characterized by the bending moment value at which the joint was destroyed. Applied loads were converted to moment acting at the joint center per cm of joint width. Figure 4. General configuration of the test setup used in the study.for bending (a) and tension (b) tests (in mm) 78

79 The ultimate moment capacity of the joint is calculated as the product of breaking load and the distance between the point of application of the load and the face of the joint. The ultimate moment capacity is, in fact, the bending moment required to break the joint and it is expressed in units of Ncm (Eckelman 2003). In this study the moment arm (L = 21cm) was measured from the point of load application to the face of the joints. Ultimate moment capacity, f, was calculated as f= F x L (Ncm) where F is the applied load (N). RESEARCH RESULTS Table 2 shows the average physical and mechanical properties of the LamPb and LamMDF used in the tests. Table 2. Average moisture content and mechanical properties of the particleboard surfaced with synthetic resin sheet (LamPb) and MDF surfaced with synthetic resin sheet (LamMDF) used in the tests Material Moisture Content (%) (COV)* Specific Gravity (COV) Internal Bond (N/mm²) (COV) Modulus of Elasticity (N/mm²) (COV) Modulus of Rupture (N/mm²) (COV) LamPb 6.5 (7.6) (5.3) (8.6) 1,986 (7.3) (3.8) LamMDF 6.1 (4.9) (2.9) (9.7) 2,868 (6.8) (9.6) * : Coefficient of variation Pilot holes serve to locate screws and facilitate their insertion in a desired direction. It was found to be difficult to insert a screw into a specimen that lacked a pilot hole, and when it was inserted, the screw had a tendency to go off at an angle, i.e., to not "go straight." Results indicate that ultimate moment capacity of joints increases as pilot hole size is increased, until the pilot hole nears the root diameter of the screw. On the average, there was a 26.1% increase in strength when pilot holes were used compared to when no pilot holes were used as shown in Table 3 and Figs 5 and 6. Panel Type Lam Pb Lam MDF Table 3. Bending and tension strength values according to panel, pilot hole and screw diameter. Pilot hole Screw diameter (mm) Loading method and number of specimens Bending Tension Kontrol Kontrol 3, , , ,5 3,5 5 5 Kontrol Kontrol 3, , ,5 5 5 Average bending strength (N) 105 (31.4) 77 (27.1) 84 (18.8) 103 (41.7) 50 (24.2) 159 (29.3) 115 (48.5) 315 (22.8) 383 (18.7) 253 (19.9) Mean ultimate moment capacity (Ncm) 2205 (21.15) 1630 (12.33) 382 (30.2) 204 (20.1) 247 (11.8) 383 (21.7) 300 (20.2) 359 (19.3) 515 (31.5) 315 (20.8) Average tension strength (N) 41,53 (19) 22,18 (12) 26,86 (7) 41,64 (14) 32,62 (32) 39,03 (12) 55,99 (12) 34,25 (14) 41,64 (8) 27,51 (7) 79

80 ,5 3,5 5 5 * standard deviation in parenthesis 275 (22.4) 327 (34.2) 383 (11.7) 253 (11.9) 29,90 (6) 35,55 (21) Figure 5. Effect of pilot hole and screw diamater on bending strength of T-type joints Figure 6. Effect of pilot hole and screw diamater on tension strength of T-type joints The multiple variance analysis (Table 4) was performed to determine the differences among the factors (panel type, screw diameter, pilot hole). It was determined by Duncan test if there is a meaningful difference among the groups Table 4 and Figs 7,8. It was carried out on data at the 0.05 significance level. Table 4. Multivariate analysis of variance results Source of Degrees of Variance freedom Sum of Square Mean Square F Value p Value Pilot hole (A) ,000 Screw diameter (B) ,000 Type of panels (C) ,000 AxB ,000 AxC ,000 BxC ,000 80

81 AxBxC ,000 Error Total Results of this analysis show that bending and tension strength of the screwed corner joints was a function of panel type, screw diameter, and pilot hole. In those specimens with pilot holes that increased from 70 to 85% of root diameter in LamMDF had a little effect on bending strength specimens. Results of means separations of moment resistances indicated that in general the joints loaded in bending have greater moment resistance than those loaded in tension. Means comparisons results indicated that, in general, the joints constructed of LamMDF showed significantly higher moment resistance the ones constructed of LamPB. Tests results of the similar previous studies concerning the material effect (Tankut, A.N. and N.Tankut 2005, Tankut, N. 2006, Zhang et al. 2005, Kasal et al. 2006) agree with this study. This significant difference in moment resistance could be explained by the fact that LamMDF has higher IB strength and screw withdrawal resistance than LamPB (Table 2). Screw Diameter and HG Pilot hole 3,5 mm Screw Diameter-2 mm Pilot hole 58,94 A 4 mm Screw Diameter-2,5 mm Pilot hole 77,63 AB 4 mm Screw Diameter-2 mm Pilot hole 84,51 AB 3,5 mm Screw Diameter- 104,86 B Kontrol 4 mm Screw Diameter- 105,06 B Kontrol 3,5 mm Screw Diameter-1.5 mm Pilot hole 119,57 BC Figure 7. Duncan test results for bending forces Screw Diameter and HG Pilot hole 3,5 mm Screw Diameter-1,5 mm Pilot hole 1284,39 A 4 mm Screw Diameter-Kontrol 1394,41 A 3,5 mm Screw Diameter-Kontrol 1399,26 A 4 mm Screw Diameter-2,5 mm Pilot hole 1757,16 AB 4 mm Screw Diameter-2 mm Pilot hole 1757,56 AB 3,5 mm Screw Diameter-2 mm Pilot hole 2017,50 B Figure 8. Duncan test results for tension forces When the screw is being driven, wood resists against it. Thus, it is necessary to apply pilot hole. As the proper pilot hole is applied to the hole, tension strength of screw is greater than the one which is not applied a pilot hole of screw. It can be said that a proper pilot hole is essential in order to avoid splitting of the face during insertion of screws as well as to obtain maximum strength. Screw joints failed owing to withdrawal and bending of screws. The primary cause of failure in the joints was fracture of the wall through which the screw passed rather than splitting of the end of the member in which the point of screw was embedded. The common mode of failure for bending specimens was the pull-out of screws from the rail with some core wood materials attached to the screw. In the bending tests, joints opened up slowly and screws bent. In general, failures were not sudden, and they occured between 90 to 120 sn. Failures of joints constructed of LamPB and LamMDF started with the screw heads crushing into the face member followed by screw withdrawal from the butt members along with some core material together, with edge splitting around the screws. In LamPB specimens the amount of core material was considerably more than those the constructed with LamMDF; contrarily the amount of edge splitting around the screws in the joints constructed of LamMDF was significantly more than in the joints constructed of LamPB. The screws did not break. CONCLUSIONS Material type, screw diameter, and pilot hole effects on the strength of T-type corner joints were investigated. Test results showed that significant differences occurred in bending moment resistances with respect to above mentioned variables. 81

82 In general, joints constructed of LamMDF yielded higher moment resistances than those of LamPB. In both bending and tension tests, LamMDF corner joints were stronger than LamPb corner joints. The small diameter of screw gave the higher tension strength, because it did not split the wood. Samples with pilot holes gave higher bending and tension strength than control samples. It is necessary to use pilot holes in order to avoid splitting of the edge during insertion of screws as well as to obtain maximum, least variable strength. The tension strength was greater than the bending strength of all T-type corner joints. As case furniture constructions are under bending forces, in LamPB using 3.5 x 50 screws with a pilot hole of 70 % of the root diameter of the screws, in LamMDF using 4 x 50 screws with 85 % of the root diameter of the screws can be recommended as the most robust corner joint type for case furniture. As case furniture constructions are under tension forces, in LamPB using 4 x 50 screws with a pilot hole of 85 % of the root diameter of the screws, in LamMDF using 3.5 x 50 screws with 85 % of the root diameter of the screws can be recommended. These experiments revealed the construction methods that should be followed to produce the stronger T-type screwed corner joints constructed of LamPB and LamMDF. REFERENCES 1. AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM)., 1997: Standard test methods for evaluating properties of wood-base fiber and particle panel materials. D a. ASTM, West Conshohocken, PA. 2. AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM)., 1997: Standard test methods for specific gravity of wood and wood-base materials. D ASTM, West Conshohocken, PA. 3. AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM)., 1997: Standard test methods for direct moisture content measurement of wood and woodbase materials. D ASTM, West Conshohocken, PA. 4. DOGANAY S., OZCIFCI A., KURELI I. 1997: The effect of edge massive on screw holding in particleboard used for furniture production. J Nat Appl Sci Gazi Univ Turkey;10:2: ECKELMAN C.A. 1975a: Screw-Holding Performance in Hardwoods and Particleboard. Forest Products Journal 25(6): ECKELMAN C.A. 1975b: Effect of Holes on the Bending Strength of Wood and Particleboard Parts. Purdue University Agr. Exp. Sta. Res. Bul. No. 922, 8 pp. 7. ECKELMAN C.A. 1978: Predicting withdrawal strength of sheet-metal-type screws in selected hardwoods, Forest Products Journal. 2S(8): ECKELMAN, C.A., MARTIN K. 1980: The Holding Strength of Four Types of Screws in Wood. Furniture Manufacturing Management 26(9):20-, 4 pp. 9. ECKELMAN C.A. 1988: The withdrawal strength of screws from a commercially available medium density fiberboard. Forest Products Journal 38(5): ECKELMAN C.A Screw, Insert, Staple, and Nail-Holding Strength of Particleboard and MDF. AES Chapt. II, A "Review and Summary of Relevant Published Literature on Fasteners and Their Use with Particleboard and MDF." National Particleboard Association. Gaithersburg 11. ECKELMAN C.A. 2003: Textbook of product engineering and strength design of furniture. West Lafayette (IN): Purdue University Press. 82

83 12. EFE H., KASAL A. 2000: Tension strength of case construction with and without demontable corner joints. Industrial Architecture Journal of Faculty of Education Ankara, 8(8): ERDIL Y.Z., ZHANG J., ECKELMAN C. A. 2002: The Holding Strength of Screws in Plywood and Oriented Strand Board. Forest Products Journal 52(6): FUJIMOTO Y., MORI M. 1983: Performance of wood screw joints for particleboard. Sci Bull Fac Agr Kyushu Univ Jpn;38(1):45 7.). 15. HO C. and ECKELMAN C.A. 1994: The use of performance tests in evaluating joint and fastener strength incase turnituie. Forest Products Journal. 44(9): JOHNSON J.W.1967: Screw holding abiility of particleboard and plywood. Rept T- 22. Forest Research Lab., Oregon State Univ, Corvallis, OR. 17. KASAL A., SENER S., BELGIN C. M., EFE H. 2006: Bending strength of screwed corner joints with different materials. Gazi Univ. J. of Sci. Gazi Universitesi Fen Bilimleri Dergisi. 19(3): LIU WQ., ECKELMAN C.A. 1998: Effect of number of fasteners on the strength of corner joints for cases. Forest Products Journal 48(1): ORS Y., OZEN R., DOGANAY S. 1998: Screw holding ability of wood materials used in furniture manufacture. Turk J Agr Forest 22(1):29 34.). 20. RAJAK Z., 1989: Efficient use of serews in the construction of comer joints for case goods. MS thesis. Purdue Univ. W. Lafayette, IN. 124pp. 21. RAJAK Z., ECKELMAN C.A. 1993: Edge and face withdrawal strength of large serews in partieleboard and medium density fiberboard. Forest Products Journal 43(4): RAJAK Z., ECKELMAN C.A. 1996: Analysis of corner joints constructed with large screws. J Trop Forest Sci 2(1). 23. TANKUT A.N., TANKUT N. 2004: Effect of some factors on the strength of furniture corner joints constructed with wood biscuits. Turkish J Agric Forestry 28(4): TANKUT A.N. 2005: Optimum dowel spacing for corner joints in 32-mm cabinet construction. Forest Products Journal 55(12): TANKUT N. 2006: Moment Resistance of Corner Joints Connected with Different RTA Fasteners in Cabinet Construction. Forest Products Journal, 56(4): TANKUT N. 2007: The effect of adhesive type and bond line thickness on the strength of mortise and tenon joints. Int J Adhes Adhes 27(6): TANKUT A. N., TANKUT N. 2005: The effects of joint forms (shape) and dimensions on the strengths of mortise and tenon joints. Turkish J Agric Forestry 29(6): ZHANG J.L., ECKELMAN C. A. 1993: Rational design of multi dowel corner joints in case construction. Forest Products Journal 43(11/12): ZHANG J.L., EFE H., ERDIL Y. Z., KASAL A., HAN N. 2005: Moment resistance of multiscrew L-type corner joints. Forest Products Journal. 55(10):

84 Streszczenie: Wpływ wiercenia otworów na wytrzymałość na zginanie skręcanych połączeń półkrzyżowych w meblach. Celem pracy było określenie wpływu wiercenia otworów, średnicy śruby oraz rodzaju materiału płytowego na wytrzymałość na zginanie oraz rozciąganie połączenia. W badaniach uwzględniono płytę wiórową laminowaną oraz MDF laminowaną, 2 średnice wkrętów oraz 3 rodzaje otworów (o średnicach 70% i 85% średnicy wkrętu oraz bez uprzednio wykonanego otworu). Wykazano, że odpowiednia średnica otworu zwiększa wytrzymałość na zginanie i rozciąganie połączenia. Corresponding author: Assoc. Prof. Nurgul Tankut Bartin University, Faculty of Forestry, Dept. of Forest Industrial Engineering Bartin, Turkey Phone: Fax: [email protected] 84

85 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Ergonomic authentication for dimensions furniture JIŘÍ TAUBER, JAROSLAV SVOBODA Mendel University in Brno, Faculty of Forestry and Wood Technology, Department of Furniture, Design and Habitation, Zemedelska 3, Brno, Czech Republic Abstract: : The dimensions of the population are constantly changing and the changes need to be applied in the dimensions of the furniture. The goal of this paper is to update the dimensions of ergonomic furniture using current anthropometric data. Special software designed to simulate human activity will be used to compare human body dimensions and furniture. The result will verify the accuracy of the current design used for ergonomic furniture. If the design is found inaccurate, new proportions will be suggested. The article describes the proposed procedure. Keywords: ergonomics, furniture, methodology ANTHROPOMETRY AND INTERIOR Anthropometry is a science that deals with the measurement of man. Anthropometric data make groundwork for appropriate furniture design and furniture dimensions. Man has always made objects to their needs in accordance with the dimensions of the human body. It ensured better performance of the objects. In the field of interior and furniture design, comfort lies primarily in the correct dimensions of the particular user. It is evident from historical discoveries. Changes in the dimensions of furniture are visible in the timeline -for example, length of bed in the Middle Ages was significantly shorter than today, because the population growth was smaller. The population in the recent decades has been growing significantly. The differences in height among countries are also being diversified. These changes must be taken in count by furniture designers and architects. It needs to be mentioned that architects and designers use anthropometric measurements of the Czechoslovak population from the 1970s and older. The data have been taken from the following publications: Furniture, people, housing by Stanislav Dlabal (1976) Neufert - Designing buildings (2000) Stand ards and regulations All publications use data of the population around the year Newer data are not available and so even the current publications use the old data. HISTORY ANTHROPOMETRY AND MEASUREMENT OF HUMAN People have been interested in the dimensions of the human body from the time immemorial. The European civilization has dealt with them since Antiquity. It involved detailed observation and measurement of people. Especially, the dimension of the human body have been essential for sculpture. be without examining the relationships and understanding the human dimensions did not go. Renaissance drawing of Leonardo da Vinci the Vitruvian Man - shows a very detailed, almost scientific, exploration into a human figure. The science of anthropometry was created in the XIX. century when a Belgian mathematician, Jacques Quetelet Lambert Adolpe wrote a book called Antropometry and in 85

86 1883 a Frenchman, Alphonse Bertillon came up with a method of identifying criminals by measuring their bodies. In the Czech country, the first measurements of the population were carried out by Prof. Jindrich Matiegka in Later, in 1951, Prof. Vojtech Fetter began measuring Czech children and the youth. It has been held regularly every ten years up today. The last measurement was carried out and evaluated in 2001 by the State Medical Institute. This research concerns the height and weight of children and the youth under the age of 18. At the same time, measurements of the Czechoslovak population between ages 6-55 were carried out at every Spartakiade (1955, 1960, 1965, 1975 and 1985), allowing to monitor the evolution in growth and change. Recent measurements from 1985 were prepared by Pavel Blaha et al. CURRENT MEASUREMENTS The measurement results show the increase in height and weight of the population and the large differences between the maximum and minimum values. Comparison of average values from the years (data have been taken from above mentioned publications) and 2010 (Table. 02, 03), maximum and minimum differences values (Table. 04), clearly indicate that the population is growing. It is to be emphasized that Czechs are among the highest nations in Europe. Experts believe that the growth of the Czech population has not stopped yet. In addition, the alarming increase in weight is caused by lack of exercise in the current lifestyle. Table. 1: The average height of an adult difference Man 174,0 cm 179,5 cm + 5,5 cm woman 162,0 cm 166,5cm + 4,5 cm Table. 2: The average weight of an adult difference Man 74,6 kg 84,0 kg + 9,4 kg woman 59,4 kg 68,8 kg +9,4 kg Table. 3: Adult height - the difference between the upper and lower limit 2010 percentil 75 percentil 25 difference Man 184,8 cm 173,6 cm 11,2 cm woman 171,2 cm 160,5 cm 10,7 cm Table. 4: Adult height - the maximum difference 2010 min. max. difference Man 162,3 cm 193,4 cm 31,1 cm woman 152,3 cm 182,6 cm 30,3 cm 86

87 Figure 1. Differences in body weight / Unisex DEVELOPMENT OF ANTHROPOMETRIC DATA Anthropometric data were processed using ergonomic software, Siemens (Tecnologic Jack) on the basis of the measured sample of the population. The software Tecnomatix Jack enables to improve the ergonomics of product designs. Tecnomatix Jack is a 3D simulation tool focused on ergonomics and behaviour at work. The software allows monitoring and evaluation of work activities and placement of the workers within a manufactory. An accurate biomechanical model of a human body, which has a total of 69 segments and 68 joints, is inserted in the virtual environment. The most detailed parts are the backbone (17 segments) and hands (16 segments). These segments can be manipulated in 2 to 3 axes. Figure 2. Tecnomatix Jack 3D simulation 87

88 Figure 3. Maximum height standing on the tips / Unisex Figure 4. The optimum height of the shelves at work standing / Unisex Figure 5. Maximum height of the peak standing / Unisex 88

89 CONCLUSION It is suggested to implement the classification of XS, S, M, L and XL used in the clothes industry, which would help the customers to choose the right size. This idea has been introduced for the first time by T. Teraoka, R. Mitsuya and K. Noro who based it on a survey of seating comfort. (XS) S M L (XL) Figure 5. Height in cm man Human-inhabited environment (the connection between architecture and interior) and product design, these changes must occur in particular: accepting changes in lifestyle; changing the current "recommended" size due to growing population, divided into size categories. This also applies to the preparation of documents for architects and designers. ACKNOWLEDGEMENTS Credits include the Grant MPO ČR FR-TI1/050 -Information system of support research, innovation, product development and furniture quality which provided funding enabling to run this research. REFERENCES 1. BLAHA, P : Antropometrie československé populace od 6 do 55 let (Československá spartakiáda 1985), (Anthropometry of the Czechoslovak population from 6 to 55 years (Czechoslovak Spartakiade 1985)). ÚNV VS Praha 2. DLABAL, S. 1976: Nábytek člověk, bydlení, (Furniture, people, housing). Praha: Ústav bytové a oděvní kultury DVOULETÁ, K. 2011: Využití antropometrie v oblasti úložného nábytku a nábytku pro práci a stravování. Diplomová práce, Brno, Mendel University in Brno, Faculty of Forestry and Wood Technology NEUFERT, E. 2000: Navrhování staveb: Příručka pro stavební odborníky, stavebníky, vyučující a studenty, (Designing buildings: guide for building professionals, builders, teachers and students). Praha: Consultinvest, ISBN : 14 89

90 Streszczenie: Ergonomiczna weryfikacja wymiarów mebli. Cechy antropometryczne populacji podlegają ciągłym zmianą i stąd też istnieje potrzeba uwzględniania tych zmian w wymiarowaniu mebli. Celem pracy jest aktualizacja wymiarów mebli na podstawie aktualnych danych antropometrycznych. Do realizacji tego celu użyto specjalnego oprogramowania przeznaczonego do symulacji czynności wykonywanych przez człowieka. Pozwoliło to na porównanie wymiarów ciała ludzkiego oraz mebli. Corresponding author: Ing. Jiří Tauber, Ph.D., Ing. Jaroslav Svoboda, Ph.D. Mendel University in Brno, Faculty of Forestry and Wood Technology, Department of Furniture, Design and Habitation, Zemedelska 3, Brno, Czech Republic [email protected] [email protected] 90

91 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Basidiomycetes growing on sleepers reused in small garden architecture BOGUSŁAW ANDRES Department of Wood Science and Wood Protection, Warsaw University of Life Science-SGGW Abstract: Basidiomycetes growing on sleepers reused in small garden architecture. Paper describes results of five-year observations of Basidiomycetes growing on sleepers reused to build garden architecture. Apart from fruit bodies of fungi with already known for capabilities of decomposing creosote-protected wood, some species have been found, not described in the literature so far. Keywords: sleepers, Basidiomycetes INTRODUCION In specialized gardening magazines, handbooks and on Web pages some years ago idea of reusing sleepers for home garden arrangement was commonly proposed. Their natural and original looks and durability caused willing usage as a decorative and constructional elements in the gardens [Skórkowska 2003]. In Poland, sleepers are made of pine, beech or oak wood. In aim to extend lifetime of sleepers in railway subgrades, they are being impregnated with oil [PN-D-95014:1997]. Premature fungi decay of sleepers is usually caused by insufficient or inaccurate saturation with oil. Decay of pine and oak sleepers starts from heartwood [Cartwright, Findlay 1951], because this part is hard or very hard to impregnate [PN-EN 350-2:2000]. Numerous works from the beginning of 20-th century deals with sleepers biodegradation caused by fungi. As most recognized basidiomycetes growing in Poland on sleepers were described such as [Wałek-Czarnecka 1933]: Armillaria mellea (Vahl.) Quél., Coniophora cerebella Pers., Coriolus versicolor (L.) Quél., Corticium sp., Daedalea quercina Pers., Hymenochaete rubiginosa (Dicks.) Lév., Leptoporus destructor (Schrad.) Fr., Lentimus squamosus Schaeff., Lenzites septaria (Wulff.) Fr., Leptoporus erubescens Fr., Irpex fusco-violaceus Fr., Merulius sclerotiorum Falck., Paxilus acheruntus Humb., Peniophora sp., Poria mucida Pers., Poria sinusa Fr., Poria Vaillantii (De Cand.) Fr., Schizophyllum commune Fr., Stereum hirsutum (Willd.) Pers., Trametes serialis Fr., Trametes squalens Karst. and Trametes trabea Pers. Skupieński [1934] found following fungi species growing on used sleepers: Armillaria mellea (Vahr.) Quél., Coriolus versicolor (L.) Quél., Daedalea quercina Pers., Lentinus squamosus Schaeff., Lenzites sepiaria (Wolf.) Fr., Ungulina marginata (Fr.) Pat., Paxillus panuoides Humb., Phellinus robustus Karst., Phellinus igniarius (L., Fr.) Pat., Poria vaporaria Fr. and Xanthochrous pini (Brot.) Pat. Worldwide literature contains many publications about fungi decaying sleepers impregnated with creosote oil: Tuszon [1905], Spraulding [1911], Schorstein [1911], Malvasin [1924] i Liese [1925] [cit. after Wałek-Czarnecka 1933]. None of the following works does not however deal with problematic of fungi growing on reused sleepers. Aim of the following work was to develop inventory of Basidiomycetes class fungi, growing on sleepers reused for garden arrangements. MATERIAL AND METHODS Field tests were performed in CZRB PAN botanical garden in Powsin. Presented area was selected for research because of numerous elements of garden architecture made of sleepers. Building of mentioned botanical garden was made in several stages, so it is hard to precisely determine usage time of sleepers, but this time is roughly estimated at 20 years minimum. 91

92 Four object types made of sleepers were found in botanical garden: Pathways of around 800 m total length, Footbridges, being extension of pathways, of 5 m total length, Slope and flower-bed protection of 70 m total length, Stairs of 90 m total length. Research in CZRB PAN botanical garden in Powsin was made between 2006 and Observations were performed between August and November, in few weeks intervals. Field tests consisted of description, photographical documentation and collection of fungi fruit bodies growing on reused sleepers. RESULTS AND DISCUSSION Table 1 shows checklist of fungi species of basidiomycetes family growing on sleepers reused for garden architecture in CZRB PAN botanical garden in Powsin. Table 1. List of fungi affecting reused sleepers in the Botanical Garden - Center for Biological Diversity Conservation in Powsin. Fungus Year Daedalea quercina (L.: Fr.) Pers. + Gloeophyllum sepiarium (Wulf.: Fr) P. Karst. + Gymnopilus penetrans (Fr.: Fr) Murrill Hymenochaete rubiginosa (Schad.: Fr.) Lév. + + Inonotus triqueter (Fr.) P. Karst. + Lentinus lepideus (Fr.: Fr) Fr. + + Leatiporus sulphureum (Bull.: Fr) Murrill + Mycena galericulata (Scop.: Fr) Gray Paxillus panuoides (Fr.: Fr.) Fr. + + Phlebia tramellosa( Schrad.: Fr) Nakasone & Burd. + Psilocybe fascicularis (Huds.: Fr.) Noordel Schizophyllum commune Fr.: Fr. + Stereum hirsutum (Willd.: Fr) Gray + + Trametes versicolor (L.: Fr.) Pilát + Amongst fungi noticed on sleepers, seven species were described in previous works [Wałek-Czarnecka 1933, Skupieński 1934, Skupieński 1937, Orłoś 1950, Cartwright, Findlay 1951, Ważny 1963, Domański, Orłoś, Skirgiełło 1967, Krajewski, Monder 2006]. Mentioned species were as follows: Daedalea quercina (L.: Fr) Pers., Gloeophyllum sepiarium (Wulf.: Fr) P. Karst., Lentinus lepideus (Fr.: Fr) Fr., Paxillus panuoides (Fr.: Fr.) Fr., Schizophyllum commune Fr.: Fr., Stereum hirsutum (Willd.: Fr) Gray and Trametes versicolor (L.: Fr.) Pilát. Except fungi species of previously stated ability of decaying of wood protected with creosote oil, on the sleepers in botanical garden following species were also found: Gymnopilus penetrans (Fr.: Fr) Murrill., Hymenochaete rubiginosa (Schad.: Fr.) Lév., Inonotus triqueter (Fr.) P. Karst., Leatiporus sulphureum (Bull.: Fr) Murrill, Mycena galericulata (Scop.: Fr) Gray, Phlebia tramellosa (Schrad.: Fr) Nakasone & Burd. i Psilocybe fascicularis (Huds.: Fr.) Noordel. Mentioned species belong to saprotrophs, decomposing dead organic matter, During literature study, presented species were not fund amongst described basidiomycetes growing on sleepers, so these found species do not belong to typical fungi decaying wood protected with creosote oil. One may suppose, that occurrence of mentioned fungi is connected with significant lowering of fungistatic substances in analyzed sleepers. Cause of that is probably continuous washing out of treatment by rain and contact with the ground. CONCLUSIONS 92

93 1. On the sleepers reused for garden architecture following known for decaying creosote protected wood fungi species were found: Daedalea quercina (L.: Fr) Pers., Gloeophyllum sepiarium (Wulf.: Fr) P. Karst., Lentinus lepideus (Fr.: Fr) Fr., Paxillus panuoides (Fr.: Fr.) Fr., Schizophyllum commune Fr.: Fr., Stereum hirsutum (Willd.: Fr) Gray and Trametes versicolor (L.: Fr.) Pilát. 2. On the reused sleepers also not previously found saprotrophic fungi species were noticed: Gymnopilus penetrans (Fr.: Fr) Murrill., Hymenochaete rubiginosa (Schad.: Fr.) Lév., Inonotus triqueter (Fr.) P. Karst., Leatiporus sulphureum (Bull.: Fr) Murrill, Mycena galericulata (Scop.: Fr) Gray, Phlebia tramellosa (Schrad.: Fr) Nakasone & Burd. and Psilocybe fascicularis (Huds.: Fr.) Noordel. REFERENCES 1. CARTWRIGHT K.ST.G., FINDLAY W.P.K. 1951: Rozkład i konserwacja drewna. PWRiL. Warszawa. 2. DOMAŃSKI S., ORŁOŚ H., SKIRGIEŁŁO A. 1967: Grzyby t. III. PWN. 3. KRAJEWSKI A., MONDER S. 2006: Grzyby na torowiskach. Wszechświat, 107 (4-6): ORŁOŚ H. 1950: Grzyby szkodliwe w budynkach i na składach drewna. Wyd. IBL. Warszawa 5. SKÓRKOWSKA A. 2003: Stare, zużyte, ale ładne i praktyczne, czyli podkłady kolejowe w ogrodzie. Murator 3: SKUPIEŃSKI F. 1934: Album ważniejszych grzybów spotykanych na podkładach kolejowych. Wyd. Ministerstwa Komunikacji. Warszawa. 7. SKUPIEŃSKI F. 1937: Czynniki mikrobiologiczne niszczące drewno użytkowe. In: Skupieński F. (red.) Grzyby domowe i inne szkodniki budulca oraz metody i środki walki. Wyd. Polskie Towarzystwo Higieniczne. Warszawa WAŁEK - CZARNECKA A. 1933: Grzyby niszczące podkłady kolejowe w Polsce. Acta Soc. Bot. Pol., vol. X (2): WAŻNY J. 1963: Oznaczanie grzybów domowych. Arkady. 10. PN-D-95014:1997 Nawierzchnia kolejowa. Sosnowe, dębowe i bukowe materiały drzewne nawierzchni kolejowej nasycane olejem impregnacyjnym. 11. PN-EN 350-2:2000 Trwałość drewna i materiałów drewnopochodnych. Naturalna trwałość drewna litego. Wytyczne dotyczące naturalnej trwałości i podatności na nasycanie wybranych gatunków drewna mających znaczenie w Europie. Streszczenie: Basidiomycetes growing on sleepers reused in small garden architecture. W pracy przedstawiono wyniki pięcioletnich obserwacji grzybów należących do podstawczaków występujących na poużytkowych podkładach kolejowych wykorzystanych do aranżacji ogrodu. Oprócz owocników grzybów o uznanych możliwościach rozkłady drewna zabezpieczonego olejem impregnacyjnym stwierdzono również gatunki nie opisane dotychczas w literaturze. Corresponding author: Bogusław Andres, Department of Wood Science and Wood Protection, Warsaw University of Life Science-SGGW, Nowoursynowska 159, Warsaw, [email protected] 93

94 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Resistance of lime wood (Tilia sp.) impregnated with Paraloid B-72 resin against cellar fungus Coniophora puteana (Schum., Fr.) Karst BOGUSŁAW ANDRES, PIOTR MAŃKOWSKI Department of Wood Science and Wood Protection, Warsaw University of Life Science-SGGW Abstract: Resistance of lime wood (Tilia sp) impregnated with Paraloid B-72 resin against cellar fungus Coniophora puteana (Schum., Fr.) Karst. Work deals with resistance of Paraloid B-72 synthetic resin impregnated lime wood against cellar fungus Coniophora puteana. Resin solutions of 5, 10 and 20% concentrations were used. In laboratory conditions, impregnated samples were exposed to fungus for 16 weeks. It was determined that lime wood impregnated with Paraloid B-72 resin is not resistant against fungi. Keywords: Paraloid B-72, Coniophora puteana, weight loss, INTRODUCTION Using of wood in inappropriate conditions leads to its destruction. Natural resistance of wood can be improved by impregnation, which means saturation of wood material with chemicals. Many antique objects, movable as well as architectural elements, because of advanced decay process, requires mechanical reinforcement. In this case, many chemical substances increasing resistance to decay are being used. In te beginning, wood was treated with mineral and plant oils, rosin, waxes, paraffin, aluminum potassium sulfate dodecahydrate, beet or cane sugar. In many cases these substances increased hydrophobic properties and dimensional stability, but could not restore its technical properties (Ważny, Kurpik, 2004). From many years, in aim to strengthen wood structure, many impregnating treatments with resin solutions are being applied. Many researchers dealer with his problem: Domasłowski, (1961), Domosławski and Zaręba (1968), Schaffer (1974), Czajnik i Ważny (1980), Paciorek (1993), Buksalewicz and others (1987), Ciabach (1998), Soldenhoff (2004). Testing of synthetic resins for wood preservation against decay were performed by Czajnik (1968). Goal of the following work was to determine Paraloid B-72 saturated lime wood (Tilia sp) resistance against cellar fungus Coniophora puteana (Schum., Fr.) Karst. In the following work, possibilities of Paraloid B-72 synthetic resin were tested, as treatment preventing of cellar fungus hyphae penetration into lime wood cells. During the test it was determined what solution strength sufficiently prevents fungus growth and increases lime wood resistance against decay. MATERIALS AND METHODS Testing was performed on mm lime wood (Tilia sp.) defect less samples of 500 kg/m 3 density. Research was conducted in accordance to PN EN 113+A2 standard. Cellar Coniophora puteana coming from collection of Division of Wood Protection of Faculty of Wood technology WULS For wood reinforcement Kremer Pigmente GmbH & Co Paraloid B-72 synthetic resin was used (catalogue no 67400) of 5, 10 and 20% solution strength. Dragon toluene was used as a solvent. Samples were impregnated in vacuum thru 30 minutes at 70 mbar. Impregnated samples were seasoned for 1 week. Samples were sterilized by short-term submerging in 70% 94

95 ethyl alcohol solution and overburning with alcohol burner. Mycelium incubation was performed in culturing chamber at 20 and with 70 relative air humidity. Time of fungus activity on tested wood reached 16 weeks. RESULTS AND DISCUSSION Table 1 shows average weight loss in all variants. Highest loss was noticed for control samples, lowest one occurred in samples saturated with 20% Paraloid B-72 solution. Table 1. Percentage weight loss in tested samples Sample type Average resin retention Average weight loss Standard deviation [kg/m 3 ] [%] [%] Control samples 0 62,13 2,94 saturated 5% 61,9 57,15 1,96 saturated 10% 77,6 52,52 1,86 saturated 20% 124,4 43,95 3,86 In aim to test significance of differences between variants of the test, variation analysis was also made. With assumption of normal distribution following statistical hypothesis were formulated: H 0 : m k =m 5% =m 10% =m 20%, H 1: at least two averages differ significantly. Table 2. Solution strength significance analysis on weight loss of samples caused by C. puteana m 0 Variance cause F emp p-value F 0.05 F 0.01 Factor- A 57,5 6,40* ,8 4,22 With the help of Microsoft Office Excel statistics were calculated. Variation analysis showed occurrence of statistically important differences between averages of tested parameters (table 2). With Tukey test, three uniform groups were isolated (table 3). Table 3. Isolation into uniform groups according to Tukey Wood sample variants Control samples saturated 5% saturated 10% saturated 20% Uniform groups a b b c Basing on the obtained results, one may state that saturation of wood with resin hinders fungus hyphae penetration. Amongst samples saturated with resin, lowest weight loss was showed with these impregnated with 20% solution, Tukey test isolated this variant into c 95

96 group. Samples saturated with 5 and 10 % resin solution were classified into single b group, so differences between these variants are statistically insignificant. Except weight loss, visual evaluation of samples decay was made. Figure 1 shows 4 samples showing average weight loss for each test variant. Control samples, not saturated with resin developed numerous, prismatic cracks. Samples fall apart under minimal compression force. Samples saturated with 5 and 10% solution showed similar behavior. Slightly better results were obtained with samples saturated with 20% resin solution, not showing cracks, not falling apart, but easily fracturable. Fig 1. Comparison of samples decayed by cellar fungus: a) control sample, b) sample saturated with 5% solution, c) sample saturated with 10% solution, d) sample saturated with 20% solution. CONCLUSIONS 1. Lime wood impregnated with Paraloid B-72 resin is not resistant against cellar fungus Coniophora puteana. 2. Paraloid B-72 resin restricts penetration of mycelium hyphae. 3. Samples saturated with 20% Paraloid B-72 solution showed lower weight loss than samples treated with 5 and 10 % solutions. 4. Paraloid B-72 resin of 20% solution strength increases fungus resistance of lime wood, but does not protect it in satisfactory degree. REFERENCES 1. BUKSALEWICZ P., GAJDZIŃSKI M., LUTOMSKI K.: Wzmacnianie drewna zabytkowego przy użyciu preparatów Petrifo i Paraloid. W : Zabytkowe drewno, konserwacja i badania, Wyd. PAX, Warszawa 1987, s CIABACH J.: Żywice i tworzywa sztuczne stosowane w konserwacji zabytków. Wyd. Uniwersytet Mikołaja Kopernika, Toruń 1998, s CZAJNIK M.: Badania nad zastosowaniem żywic syntetycznych do zabezpieczenia drewna przed rozkładem powodowanym przez grzyby. W: Materiały Muzeum Budownictwa Ludowego w Sanoku. Wyd. Muzeum Budownictwa Ludowego w Sanoku, Sanok CZAJNIK M., WAŻNY J.: Zastosowanie żywic syntetycznych w konserwacji drewna zabytkowego. Modyfikacja drewna. Zeszyty Probl. Postępów Nauk Rolniczych, 1980, z. 231, s DOMASŁOWSKI W.: Konserwacja drewna pod zmniejszonym ciśnienie. W: Zagadnienia konserwacji drewna. Wyd. Ministerstwo Kultury i Sztuki, Zarząd Muzeów i Ochrony Zabytków, Warszawa 1961, s DOMASŁOWSKI W., ZARĘBA T.: Badania nad ustaleniem optymalnych warunków impregnacji drewna roztworami żywic epoksydowych. Zesz. Nauk. UMK. Zabytkoznawstwo i Konserwatorstwo III, 1968, s PACIOREK M.: Badania wybranych tworzyw termoplastycznych stosowanych do impregnacji drewna. W: Studia i Materiały Wydziału Konserwacji i Restauracji Dzieł Sztuki Akademii Sztuk Pięknych w Krakowie, T III, Kraków

97 8. SCHAFFER E.: Consolidation of Painted Wooden Artifach. Studies on Conservation, 1974, No 4, s SOLDENHOFF B.: Żywice chemoutwardzalne stosowane w konserwacji drewnianych obiektów zabytkowych. W: Ochrona drewna - XXII Sympozjum, wyd. SGGW, Warszawa 2004, s WAŻNY J., KURPIK W.: Konserwacja drewna zabytkowego w Polsce historia i stan badań. W: Ochrona drewna. Mat. z XXII Sympozjum, Wyd. SGGW Warszawa 2004, s PN A2 Środki ochrony drewna. Oznaczanie wartości grzybobójczej wobec rozkładających drewno grzybów Basidiomycetes hodowanych na pożywce agarowej. Streszczenie: Badanie odporności drewna lipy (Tilia sp.) nasyconego żywicą Paraloid B-72 na działanie grzyba piwnicznego Coniophora puteana (Schum., Fr.) Karst. W pracy przedstawiono wyniki badań dotyczących odporności drewna lipy nasyconego żywicą syntetyczną Paraloid B-72 na działanie grzyba piwnicznego C. puteana. Zastosowano żywice o stężeniu: 5, 10 i 20%. W warunkach laboratoryjnych przez 16 tygodni próbki drewna poddane były działaniu grzyba. Wykazano, że drewno lipy nasycone żywicą Paraloid B-72 nie jest odporne na działanie C. puteana. Corresponding authors: Bogusław Andres, Piotr Mańkowski, Department of Wood Science and Wood Protection, Warsaw University of Life Science-SGGW, Nowoursynowska 159, Warsaw, [email protected], [email protected] 97

98 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Chemical studies of ozone impact on pinewood (Pinus sylvestris L.) degradation ANDRZEJ ANTCZAK 1, PIOTR MAŃKOWSKI 1, PIOTR BORUSZEWSKI 2 1 Department of Wood Science and Wood Protection, Warsaw University of Life Sciences SGGW 2 Department of Technology, Organization and Management in Wood Industry, Warsaw University of Life Sciences SGGW Abstract: Chemical studies of ozone impact on pinewood (Pinus sylvestris L.) degradation. The purpose of these studies was verification the impact of ozone on wood degradation. Study the degree of wood degradation was carried out using classical chemical methods content determination of substances soluble in 1% NaOH, extractives and cellulose isolated by Seifert method. Also, in this work modern analytical SEC method was used to determine the polymerization degree of the main wood structural component cellulose. On the basis of these results, it was observed, that ozone increases of the content of substances soluble in 1% NaOH and extractives. This indicates, that the wood structural substances are decomposed: the part of lignin and polysaccharides (hemicelluloses, cellulose) - especially with a low degree of polymerization. On the basis of chromatographic analysis (SEC), it appears that the cellulose of the highest molar mass is also prone to depolymerization. Although the percentage content of the cellulose does not change, but under the influence of ozone comes to qualitative change of cellulose - decrease of polymerization degree. Keywords: ozone, wood degradation, cellulose degradation, SEC, 1% NaOH, cellulose, extractives INTRODUCTION In recent years the interest in ozone as oxidizing substance has grown up. Ozone, for example, is used in pulp bleaching processes. Its bigger interest is related with the introduction of environmental policy, under the influence of which bleaching methods have been developed without the use of elemental chlorine - ECF (Elemental Chlorine Free) and the methods totally free of any chlorine compounds - TCF (totally chlorine free). According to the TCF technology classical chlorine agents are replaced by oxygen bleaching agents: oxygen (O 2 ), hydrogen peroxide (H 2 O 2 ) and ozone (O 3 ). However, the use of ozone in the bleaching processes is not entirely beneficial. It is associated with poor selectivity and heterogeneity of the strong oxidant, which in turn causes degradation not only lignin, but also polysaccharides - even cellulose [Chirat and Lachenal 1994, Simoes and Castro 2001]. Another recently popular direction in wood protection is the use of ozone as a disinfectant agent. Ozone treatments are performed in order to eliminate the biological factors of wood degradation. Ozone eliminates the insects, mites and even mold fungi spores. This method can be used to disinfect the entire building including all its internal objects. Negative side of the ozone application is its impact on the degradation of wood. However, the degree of degradation caused by the use of ozone is incomparable lower than the degree of degradation caused by wood insect and fungi. To a large extent the cause of significant resistance of wood to the oxidizing agent (ozone) is the presence of natural antioxidants (extractives and lignin). Much faster degradation under the influence of ozone occurs for directly exposed cellulose [Antczak 2010]. An additional serious problem associated with ozonization of historic wooden objects could be a risk of irreversible destruction of very valuable ornaments (polychrome), occurring both inside and outside the building. Study the degree of wood degradation can be carried out using classical chemical methods, or by using more complex but more accurate instrumental methods. To the former can include the content determination of substances soluble in 1% aqueous solution of sodium hydroxide (NaOH). It is known, that in dilute solutions of alkali polysaccharides with a low 98

99 degree of polymerization (hemicelluloses and part of cellulose) are particularly susceptible to dissolution. Moreover partially degraded lignin also can be soluble. The increase of content of substances soluble in 1% NaOH, may be evidence of wood degradation process [Fengel and Wegener 2003]. Another chemical method to study the degradation degree of wood is instrumental modern technique - the size exclusion chromatography (SEC). Using the SEC method you can monitor the degree of degradation of structural wood substances such as cellulose, hemicelluloses or lignin. This method gives information about the weight average molar mass (M w ), the number average molar mass (M n ) and also, what is the most important, the molar mass distribution (MMD) of polymeric sample. Moreover, the degree of polymerization (DP) can be obtained. The aim of these studies was verification the impact of ozone on wood degradation. In this work modern analytical SEC method was used to determination the degree degradation of the main wood structural component cellulose. MATERIALS AND METHODS In these studies material from hardwood zone of about 90-year-old pine (Pinus sylvestris L.) was used. Average density of wood used for the study was g/cm 3. To aging tests with ozone, rectangular samples were used, cut along fibers with dimensions (2 x 2 x 3 cm). Ozone treatment was carried out at room temperature (25 C), about 40% relative humidity, in closed vessel (desiccator) and in the flow system (continuous gas supply - air). To obtain the ozone, generator of A2Z Ozone Systems company was used. During the ozone treatment the gas supply flow (air / O 3 ) was 1dm 3 /min. Iodometry method was used to determine the percentage content of generated ozone in the air, which was 0.4% w. Aging time of wood samples in the ozone atmosphere was 7 and 14 days. In the presented time intervals samples were collected to examine the degree of wood degradation. To examine the degree of wood degradation by chemical methods, the samples were ground using a laboratory mill SM100 (Retsch company). Sawdust fraction passing the sieve with 1.02 mm and remaining on 0.49 mm mesh sieve was used. The following tests were performed to investigate the degradation of wood under the influence of ozone: - determination of low-molecular substances content soluble in organic solvents (chloroform ethanol mixture: 93-7 % w ) [Antczak et al. 2006] - determination of substances content soluble in 1% NaOH [Krutul 2002] - determination of cellulose content according to Seifert method [Krutul 2002] - determination of polymerization degree of cellulose by SEC analysis SEC analysis Preparation of cellulose samples to analysis In order to study cellulose degradation in aged wood, cellulose was isolated by Seifert method. Then dried at 105 C cellulose samples were submitted to activation and dissolution procedure. The procedure was carried out in vacuum Baker system SPE-12G and was as follows: - cellulose samples (15 mg) were placed in test-tubes (6 ml), poured distilled water (3 ml) and allowed to swell overnight; - next day the samples were carried to capillary tubes and subsequently washed with methanol, filtered and poured the next portion of methanol and left for 1 hour; this procedure with methanol was repeated twice; 99

100 - after that, the samples were washed with N,N-dimethylacetamide (DMAc), filtered and poured the next portion of DMAc and left for 1 hour; this procedure was repeated and cellulose with DMAc was left untill the next day; - next day, the samples were filtered and poured 8% lithium chloride (LiCl) in DMAc (4 ml); - cellulose dissolution in 8% LiCl/DMAc was realised using mixer (RM-2M, Elmi company); - after 1-2 days of dissolution, part of the sample (0.2 ml) was diluted to 0.5% LiCl concentration with pure DMAc (3 ml); - finally, prepared samples were submitted to SEC analysis. Conditions of SEC analysis SEC analysis of cellulose samples was carried out with using HPLC (High Performance Liquid Chromatography) system (LC-20AD, Shimadzu company), which was equipped with differential refractive detector (RID 10A, Shimadzu), pump (LC-20AD, Shimadzu) and oven (CTO-20A, Shimadzu). SEC analysis conditions were as follows: - 0.5% LiCl/DMAc as eluent - column crosslinked polystyrene-divinylbenzene gel (PSS GRAM 10000, 10µ, mm) connected with guard column (PSS GRAM 10µ) - oven temperature: 80 C - flow rate: 2ml/min - injection volume: 200µl The chromatographic data were processed with PSS WinGPC scientific 2.74 software. Twelve narrow molecular weight polystyrene standards (Polymer Laboratories) were used to calibrate the column. The polystyrene standards were prepared as mixed standards in four separate solutions in DMAc. The first standard solution contained polystyrene of the following peak molecular mass: , and Da, the second contained: , and Da, the third contained: , and Da, and the fourth contained: , and 580 Da. This polystyrene standards were used to calculate molecular mass of cellulose according to Mark-Houwink universal calibration: [η]=k M α, where K and α are parameters, which depend on polymer type, solvent and temperature. For our chromatographic conditions, that parameters are the following: for polystyrene K= cm 3 /g and α=0.642 [Timpa 1991] and for cellulose K= cm 3 /g and α=0.957 [Bikova and Treimanis 2002]. RESULTS AND DISCUSSION In Fig. 1, 2 and 3 the impact of ozone on the percentage content of substances occurring in pinewood was presented. On the basis of results can be observed degrading effect of ozone on the wood. Strongly oxidative gas atmosphere (0.4% of ozone in air) initiates the degradation of structural wood components (especially substances with the low degree of polymerization). Evidence of this is increase of the content of substances soluble in dilute alkali (Fig. 1). The increase is the greatest at the beginning of ozonization (within the first week). In relation to the control sample, after one week of ozonization, the content of substances soluble in 1% NaOH is 2.5 times greater. Prolongation of ozonization to two weeks does not cause a significant increase in this parameter. Certainly, at the beginning depolymerization reaction of the wood structural components occurs in the most easily accessible areas for ozone (amorphous regions). Subsequently, less accessible areas are 100

101 attacked, which is associated with a slower course of degradation reaction and a lesser increase of substances soluble in dilute alkali. substances soluble in 1% NaOH content [%] ,1 control 29,9 after 1 week ozonation 32,4 after 2 weeks ozonation sample type Fig. 1. Ozone influence on the content of substances soluble in 1% NaOH from pinewood (Pinus sylvestris L.) The unfavourable effect of ozone on the wood is also reflected in the increasing content of low molecular soluble substances in a mixture of organic solvents (chloroform - ethanol: 93-7%). Fig. 2 shows percentage content of wood extractives in pinewood (Pinus sylvestris L.), which has been subjected to ozone. Two-week ozonization (0.4% of ozone in air) causes an increase in low molecular substances content. This demonstrates the gradual disintegration of the structural substances: lignin and polysaccharides (hemicelluloses, cellulose) - probably with a low degree of polymerization from amorphous regions. 8 6,7 extractives content [%] ,1 5,3 0 control after 1 week ozonation after 2 weeks ozonation sample type Fig. 2. Ozone influence on the content of extractives from pinewood (Pinus sylvestris L.) Fig. 3 shows percentage content of cellulose separated by Seifert method fr om pine wood. Cellulose separated by Seifert method represents a polysaccharides fraction from wood 101

102 with the highest degree of polymerization. Two-week ozonization (0.4% of ozone in air) practically does not change the percentage content of cellulose. 60 cellulose content [%] ,7 44,0 44,2 0 control after 1 week ozonation after 2 weeks ozonation sample type Fig. 3. Ozone influence on the content of cellulose from pinewood (Pinus sylvestris L.) Interesting results were obtained in the SEC method. The weight average m olar mass and polymerization degree of cellulose isolated from pinewood by Seifert method were determined (Fig. 4). 3, (Mw/Da) ,2 3 2, P w weight average molar mass weight average polymerization degree 2,6 control after 1 week ozonation after 2 weeks ozonation sample type 1600 Fig. 4. Ozone influence on the weight average molar mass and polymerization degree of cellulose isolated from pinewood (Pinus sylvestris L.) by Seifert method Based on chromatographic results presented in Fig. 4, it can be concluded that under the influence of ozone occurs to initiate a degradation process of cellulose. Using the molar mass distribution curves (Fig. 5), it appears that the initial depolymerization process may undergo even a cellulose fraction of the highest molar mass. In Fig. 5 it can be observed a gradual decrease in the content of cellulose fraction of the highest molar mass (range Da). 102

103 On the other hand there is a gradual increase in the content of cellulose fraction of lower molar mass (range Da). after 2 weeks ozonation after 1 week ozonation detector signal/conventional unit increase control sample decrease molar mass/da Fig. 5. Molar mass distributions of ozonated cellulose isolated from pinewood (Pinus sylvestris L.) by Seifert method Such a course of cellulose degradation process under the influence of ozone explains the lack of change in the percentage content of cellulose with the highest degree of polymerization presented earlier in Fig. 3. Published literature information confirms, that as a result of ozonization, begins to cleavage of the glycosidic bond in the cellulose chain [Simoes and Castro 2001, Lemeune et al. 2004]. The consequence of this is a decrease of the polymerization degree of cellulose. Lowering the cellulose molar mass is very undesirable phenomenon because it is associated with a decrease in wood strength. This may eventually lead to total destruction of a wooden object. SUMMARY AND CONCLUSIONS Ozone as a substance with a very high oxidizing potential causes gradual degradation of pine wood. Under the influence of ozone increases the content of substances soluble in 1% NaOH and extractives. This indicates, that the wood structural substances are decomposed: the part of lignin and polysaccharides (hemicelluloses, cellulose) - especially with a low degree of polymerization. On the basis of chromatographic analysis (SEC), it appears that the cellulose of the highest molar mass is also prone to depolymerization. Although, the percentage content of the cellulose does not change (quantitative composition before and after ozonization practically the same), but under the influence of ozone comes to qualitative change of cellulose (decrease of polymerization degree). In summary, the use of ozone in the context of cellulose and wood is always associated with degradation process. Poor selectivity and strong oxidizing properties of this substance may contribute to the total destruction of the cellulosic material or wood. This phenomenon is particularly undesirable when dealing with objects of high historical value. Thus, the use of 103

104 ozone to the pulp and wood materials should be done only in justified extreme cases, and in the shortest possible time. REFERENCES 1. ANTCZAK, A. (2010). Wpływ substancji stabilizujących na degradację celulozy drewna sosny zwyczajnej (Pinus sylvestris L.). Praca doktorska, SGGW, Warszawa. 2. ANTCZAK, A., RADOMSKI, A., ZAWADZKI, J. (2006). Benzene Substitution in Wood Analysis. Annals of Warsaw Agricultural University, Forestry and Wood Technology, 58, BIKOVA, T., TREIMANIS, A. (2002). Problems of the MMD analysis of cellulose by SEC using DMA/LiCl: A review. Carbohydrate Polymers, 48, CHIRAT, C., LACHENAL, D. (1994). Effect of ozone on pulp components application to bleaching of kraft pulps. Holzforschung, 48, FENGEL, D., WEGENER, G. (2003). Structure and Ultrastructure, In Wood Chemistry Ultrastructure Reactions, Walter de Gruyter, Berlin, Germany. 6. KRUTUL, D. (2002). Ćwiczenia z chemii drewna oraz wybranych zagadnień chemii organicznej, SGGW, Warszawa. 7. LEMEUNE, S., JAMEEL, H., CHANG, H.-M., KADLA, J. F. (2004). Effects of Ozone and Chlorine Dioxide on the Chemical Properties of Cellulose Fibers. Journal of Applied Polymer Science, 93, SIMOES, R., CASTRO, J. (2001). Ozone depolymerization of polysaccharides in different materials. Journal of Pulp and Paper Science, 27(3), TIMPA, J.D. (1991). Application of universal calibration in gel permeation chromatography for molecular weight determinations of plant cell wall polymers; cotton fiber. Agrric. Food Chem., 39,

105 Streszczenie: Badania chemiczne wpływu ozonu na degradację drewna sosny (Pinus sylvestris L.). Celem badań była weryfikacja wpływu ozonu na degradację drewna. Badanie stopnia degradacji drewna zostało przeprowadzone przy użyciu klasycznych metod chemicznych oznaczanie zawartości substancji rozpuszczalnych w 1% NaOH, substancji ekstrakcyjnych i celulozy wyodrębnionej metodą Seiferta. Ponadto, w tej pracy do wyznaczenia stopnia polimeryzacji głównego składnika drewna celulozy wykorzystano nowoczesną technikę analityczną (SEC). Na podstawie wyników zaobserwowano, że pod wpływem ozonu dochodzi do wzrostu zawartości substancji rozpuszczalnych w 1% NaOH i substancji ekstrakcyjnych (małocząsteczkowych). Wskazuje to na rozpad substancji strukturalnych drewna: część ligniny i polisacharydów (hemiceluloz, celulozy) szczególnie o niskim stopniu polimeryzacji. Na podstawie analizy chromatograficznej (SEC) okazuje się, że również celuloza o najwyższej masie cząsteczkowej jest podatna na depolimeryzację. Pomimo, że procentowa zawartość celulozy nie ulega zmianie, to pod wpływem ozonu dochodzi do jakościowej zmiany celulozy spadku stopnia polimeryzacji. Corresponding authors: Andrzej Antczak, Piotr Mańkowski Department of Wood Science and Wood Protection, Warsaw University of Life Sciences (SGGW) ul. Nowoursynowska 159, Warsaw, Poland [email protected] [email protected] Piotr Boruszewski Department of Technology, Organization and Management in Wood Industry, Warsaw University of Life Sciences (SGGW) ul. Nowoursynowska 159, Warsaw, Poland [email protected] 105

106 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Application of artificial intelligence in the wood industry BOGUSŁAW BAJKOWSKI Department of Mechanical Woodworking, Warsaw University of Life Sciences - SGGW Abstract: Application of artificial intelligence in the wood industry. Computer performance is to carry out the tasks arising from the algorithm. Artificial Intelligence is to create a machine that mimics human thinking. The study characterizes the various systems of artificial intelligence and their application in the woodworking industry. Keywords: artificial intelligence, wood industry INTRODUCTION The history and development of artificial intelligence systems can be distinguished from the knowledge base called ekspert systems, controllers with fuzzy logic, artificial neural networks, genetic algorithms and hybrid systems, such as a combination of neural networks with genetic algorithms. CHARACTERISTICS ARTIFICIAL INTELLIGENCE SYSTEMS Expert Systems are complex computer programs from the encoded knowledge of people - experts in the field. The decision in expert systems is taken on a subsequent election to the most accurate comparison of the situation to the system resources. Working the system is thus not exactly as a man - an expert who can decide not only on the basis of familiar patterns and rules, but also intuition and experience. Another disadvantage of the expert system is the need to process a large number of parameters needed to strictly define the situation. Fuzzy Logic responds to the need to define vague terms, or even abstract. Machine, whose task is turning on the lights after dark, it is easy to adapt to the task: "If the light intensity is x, then attach lighting". In everyday life we do not use too often, however, numerical terms. As a rule, we want the machine was able to accomplish the task: "When it gets dark a light switch". Fuzzy logic is just clarifying concepts such as "When it gets dark". For several years there is an increasing number of application drivers whose working principle is based on fuzzy logic. They are implemented successfully for both household use and for complex processes. Genetic Algorithms algorithms are modeled on the mechanisms of natural selection and heredity. In every generation there arises a set of new organisms, created from fragments of the fittest organisms of the previous generation. The basis for the functioning of the genetic algorithm is a computerized imitation of a chromosome. It is usually a string by pre-specified length, subject activities simulating the process of evolution. All activities are dependent on "environment" as to whether the chromosomes will survive or not depends on the particular method of assessing how well they excel in your environment. Genetic algorithm works in several stages. The first step is to generate a population of chromosomes. The next step is the process of evaluation of each chromosome from the generated population. Depending on the outcome of this assessment, the system selects the best suited to this environment chromosomes and combines them in pairs, simulating the reproductions, or creating new chromosomes, which are a random combination of individual elements of "parents." In addition, the new chromosomes are subjected to a simulated mutation / substitution of a string of random elements / and the units do not meet environmental requirements after a while they die. 106

107 The most popular system of artificial intelligence is neural networks. The neural network is a simplified model of the brain. It is capable not only to the inference based on clear evidence and act in accordance with the agreed schedule, but also to remember, clear facts and make their own decisions. Neural network - like the brain - is composed of neurons connected to each other in different schedules /in neural network in this role satisfy simple processors/. It has many entry points, for which information is transmitted from the external world / are mostly simple figures /, and many outputs points, which occur when processing information. The result of the network is a system of information on output, so the network operates on the principle of separation and sorting, and not data processing. Adaptation of the neural network to solve a particular task is carried out through its learning using the standard stimuli and the corresponding desired response, rather than clarify the algorithm and save it as a program, as with traditional methods. The result is that neural networks are used where the use of traditional methods encounter great difficulties, especially in tasks requiring matching of information, such as the prediction, diagnosis, classification and diagnosis. Other frequently encountered application of neural networks relate to robotics, automation and optimization problems. In technical applications are used primarily single-cell many-layered networks. Figure 1 shows an example of such a network. Marked with circles and segments connecting the neurons represent the weighted connections, where information flows only one way. Fig. 1. Unidirectional layer neural network The network performs a nonlinear function depending on the output from the input whose shape is appropriately adjusted during the learning process. Well-designed neural network is able to "learn" the approximate any function of many variables. In the process of learning network, practically speaking, it creates a statistical model of a recognized relationship. Furthermore, neural networks are well placed to process data that contain noise or are incomplete. Improved process control of drying process on the measurement of wood moisture content is to use expert systems, Figure 2 (Laco, Čičel 1991, Malawka 1996, Larsson, Moren 2003). The source of knowledge is a human-expert / in our case, knowledge of lumber drying and automatic control of continuous processes / encoding of this knowledge deals with the 107

108 system designer, and computer generated solutions. How to deal expert system is similar to the process of finding a solution for professionals working in the field. However, in the traditional methods it is necessary to conduct the precise wording of the algorithm solve the problem. Fig. 2. Block scheme of control system of the dryer with the use of expert system: 1 - dryer chamber. 2 - timber in the dryer, 3 - controller, 4 - computer, 5 - expert system, 6 - operator The wood industry has increased the number of research in which computer-assisted image-processing systems are used for automatic visual inspection. First promising results were obtained when detecting holes knots, cracks, resin pockets, etc. One takes place also also the classification of wood in the structure of machined surface. This is important, for example, to sort parguet blocks ( Hand sorting eg oak parquet blocks is made by the following criteria: natural oak, band oak, rustic oak. These same principles also used with automatic classification of parquet blocks. The foundation of this course of action is to characterize the surface by analyzing the characteristics of wood, consisting of 128 elements. Applied to describe the global characteristics of machined surface structure, while local changes are largely not taken into account. Analysis of characteristics allows for proper classification of parquet bloks. As a classifier, on the basis of the characteristics of wood, using neural network. This network has the capacity to adapt quickly when changing the product or product classes. The importance of the sawmill industry has the proper classification of lumber. The implementation of the automatic classification of timber due to the presence of knots using neural networks ( / smog / knotclass / smoeng.html). Knots have been divided into seven classes. The point is classified based on the code of knot shape using the appropriate filter. The signal from the filter is the input to the neural network. Neural network output signal is information on the degree of suitability for further processing boards. Detection of internal structural defects in the logs on the principle of defectoscope is used in recent years increasingly. Most of this is used for computed tomography, to obtain information on the location, size and type of internal defects in logs ( In order to automatically interpret the information received from the scan log apply neural network, which provides the operator saw the data needed to perform the right decision sawing. In order to determine the blunt blade tool analyzes the sound during the cutting of wood on the machine. The intensity of the sound caused by hitting the blade in the wood depends on its degree of blunting. During operation, the tool changes to both the intensity of the emitted acoustic signal, and how the spectrum. Observing the change in the level of the 108

109 acoustic signal intensity and spectral characteristics of the changes determines the condition of cutting tool wear. For the identification of tool wear indicator used a neural network ( On the basis of changes in the intensity of the acoustic signal and its frequency spectrum changes in the neural network identified three stages of tool wear. This gives the opportunity to assess the degree of cutting tool wear without interrupting the machining process. This is important in automated machining systems. The density of wood chips is an important factor in the quality and efficiency of the pulp. Using neural network predicted the scattering density chip, depending on the characteristics of crop and trees (Schultz, et al., 1998). Four groups of age of stand, five classes of diameter at breast height (breast height diameters) and three fixed position tree trunks were used as inputs of neural network. The analysis found to be higher density chips were manufactured by the younger stands, and the lowest position of the trunk. On this basis, the simulator was designed to predict the performance of pulp, depending on the characteristics of the stand. When the control quality of construction should take account of their strength by controlling the elasticity of wood materials, expressed in terms of elastic modulus. The dynamic modulus can be determined by examining the phenomena of wave propagation in a vibrating sample. Forced oscillations in the sample raises through ultrasound waves or impulse hammer with a hammer striking the forehead of the sample. For the classification of pieces of wood used neural network ( Network input parameters are the resonant frequency of vibration, wave propagation velocity, humidity, density, shape and dimensions of samples. At the output of neural network we obtain a signal indicating the value of dynamic modulus of elasticity. CONCLUSIONS There are several significant disadvantages of expert systems. Expert systems do not have the skills to learn, generalize solutions, also can not properly respond to the noisy, incomplete, or previously unknown information. Also, fuzzy systems are not systems of learning: "knowledge" that contain placed there by experts in other fields. Genetic algorithms are primarily used in the optimization techniques. The condition for efficient use of neural networks is considerable knowledge and experience in the field of neural networks, as well as in discipline, in which networks are to be applied. The wood industry is increasingly used various methods of artificial intelligence, especially neural networks. 109

110 REFERENCES 1. FUJII, YOSHIHISA, et al., 1995: Pattern Recognition of Sound in Wood Cutting with Neural Network KOSMOL J.: 1996 Laboratorium z układów pomiarowo-kontrolnych i diagnostycznych. Politechnika Śląska, Gliwice 3. LACO D., ČIČEL M., 1991: Riadenie sušenia reziva s využitim počitačového expertného systému. Drevo 6 4. LARSSON R., MORĖN T., 2003: Implementation of Adaptive Control Systems in Industrial Dry Kilns. 8 International IUERO Wood Drying Conference 5. MULAWKA J., 1996: Systemy ekspertowe. WNT, Warszawa 6. RAJCIC V., 1998: Neural Network for Classification Based on Non Destructive Testings RECKNAGEL M., : Sortierung von Parkettlamellen mit neuronalen Netzen ROBERTS G., 1999: Inteligentna mechatronika. Pomiary Aytomatyka Robotyka, SCHMOLDT, LI, ABBOTT: Log Defect Recognition Using CT-images and Neural Net Classifiers SCHULTZ E. B., et al.,!999: A neural network model for wood chip thickness distributions. Wood and Fiber Science. Vol. 31,1 11. SMOLANDER S.: Classification of unprocessed timber with neural methods. Streszczenie: Zastosowanie sztucznej inteligencji w przemyśle drzewnym. Działanie komputera polega na wykonywaniu zadań wynikających z zastosowanego algorytmu. Sztuczna inteligencja /Artificial Intelligence/ polega na stworzeniu maszyny naśladującej myślenie człowieka. W pracy scharakteryzowano różne systemy sztucznej inteligencji oraz ich zastosowanie w przemyśle drzewnym. Corresponding author: Bogusław Bajkowski Wood Mechanical Processing Department, Wood Industry Mechanisation and Automation Institute, Warsaw University of Life Sciences - SGGW Warsaw, Nowoursynowska 159 str. Poland [email protected] 110

111 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Computer techniques in automatized wood industrial company BOGUSŁAW BAJKOWSKI Department of Mechanical Woodworking, Warsaw University of Life Sciences - SGGW Abstract: Computer techniques in automatized wood industrial company. One analysed technicses computer in automatized wood industrial company. One ascertained the necessity of the usage of the computer technics on all surfaces of the activity of the firm. Only like this the firm can quickly react on needs of receivers. The special attention one ought to turn on the use of the computer technics in production. Keywords: integrated manufacturing, CIM, FMS INTRODUCTION On purpose the present firm is the production of products gode in the short time, at small costs. It there is subjected to considerable pressures externa and internal. On one hand this is the incessant height of costs of the production consequential from enlarged costs of the energy, materials and the labour. On the other hand the intensification of the competition, the height of requirements of customers and the market. The uncertainty, what carry with themselves constringenting markets and the shakiness of the capital causes that the present firm must quickly react on needs of the market. The position of the firm on the present market represents the drawing 1. Fig. 1. The position of the firm on the present market The present market is a market of the customer, and not as before a market of the producer. He seeks corner variants of the same article eg. tables in different colours, couches with different the upholstery etc. does not interest him the large-scale production which does not make possible the free choice. 111

112 The life cycle of the article consists of three phases: phases of the projection, the phase of the production and the phase of the use. Because all the time appear on the market new products the phase of the use all the time it surrenders to the shortening. The extension of the time production the new article drives so to the loss of the market rating. In such situation the computer technics is indispensable on all surfaces of the activity of the firm. The computer aid moves in all activities of the firm, to begin from plannings and the construction, and having finished on the dispatching of ready made products. COMPUTER TECHNICSES 1. Production Planning and Control PPC. Is this production planning and the control her so, so that products become produced in planned time-limit and complied with requirements qualitative at least costs of the production. Within the framework of production plannings one executes three main assignments : - the planning of the programme production, - the planning of the application of materials, - the planning of time-limits and weights of machines /of workplaces/. 2. Computer Aided Design CAD, the computer aid of the projection of the construction. The full process of the construction consists of three phases: - the conceptional phase - the utilization CAD is still in the country all the time very not large, - phases of the projection - the utilization CAD is not large, - phases of the preparation of the records - the utilization CAD greatest. Systems CAD can be integrated with other systems eg. with the system to generating of programmes on machine tools CNC, with the system to the analysis of the computational construction - most often calculations FEM - Finite Element Method. At present the time of draughtsmen CAD slowly draws to end. Now the skill of very efficient drawing no longer is sufficing. Generally, follows the retreat from tools drawing toward of applications helping the work of the constructor. The application grows on constructors knowing such programmes as eg. CATIA, PRO/E etc. Simple programmes drawing of course will survive, to find to themselves niches too narrow for advanced packs Cax Integrated Manufacturing. 3. Computer Aided Planning or Computer Aided Process Planning CAP,CAPP - the computer aid of the planning. This is the process of the transformation of raw material /of the semimanufactured article/ into the ready product complying with requirements definite in the project. A result of the work of the technologist is worked out technological records. She contains data about the technological gear, manners of fastening of objects worked, technological surpluses, tolerances of the realization, tools, parameters of the machine cutting, machine tools, technological devices etc. Computerly the helping planning considerably makes easy and shortens the time of the preparation of the technological records. 4. Computer Aided Quality Control CAQ. It serves to the continuous estimation of the quality of the product and processes of his production from first phases of the formation, until the final inspection of the functionality of the product. Makes possible the success of the agreement of technological foundations with obtained exactitude of the tooling and the assembly. At the estimation of the quality of the production the large part play systems of the statistical control with the process eg. the diagram Pareto, the time sheet, the histogram etc. 5. The computer technics in production - CAM /Computer Aided Manufacturing/. The use of the computer technics in production is dependent on from the degree of her automatization and embraces the aid computer controls of machines and devices and their 112

113 programming by means the computer. Systems CAM embrace all practical systems in production. To reckon them one ought controlled machine tools numerally, industrial robots, forwarding systems, systems controlled stockpilings by means computers. A name CAM is also embraced programming technique of machine tools and controlled devices numerally by means the computer. The use of the computer technics in production one ought to examine with reference to two different types of the organization production: - when each machines or technological devices are not related into the system of the production, - when machines and technological devices create the system of the production. In the first case will appear single machines and technological devices conventional and controlled numerally, and the computer aid of the production will limit itself to the preparation of processings and programmes of the control on each machine tools. In the case, when machines create the system production, computer systems helping the process of the production must be with themselves integrated. They come into being then so-called Flexible Manufacturing System FMS. The Flexible Manufacturing System this is the arrangement of machine tools CNC /Computer Numerical Control/ joint automatized forwarding system, administered by the central sensor-based computer of control work of machines and the forwarding system. Thanks to the computer control is possible the quick change of the programme of the work of productive devices, in accordance with changing assignments. The idea of the elastic productive system is connected first of all with processes of the mechanical tooling of elements. In the dependence from the number and the kind of machines, their destinations and the spatial distribution one can favour following basic types of elastic productive systems. Fig. 2. Flexible manufacturing cell The Flexible manufacturing cell /Fig. 2/ is a most simple type of the elastic productive system. Consists of one machine tool about the control of the type CNC /is usually this manufacturing centre/, equipped into changers of tools and elements and bufora of goods for further processing and worked elements. Clever he is to work partly without the service. With the whole steers the superior computer - the computer of the module. In the wood industry, by means elastic productive modules is executed tooling of frame- constructions on millingmachines CNC and edging of record- furniture- elements. 113

114 Fig. 3. Flexible productive socket The Flexible productive socket /Fig. 3/ consists of several productive connected modules with the certain kind of the article or the integrated processing mutually across the transportation, the stockpiling and the common computer control. Fig.. 4. Flexible production line The Flexible production line /Fig. 4/ this is the gathering of specialistic machines seated in compliance with an order of the exercise of the operation. Works similarly as automatic production line, differents however from her with the ability to frequent and quick rearmings. Thanks to the use of machine tools CNC of the act of rearming of the line limit themselves to the retooling, tooling handles and programmes of the tooling. The flexible productive net in general consists of several mutually related lines, nests or single modules. This is the most composite kind of the elastic productive system. The strategy of the computer integration of the industrial company well-known under the name CIM /Computer Integration Manufacturing/, consists in the connection of all divisions of the firm with the network computer. During the realization of systems CIM were met on following problems: the necessity of the full automatization in the area production and the lack of the compatibility of computer systems serving different functions of the firm. In the reality present solutions CIM are in the most island solutions, i.e. refer not the all firm, and only his chosen areas. The integration of methods CIM in the firm should make for creations fully automatized and computerized factory of the future. CONCLUSIONS The firm perhaps quickly to react on needs of receivers to use computer technicses on all surfaces of the activity of the firm. The special attention one ought to turn on the use of the computer technics in production. 114

115 REFERENCES 1. BAIER A., et al., 1997: Techniki komputerowe w projektowaniu procesów wytwórczych. Prace Naukowe Instytutu Technologii Maszyn i Automatyzacji Politechniki Wrocławskiej, Wrocław 2. CHLEBUS E., 2000: Techniki komputerowe CAx w inżynierii produkcji. WNT, Warszawa 3. SANTAREK K., STRZELCZAK S., 1989: Elastyczne systemy produkcyjne. WNT, Warszawa 4. SKOŁUD B., 1997: Komputerowo zintegrowane wytwarzanie. Wyd. Politechniki Śląskiej, Gliwice 5. WEISS Z., 1998: Techniki komputerowe w przedsiębiorstwie. Wyd. Politechniki Poznńskiej, Poznań Streszczenie: Techniki komputerowe w zautomatyzowanym przedsiębiorstwie drzewnym. Przeanalizowano techniki komputerowe w zautomatyzowanym przedsiębiorstwie drzewnym. Stwierdzono konieczność stosowania techniki komputerowej na wszystkich płaszczyznach działania przedsiębiorstwa. Tylko w ten sposób przedsiębiorstwo może szybko reagować na potrzeby odbiorców. Szczególną uwagę należy zwrócić na zastosowanie techniki komputerowej w produkcji. Corresponding author: Bogusław Bajkowski Wood Mechanical Processing Department, Wood Industry Mechanisation and Automation Institute, Warsaw University of Life Sciences - SGGW Warsaw, Nowoursynowska 159 str. Poland [email protected] 115

116 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Studies regarding the influence of forces and torques on the quality of surfaces obtained at wood drilling S. M. BARBU 1, L.A.M.BADESCU 2, L. JAVOREK 3 1,2 Wood Machining Center of Excellence, Transilvania University of Brasov, Romania 3 Department of Woodworking Machines and Equipment, Faculty of Environmental and Manufacturing Technology, Technical University in Zvolen, T. G. Masaryka 24, Zvolen, Slovakia Abstract: The paper presents some results and discussions regarding the influence of forces and torques on the wood drilling in radial, longitudinal and tangential section on surfaces qualities obtained using helical drills with diameter 10 mm. Surface quality was analyzed in two ways: the appearance of the surface hole (entry and exit of the drill from the workpiece) and processed surface roughness. Keywords: Beech, Forces, Torques, Helical drill, Quality, Surface roughness INTRODUCTION Starting from the hypothesis that the quality of processed surface is influenced by the variation of forces and torques during the process (namely: the size of forces have an influence on the processed surfaces roughness and affect the appearance of the surface when the drill entry and exit from the workpiece), the authors of the paper presents some results obtained on the basis of research on these issues. METHOD AND EXPERIMENT To carry out the experiment was designed a physical analogue model (measurement of dynamic parameters (F, P) using models that kinematic parameters (v c, v f ) are reduced-scale (F = f (v c, v f ) P = f (F, v c )), but still retains the original system ratio (v c / v f )), using tangible representation. Nomenclature v c v f n F M cutting speed feed rate (feed speed) rotational speed force torque moment A. Determination of forces and torques in drilling Equipment and materials Test bench for determination consists of: FUS-22 milling machine, FT 100 device for measuring forces and torques in drilling, FT 100 amplifier, National Instruments NI USB data acquisition board and a torque key. (Fig.1) For making the holes it was used a helical drill plated with CMS with cylindrical shaft flattened 10 mm diameter, with two channels, the top angle 2 r = 60 0 and the propeller angle ω = From beech timber with 8-12 % humidity was cut samples in radial, longitudinal and tangential section with the size L x W x T= 50 [mm] x 19 [mm] x 25 [mm]. 116

117 Working method The determination was taken by the following steps: - Before starting the work the amplifier was left to go 30 minutes to stabilize the temperature, during that time was checked the working parameters. - Each sample was collected in the device with a torque key with the same force of 9,58 N. - Each sample was carried a hole, and for each working parameter were performed five repetitions. - Experiments were performed in these working conditions: speed 345, 550, 874 and 1371 rot/ min and feed rates 100, 160 and 250 mm/min. - Before measuring the values for forces and moments from the amplifier, these values were brought back to zero. - Measurement frequency is 172 Hz per second (we have a value at seconds) - Data obtained were acquired in Excel using an application in LabView software - The values for forces and torques were recorded in volts, and the conversion in Nmm was done by multiplying registered values with for torques and in N by multiplying the values with 400 for forces, for the case when the amplifier was set to 10. Hamburg a Aplificator FT 100 b FT 100 devices type Gunt- c d e Fig 1. Equipment used for testing: a. Experimental bench for determination of the forces and torques during drilling b. FT 100 devices for measuring forces and torques during drilling c. FT 100 Aplificator d. National Instruments card NI USB-6210 data acquisition e. Kit torque keys B. Equipment for determining the surface roughness processed The drilled surface roughness was measured with Mitutoyo roughness type SJ-201P with PC connection and for acquisition and filtering data was done using software Surftest SJ-201P ver Working method To obtain more conclusive results, the measurement of surface roughness at wood drilling was made in 8 points for each hole by rotating the sample with a period T = 45 and on depth of the hole in three points H1, H2 and H3. For roughness measurements was chosed the wavelength l = 0.8 mm (without damaging the hole), length of assessment contains five lengths of the n=5 and 50 PC filter (Gaussian). 117

118 The analysis of surfaces roughness was made by measuring parameters roughness Ra, Rz and Rq. The experimental model designed through tangible representation for measuring the roughness is proposed a patent in consequently can not be presented in this article. RESULTS A. Forces and torques In figure 2 is showed the variation of forces, torques and surface roughness of the drilling of beech in radial and longitudinal section for the feed rate 250 mm/min depending on the speed. Variation of forces (F) and torques (M) of longitudinal beech drilling according rotation speed and feed rate 250mm/min M [Nmm], F[N M F Rotation speed [rot/min] The variation of surface roughness of longitudinal beech drilling according rotation speed for feed rate 250 mm/min Surface roughness Ra, Rz Ra Rz Rq Rotation speed [rot/min] 118

119 Variation of forces (F) and torques (M) of radial beech drilling according rotation speed and feed rate 250mm/min Mt [Nmm], F[N Mt F Rotation speed [rot/min] The variation of surface roughness of radial beech drilling according rotation speed for feed rate 250 mm/min Surface roughness Ra, Rz, Rq Ra Rz Rq Rotation speed [rot/min] Fig. 2. The variation of forces, torques and surface roughness of the drilled beech in radial and longitudinal section for the feed rate 250 mm / min depending on the speed. B. The state of surfaces In figure 3 is showed the surface appearance at the entry and exit of the drill from the workpiece (beech) cutted in tangential section (a), longitudinal (b) and radial (c) at the feed rate 250 mm/ min and rotation speed 1371 rot/min. a b c The surface appearance at the entry the drill in the workpiece 119

120 a b c The surface appearance at the exit the drill from the workpiece Fig.3. The surface appearance at the entry and exit of the drill from the workpiece (beech) cutted in tangential section (a), longitudinal (b) and radial (c) at the feed rate 250 mm/min and rotation speed 1371 rot/min. DISCUSSION AND CONCLUSIONS Analyzing the appearance of holes at entrance and exit of the drill from the wood and the variation of cutting forces, we see that the holes made along the fibers are of high quality. Resulted surface in this case does not present pulling fiber compared with the holes made in tangential and radial direction. The explanation could be that the geometry of drill used is specific at the longitudinal cutting. Regarding the roughness, utilization of the same geometry of drill, show that surface condition resulted does not depend decisive by the drill geometry. Confirmation this conclusion is brought by the averaging values both for Ra, Rq and Rz roughness parameters, as well as dynamical parameters F and M, depending on the direction of processing and parameters of cutting used, presented in Table 1: Table 1. Ra, Rz and Rq roughness parameters and dynamic parameters F and M in drilling of beech Beech Diameter of drill (mm) Cutting direction v f (feed rate) (mm/min) n (rotation speed) (rot/min) Ra [μm] Rz [μm] Rq [μm] M [Nmm] 10 Longitudinal Longitudinal Longitudinal Longitudinal Radial Radial Radial Radial Tangential Tangential Tangential Tangential In consequence, we can say that drill geometry influencing insignificant both the roughness (variations of roughness values in tangential and radial cutting compared with the longitudinal cutting, between 0.2 and 0.8%) and cutting forces and torques (different values between 1 and 3.6%), but can influence significantly the apperance of the holes at the entry and the exit from the material. According to specialized literature, the quality of processing varies depending on the direction of processing and the drill geometry. For increasing the productivity, reducing the use of tools F [N] 120

121 and of auxiliary adjusting time, based on data obtained without taking into consideration the power consumption, the authors recommend using this type of drill for processing of beech in either direction (radial, longitudinal or tangential) if the hole is not visible. REFERENCES 1. BADESCU, L.A.M. (2002): Modelarea si optimizarea proceselor prin aschierea lemnului. Editura Infomarket, Brasov. 2. BARBU,S.M., BADESCU, L. A. M. (2010): Energy Consumption, an Possible Factor in the Assessment of Surface Drills Quality at Beech Wood, International Conference on Urban Sustainability, Cultural Sustainability, Green Development Green Structures and Clean Cars (USCUDAR 2010), September 2010, Malta, ISSN: , ISBN: BARBU, S. M., BADESCU, L., JAVOREK, Ľ. (2010): Studies concerning the chip formation at the longitudinal drilling of the beech wood with help high speed camera. In Annals of Warsaw university of life sciences. Forestry and Wood Technology. - Warszawa : Warszaw University of Life Sciences Press, ISSN No. 72 (2010), p SR EN ISO Specificatii Geometrice pentru Produse. Starea suprafetei: Metoda profilului Caracteristici metrologice ale filtrelor cu corectie de faza, SR ISO 4287 Specificatii Geometrice pentru Produse. Starea suprafetei: Metoda profilului Termeni, definitii si parametri de stare a suprafetei. Acknowledgement The contribution was created during the solution of project CEEPUS network CII-SK as a result of activity and cooperation of authors. Streszczenie: Wpływ sił i momentów na jakość powierzchni po obróbce wierceniem. Praca prezentuje wyniki ich analizę wpływu sił i momentów przy wierceniu wiertłem 10 mm wzdłuż, w poprzek i prostopadle do włókien, na jakość powierzchni. Jakość analizowano na dwa sposoby, oceniając jakość krawędzi otworu (krawędź otworu wejścia oraz wyjścia wiertła) oraz powierzchnię wewnątrz. Corresponding authors: Eng. Simona-Maria BARBU Transylvania University of Brasov, 29 B-dul Eroilor, Brasov, Romania address: [email protected] Prof. Dr. Eng. Loredana Anne-Marie BADESCU Transylvania University of Brasov, 29 B-dul Eroilor, Brasov, Romania address: [email protected] Assoc. Prof. Dr. Eng. Lubomir JAVOREK Department of Woodworking Machines and Equipment, Technical University in Zvolen T. G. Masaryka 24, Zvolen, Slovakia address : [email protected] 121

122 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) The analysis of selected parameters characterising economic condition of furniture manufacturer - Forte SA JUSTYNA BIERNACKA Department of Technology, Organisation and Management in Wood Industry, Faculty of Wood Technology, Warsaw University of Life Sciences (SGGW) Abstract: The analysis of selected parameters characterising economic condition of furniture manufacturer Forte SA. In this paper changes of the major values affecting the economic condition of any enterprise, regardless of the form of business and type of activity were analysed on the example of Forte SA - a representative of furniture industry. This values analysis can provide many useful data, namely facilitate the decision of potential investors and contractors. The data can be useful for further, more detailed analysis, primarily in the competitiveness analysis of individual wood industry enterprise at the domestic wood industry market but also compared to companies from other countries. Keywords: profitability, liabilities, economic condition, furniture industry. INTRODUCTION Although the analysis of the economic situation of selected company even by the beginner investigator may seen quite simple, but an amateur analyst can skip a number of important economic values. That unfortunately happens quite often. Conducting the analysis in the direction of future investments in the stock market an amateur analyst focuses mostly on values such as net profit and gross profit, values resulting from company functioning in given period. In addition, beginner researcher in his analysis focuses mostly on the results of period which he is interested in, forgetting that the values of past periods can significantly affect future results and decisions taken by company s managers, related with its future market strategy. An amateur investor is also affected by the current mood of the stock exchange, and so the market psychology, following "the crowd" one time, another time taking decisions "against the market." Failures may result in discouragement to invest in the stock market. While the novice researcher may be affected by current mood, the flawed decisions can bring uncertainty and large losses in the future for prospective contractor. In the analysis of the company economic situation many factors are used in greater or lesser degree affecting the company situation. The most significant are: the financial result, operating profit, sales revenues, selling costs, receivables or liabilities. RESULTS In this paper the analysis of changes in selected economic values of representative of furniture industry, Forte SA in was analysed. The data was taken from the company's quarterly statements publicly available. The analysis was based on changes in the values of the operating profit, changes in sales revenues and changes of short-term and longterm debt. 122

123 Figure 1 shows the changes in volume of sales revenues achieved by the Forte SA company in each quarter in Baselines are the sales revenues achieved by the company in the subsequent quarters of q 06 2 q 06 3 q 06 4 q 06 1 q 07 2 q 07 3 q 07 4 q 07 1 q 08 2 q 08 3 q 08 4 q 08 1 q 09 2 q 09 3 q 09 4 q 09 1 q 10 2 q 10 3 q 10 4 q 10 Change [%] Forte's SA sales revenues changes Quarters Figure 1. Forte s SA sales revenues changes in (2005 subsequent quarters = 100%) Figure 1 analysis shows that in the first analyzed year sales revenues were relatively stable and reached around 10% of the value recorded in the same quarter in The value of sales revenues in 2007 ranged from about 20 to 30% higher than in the base year. In 2008, Forte SA reported sales revenues reaches 20% growth in relation to the correspondent period in Despite a very good start in 2009 (sales revenues in 1 st quarter of 2009 increased by over 40% of the size recorded in the corresponding quarter of 2005), in subsequent quarters sales revenues are reduced. The lowest value of the sales revenues Forte SA recorded in 1 st quarter The situation allows to negatively evaluate the decreasing of sales revenues in this period by only almost 10% compared to 1 st quarter In subsequent quarters, the sales revenues are improving, but the highest value of sales revenues obtained by company in the last year of the analysis is even lower than levels noted in Figure 2 shows a graphic illustration of changes in operating profits in the company Forte SA. Change [%] q 06 2 q 06 3 q 06 4 q 06 1 q 07 2 q 07 3 q 07 4 q 07 1 q 08 2 q 08 3 q 08 4 q 08 1 q 09 2 q 09 3 q 09 4 q 09 1 q 10 2 q 10 3 q 10 4 q Forte's SA operating profit changes Quarters 123

124 Figure 2. Forte s SA operating profit changes in (2005 subsequent quarters = 100%) Analysis of changes in operating profits of Forte SA presented in Figure 2 shows that usually in the last quarters of the years the amount of operating profit is highest. The exception is the year 2008, in which the higher operating profit of the company was recorded in 1 st quarter. As in the case of sales revenues, in the first two years of analysis the operating profit values generated by Forte SA remain at a similar level, but they are up to 2 times lower than the volume recorded in Only in 1 st quarter 2008 operating profit volumes are similar to those of the corresponding period of The highest value of operating profit throughout all the period were recorded in the 4 th quarter of a change compared to the same quarter of 2005 amounted to approximately 200%. In the last year of the analysis, the operating profits are reduced again - in the best quarter, they amount to little more than 50% of values from Change [%] The analysis of changes of the company long-term liabilities in shows Figure q 06 2 q 06 3 q 06 4 q 06 1 q 07 2 q 07 3 q 07 4 q 07 1 q 08 2 q 08 3 q 08 4 q 08 1 q 09 2 q 09 3 q 09 4 q 09 1 q 10 2 q 10 3 q 10 4 q Forte's SA long-term debt changes Quarters Figure 3. Forte s SA long-term debt changes in (2005 subsequent quarters = 100%) The Figure 3 analysis shows that the company maintains its long-term debt to less than 1,5 times the debt of This is a very optimistic premise for potential investors and contractors, because despite the increase in production costs with an inflation increase, the company reduces the amount of long-term loans to remain the same or lower level. It is worth mentioning the year 2010 in which company, possibly analysing the economic situation and the global crisis decreases its debt to a level even lower than in The Figure 4 shows a graphic illustration of changes in the values of Forte SA shortterm debt in the years

125 Change [%] q 06 2 q 06 3 q 06 4 q 06 1 q 07 2 q 07 3 q 07 4 q 07 1 q 08 2 q 08 3 q 08 4 q 08 1 q 09 2 q 09 3 q 09 4 q 09 1 q 10 2 q 10 3 q 10 4 q Forte's SA short-term debt changes Quarters Figure 4. Forte s SA short-term debt changes in (2005 subsequent quarters = 100%) Short-term debt of the Forte SA company, which Figure 4 shows reached the maximum value in the 1 st quarter of 2008, it was almost 60% more than in the corresponding period of Figure 1 analysis shows that the amount of short-term debt unit 2008 was at a fairly high level. From 2008, Forte SA is trying to reduce the debt (to the end of 2008 a short-term liabilities are less than about 20% of the volume of 2005). In 2009, the company continues its policy of maintaining low debt levels. The amount of short-term debt increases again in CONCLUSIONS Analysis of selected economic values, that characterize the economic situation of Forte SA allow to note that the year 2009 was particularly successful for the company. In this year Forte SA recorded the highest values of operating profit, while repay its short-term and long term liabilities. Analysis of more than one year of company functioning and the reference of economic values to a single continuous period in the company s history only allows to reliably assess of the entity. It is also important to use several economic values, because considering only a selected value can not give the correct picture of the whole economic situation of a company. Analyst studying the economic situation of a company having the most important data directly from the company should also uses the data related with national economy and the information derived from foreign markets. In the case of the Polish economy the most important information that could affect the company are the results of inflation, which may be associated with an increase in energy and fuel costs and the potential increases in interest rates, which may affect the cost of credit. REFERENCES 1. GOŁĘBIOWSKI G., TŁACZAŁA A., 2005: Analiza ekonomiczno finansowa w ujęciu praktycznym, Diffin, Warszawa; 2. SEDLIAČIKOVÁ M., 2010: Financial analysis "ex-ante" - an elementary tool of financial controlling, Annals of Warsaw University of Life Sciences. Forestry and Wood Technology, No. 70, p ; 3. SEREDYŃSKI R., SZARUGA K., DZIEDZIA M., 2009: Operacje gospodarcze w praktyce księgowej, Ośrodek Doradztwa i Doskonalenia Kadr Sp. z o.o., Gdańsk;

126 &_OID=20&_Lang=pl&_SOID=25&_Site=ESPI&_ISIN=PLFORTE00012&_Check Sum= Streszczenie: Analiza wybranych wielkości charakteryzujących kondycję ekonomiczno finansową producenta mebli, spółki Forte SA. W niniejszym opracowaniu poddano analizie zmiany najważniejszych wielkości ekonomicznych wpływających na efektywność gospodarowania każdego przedsiębiorstwa niezależnie od formy prawnej jego działalności oraz branży, w której funkcjonuje. W pracy ocenie efektywności gospodarowania poddano przedstawiciela branży meblarskiej, spółkę Forte SA. Analiza przedstawionych wielkości dostarczyć może wielu pomocnych danych, przede wszystkim ułatwić ocenę sytuacji ekonomiczno finansowej przedsiębiorstwa potencjalnym inwestorom i kontrahentom oraz posłużyć w dalszych szczegółowych analizach konkurencyjności jednostki na rynku drzewnym w Polsce a także na tle innych przedstawicieli branży na świecie. Corresponding author: Justyna Biernacka Department of Technology, Organisation and Management in Wood Industry, Faculty of Wood Technology, Warsaw Agricultural University (SGGW) Warsaw, ul. Nowoursynowska [email protected] 126

127 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) The analysis of selected parameters characterising economic condition of Paged SA JUSTYNA BIERNACKA Department of Technology, Organisation and Management in Wood Industry, Faculty of Wood Technology, Warsaw University of Life Sciences (SGGW) Abstract: The analysis of selected parameters characterising economic condition of Paged SA. In this paper changes of the major values affecting the economic condition of any enterprise, regardless of the form of business and type of activity were analysed on the example of Paged SA - a representative of wood industry. This values analysis can provide many useful data, namely facilitate the decision of potential investors and contractors. The data can be useful for further, more detailed analysis, primarily in the competitiveness analysis of individual wood industry enterprise at the domestic wood industry market but also compared to companies from other countries. Keywords: profitability, liabilities, economic condition, wood industry. INTRODUCTION Although the analysis of the economic situation of selected company even by the beginner investigator may seen quite simple, but an amateur analyst can skip a number of important economic values. That unfortunately happens quite often. Conducting the analysis in the direction of future investments in the stock market an amateur analyst focuses mostly on values such as net profit and gross profit, values resulting from company functioning in given period. In addition, beginner researcher in his analysis focuses mostly on the results of period which he is interested in, forgetting that the values of past periods can significantly affect future results and decisions taken by company s managers, related with its future market strategy. An amateur investor is also affected by the current mood of the stock exchange, and so the market psychology, following "the crowd" one time, another time taking decisions "against the market." Failures may result in discouragement to invest in the stock market. While the novice researcher may be affected by current mood, the flawed decisions can bring uncertainty and large losses in the future for prospective contractor. In the analysis of the company economic situation many factors are used in greater or lesser degree affecting the company situation. The most significant are: the financial result, operating profit, sales revenues, selling costs, receivables or liabilities. RESULTS In this paper the analysis of changes in selected economic values of representative of wood industry, Paged SA in was analysed. The data was taken from the company's quarterly statements publicly available. The analysis was based on changes in the values of the operating profit, changes in sales revenues and changes of short-term and long-term debt. Figure 1 shows the changes in volume of sales revenues achieved by the Paged SA company in each quarter in Baselines are the sales revenues achieved by the company in the subsequent quarters of

128 35 Change [%] q 06 2 q 06 3 q 06 4 q 06 1 q 07 2 q 07 3 q 07 4 q 07 1 q 08 2 q 08 3 q 08 4 q 08 1 q 09 2 q 09 3 q 09 4 q 09 1 q 10 2 q 10 3 q 10 4 q 10 Paged's SA sales revenues changes Quarters Figure 1. Paged s SA sales revenues changes in (2005 subsequent quarters = 100%) Figure 1 analysis shows that the highest values of sales revenues the company received in 2007 and Results of sales revenues are 20 do 30% higher then the values of sales revenues in Better results of sales revenues in every first two quarters of the year can be observed. Values of sales revenues in 2009 and 2010 are not as good as in the 1 st quarter of 2008, however, they fluctuate from about 10 to 20% of the values in the base year. Figure 2 shows a graphic illustration of changes in operating profits in the company Paged SA. Change [%] q 06 2 q 06 3 q 06 4 q 06 1 q 07 2 q 07 3 q 07 4 q 07 1 q 08 2 q 08 3 q 08 4 q 08 1 q 09 2 q 09 3 q 09 4 q 09 1 q 10 2 q 10 3 q 10 4 q Paged's SA operating profit changes Quarters Figure 2. Paged s SA operating profit changes in (2005 subsequent quarters = 100%) Operating profits analysis of Paged SA presented in Figure 2 shows that in the first analysed year operating profit values are similar to those from the base year Only the last quarter of 2006 operating profit values are reduced by about 23% compared to In the subsequent year the values of operating profits are improving again - the highest value of the operating profit Paged SA reached in the 1 st quarter of 2007, it is nearly 28% more then in corresponding period of The values of operating profit in 2008, however, are reduced to a value of more than half lower than in the base year. In 2009 the operating profit values are improving again. The results of Paged SA reach in the 4 th quarter 2009 the value of more than 128

129 130% higher than the value recorded in 4 th quarter The decrease in the operating results of Paged SA observed in 2010 may have a negative influence on the company s situation in the future. The values of the operating profits in the last three quarters of analysis represent almost half of the level of operating profit noted in Change [%] The analysis of changes of the company long-term liabilities in shows Figure q 06 2 q 06 3 q 06 4 q 06 1 q 07 2 q 07 3 q 07 4 q 07 1 q 08 2 q 08 3 q 08 4 q 08 1 q 09 2 q 09 3 q 09 4 q 09 1 q 10 2 q 10 3 q 10 4 q 10 Paged's SA long-term debt changes Quarters Figure 3. Paged s SA long-term debt changes in (2005 subsequent quarters = 100%) The Figure 3 analysis shows that in the initial period of analysis the long-term debt of Paged SA is kept at a near constant level, lower even than in This situation in the second half of 2006 year can be observed. The lowest long-term debt values are observed in the 4 th quarter of 2006 and reached nearly 50% of the liabilities level noted in 4 th quarter of A gradual increase in the level of long-term debt is characterising subsequent quarters of analysis. In 2007, the long-term liabilities in Paged SA reaches already 150% of the value of the base year. The long-term debt of Paged SA in 2008 increases to 250%, and in 2009, up to 650% of long-term liabilities in Only last analysed year brings lower long-term debt all the debts were fully paid. The Figure 4 shows a graphic illustration of changes in the values of Paged SA shortterm debt in the years Change *10^2 [%] q 06 2 q 06 3 q 06 4 q 06 1 q 07 2 q 07 3 q 07 4 q 07 1 q 08 2 q 08 3 q 08 4 q 08 1 q 09 2 q 09 3 q 09 4 q 09 1 q 10 2 q 10 3 q 10 4 q 10 Paged's SA short-term debt changes Quarters 129

130 Figure 4. Paged s SA short-term debt changes in (2005 subsequent quarters = 100%) One of the biggest changes in the components of Paged SA balance sheet during analysed period in the case of short-term liabilities can be observed. Analysis of the data illustrated in Figure 4 allow to note that in last quarters of each year the company s short-term debt increases. The highest increases in short-term debt can be observed in 4 th quarter of 2008 and 4 th quarter of CONCLUSIONS Analysis of selected economic values, that characterize the economic situation of Paged SA allow to note that the results of the company are decreasing since With rising liabilities revenues from sale is reduced. The collapse of worldwide sales as a result of the economic crisis may be a factor causing this situation. Rising costs of company s functioning with the sales revenues and operating profits remaining a similar or lower level than in 2005 do not allow for a positive perception of the future. Analysis of more than one year of company functioning and the reference of economic values to a single continuous period in the company s history only allows to reliably assess of the entity. It is also important to use several economic values, because considering only a selected value can not give the correct picture of the whole economic situation of a company. Analyst studying the economic situation of a company having the most important data directly from the company should also uses the data related with national economy and the information derived from foreign markets. In the case of the Polish economy the most important information that could affect the company are the results of inflation, which may be associated with an increase in energy and fuel costs and the potential increases in interest rates, which may affect the cost of credit. REFERENCES 1. GOŁĘBIOWSKI G., TŁACZAŁA A., 2005: Analiza ekonomiczno finansowa w ujęciu praktycznym, Diffin, Warszawa; 2. SEDLIAČIKOVÁ M., 2005: Zvyšovanie hospodárnosti podniku cestou identifikácie rezerv vo finančnom riadení, Logisticko-distribučné systémy : medzinárodná vedecká konferencia : zborník referátov, Zvolen : Technická univerzita vo Zvolene, p ; 3. SEREDYŃSKI R., SZARUGA K., DZIEDZIA M., 2009: Operacje gospodarcze w praktyce księgowej, Ośrodek Doradztwa i Doskonalenia Kadr Sp. z o.o., Gdańsk; 4. &_OID=20&_Lang=pl&_SOID=25&_typRap=39&_Site=ESPI&_ISIN=PLPAGED0 0017&_CheckSum=

131 Streszczenie: Analiza wybranych wielkości charakteryzujących kondycję ekonomiczno finansową przedstawiciela przemysłu drzewnego, spółkę Paged SA. W niniejszym opracowaniu poddano analizie zmiany najważniejszych wielkości ekonomicznych wpływających na efektywność gospodarowania każdego przedsiębiorstwa niezależnie od formy prawnej jego działalności oraz branży, w której funkcjonuje. W pracy ocenie efektywności gospodarowania poddano przedstawiciela przemysłu drzewnego, spółkę Paged SA. Analiza przedstawionych wielkości dostarczyć może wielu pomocnych danych, przede wszystkim ułatwić ocenę sytuacji ekonomiczno finansowej przedsiębiorstwa potencjalnym inwestorom i kontrahentom oraz posłużyć w dalszych szczegółowych analizach konkurencyjności jednostki na rynku drzewnym w Polsce a także na tle innych przedstawicieli branży na świecie. Corresponding author: Justyna Biernacka Department of Technology, Organisation and Management in Wood Industry, Faculty of Wood Technology, Warsaw Agricultural University (SGGW) Warsaw, ul. Nowoursynowska [email protected] 131

132 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) The analysis of selected parameters characterising economic condition of Grajewo SA JUSTYNA BIERNACKA Department of Technology, Organisation and Management in Wood Industry, Faculty of Wood Technology, Warsaw University of Life Sciences (SGGW) Abstract: The analysis of selected parameters characterising economic condition of Grajewo SA. In this paper changes of the major values affecting the economic condition of any enterprise, regardless of the form of business and type of activity were analysed on the example of Grajewo SA - a representative of wood industry. This values analysis can provide many useful data, namely facilitate the decision of potential investors and contractors. The data can be useful for further, more detailed analysis, primarily in the competitiveness analysis of individual wood industry enterprise at the domestic wood industry market but also compared to companies from other countries. Keywords: profitability, liabilities, economic condition, wood industry. INTRODUCTION Although the analysis of the economic situation of selected company even by the beginner investigator may seen quite simple, but an amateur analyst can skip a number of important economic values. That unfortunately happens quite often. Conducting the analysis in the direction of future investments in the stock market an amateur analyst focuses mostly on values such as net profit and gross profit, values resulting from company functioning in given period. In addition, beginner researcher in his analysis focuses mostly on the results of period which he is interested in, forgetting that the values of past periods can significantly affect future results and decisions taken by company s managers, related with its future market strategy. An amateur investor is also affected by the current mood of the stock exchange, and so the market psychology, following "the crowd" one time, another time taking decisions "against the market." Failures may result in discouragement to invest in the stock market. While the novice researcher may be affected by current mood, the flawed decisions can bring uncertainty and large losses in the future for prospective contractor. In the analysis of the company economic situation many factors are used in greater or lesser degree affecting the company situation. The most significant are: the financial result, operating profit, sales revenues, selling costs, receivables or liabilities. RESULTS In this paper the analysis of changes in selected economic values of representative of wood industry, Grajewo SA in was analysed. The data was taken from the company's quarterly statements publicly available. The analysis was based on changes in the values of the operating profit, changes in sales revenues and changes of short-term and longterm debt. Figure 1 shows the changes in volume of sales revenues achieved by the Grajewo SA company in each quarter in Baselines are the sales revenues achieved by the company in the subsequent quarters of

133 Change [%] q 07 2 q 07 3 q 07 4 q 07 1 q 08 2 q 08 3 q 08 4 q 08 1 q 09 2 q 09 3 q 09 4 q 09 1 q 10 2 q 10 3 q 10 4 q 10 Grajewo's SA sales revenues changes Quarters Figure 1. Grajewo s SA sales revenues changes in (2007 subsequent quarters = 100%) Figure 1 analysis shows that sales revenues in the first quarter of the analysis are at a satisfying level, which is over 40% more than in the base year. In subsequent quarters of 2007 the sales revenues reduces. Value of sales revenues increases again in 1 st quarter of This is the best result company Grajewo SA obtained in the entire period. The good results of sales revenues, however, did not persist in a further period. In subsequent quarters of 2008 and even 2009 the sales revenues decreases and reach the lowest level throughout all analysed period in the 4 th quarter of The values of the end of 2009 are only slightly higher than those from 2006, which reflecting the company difficulties of selling its products. In 2010, the situation improves and sales revenues oscillates at around 20% more than in the year Figure 2 shows a graphic illustration of changes in operating profits in the company Grajewo SA. Change [%] q 07 2 q 07 3 q 07 4 q 07 1 q 08 2 q 08 3 q 08 4 q 08 1 q 09 2 q 09 3 q 09 4 q 09 1 q 10 2 q 10 3 q 10 4 q Grajewo's SA operating profit changes Quarters Figure 2. Grajewo s SA operating profit changes in (2006 subsequent quarters = 100%) Analysis of changes in operating profits of Grajewo SA presented in Figure 2 shows that in almost the entire period of the analysis operating profits results reduces. Initially, in a 1 st 133

134 quarter 2007, the company has recorded values of operating profits of more than half higher than value form the corresponding quarter of previous year. In the next year of analysis operating profit reduces again and records values lower at about 50% than in Year 2009 does not bring the company an improvement in operating profits. Values in this year continues decrease and reach almost 100% less than the results obtained by the company in The lowest score of operating profit was recorded in 1 st quarter of 2010 and it was almost 150% less than in The results of subsequent quarters of 2010, however brings hope, that if the trend continues, the results should reach a satisfying operating profit, higher that in the year Change *10^2 [%] The analysis of changes of the company long-term liabilities in shows Figure q 07 2 q 07 3 q 07 4 q 07 1 q 08 2 q 08 3 q 08 4 q 08 1 q 09 2 q 09 3 q 09 4 q 09 1 q 10 2 q 10 3 q 10 4 q 10 Grajewo's SA long-term debt changes Quarters Figure 3. Grajewo s SA long-term debt changes in (2006 subsequent quarters = 100%) The Figure 3 analysis shows that company Grajewo SA long-term liabilities steadily increases. The lowest level of long-term debt can be observed in the initial period of analysis, namely in the 1 st quarter of 2007, the highest level in the 1 st quarter 2008, 1 st quarter 2009 and 1 st quarter The highest value of long-term liabilities in the entire analysed period was observed in the 1 st quarter of 2010 and reached more than 700 times of the value from Such results of long-term liabilities may cause negative effects in the future. The Figure 4 shows a graphic illustration of changes in the values of Grajewo SA shortterm debt in the years

135 Change [%] q 07 2 q 07 3 q 07 4 q 07 1 q 08 2 q 08 3 q 08 4 q 08 1 q 09 2 q 09 3 q 09 4 q 09 1 q 10 2 q 10 3 q 10 4 q 10 Grajewo's SA short-term debt changes Quarters Figure 4. Grajewo s SA short-term debt changes in (2006 subsequent quarters = 100%) Short-term debt of the Grajewo SA company, which shows Figure 4, in the entire period oscillates at a similar level. In the two early years of analysis company s short-term liabilities achieve maximum level of 150% of short-term debt in Only at the end of 2009 in the 4 th quarter the value of company s short-term debt reaches value 25 times higher than that in year year seems to be promising, because short-term liabilities reduces to a level less than half higher than recorded in CONCLUSIONS Analysis of selected economic values that characterising the economic situation of the company Grajewo SA suggests that the good situation of the company were noted only in the 2007 of the 4 years selected for the analysis. In this period the company reached a satisfactory amount of sales revenues and operating profits, while its liabilities remained at a inconsiderable level. Subsequent years of company s functioning bring the collapse in sales revenues, what results a necessity to financing current company s functioning by loans, which can be seen in company s debt level in subsequent years. Analysis of selected economic values, that characterize the economic situation of Grajewo SA allow to note that the year 2009 was particularly successful for the company. In this year Grajewo SA recorded the highest values of operating profit, while repay its shortterm and long term liabilities. Analysis of more than one year of company functioning and the reference of economic values to a single continuous period in the company s history only allows to reliably assess of the entity. It is also important to use several economic values, because considering only a selected value can not give the correct picture of the whole economic situation of a company. Analyst studying the economic situation of a company having the most important data directly from the company should also uses the data related with national economy and the information derived from foreign markets. In the case of the Polish economy the most important information that could affect the company are the results of inflation, which may be associated with an increase in energy and fuel costs and the potential increases in interest rates, which may affect the cost of credit. 135

136 REFERENCES 1. GOŁĘBIOWSKI G., TŁACZAŁA A., 2005: Analiza ekonomiczno finansowa w ujęciu praktycznym, Diffin, Warszawa; 2. SEDLIAČIKOVÁ M., 2004: Teoretické a praktické prístupy k finančnému controllingu, Ekonomika a manažment podnikov: medzinárodná vedecká konferencia : zborník referátov, Zvolen : Technická univerzita vo Zvolene, p ; 3. SEREDYŃSKI R., SZARUGA K., DZIEDZIA M., 2009: Operacje gospodarcze w praktyce księgowej, Ośrodek Doradztwa i Doskonalenia Kadr Sp. z o.o., Gdańsk; 4. &_OID=20&_Lang=pl&_SOID=25&_typRap=39&_Site=ESPI&_ISIN=PLZPW &_CheckSum= Streszczenie: Analiza wybranych wielkości charakteryzujących kondycję ekonomiczno finansową przedstawiciela przemysłu drzewnego, spółkę Grajewo SA. W niniejszym opracowaniu poddano analizie zmiany najważniejszych wielkości ekonomicznych wpływających na efektywność gospodarowania każdego przedsiębiorstwa niezależnie od formy prawnej jego działalności oraz branży, w której funkcjonuje. W pracy ocenie efektywności gospodarowania poddano przedstawiciela przemysłu drzewnego, spółkę Grajewo SA. Analiza przedstawionych wielkości dostarczyć może wielu pomocnych danych, przede wszystkim ułatwić ocenę sytuacji ekonomiczno finansowej przedsiębiorstwa potencjalnym inwestorom i kontrahentom oraz posłużyć w dalszych szczegółowych analizach konkurencyjności jednostki na rynku drzewnym w Polsce a także na tle innych przedstawicieli branży na świecie. Corresponding author: Justyna Biernacka Department of Technology, Organisation and Management in Wood Industry, Faculty of Wood Technology, Warsaw Agricultural University (SGGW) Warsaw, ul. Nowoursynowska [email protected] 136

137 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Stress distribution along the contour of a circular opening in wooden plate loaded by in-plane bending moment FERDINAND BODNÁR 1), MAREK JABŁOŃSKI 2) 1) Department of Mechanics and Engineering, Technical University in Zvolen, Slovakia 2) Faculty of Wood Technology, Warsaw University of Life Sciences SGGW Abstract: Stress distribution along the contour of a circular opening in wooden plate loaded by in-plane bending moment. The analytical solution of stresses around the circular hole boundary in two-dimensional wooden plate modelled as orthotropic linear elastic material is presented here. The orthotropic plate with the circular hole is subjected to an in-plane bending loading. The aim is to know the influence of the circular hole and of the principal directions of elasticity on concentration of stresses. Realised computations of the hoop stress on the opening boundary and of the stress concentration factor are based on the linear theory of anisotropic bodies with using of a complex variable method. Keywords: stress concentration, circular hole, wooden plate, in-plane bending. INTRODUCTION It is well known that holes cause serious problems of stress concentrations due to the geometry discontinuity. These problems are even more serious in structures of materials with anisotropic behaviour. In order to predict the structural behaviour of these structures, it is necessary to study the effect of anisotropy and type of loading on stress distribution around the holes. Analytical calculation of stress concentrations in plate with infinite dimensions under mechanical loads have been performed by many authors mainly using the methods of complex valued stress functions and conformal mappings. Ukadgaonker and Rao [5] adapted Savin s formulation to get general solution for in plane loading problem. Mathematically elegant and technically powerful in determining the two-dimensional deformations of anisotropic elastic solids is Stroh formalism [3], [4], [1]. Here the Lechnickij s [2] complex variable approach is used for calculation of stress concentration around circular opening in wooden plate modelled as orthotropic material. THEORETICAL BACKGROUND To get solution of two dimensional anisotropic elasticity problems, it is necessary to solve basic equation of theory of the plane elasticity of anisotropic bodies (1) for given boundary conditions U U U U U a 22 2a26 (2a12 a66 ) 2a16 a11 0. (1) x x y x y x y y The Lechnickij s formalism the given problems formulate in terms of the analytic functions, Φ k z k, of the complex variable, z k xk iyk ( k 1, 2), i 1, where x k x k y, y y, ( k 1, 2). k k 137

138 The parameters k and k are the real and imaginary parts of complex parameters k k i k, (2) which can be determined from the following characteristic equation a11 2a16 (2a12 a66 ) 2a26 a22 0, (3) where the roots k are always complex or purely imaginary in conjugate pairs as 1, 1 ; 2, 2. As it is evident from Eq. (3), these complex parameters represented by Eq. (2) depend on the compliance coefficients a ij (i,j = 1, 2, 6) of the anisotropic plate. The Airy s stress function U(x,y) can be represented by arbitrary functions F of variables z U ( z 2 x, y) F ( z ) F ( z ) F ( z ) F ( ). (4) By introducing the designations dfk Φk zk ( 1, 2), dz k k Φ z dφ k k k ( 1, 2) dzk the stress components in terms of Φ k z k ) can be formulated as y xy 2 2 x 2 Re 1 Φ1 ( z1) 2Φ2 ( z 2 Re Φ ( z ) Φ ( z ), 2 Re 1 Φ ( z ) Φ ( z ) ) 2, k k, Substituting the expressions for x, y, xy to transformation formulas for normal and tangential stress components in a plane with an arbitrary directed normal n, these stress components are n 2Re n 2Re 2 2 cos n, y 1 cos n, x Φ1 ( z1) cos n, y 2 cos n, x cos n, y 1 cos n, x cos n, x 1 cos n, y Φ 1 ( z1) cos n, y cos n, x cos n, x cos n, y Φ ( z ) k Φ ( z 2 2 ), (6) (5) CONCENTRATION OF STRESSES IN ORTHOTROPIC PLATE WITH CIRCULAR OPENING AT BENDING BY IN-PLANE MOMENTS A rectangular beam, which is a plate with a circular opening at the center, is bent by moments M applied to both sides in the middle plane. The principal directions of elasticity, parallel with axes x and y, do not coincide with the direction of plate sides. Their orientation is characterized by angle φ (Fig. 1). The largest stress concentration is on the opening edge. The normal stress acting on areas normal to opening edge, i.e., on radial planes located at the edge of the opening, is one principal stress, second principal stress, as it is evident from given boundary condition, is equal zero. The stresses in the plate are obtained by summing stresses in a solid beam plate subjected to pure bending and the stresses obtained by functions Φ k z k. So the hoop stress at individual contour points given by angle θ is expressed by formula 138

139 Fig. 1 Problem configuration Ma E 3 k 1 k 1 k n cos 2 sin cos 2J E1 2 n k k 2n 1 n 1 n k 1 k 2n cos sin cos sin 1 n k k n 1 1 n cos sin cos cos 1 k 1 k n cos 2 cos sin, (7) where J is the inertia moment of the transverse cross section of a solid (of the unweakened plate), E1 is Young s modulus in principal direction, E is Young s modulus in the direction tangent to the opening contour, a is a radius of the opening, k and n denote k 1 2, n i 1 2, is the polar angle measured from the x-axis and is an angle between the principal direction of elasticity and plate axis. RESULTS OF NUMERICAL EXAMPLES Calculation of stress distribution was made for tangential wooden plate of Picea Excelsa modeled as the orthotropic plate with the circular opening. The rectangular plate is bent by moments M, radius a of the opening is taken to be small in comparison with the length of the plate sides and the principal directions of elasticity are assumed as axes x and y. The axes x (parallel with wood fibers) forms an angle φ with the plate axis x. Used engineering constants in principal material directions - Young s moduli E1, E2, Poisson ratios 1, 2 and shear modulus G 12 - have values: E MPa, E2 650 MPa, , , G MPa. Complex parameters calculated from equation (2) are: i, i. Distribution of the hoop stress on the hole boundary for solved cases of the angle φ (φ= 0, φ= 45 and φ= 90 ) is presented in Fig. 2, where a ash-grey line displays the hoop 139

140 c) a) b) Fig. 2 Distribution of : a) φ= 0, b) φ= 45, c) φ= 90 stress distribution in isotropic material. To denote the highest stress caused by the hole, the stress concentration factor (SCF) is used. The stress concentration factor for this case of loading is defined to be the maximum stress at the opening boundary divided by a stress Ma from the unweakened plate. J Calculated stress concentration factors of wooden plate for observed orientation of fibers and SCF in the isotropic material at given manner of loading are given in Table 1. Table 1. Stress concentration factors Picea Excelsa = 0 = 45 = 90 Isotropic material SCF 3,09 2,26 1,59 2,00 CONCLUSION Circular opening causes stress concentration in the wooden plate loaded by in-plane bending moments. Distribution of the hoop stress at the opening boundary depends on angle φ between the plate axis and fibers direction. The stress concentration factor achieves maximal value when fibers orientation is parallel with plate axis. In this case the maximal hoop stress is at contour point given by angle 90 and 270. When φ= 45, extreme value of hoop stress is in locations about 118 and 298. For φ= 90, these locations are about

141 and 257. Extreme values in isotropic material are in regions, where the opening edge crosses the plate axis x. REFERENCES 1. BODNÁR F., JABŁOŃSKI M. 2010: Stress concentration factors of an anisotropic elastic plate with elliptical hole. Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology No 71. Warsaw, p LECHNICKIJ S. G. 1957: Anizotropnyje plastinki. Moskva: Gostechizdat, Moskva- Leningrad: 1957, 463 pp. 3. STROH A. N. 1958: Dislocations and cracks in anisotropic elasticity. Philosophical Magazine 7, TING T.C.T. 1996: Anisotropic Elasticity Theory and Applications. Oxford Science Publications, New York. 5. UKADGAONKER V. G., RAO D. K. N. 2000: A general solution for moments around holes in symmetric laminates. Composite Structures, 49, Streszczenie: Rozkład naprężeń wokół okrągłego otworu w drewnianej płycie obciążonej momentem zginającym. Przedstawiono rozwiązanie analityczne rozkładu naprężeń wokół otworu w dwuwymiarowej płycie drewnianej modelowanej jako ortotropowy materiał elastyczny. Ortotropowa płyta poddana jest naprężeniom zginającym. Celem pracy było określenie wpływu otworów i głównych kierunków sprężystości na rozkład naprężeń. Wyliczenia naprężeń obwodowych na granicy otworu i wpływu roskłądu naprężeń oparto na teorii liniowej ciał anizotropowych używając metody wielu zmiennych. This research was supported by Slovak Scientific Grant Agency under project No. 1/0579/08 Stress and strain analysis around stress concentrators in parts of wooden constructions. Corresponding authors: Ferdinand Bodnár, Department of Mechanics and Engineering, Technical University in Zvolen, Slovakia, [email protected] Marek Jabłoński, Faculty of Wood Technology, Warsaw University of Life Sciences SGGW, Warsaw, 159 Nowoursynowska st., Poland [email protected] 141

142 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Characteristics of selected fireproof properties of particleboard made from particles impregnated with salt agent PIOTR BORUSZEWSKI 1, PIOTR BORYSIUK 1, WALDEMAR JASKÓŁOWSKI 2, KAROLINA FAJKOWSKA 1, MARIUSZ MAMIŃSKI 1, IZABELLA JENCZYK- TOŁŁOCZKO 1 1 Faculty of Wood Technology, Warsaw University of Life Sciences SGGW 2 Department of Combustion and Fire Theory, The Main School of Fire Service SGSP Abstract: Characteristics of selected fireproof properties of particleboard made from particles impregnated with salt agent. This paper presents results of selected fireproof properties of three-layer particleboard made from pine particles impregnated with open for general use bio- and salt fireproof agent for wood protection, based on quaternary ammonium compounds and boric acid. It leads to conclusion that impregnation of particleboards increases the fire resistance in relation to unprotected materials. Keywords: particleboards, fireproof properties, salt agent INTRODUCTION Materials designed for furniture and construction are obliged to meet the requirements of fire resistance. Wood is a material particularly susceptible to fire, which is related with its structure and chemical composition. Particleboard as a wood-based material, is widely used in the furniture industry. Therefore, just as wood, it should be resistant to a variety of degradative factors, including fire (Drysdale 2001, Osipiuk 2001, Grexa et al. 2003, Kozłowski et al. 1999). Salt agents can not fully protect the material against the spreading of fire, but their impact on reduction of its effects is significant. Development of flame retardants production technology leads to new recipes, designed to improve their properties and to make an agent application easier, as well as eliminating the negative effects on human and surrounding environment. Nowadays, due to the ease of application, the most common are salt preparations called antipirenes. Impact of salt fire-retardants addition has not been fully examined yet, especially new generation agents in case of selected fire-retardant s properties of wood-based materials produced with their addition (Babrauskas 2005). MATERIAL AND METHODS The research was carried with open for general use salt bio- and flame retardant for wood protection. The product is sold as a water-based paste with 58-60% content of solids. Among others it consists of quaternary ammonium compounds (3%) and boric acid (about 3%). Preservative raises fire-retardant properties and bio-protection, which allows to protect wood against fungi and insects. The manufacturer determines the penetration of the product on 2 mm at a moisture content of impregnated material with 12% and 5 mm at 28% (AT /2007). The product was used for wood particles impregnation, then three-layered particleboard was made with them (assumed thickness was 12 mm and density was 650 kg/m 3 ). From the product, water solution was prepared (3 pbw of agent, 1 pbw of water), which was used for further wood particles impregnation (separately for inner and outer layers). After the initial drying of particles at 21 C, actual drying was performed, which was conducted at 80 C for 30 minutes, what allowed the particles to achieve a final moisture content of 6%. Impregnated and dried wood particles were glued in tumble binder with urea-formaldehyde 142

143 resin, in an amount of 10% based on the completely dry particles weight. Unit recipe of glue contained 50 g of urea-formaldehyde resin at a concentration of 66%, 2 g of ammonium chloride and 15 g of water. From glued particles a mat was formed, which was then compressed in the platen press, at 180 C and a unit pressure of 2.5 MPa for 5 minutes. From prepared boards samples were cut for the oxygen index flammability test and the flammability test for a single-flame. Oxygen index flammability test This study allows to determine flammability of tested materials. Oxygen index is the smallest percentage of oxygen in the air mixture, which sustains constant burning of the material in laboratory conditions. Examination was performed in accordance to ISO :1999: Plastics - Determination of burning behaviour by oxygen index. Test samples were cut from previously prepared boards. The dimensions of mouldings were 10 cm long and 1 cm wide. Examination was held in equipment prepared specially for this purpose. The sample was positioned vertically and covered from the top with a shade, according to the scheme shown in Figure 1. a - Chimney (height: 450 mm, diameter: 95 mm) b - Moulder for research c - Moulder grip d - Screen made of wire mesh e - Diffuser ring f - Mixture of oxygen and nitrogen Fig. 1. Scheme of the equipment for the oxygen index test Gas-jet was a source of fire, which was applied for 30 seconds to the top of the sample. Every 5 seconds the burner was moved away from the sample in order to check the uniformity of sample s top burning. Amount of nitrogen and oxygen flow was regulated with the valve and the process of sample burning was observed, as well as time after which burning of 50 mm of the sample s top took place. Oxygen index measurement method is used for comparison of various materials flammability in assessing the impact of additional filler materials including various kinds of flame retardants. However, it should be noted, that oxygen index can not be used for materials classification in terms of fire hazard. Single-flame source test Examination is a modification of the method described in standard PN-EN ISO :2004 Reaction to fire tests - Ignitability of products subjected to direct impingement of flame - Part 2: Single-flame source test. The modification consists on time measurement 143

144 after which flame reaches 15 cm of sample s height, which allows to specify not only the flammability of the material, but also to observe how fast the flame spreads. Test samples were cut from previously prepared boards. Dimensions of mouldings were 25 cm long and 9 cm wide. Research was conducted on a specially prepared test stand (Fig. 2). Fig. 2. Stand for flammability test of materials treated with direct flame influence, according to PN-EN ISO :2004 in laboratory of Department of Combustion and Fire Theory, The Main School of Fire Service SGSP Research was performed with the use of a gas-jet, put for 120 seconds to the sample surface. The burner was fitted on a horizontal panel wich allowed it to uniformly move in a horizontal plane, along the central axis of the test chamber. It was combined with a precise valve, allowing adjustment of the flame. Sample holder constituted double, U-shaped frame from stainless steel, with a width of 15 mm and thickness of 5 mm (Fig. 3). The frame was balted with screws, which prevented from deformation and sliding of the sample during the test. Use of the holder allowed to subject samples for direct flame exposure. Test was carried out by continuous flame exposure on the surface. Fig. 3. Sample holder RESULTS AND DISCUSSION Obtained work results are set together in tables 1 and 2. Oxygen index of particleboard samples made of particles, which were not protected with fireproof agent was 29.2%, while for boards made of particles protected with flame retardant, this ratio was 33.9% (Table 1). 144

145 Table 1. Results of oxygen index flammability test (bolded text indicates the lowest value of oxygen index for particular samples) Samples without fire-retardant Sample No Concentration of oxygen in the mixture (%) Observations 1 25 Sample do not burn 2 27 Flame visible for 1 min 30 sec Flame visible for 1 min 40 sec Fire was sustained for 3 minutes, 4.5 cm of sample have been burned 5 30 Fire was sustained for 3 minutes, 2.5 cm of sample have been burned Fire was sustained for 3 minutes, 4.5 cm of sample have been burned Fire was sustained for 3 minutes, 15 cm of sample have been burned 8 29 Fire was sustained for 1 min 50 sec Fire was sustained for 2 min 20 sec, 0.5 cm of sample have been burned Sample No Concentration of oxygen in the mixture (%) Samples with fire-retardant Observations cm of sample have been burned in 31 sec cm of sample have been burned in 2 min 46 sec cm of sample have been burned in 1 min 2 sec 4 32 Fire was sustained for 2 minutes, 8 mm of sample have been burned 5 33 Fire was sustained for 1 min 40 sec, 7 mm of sample have been burned 6 34 Fire was sustained for 1 min 8 sec, 5 mm of sample have been burned Fire was sustained for 1 min 40 sec, 5 mm of sample have been burned Fire was sustained for 1 min 24 sec, 5 mm of sample have been burned Fire was sustained for 3 minutes In Table 2, results of reaction to fire test based on the single-flame source test are presented. For particleboard made of particles, which were not protected which fireproof agent, the average height of flame after 120 seconds was 80mm, while for samples made from particleboards previously protected with fireproof agent, the height of flame was reduced by an average of 10 mm. 145

146 Table 2. Results of reaction to fire test Presence of fire-retardant Time [s] Average height of flame [mm] Without fire-retardant With fire-retardant CONCLUSIONS On the basis of conducted research it can be stated, that impregnation of particles for particleboards production, with the agent based on quaternary ammonium compounds and boric acid, is beneficial for improving fireproof properties defined in the work. REFERENCES 1. BABRAUSKAS V. 2005: Charring rate of wood as a tool for fire investigations. Fire Safety Journal 40 (2005) DRYSDALE D. 2001: Introduction to Fire Dynamics, J.Willey & Sons Inc. 3. GREXA O., POUTCH F., MANIKOVA D., MARTVONOVA H., BARTEKOVA A. 2003: Intumescence in fire retardancy of lignocellulosic panels. Polymer Degradation and Stability 82 (2003) KOZŁOWSKI R., MIELENIAK B., HELWIG M., PRZEPIERA A. 1999: Flame resistant lignocellulosic-mineral composite particleboards. Polymer Degradation and Stability 64 (1999) OSIPIUK J. 2001: Trwałość zabezpieczenia drewna solnymi środkami ogniochronnymi. Wydawnictwo SGGW 6. PN-EN ISO : 2004 Badanie reakcji na ogień. Zapalność materiałów poddanych bezpośredniemu działaniu płomienia. Część 2: Badanie przy działaniu pojedynczego płomienia ( Reaction to fire tests - Ignitability of products subjected to direct impingement of flame - Part 2: Single-flame source test ) 7. PN-EN ISO : 1998 Oznaczenie zapalności tworzyw sztucznych metodą wskaźnika tlenowego ( Plastics - Determination of burning behaviour by oxygen index ) Streszczenie: Charakterystyka wybranych właściwości ogniochronnych płyty wiórowej z wiórów impregnowanych preparatem solnym. W pracy przedstawiono wyniki badań wybranych właściwości ogniochronnych płyt wiórowych trójwarstwowych wytworzonych z sosnowych wiórów drzewnych impregnowanych ogólnodostępnym bio- i ogniochronnym środkiem solnym do zabezpieczania drewna, na bazie czwartorzędowych związków amoniowych i kwasu borowego. W podsumowaniu stwierdzono, że przeprowadzona impregnacja zwiększa ognioodporność płyt wiórowych względem tworzyw niezabezpieczonych. Corresponding authors: Piotr Boruszewski, Warsaw University of Life Sciences SGGW, Faculty of Wood Technology 159 Nowoursynowska St., Warsaw, Poland [email protected] Waldemar Jaskółowski, The Main School of Fire Service, Department of Combustion and Fire Theory 52/54 Słowackiego St., Warsaw, Poland [email protected] 146

147 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Influence of flakes impregnation with salt flame retardants on selected physical and mechanical properties of OSB PIOTR BORUSZEWSKI 1, PIOTR BORYSIUK 1, WALDEMAR JASKÓŁOWSKI 2, ANTONI ŚWIĘCKI 1, MARIUSZ MAMIŃSKI 1, IZABELLA JENCZYK-TOŁŁOCZKO 1 1 Faculty of Wood Technology, Warsaw University of Life Sciences SGGW 2 Department of Combustion and Fire Theory, The Main School of Fire Service SGSP Abstract: Influence of flakes impregnation with salt flame retardants on selected physical and mechanical properties of OSB. In this study, selected physical and mechanical properties of OSB made from flakes impregnated with two fireproof agents: A) on the basis of quaternary ammonium compounds and boric acid and B) on the basis of diammonium hydrogen phosphate, citric acid and sodium benzoate. It was concluded that impregnated flakes increase fire resistance of the material, reducing the mechanical properties at the same time. Keywords: OSB, fire resistance, physical and mechanical properties. INTRODUCTION Solid wood, despite the fast price growth is still widely used as: - construction timber (beams, squared log, batten, latch) for engineering structures, and roof constructions et al., - building timber on scaffolding, fencing and roof covering, - sawnwood used for furniture, joinery and panelling, - timber semi-products (strips, batten) for further processing (Kobiela 2004). Problem of the high-quality structural timber deficit, forces its replacement with wood based materials (Hikiert and Oniśko 2006). The main raw material for the wood-based panels industry is small and medium sized wood, as well as waste material. Produced materials characterize with relatively low specific weight in relation to their strength properties. In the upcoming years, wood-based panels industry will evolve in the direction of new materials production, lighter, with better properties, using materials with lower densities. Production processes are being changed for better efficiency, energy savings, as well as are becoming more environmentally friendly. Unfortunately, wood and wood-based materials are flammable and susceptible to all kinds of corrosion caused by biotic and abiotic factors (Osipiuk 2001). Therefore, solutions for eliminating a large extent of these disadvantages are researched (Giancaspro et al. 2009). Protection of finished wood-based panels with antipirens was not yet generally applicable. Using flame retardants to impregnate the grinded material during the manufacturing process, immediately after grinding of round wood into particles might be a better solution (Ayrilmi 2007, Drysdale 2001). MATERIAL AND METHODS Researches of strength properties were performed on three-layer OSB with thickness of 10 mm, and density of 600 kg/m 3. Flakes for OSB production have been previously impregnated with two fireproofing agents: A) based on quaternary ammonium compounds and boric acid and B) based on diammonium hydrogen phosphate, citric acid and sodium benzoate. Pine flakes were used. At the beginning of studies, impregnants in form of 10% solutions were 147

148 applied on flakes by spraying in a rotating tumbler, and then they were dried at 80 C to moisture content of 6%. Parameters of the boards production were: glue content - 10%, the unit press pressure of 2.5 MPa, unit pressing time - 18 sec/mm of thickness, temperature of 130 C. Phenol-formaldehyde resin with the addition of resorcinol was used for boards production in order to reduce the pressing temperature from 180 ºC to 130 ºC. Three levels of retention were used: 15 kg/m 3, 30 kg/m 3 and 45 kg/m 3. Series of control boards, without fireproofing agent was also produced. From produced OSB, samples were cut for following tests: - Flammability of products subjected to direct impingement of single-flame according to PN-EN ISO : Oxygen index flammability test according to PN ISO : Determination of modulus of elasticity in bending and of bending strength according to PN EN Determination of perpendicular tensile strength to the surface of the boards according to PN EN 319. Test samples were cut along the fibres. RESULTS AND DISCUSSION Results of the flammability test of products subjected to direct impingement of singleflame are presented in Table 1. Edge exposure study was conducted. None of the variants were ignited during the operation of the flame for 120 seconds. Table 1. Single-flame source flammability test Agent and its retention Was there ignition after 15 sec? Was there ignition after 30 sec? Is burning selfsustained? Average flame height after 120 sec Were drops and waste produced? Control No No No 87.5 mm No A 15 kg/1m 3 No No No 67.5 mm No A 30 kg/1m 3 No No No 57.5 mm No A 45 kg/1m 3 No No No 45.0 mm No B 15 kg/1m 3 No No No 77.5 mm No B 30 kg/1m 3 No No No 76.0 mm No B 45 kg/1m 3 No No No 70.0 mm No Characteristics of produced smoke Trace amounts Boards made of flakes impregnated with agent A, with retention of 45 kg/m 3, achieved the highest fire resistance - after 120 seconds of flame exposition, carbonization has reached only 4.5 cm. This is almost twice better result than for the sample impregnated with agent B at the same retention. Generally, boards protected with agent A showed better resistance to a single flame. Impregnating with both agents had a positive impact on the fire resistance. During the arson, smoke was produced in small ammounts, and there were no wastes. Burning was not sustained. Test samples satisfy one of the classification criteria Fs <150 mm after a period of 20 seconds, allowing to qualify them for Euro Class Bfl or lower (Cfl, Dfl, Efl) (according to PN-EN ISO :2004). Appearance of the boards after conducted fire test are presented in Figure

149 Control A 15kg/m 3 A 30kg/m 3 A 45kg/m 3 B 15kg/m 3 B 30kg/m 3 B 45kg/m 3 Fig. 1. Samples after single-flame source test test was conducted on the basis of oxygen index method. The results obtained in oxygen index flammability tests are shown in Figure 2. The study showed increased fire resistance of produced OSB. Highest oxygen index was achieved by boards impregnated with agent A at the retention of 45 kg/m 3. To sustain burning of the sample, oxygent content of 51% in the air was needed. Control samples achieved oxygen index of 27%. As an example, oxygen index for wood ranges from 22.4% to 24.6%. Increase of fire resistnace of control boards may have been a result of applied resin and a high degree of compression of material. Boards made of flakes impreganted with agent A showed a higher oxygen index than boards impregnated with agent B at the corresponding retention. Oxygen indexes for agents A (30 kg/m 3 ) and B (45 kg/m 3 ) hardly differ, but the consumption of agent B is much bigger. Fig. 2. Oxygen index values for peculiar variants. Results of determination of static bending strength are presented on Figure 3 and the comparison of results of modulus of elasticity in bending strength, made of pine flakes impregnated with two types of fireproofing agents at three different retentions, are presented in Table

150 Boards made of flakes impregnated with both agent A and B, with retentions of 30 and 45 kg/m 3, show similar static bending strength. Reduction of agent B retention to 15 kg/m 3 resulted in a slight (statistically insignificant) increase in strength relative to the control variant. Increasing the retention of the agent B to the level of 30 and 45 kg/m 3 resulted in lower bending strength (30 N/mm 2 ). This value is lower than the value for control sample. Standard PN EN-310 specifies the strength of OSB at 30 N/mm 2. The values obtained for samples impregnated with agent B are comparable. Samples impregnated with agent A are not eligible for this limit, with the bending strength of 20 N/mm 2. Fig. 3. Static bending strength (MOR) for particular variants. Determination of modulus of elasticity in bending of tested materials showed its highest value for boards made of flakes saturated with agent B with retention of 15 kg/m 3. Addition of agent A had negative impact on the value of the modulus of elasticity Standard PN EN 310 specifies the modulus of elasticity for OSB/4 at the level of 4800 N/mm 2, and for OSB/3 at the level of 3500N/mm 2. Table 2. Value of modulus of elasticity (MOE) Sample MOE [N/mm 2 ] MOE according to PN-EN 310 OSB/4 [N/mm 2 ] MOE according to PN-EN 310 OSB/3 [N/mm 2 ] Control 4607 A 15 kg/m A 30 kg/m A 45 kg/m B 15 kg/m B 30 kg/m B 45 kg/m

151 Results of the determination of perpendicular tensile strength to the surface of the boards are presented in Figure 4. Just as in the previous examinations, boards made from flakes impregnated with agent B with retention of 15 kg/m 3 were the only ones that met the requirements of the standard and showed higher strength in comparison to the control variant. It should be noted that this difference was statistically insignificant for the level of confidence of 95%. With the increase of impregnant retention, perpendicular tensile strength (to the surface of the boards) of the boards significantly decreased. Standard PN EN-310 defines a tensile strength of the OSB/4 at 0.5 N/mm 2. Fig. 4. Perpendicular tensile strength to the surface of the boards (IB). CONCLUSIONS Impregnation of flakes, before the process of pressing, with agents based on quaternary ammonium compounds and boric acid as well as diammonium hydrogen phosphate, citric acid and sodium benzoate, had a positive impact on the fire resistance of tested material. Agent A in greater extent than agent B improves the fire resistance of OSB, under the same retention. OSB unprotected with any impregnant has better fire resistance than solid wood. The use of fireproof impregnation in the retention of more than 15 kg/m 3 decreases mechanical properties of the material. Flakes impregnation with agent A definitely improves fire-retardant properties of boards, however it worsens their mechanical propeties, in comparison with boards where particles were impregnated with agent B. 151

152 REFERENCES 1. AYRILMI N. 2007: Effect of fire retardants on internal bond strength and bond durability of structural fiberboard. Building and Environment 42 (2007) DRYSDALE D. 2001: Introduction to Fire Dynamics, J.Willey & Sons Inc. 3. GIANCASPRO J., PAPAKONSTANTINOU CH., BALAGURU P. 2009: Mechanical behavior of fire-resistant biocomposite. Composites: Part B 40 (2009) HIKIERT M.A., ONIŚKO W Strategia rozwoju przemysłu płyt drewnopochodnych w Polsce do 2013 roku. Wyd. Instytut Technologii Drewna, Poznań 5. KOBIELA S. 2004: Środki bio- i ogniochronne do drewna i materiałów drewnopochodnych, Pożarnik nr 3/ OSIPIUK J. 2001: Trwałość zabezpieczenia drewna solnymi środkami ogniochronnymi. Wydawnictwo SGGW Streszczenie: Wpływ impregnacji wiórów solnymi środkami ogniochronnymi na wybrane właściwości fizyko-mechaniczne płyty OSB. W pracy zbadano wybrane właściwości fizykomechaniczne płyt OSB wyprodukowanych z wiórów zaimpregnowanych dwoma preparatami ogniochronnymi: A) na bazie czwartorzędowych związków amoniowych i kwasu borowego i B) na bazie wodorofosforanu amonu, kwasu cytrynowego i benzoesanu sodu. Stwierdzono, że zaimpregnowane wióry wstęgowe podwyższają odporność ogniową materiału, przy jednoczesnym obniżeniu właściwości mechanicznych Corresponding authors: Piotr Boruszewski Warsaw University of Life Sciences SGGW, Faculty of Wood Technology 159 Nowoursynowska St., Warsaw, Poland [email protected] Waldemar Jaskółowski The Main School of Fire Service, Department of Combustion and Fire Theory 52/54 Słowackiego St., Warsaw, Poland [email protected] 152

153 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Screw holding ability of the lignin-bonded biocomposites PIOTR BORUSZEWSKI, PIOTR BORYSIUK, MARIUSZ MAMIŃSKI Faculty of Wood Technology, Warsaw University of Life Sciences SGGW Abstract: Screw holding ability of the lignin-bonded biocomposites. Biocomposites derived from the unmodified and enzymatically modified lignin, hemp shives and shellac were manufactured in injection moulding process. The boards were characterized by hardness and screw holding ability. It was found that screw holding ability of the tested boards was comparable to those for particleboard and MDF. Moreover, addition of shellac results in increase in that parameter, however the influence of the enzymatic treatment on screw holding occurred ambiguous and strongly dependent on the enzyme type. Keywords: lignin, enzymatic modification, biocomposites, screw holding capacity INTRODUCTION Biocomposites so called green composites are the materials made of natural fibers (e.g. wood fibers) with biopolymers or bioplastics (Mohanty et al. 2000, Maya and Sabu 2008). As natural biodegradable polymer matrices polysaccarides (starch, cellulose, chitin), proteins (collagen/gelation, casein, albumin, fibrogen, silks), polyesters (polyhydroxyalkanoates) and other polymers (lignin, lipids, shellac, natural rubber) can be used (Stevens 2002). Lignin, aside from cellulose and hemicelluloses, is one of the main constituents of wood. Its content varies from 20 to 30%. When heated, lignin becomes plasticized so that it can be used as a binder for natural fibers (Li et al. 1997, Chakar and Ragauskas 2004, Kadla and Kubo 2004, Le Digabel and Ave rous 2006, Guigo et al. 2009). Enzymatic treatments may improve performance of lignin-based biocomposites (Widsten and Kandelbauer 2008). Up-to-date investigations showed that density ( kg/m 3 ) and other properties of those types of composites were comparable to those of glass-fiber reinforced plastics (Mohanty et al. 2000). On the other hand, when compared to the hardboard from wet method, lignin-bonded fiberboards exhibit increased hydrophobicity (Boruszewski et al. 2010). Nowadays, the field of biocomposites applications constantly extends. They are used for furniture and interior applications. What is worth nothing, lignin-bonded biocomposites can be easily 3D-formed in injection moulding or extrusion moulding process. Due to applications in furniture, screw holding ability seems to be a feature necessary to examine. MATERIAL AND METHODS The boards composed of hemp shives (STW 150), Indulin AT (unmodified or enzymatically modified) as the binder and shellac additive were made by injection moulding. The prepared boards characteristics were presented in Table 1. The boards of dimensions 300 x 300 mm 2 were manufactured at the Faculty of Mechanical Engineering, Chemnitz University of Technology. Prior to injection moulding raw materials were dried at 60ºC to 2% moisture content. Mat forming: pre-pressing ~10 N/mm 2, hot pressing ~1 N/mm 2, postpressing ~5 N/mm 2. Injection temperature 162ºC. 153

154 Table 1. Lignin-bonded boards characteristics Panel Receipt Lignin Fiber Additive type (Lignin/Fibre/Additive) A STW %/45%/0% IAT B STW 150 Shellac dewaxed 40%/45%/15% C STW %/45%/0% IAT treated ULB* D STW 150 Shellac dewaxed 40%/45%/15% E STW %/45%/0% IAT treated H F 2 O STW 150 Shellac dewaxed 40%/45%/15% * Laccase from Cerrena unicolor The following properties of the boards were analyzed: density profile on a laboratory density profile measuring system GreCon DA-X. Measurement resolution 0.02 mm at rate 0,05 mm/s. Brinell hardness (according to EN 1534:2000 Wood and parquet flooring. Determination of resistance to indentation (Brinell). Test method) screw holding ability (according to EN 13446:2004 Wood-based panels. Determination of withdrawal capacity of fasteners). Ten specimens were tested in each batch. Statistical significance of differences was tested by Student t-test at 95% confidence interval. RESULTS AND DISCUSSION Screw holding ability in the perpendicular setting results were shown in Table 2 and in Fig. 2. The feature determines fasteners load bearing capacity e.g. especially in furniture. It depends on the density, elasticity and cohesion of the holding material. Density of the boards ranged from 1312 to 1383 kg/m 3. In general, comparison of the properties can be made when differences between the respective variables do not exceed 10%. The differences in density of the examined boards did not exceed 5.4%. Cross-sectional density variations were shown in Fig. 1. The examined materials, regardless of the thickness, exhibited uniform crosssectional density profile. Table 2. Properties of the tested boards Panel Thickness Density Brinell hardness Screw holding ability type [mm] [kg/m 3 ] x [%] [N/mm 2 ] x [%] [N/mm] x [%] A B C D E F x variation coefficient Screw holding ability for all the tested series ranged from N/mm to N/mm (Table 2, Fig. 2). For the series with shellac as additive, a statistically significant increase in that parameter (16 38%) was observed. The effect of shellac on the hardness was also found. The observed 8-11% increase may be explained by natural high hardness of shellac (Unger et al. 2001). 154

155 Density [kg/m 3 ] EC A F D B 0 0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 Thickness [mm] Fig. 1. Cross-sectional density profiles of the tested boards Screw holding Brinell hardness Screw holding [N/mm] Brinell hardness [N/mm 2 ] A B C D E F 0 Panel type Fig. 2. Screw holding ability and hardness of the boards Thus, the presented results revealed that enzymatic treatments did not contribute much to the mechanical performance of the studied boards. The effect of type of the enzyme used is ambiguous, since either increase or decrease in screw holding ability was found, respectively for and enzyme. Moreover, the differences were statistically significant at 95% confidence interval. It also must be stressed that the synergistic effect of shellac addition and enzymatic modification of lignin always lowered screw holding ability. Thus, the obtained values of screw holding are comparable to those of particleboards or MDF: N/mm (Niemz 1993), when the thickness of the material is neglected. 155

156 CONCLUSIONS The studied lignin-bonded fiber composites made by injection moulding exhibited screw holding capacity of N/mm2, while the shellac addition contributed to improved screw holding. The observed differences are statistically significant. However, the influence of the enzymatic treatment on screw holding occurred ambiguous and strongly dependent on the enzyme type. REFERENCES 1. BORUSZEWSKI P., BORYSIUK P., DOBROWOLSKA E., MAMIŃSKI M., NICEWICZ D., 2010: Interactions with water of novel wood-fiber material with lignins as binder. Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology, 71/2010, CHAKAR F. S., RAGAUSKAS A. J., 2004: Review of current and future softwood kraft lignin process chemistry. Industrial Crops and Products 20, GUIGO N., VINCENT L., MIJA A., NAEGELE H., SBIRRAZZUOLI N., 2009: Innovative green nanocomposites based on silicate clays / lignin / natural fibres. Composites Science and Technology 69, KADLA J. F., KUBO S., 2004: Lignin-based polymer blends: analysis of intermolecular interactions in lignin synthetic polymer blends. Composites: Part A 35, LE DIGABEL F., AVE ROUS L., 2006: Effects of lignin content on the properties of lignocellulose-based biocomposites. Carbohydrate Polymers 66, LI Y., MLYNAR J., SARKANEN S., 1997: The First 85% Kraft Lignin-Based Thermoplastics. Journal of Polymer Science Part B: Polymer Physics 12 (35), MAYA J. J., SABU T., 2008: Biofibres and biocomposites. Carbohydrate Polymers 71, MOHANTY A. K., MISRA M., HINRICHSEN G., 2000: Biofibres, biodegradable polymers and biocomposites: An overview. Macromolecular Materials and Engineering 276/277, NIEMZ P., 1993: Physik des Holzes und der Holzwerkstoffe. DRW-Verlag 10. STEVENS E. S., 2002: Green Plastics. Princeton: Princeton University Press. 11. UNGER A., SCHNIEWIND A. P., UNGER W., 2001: Conserwation of Wood Artifacts. Springer Verlag, Berlin. 12. WIDSTEN P., KANDELBAUER A., 2008: Laccase applications in the forest products industry: A review. Enzyme and Microbial Technology 42,

157 ACKNOWLEDGMENT This work was carried out as a part of the ERA-IB-project: Improvement of strength properties and reduction of emission of volatile organic compounds by enzymatic modification of lignin containing biopolymers and composites (VOC reduction of lignin containing materials) EIB Streszczenie: Zdolność utrzymywania wkrętów w biokompozytach spajanych ligniną. Biokompozyty na bazie ligniny niemodyfikowanej i modyfikowanej enzymatycznie, włókien konopnych i szelaku były wytwarzane metodą wtryskiwania. Dla wytworzonych płyt wyznaczono ich twardość i zdolność utrzymywania wkrętów. Ustalono, że badane płyty charakteryzują się zdolnością utrzymania wkrętów na poziomie zbliżonym do płyt wiórowych i MDF. Wyższe wartości uzyskują kompozyty zawierające w swojej recepturze dodatek szelaku natomiast modyfikacja enzymatyczna ligniny wpływa niejednoznacznie na wartość zdolności utrzymywania wkrętów. Jej efekt jest uzależniony od efektywności zastosowanego enzymu. Corresponding authors: Piotr Boruszewski, Piotr Borysiuk, Mariusz Mamiński, Faculty of Wood Technology, Warsaw University of Life Sciences SGGW, Warsaw, 159 Nowoursynowska st., Poland, [email protected] [email protected] [email protected] 157

158 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Bonding quality of veneers protected with fireproofing preservation based on diammonium hydrogen phosphate, citric acid and sodium benzoate PIOTR BORYSIUK, KRZYSZTOF KRAJEWSKI, PIOTR BORUSZEWSKI, IZABELLA JENCZYK-TOŁŁOCZKO, MAREK JABŁOŃSKI Faculty of Wood Technology, Warsaw University of Life Sciences SGGW Abstract: Bonding quality of veneers protected with fireproofing preservation based on diammonium hydrogen phosphate, citric acid and sodium benzoate. In the study, joints strength in three-layer plywood glued with ureaformaldehyde resin, made from pine and beech veneers impregnated with fireproofing preservation based on diammonium hydrogen phosphate ammonium phosphate, citric acid and sodium benzoate, was determined. It was estabilished that for pine plywood, veneers impregnation does not affect the strength of joints, and in case of beech plywood veneer impregnation caused a decrease in strength by about 20%. Keywords: bond quality, fireproofing protection, plywood INTRODUCTION Plywood is a valuable construction material used in building industry, both for a permanently embedded components and interior furnishings devices. Its use is justified due to advantageous strength parameters resulting from its layered structure. Certain limitation of its use arises from lack of fire resistance. This aspect plays an important role in terms of buildings safety (Wytwer 1994). One of the possibilities of improving plywood resistance to fire is impregnation of veneers with flame-retardants, during technological process, before gluing of veneers. This solution allows to receive a material protected in the entire volume. However, in case of this solution, there is a danger of glue joints strength declining, due to the negative impact of impregnant on the adhesion of glue to the wood surface, as well as impregnant reaction during hot pressing of plywood (Wytwer and Starecki 1995, Dziurka et al. 2006, Domański et al. 2007, Borysiuk et al. 2008). The current market offers new preservatives reducing flammability of wood, which are based on ecological and non-toxic organic ingredients, so that they can be successfully used in a human environment. One of such agents is fireproofing preservation based on diammonium hydrogen phosphate, citric acid and sodium benzoate (US ). In these studies, the influence of the veneer impregnation (with this preservation) on the strength of glue joints in plywood based on these veneers was identified. MATERIAL AND METHODS Pine and beech veneers with a nominal thickness of 1.5 mm and density, respectively: 484 kg/m 3 and 676 kg/m 3 were pressure protected with fireproofing preservation based on diammonium hydrogen phosphate, citric acid and sodium benzoate. The product was used as water solution having a concentration of 20%. Average retention of the preparation was 50 kg per 1 m 3 for beech veneer and 47.5 kg per 1 m 3 to pine veneer. After impregnation, veneers were dried at C, to the moisture content of about 5%. 3-layer plywood from impregnated and non-impregnated veneers was produced on the basis of urea-formaldehyde resin. Glue recipe and parameters of plywood gluing are presented in Table

159 Table 1. Glue recipe and parameters of plywood gluing Parameter Value Glue recipe UF resin 100 pbw, hardener (10 % solution of (NH 4 ) 2 SO 4 ) 4 pbw, aggregate (wheat flour) 15 pbw, water 10 pbw Glue spread 160 g/m 2 Pressing temperature 110 o C Unit press pressure pine veneer 1.0 MPa, beech veneer 1.2 MPa Time of pressing 330 sec After production, plywood was conditioned for 1 week under laboratory conditions, and then samples were obtained for shear strength of glue joints testing in accordance with EN The study was conducted on both dry samples and after wetting samples in water for 24 h. For each variant 15 samples were prepared. RESULTS AND DISCUSSION Research results of plywood gluing quality are shown in Table 2 and Figures 1 and 2. Generally it can be stated, that statistically, impregnation of veneers with the fireproofing preservation did not influence the strength of joints in pine plywood. Both in the dry test and after wetting in water for 24 h, similar strength results were observed at the level of: 1.5 N/mm 2 and 1.1 N/mm 2. Table 2. Research results of plywood gluing quality Shear strength of glue joints Sample Dry conditions After wetting [N/mm 2 ] x [%] [N/mm 2 ] x [%] Pine plywood non-impregnated veneers Pine plywood impregnated veneers Beech plywood non-impregnated veneers Beech plywood impregnated veneers x coefficient of variation Bond quality [N/mm 2 ] 2,2 2,0 1,8 1,6 1,4 1,2 1,0 0,8 0,6 0,4 0,2 0,0 non-impregnated veneers impregnated veneers Fig. 1. Shear strength of pine plywood made of impregnated and non-impregnated veneers dry conditions after wetting 159

160 Bond quality [N/mm 2 ] 2,2 2,0 1,8 1,6 1,4 1,2 1,0 0,8 0,6 0,4 0,2 0,0 non-impregnated veneers impregnated veneers Fig. 2. Shear strength of beech plywood made of impregnated and non-impregnated veneers dry conditions after wetting In case of beech plywood, veneer impregnation with preparation influenced on declining of glue joints strength in 19% for dry test and 16% for the determination after wetting in water for 24 hours. Obtained differences were statistically significant in nature, however it should be noted that glue joints produced in both cases meet the assumptions of the EN (glue joints strength of more than 1 N/mm 2 ). For both pine and beech plywood, diversity of destruction of glue joints in wood achieved in dry test was in the range of %. In case of testing the samples after wetting in water, destruction of joints usually took place in glue joints (wood failure 0 10%). At the same time it can be noticed, that at the examination of samples after wetting in water, the results obtained for plywood produced from impregnated veneers were characterised by an average of 8% greater variability performance compared to plywood made of non-impregnated veneers. CONCLUSIONS On the basis of conducted researches it can be stated: 1. Impregnation of pine veneers with fireproofing preservation based on diammonium hydrogen phosphate, citric acid and sodium benzoate does not affect joints strength in plywood made from them with the use of urea-formaldehyde resin, in the range tested. 2. Impregnation of beech veneers with fireproofing preservation based on diammonium hydrogen phosphate, citric acid and sodium benzoate reduces joints strength in plywood made from them with the use of urea-formaldehyde resin, in the range tested. However, it should be noted that obtained results meet the requirements of EN in the scope of joints strength. REFERENCES 1. BORYSIUK P., DZIURKA D., JABŁOŃSKI M., ZBIEĆ M. 2008: Gluability of pine wood protected with bio and fire preservaties. VIIth International Symposium Composite Wood Materials Zvolen, June s DOMAŃSKI M., DZIURKA D., JABŁOŃSKI M., KRAJEWSKI K. 2007: Shear strength of selected glue types in pine wood protected with multipurpose bio and fireproofing FIRESMART BIO P/POŻ preservative. Annals of Warsaw University of Life Sciences SGGW, Forestry and Wood Technology No s DZIURKA D., JABŁOŃSKI M., OSIPIUK J., SEDLIAČIK J., ZBIEĆ M 2006: Shear strenght of Melfemo S melamine-urea-phenol-formaldehyde glue bonds in pine wood 160

161 preserved with fire-proof agents. VIth International Symposium Composite Wood Materials Zvolen, June , s PN-EN 314-1: Plywood. Bonding quality. Test methods. 5. PN-EN 314-2: Plywood. Bonding quality. Requirements. 6. United States Patent No: US Flame retardant chemical composition. Jun 15, WYTWER T. 1994: Przeciwogniowe zabezpieczanie drewna, IX Konferencja Kontra 94. Trwałość budowli i ochrona przed korozją. s WYTWER T., STARECKI A. 1995: Wpływ środka ognioochronnego Fungitoxu NP. na właściwości sklejki bukowej. Materiały konferencyjne na XII Sympozjum Pokroky vo výrobe a použiti lepidiel v drevopriemysle, Zvolen, , s Streszczenie: Jakość sklejenia fornirów zabezpieczonych środkiem ogniochronnym na bazie wodorofosforanu amonu, kwasu cytrynowego i benzoesanu sodu. W ramach badań określono wytrzymałość spoin w sklejkach trójwarstwowych klejonych żywicą UF wytworzonych z fornirów sosnowych i bukowych zaimpregnowanych preparatem ogniochronnym opartym na kompozycji wodorofosforanu amonu, kwasu cytrynowego i benzoesanu sodu. Ustalono, że w odniesieniu do sklejek sosnowych, impregnacja fornirów nie wpływa na wytrzymałość spoin, zaś w przypadku sklejek bukowych impregnacja fornirów powodowała spadek wytrzymałości o około 20 %. Corresponding authors: Piotr Borysiuk, Krzysztof Krajewski, Piotr Boruszewski, Izabella Jenczyk-Tołłoczko, Marek Jabłoński Faculty of Wood Technology, Warsaw University of Life Sciences SGGW, Warsaw, 159 Nowoursynowska st., Poland, [email protected] [email protected] [email protected] [email protected] [email protected] 161

162 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Mechanical properties of glue bonds in black locust wood treated with ammonia PIOTR BORYSIUK 1), MAREK JABŁOŃSKI 1), ANNA POLICIŃSKA-SERWA 2), EVA RUŽINSKÁ 3) 1) Faculty of Wood Technology, Warsaw University of Life Sciences SGGW 2) Building Research Institute Warsaw 3) Department of Environmental Technology, Faculty of Environmental and Manufacturing Technology, Technical University in Zvolen, Slovakia Abstract: Mechanical properties of glue bonds in black locust wood treated with ammonia. Work deals with strength of bonds in smoked black locust wood, glued with MUF, PVAc and EPI glues. Smoking (ammonia treatment) of black locust wood deteriorates strength of bonds, because of lowered wettability, especially with water-based resins of lower solution strength. Best results, in both dry and wet state, were gained with the usage of MUF glue. RUŽINSKÁ 4) Keywords: Black locust, smoked wood, bond strength INTRODUCTION Wood is being used by humanity for ages, and in a numerous applications, as a tool, weapon, shelter, toy etc. Such an utilization is caused by ease of use, wide avaiibility and looks color, pattern, finish and especially natural look. Most precious species of wood are being chosen especially for the visual advantages, which usually come along with exceptional strength and durability properties, especially in exotic species. Some domestic, cheaper wood can be modified to reach visual looks of exotics, being suitably strong for demanding applications such as flooring Hill 2006). Processing of wood in high temperatures or ammonia is especially designed for darkening of lightly colored wood. Ammonia processing of wood is widely used by carpenters (Tinkler 1921). Treatment may be made with aqua ammonia (ammonia saturated water) (Oniśko and Matejak 1971) or by smoking (in gaseous ammonia) (Weigl et al a,b). Modification bases on chemical reaction of tannins with gaseous ammonia, which causes darkening of wood, even down to black color. Such processing is usually used with oak wood (Quercus sp.), sometimes with black locust (Robinia pseudoacacia L.) or sweet cherry wood (Prunus avium L.) (Weigl et al. 2007, 2009 a,b). Unfortunately, mechanical properies are usually affected along color modification (Bariska 1969, Oniśko and Matejak 1971, Weigl et al a,b). Amongst other effects lowered wood gluability may occur (Pióro 2009) causing unquestionable harm to layered wood materials. Objective of his work was to determine ammonia treatment influence on black locust wood bonds mechanical properties, with MUF, PVA and EPI glues. 162

163 METHODIC Black locust wood (Robinia pseudoacacia L.) of density 748 kg/m 3, treated with gaseous ammonia (wood smoking) was used for tests. Wood was modified in in gas environment (wood exposed to ammonia fumes). Unmodified black locust wood (Robinia pseudoacacia L.), density 711 kg/m 3 was also tested as an control samples. Wetting angle (θ) measurement of test samples was made wit Phoenix 300 goniometer. Wetting angle of all tested specimens was measured after 60 seconds from drop settling. Wood bonds quality tests were made accordingly to EN 204: 2002 standard - Classification of thermoplastic wood adhesive for non-structural applications and EN 205: 2005 standard - Test methods for wood adhesives for non-structural applications - Determination of tensile shear strength of lap joint. Shear strength tests of bonds were made with dry and 4-day soaked samples (water at 20 ± 1 o C -D3 grade glue test). MUF, PVAc and EPI glues were used for the tests. Glue types and gluing parameters are presented in tables 1 and 2. Table 1. Glue characteristics and. Glue Durability class Viscosity Dry mass [mpas] [%] MUF D PVAc D EPI D Table 2. Gluing parameters Glue Glue spread* Pressing temperature* Pressing time* Maximum unit pressure* [g/m 2 ] [ o C] [min] [MPa] MUF 180 PVAc ,0 EPI 30 * gluing parameters selected according to the manufacturer's glue Ten tests were made for each combination, T-Student test at significance level 95 % showed statistical importance of the results. RESULTS Smoking of black locust caused hydrophobizaton of the wood. Wetting angle: ammonia-modified wood 58 o ± 5 o, unmodified wood 16 o ± 3 o. Over three times increase of wetting angle has severe impact on water-based glues. Shear strength tests are presented on figures 1-3. In dry state no statistically important differences were found between smoked and unsmoked wood bonded with all three glues. Shear strength ranged 9,4 10,6 N/mm 2 (variation coefficient 8 18 %) for smoked wood and 10,1 10,5 N/mm 2 (variation coefficient 14 %) for control samples. D3 grade requires strength of 10 N/mm 2. EN 204: 2002 standard however states only about beech wood. Smoked wood shows fracture in the wood itself in 55 % samples, in control samples this reaches around 80 %. 163

164 Shear strength [N/mm 2 ] 14,0 12,0 10,0 8,0 6,0 4,0 2,0 0,0 dry ammonia-modified wood after 4 days soaking in water unmodified wood Fig. 1. Shear strength results of Black locust samples glued with MUF. Shear strength [N/mm 2 ] 14,0 12,0 10,0 8,0 6,0 4,0 2,0 0,0 dry ammonia-modified wood after 4 days soaking in water unmodified wood Fig. 2. Shear strength results of Black locust samples glued with PVAc Shear strength [N/mm 2 ] 14,0 12,0 10,0 8,0 6,0 4,0 2,0 0,0 dry ammonia-modified wood after 4 days soaking in water unmodified wood Fig. 3. Shear strength results of Black locust samples glued with EPI. 164

165 Smoked wood in case of PVAc and EPI glues shows 7% decrease in bond strength. It is probably caused by higher wetting angles. Dry mass of PVAc equals 58 %, EPI 57 %, and MUF 69 % in comparison to MUF glue, so their penetrating properties may be lower. In wet state, MUF and EPI glues show statistically important shear strength decrease at 67 % and 56 % respectively, with fracture typically in the bond. PVAc glue applied to unsmoked wood shows 100 % separation after soaking, with shear strength 2,1 N/mm 2 level. Minimal shear strength of 2 N/mm 2 is required in accordance to EN 204: 2002 standard. Smoked wood shows lower mechanical properties possibly due to increased wood swell in tangential direction (Oniśko and Matejak 1971, Weigl et al b), which increases tensile strain in the bond to higher values than in unsmoked wood. CONCLUSION Smoking of black locust wood changes its physical properties, decreasing physical strength of bonds made with MUF, PVAc and EPI adhesives. Between all the glues tested, MUF glue shows best results in both wet and dry states, in comparison to other ones. REFERENCES: 1. BARISKA M. 1969: Plastifizierung des Holzes mit Ammoniak in Theorie und Praxis. Holz-Zentralblatt 95 (84): HILL C. 2006: Wood Modification: Chemical, Thermal and Other Processes. John Wiley & Sons Ltd, West Sussex, England. 3. ONIŚKO W., MATEJAK M. 1971: Einfluß 25%iger Ammoniaklösung auf die physikalischen und mechanischen Eigenschaften des Holzes. Holztechnologie 12 (1): PIÓRO P. 2009: Dąb wędzony niełatwe zadanie dla parkieciarza, Podłoga 2/2009, TINKLER C.K. 1921: Fumed oak and natural brown oak. Biochem J 15 (4): WEIGL M., Gündüz M., Müller U. 2009a: On the mechanical stability of ammonia treated wood. In: Hill CAS, Militz H (eds) 4th European Conference on Wood Modification. 27 th 29 th April 2009, Stockholm, Sweden. 7. WEIGL M., PÖCKL J., GRABNER M. 2009b: Selected properties of gas phase ammonia treated wood. Eur. J. Wood Prod. (2009) 67: WEIGL M., PÖCKL J., MÜLLER U., PRETZL H., GRABNER M., 2007: UVresistance of ammonia treated wood. In: Hill CAS, Jones D, Militz H, Ormondroyd GA (eds) 3rd European Conference on Wood Modification. 15 th 16 th October 2007, Cardiff, UK. 165

166 Streszczenie: Wytrzymałość spoin klejowych w klejonym drewnie akacji zmodyfikowanej amoniakiem. W trakcie badań określono wytrzymałość na ścinanie połączeń klejowych wykonanych z drewna akacji modyfikowanej amoniakiem przy zastosowaniu klejów MUF, PVAc i EPI. Wykazano, że modyfikacja drewna akacjowego amoniakiem pogarsza zwilżalność jego powierzchni wodą. W konsekwencji pogorszeniu ulega wytrzymałość spoin wytworzonych z wykorzystaniem klejów na bazie wodnej o mniejszej zawartości suchej masy. Najlepsze właściwości wytrzymałościowe spoin, biorąc pod uwagę oznaczenie na sucho i po moczeniu w wodzie, uzyskano dla kleju MUF. Corresponding authors: Piotr Borysiuk, Faculty of Wood Technology, Warsaw University of Life Sciences SGGW, Warsaw, 159 Nowoursynowska st., [email protected] Marek Jabłoński, Faculty of Wood Technology, Warsaw University of Life Sciences SGGW, Warsaw, 159 Nowoursynowska st., Poland, [email protected] Anna Policińska - Serwa, Building Research Institute, Warszawa, ul. Ksawerów 21 [email protected] Eva Ružinská, Faculty of Environmental and Manufacturing Technology, Department of Environmental Technology, Technical University in Zvolen, Slovakia, [email protected] 166

167 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Flammability of plywood made from veneers protected with flame retardant based on diammonium hydrogen phosphate, citric acid and sodium benzoate PIOTR BORYSIUK 1, WALDEMAR JASKÓŁOWSKI 2, PIOTR BORUSZEWSKI 1, IZABELLA JENCZYK-TOŁŁOCZKO 1, MAREK JABŁOŃSKI 1, DAWID BYLIŃSKI 1 Faculty of Wood Technology, Warsaw University of Life Sciences SGGW 2 The Main School of Fire Service Abstract: Flammability of plywood made from veneers protected with flame retardant based on diammonium hydrogen phosphate, citric acid and sodium benzoate. In this study the impact of pine and beech veneer protection with flame retardant based on diammonium hydrogen phosphate, citric acid and sodium benzoate on the flammability of plywood made from them has been determined. Retention of the agent in veneers was kg per 1 m 3. It was determined that impregnated plywood manufactured from veneers do not sustain burning after removal of the source of fire. When taking into account values of oxygen index, greater fire resistance characterize pine plywood (oxygen index - 49%) in comparison to beech plywood (oxygen index - 36%). Keywords: plywood, fireproofing protection, reaction to fire, oxygen index INTRODUCTION Wood and wood-based materials, including plywood, still remain one of the most important materials used in construction or furniture. To use them one should be aware that their resistance to degradation is largely limited. In construction, one of the most important parameters of materials is fire resistance. It is particularly important in relation to wood and wood-based materials, which are inflammable materials. Fire resistance of these materials can be improved by applying different types of flame retardants (Osipiuk 2001, Krajewski and Witomski 2005). They can be implemented at the stage of materials production, or applied to the final product (Kartal et al. 2007). As a result, time of the material inflammation can be extended, reduced, or can eliminate flaming phase of burning, reduce the speed of fire spreading or accelerate creating a layer of charcoal on the surface of wood, which makes heat transfer inside the material harder (Drysdale 2001, Osipiuk 2001, Krajewski and Witomski 2005). Nowadays, new impregnants, which reduce wood flammability, are available on the market. They are based on ecological and non-toxic organic ingredients, so that they can be successfully used in a human environment. One of such agents is a flame retardant based on diammonium hydrogen phosphate, citric acid and sodium benzoate (US ). In this study, flammability of plywood made from veneers protected with agent mentioned above was investigated. MATERIAL AND METHODS Pine and beech veneers, which nominal thickness was 1.5 mm and density, respectively: 484 kg/m 3 and 676 kg/m 3 were impregnated with flame retardant based on diammonium hydrogen phosphate, citric acid and sodium benzoate. The type of agent used was a water solution with a concentration of 20%. Average agent retention was 50 kg per 1 m 3 for beech veneer and 47.5 kg per 1 m 3 for pine veneer. After impregnation, veneers were dried at C, to the moisture content of about 5%. From both, impregnated and non- 167

168 impregnated veneers, 3-layered plywood was produced on the basis of urea-formaldehyde resin. Glue recipe and bonding parameters are presented in Table 1. Table 1. Glue recipe and parameters of plywood bonding Parameter Value Glue recipe UF resin 100 pbw, hardener (10% solution of (NH 4 ) 2 SO 4 ) 4 pbw, aggregate (wheat flour) 15 pbw, water 10 pbw Glue spread 160 g/m 2 Pressing temperature 110 o C Unit press pressure pine veneer 1.0 MPa, beech veneer 1.2 MPa Time of pressing 330 s After production, plywood was conditioned for 1 week in the laboratory. Next, samples were obtained for further tests. Flammability of plywood was tested with two methods: 1. method of reaction to fire testing according to EN ISO Dimensions of samples were as followed: 250 x 90 x 4 mm 3. As a result of measurement, it was recorded: whether the ignition of the sample took place, whether the top of the flame reached a height of 150 mm above the location on which the flame work, what is the visual condition of the sample. 2. oxygen index method based on the standard ISO :1999. Oxygen index is the lowest percentage of oxygen in air mixture, which in laboratory conditions supports constant burning of the material. Tested samples had dimensions of 100 x 10 x 4 mm 3. Oxygen index measurement method is used to compare the flammability of different materials while assessing the modification of the same type of material, and the impact of additional fillers including various types of flame retardants. Oxygen index does not classify materials in terms of fire risk. RESULTS AND DISCUSSION The test results of reaction to fire are presented in Table 2. Generally it can be stated, that both pine and beech plywood made from veneers impregnated with tested agent do not sustain burning after contact with flame for 30 sec. In the point of flame and sample contact appeared a thin, compact charred layer of wood, which limited emissions of flammable compounds from wood to the environment. In case of plywood manufactured from nonimpregnated veneers, after 30 seconds of exposure to flame some samples (2 of 3 in case of pine plywood and 1 of 3 in case of beech plywood) have ignited. Flame was so large and rapid, that it had to be extinguished. In case of pine and beech plywood manufactured from impregnated veneers, flame height after 30 sec was between mm, while for plywood manufactured from non-impregnated veneers this height was mm. However, it should be noted, that impregnation had greater influence on the diversity of the flame height in case of pine veneers. Examples of plywood samples after the test for reaction to fire is shown in Figure

169 Table 2. Reserach results of reaction to fire of pine and beech plywood Sample Ignition of Height of flame top achieved number sample after 30 s [mm] Overall condition of sample Pine plywood non-impregnated veneers P 1 No 62 Bad, burning visible P 2 Yes 108 Very bad, burning of sample P 3 Yes 148 Very bad, burning of sample Pine plywood impregnated veneers PI 1 No 59 Carbonization on the surface PI 2 No 70 Carbonization on the surface PI 3 No 64 Carbonization on the surface Beech plywood non-impregnated veneers B 1 No 64 Bad, burning visible B 2 No 60 Bad, burning visible B 3 Yes 154 Very bad, burning of sample Beech plywood impregnated veneers BI 1 No 71 Carbonization on the surface BI 2 No 63 Carbonization on the surface BI 3 No 82 Bad, burning visible Fig. 1. Samples after examination for reaction to fire: A pine plywood made from non-impregnated veneers, B pine plywood made from impregnated veneers, C beech plywood made form non-impregnated veneers, D beech plywood made from impregnated veneers. The results of flammability test with oxygen index method are shown in Table 3. During the test, time of burning and length of sample s burned part were difficult to compare, because they only determined if the trial could be considered as a success or failure. The test was considered successful when the sample was burning for 180 seconds, or if the flame burnt 50 mm of sample length. Oxygen index, which is the smallest percentage of oxygen in the air mixture needed for combustion of 50 mm of samples, or allowing to keep burning for 180 seconds, was the only characteristic compared in this study. Samples of pine and beech plywood manufactured from unprotected veneers were burned (in the range tested) at concentration of approximately 28% oxygen in the air. It is worth noting, that burning 50 mm of pine plywood sample happened within 180 sec, while in case of beech it was 79 sec. In case of plywood manufactured from impregnated veneers, oxygen index values were, respectively 49% for pine plywood and 36% for beech plywood. 169

170 Table 3. The results of flammability tests for pine and beech plywood with the use of oxygen index - gray color indicates the lowest value of oxygen index for particular samples. Oxygen concentration Observations Sample number (%) Pine plywood non-impregnated veneers P No ignition of sample P After 97 sec. 50 mm of sample were burned P After 180 sec. 50 mm of sample were burned P After 114 sec. 34 mm of sample were burned P After 180 sec. 50 mm of sample were burned Pine plywood impregnated veneers PI No ignition of sample PI No ignition of sample PI After 180 sec. 50 mm of sample were burned PI After 90 sec. 26 mm of sample were burned PI After 180 sec. 42 mm of sample were burned Beech plywood non-impregnated veneers B After 13 sec. 5 mm of sample were burned B After 50 sec. 50 mm of sample were burned B After 74 sec. 38 mm of sample were burned B After 80 sec. 50 mm of sample were burned B After 79 sec. 50 mm of sample were burned Beech plywood impregnated veneers BI After 56 sec. 24 mm of sample were burned BI After 30 sec. 50 mm of sample were burned BI After 48 sec. 50 mm of sample were burned BI After 68 sec. 50 mm of sample were burned BI After 57 sec. 50 mm of sample were burned CONCLUSIONS On the basis of conducted research, following conclusion can be drawn: 1. Plywood made of pine and beech veneers, impregnated with flame retardant based on diammonium hydrogen phosphate, citric acid and sodium benzoate, have increased fire resistance in relation to plywood made from unprotected veneers. 2. None of the attempts of exposure to fire of plywood manufactured from impregnated veneers, resulted in sustaining effect of burning. 3. While taking into account the value of oxygen index, in a similar retention of flame retardant in veneers (47-50 kg per 1 m 3 ), pine plywood (oxygen index - 49%) characterizes greater fire resistance in comparison to beech plywood (oxygen index - 36%). 170

171 REFERENCES 1. DRYSDALE D., 2001: Introduction to Fire Dynamics, J.Willey & Sons Inc. 2. EN ISO Reaction to fire tests - Ignitability of products subjected to direct impingement of flame - Part 2: Single-flame source test. 3. ISO Plastics - Determination of burning behaviour by oxygen index. 4. KARTAL N., AYRILMIS N., IMAMURA Y., 2007: Decay and thermal resistance of plywood treated with various fire retardants. Building and Environment 42, KRAJEWSKI A., WITOMSKI P., 2005: Ochrona drewna surowca i materiału. Wydawnictwo SGGW 6. OSIPIUK J., 2001: Trwałość zabezpieczenia drewna solnymi środkami ogniochronnymi. Wydawnictwo SGGW 7. United States Patent No: US Flame retardant chemical composition. Jun 15, 2010 Streszczenie: Palność sklejek wytworzonych z fornirów zabezpieczonych środkiem ogniochronnym na bazie wodorofosforanu amonu, kwasu cytrynowego i benzoesanu sodu. W ramach badań określono wpływ impregnacji fornirów sosnowych i bukowych preparatem ogniochronnym opartym na kompozycji wodorofosforanu amonu, kwasu cytrynowego i benzoesanu sodu na palność wytworzonych z nich sklejek. Retencja preparatu w fornirach wynosiła kg na 1 m 3. Ustalono, że sklejki wytworzone z zaimpregnowanych fornirów nie podtrzymywały palenia po usunięciu źródła ognia. Uwzględniając wartości indeksu tlenowego, większą ognioodpornością charakteryzują się sklejki sosnowe (indeks tlenowy 49 %) w stosunku do sklejek bukowych (indeks tlenowy 36 %). Corresponding authors: Piotr Borysiuk, Piotr Boruszewski, Izabella Jenczyk-Tołłoczko, Marek Jabłoński Faculty of Wood Technology, Warsaw University of Life Sciences SGGW, Warsaw, 159 Nowoursynowska st., Poland, [email protected] [email protected] [email protected] [email protected] Waldemar Jaskółowski The Main School of Fire Service Warsaw, 52/54 Słowackiego st., Poland, [email protected] 171

172 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Possibilities of single-stage pressing of veneered particleboards PIOTR BORYSIUK, MARCIN ZBIEĆ, PIOTR BORUSZEWSKI, MARIUSZ MAMIŃSKI, ANDRZEJ MAZUREK Faculty of Wood Technology, Warsaw University of Life Sciences SGGW Abstract: Possibilities of single-stage pressing of veneered particleboards. Following work describes possibility of single-stage pressing of veneered particleboards. Three variants of the 16mm thick boards of 620kg/m3 density were manufactured for the test: (1) single-layer particleboard, (2) single-layer double-stage pressed veneered particleboard (3) single layer single-stage pressed veneered particleboard. Manufactured particleboards were tested against density distribution, MOR, MOE, IB, Stell and absorbability after 24h soaking in water. Possibility of single-stage pressing of veneered particleboards was established, it was also determined that mechanical properties of such boards are mainly dependent on grain direction in the outer veneers. Veneered particleboards have usually better physical properties, such as swell and absorbability. Keywords: particleboard, veneer, mechanical properties INTRODUCTION Production of layered wood based materials with veneers such as plywood and blockboards, does not loose its popularity over the years. Especially last mentioned blockboards can be made of poor quality material but perfectly finished with high quality veneers (Holzhacker i in. 1967, Starecki i in. 1994). Difficulties with obtaining of high quality wood stock and continuously lowering quality let assume, that layered material market May gain especially in production of various wood-based boards of high quality surfaces finished with veneer. Additionally, such boards may be produced within the framework of developing lightweight wood based materials segment (Borysiuk and others 2005). Internal layer of the particleboard may be made of waste material (Gökay and Gűrsel 2005, Czechowska and others 2008, Dziurka and Łęcka 2010). Effectiveness of boards production increases, if whole manufacturing process (especially pressing stage) will be optimized down to limited number of operations. Following work tests possibilities of single-stage pressing of veneered particleboards. MATERIAL AND METHODS Within the framework of the research, three 16 mm trick board types of 620 kg/m 3 density were produced: variant I single-layer particleboard, variant II single layer veneered particleboard produced in two stages, first 14 mm board was pressed, and then finished by veneer. variant III single layer veneered particleboard, manufactured in single operation. For production of the board industry grade internal layer chips of 6% moisture content and 1,4 mm pine veneers were used. Boards were bonded with UF resin based glue (Unitary formula: resin 100 part by weight, hardener 10% (NH 4 ) 2 SO 4 solution 4 p.b.w., water 10 p.b.w.) In case of veneering (variant II) glue was filled with rye flour at 10 p.b.w. Following pressing parameters were used (variant I, III and particleboard of II variant): glue load 10 %, pressing temperature 180oC, maximal unit pressure 2,5 MPa, pressing factor 18 s/mm. In case of veneering of the particleboards (variant II) parameters used were as 172

173 follows : glue load 160 g/m 2, pressing temperature 120 o C, maximal unit pressure 1,0 MPa, pressing time180 s. Produced boards were conditioned by 7 days in laboratory conditions (20 ± 2 o C, 65 ± 5% humidity). MOR and MOE (along major and minor axis of outer veneers) according to EN 310:1994, IB according to EN 319:1999, swelling and absorbability after 2 and 24h on soaking in water according to EN 317:1993 and density profile have been examined for the manufactured boards. Ten specimens selected according to density have been used for determination of each of the examined features. Statistic significance of the differences has been determined on the basis of T-Student test for confidence level of 95%. RESULTS AND DISCUSSION Test results are presented in tables 1 and 2. Manufactured boards, independently of the variant, showed similar density ranging from 629 up to 639 kg/m 3. Boards varied although at density distributions presented on figure 1. In case of single-layer particleboards (variant I), typical U-shaped distribution was noticed. In case of veneered particleboards pressed in two stages (variant II), internal layer again show typical U-shaped density distribution, but outer veneer layers showed visible density drop down to kg/m 3. This was caused by relatively low compression ratio of the veneers when pressing (around 10%). Veneered particleboards pressed with one-stage process (variant III) showed more regular and uniform density distribution. This testifies about uniform compression of all layers (chips and veneers) during pressing. Fig. 1. Density distribution of tested boards Table 1. Strength properties MOR MOE Density Variant major axis minor axis major axis minor axis IB [kg/m 3 ] [N/mm 2 ] x * [N/mm 2 ] x * [N/mm 2 ] x * [N/mm 2 ] x * [N/mm 2 ] x * I , , ,78 10 II , , ,71 17 III ,2 8 13, ,60 ** 25 * variation coefficient [%] ** all samples fractured between board and veneer Produced boards showed variable MOR and MOE parameters in dependence on testing direction (along or across the outer layer veneers). Application of veneers to outer layers strengthened the boards in major axis (MOR and MOE gained around %) with simultaneous drop in minor axis (by around %). Obtained results were statistically important at 95% confidence level. They were caused by variable wood strength (along and cross the grain) standing for outer layer of the boards (variant II and III), the rother cause was lowered density of the external layers of the boards, which is shown on density distributions on fig. 1. Lowered density of outer layers affects strength properties (MOR and MOE) of the 173

174 two-stage pressed veneered particleboards (variant II) in comparison to single-stage veneered particleboards (variant III). It is necessary to remark, that differences are statistically important only with MOE in the major axis direction (along the grain of the outer veneer layers). Considering IB it is necessary to conclude that obtained strengths in variant I and II are similar (differences not statistically important). Strength drop in variant III was caused by weak bonding of veneers with the board fracture showed up in this area. One has to remark, that in comparison to variant I difference was statistically important, but in comparison to variant II is not. Table 2. Absorbability and swell of the boards Swell Absorbability Variant after 2h after 24h after 2h after 24h [%] x * [%] x * [%] x * [%] x * I 19,0 7 21,6 7 67,1 8 80,1 6 II 10, , , ,5 7 III 15, ,8 9 56, ,4 3 * variation coefficient [%] Veneered particleboards produced in two stages (variant II) showed lower swell and absorbability results in comparison to other tested variants (I and III). This phenomena was connected with low compression of outer layer veneers, which again causes low tendency to recompression. Veneered particleboards (variant II and III) show statistically important lowering of absorbability in comparison to regular particleboards (variant I). CONCLUSIONS Basing on the performed tests one may conclude that: 1. It is possible to produce veneered particleboards in single technological operation; 2. Veneered particleboards produced in single operation show increased strength properties (in major axis, along the grain of outer veneers) in comparison to regular particleboards with similar thickness and density; 3. Veneered particleboards produced in single operation hale similar MOR and MOE parameters as two-stage pressed veneered particleboards; 4. Veneered particleboards produced in single or double operation show increased physical properties in comparison to regular particleboards; 5. Veneered particleboards produced in single operation have more uniform density profile in comparison to two-stage pressed veneered particleboards and regular particleboards. REFERENCES 1. BORYSIUK P., DZIURKA D., JABŁOŃSKI M., ZBIEĆ M., 2005: Application of waste corrugated cardboard as an internal layer of blockboard. Annals of Warsaw Agricultural University, Forestry and Wood Technology, 56/05, CZECHOWSKA J., BORYSIUK P., MAMIŃSKI M., BORUSZEWSKI P., 2008: Lowdensity particleboards filled with waste PUR foam. Annals of Warsaw University of Life Sciences SGGW, Forestry and Wood Technology, 63, DZIURKA D., ŁĘCKA J., 2010: Veneered lightweight particleboards for furniture industry. Annals of Warsaw University of Life Sciences SGGW, Forestry and Wood Technology, 71, ; 4. GÖKAY N., GŰRSEL Ç., 2005: The influence of lamination technique on the properties of particleboards; Building and Environment, 40, 83-87; 174

175 5. HOLZHACKER A., MĘTRAK C., ŻUROWSKI J., 1967: Meblarstwo. Wydawnictwo Przemysłu Lekkiego i Spożywczego, Warszawa 6. PN-EN 310 Płyty drewnopochodne. Oznaczanie modułu sprężystości przy zginaniu i wytrzymałości na zginanie 7. PN-EN 317 Płyty wiórowe i płyty pilśniowe. Oznaczanie spęcznienia na grubość po moczeniu w wodzie 8. PN-EN 319 Płyty wiórowe i płyty pilśniowe. Oznaczanie wytrzymałości na rozciąganie w kierunku prostopadłym do płaszczyzn płyty 9. STARECKI A., DROUET T., LEŚNIKOWSKI A., ONIŚKO W., 1994: Technologia tworzyw drzewnych. Wydawnictwa Szkolne i Pedagogiczne, Warszawa Streszczenie: Badanie możliwości jednoetapowego wytwarzania płyt fornirowo-wiórowych. Praca opisuje możliwość jednoetapowego wytwarzania płyt wiórowych fornirowanych. W ramach pracy wykonano 3 warianty płyt o grubości 16mm i gęstości nominalnej 620kg/m3: (1) płyta wiórowa jednowarstwowa, (2) płyta wiórowa jednowarstwowa fornirowana w dwóch etapach, (3) płyta wiórowa jednowarstwowa fornirowana w jednym etapie. Dla wytworzonych płyt zbadano profil gęstości, MOR, MOE, IB spęcznienie i nasiąkliwość po 24h moczenia w wodzie. Ustalono, że istnieje możliwość wytwarzania płyt wiórowych fornirowanych w 1 operacji, przy czym ich parametry wytrzymałościowe uzależnione są na ogół od kierunku przebiegu słojów w fornirach. Płyty fornirowane charakteryzują się równocześnie korzystniejszymi parametrami fizycznymi (spęcznienie i nasiąkliwość). Corresponding authors: Piotr Borysiuk, Marcin Zbieć, Piotr Boruszewski, Mariusz Mamiński, Andrzej Mazurek, Faculty of Wood Technology, Warsaw University of Life Sciences SGGW, Warsaw, 159 Nowoursynowska st., Poland, [email protected] marcin_ [email protected] [email protected] [email protected] [email protected] 175

176 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) The impact of wood staining with specific synthetic dyes on pine wood gluability PIOTR BORYSIUK 2), ANNA DANIHELOVA 1), MAREK JABŁOŃSKI 2), ANNA POLICIŃSKA-SERWA 3), EVA RUŽINSKÁ 4) 1) Faculty of Wood Technology, TU Zvolen 2) Faculty of Wood Technology, Warsaw University of Life Sciences SGGW 3) Building Research Institute - Warsaw 4) Department of Environmental Technology, Faculty of Environmental and Manufacturing Technology, Technical University in Zvolen, Slovakia Abstract: The Impact of Wood Staining with Specific Synthetic Dyes on Pine Wood Gluability. For the purpose of the paper tests were carried out to determine the shear strength of polyvinyl acetate and polyurethane adhesive-bonded joints in pine wood stained with varied kinds of synthetic dyes used to colour wood or impregnates designed to protect wood. The shear strength of adhesive-bonded joints in stained wood was compared against that in natural wood. The tests were performed in dry and wet conditions. Key words: wood bonding, wood staining, bonded construction wood, INTRODUCTION The recent years have seen remarkable developments in the production of lumber construction elements. This has been possible due to the introduction of state-of-the-art technologies of processing wood designed for construction. Among other things, the use of weather-proof adhesives, methods of bonding selected lumber and weather-proof impregnates ensure a higher durability of elements, thus alleviating the need to carry out maintenance and apply corrosion protection while they are in use. State-of-the-art technologies of bonded constructions make these elements more durable compared to solid wood and provide more flexibility when it comes to the shaping of these constructions, with transport possibilities being the only limitation. Impregnation protects wood from the destructive influence of biotic and abiotic factors, whereas its additional staining influences its aesthetics and finish. The quality and aesthetics of finish is greatly enhanced by synthetic dyes being added to impregnates. MATERIAL AND EXPERIMENT METHOD The aim of the paper was to determine the impact that staining pine elements bonded with the single element polyurethane adhesive Kestopur 1010 and the single element polyvinyl acetate Kestokol D 400 has on the durability of adhesive-bonded joints. The following dyes used in stains and impregnates were applied: an acid dye metanil yellow extra 100% (Acid Yellow 36), a base dye malachite green (Basic Green 4) and a hellion dye Hellion Red 8B 125% (Direct Red 81). Acid dyes are mainly sodium salts or calcium salts of nitroso, azo, nitro and other dyes. They contain the characteristic groups S0 3 H, COOH and OH and dissolve in water well, creating small particles in the solution. Base dyes are ammonium, sulphonium or oxonium salts of hydrochrolic, oxalic and sulphuric acids and contain the characteristic amid groups. Base dyes dissolve easily in water and ethanol, creating small particles in the solution. Hellion dyes are a group of direct ones (these are mainly azo dyes with the characteristic group N=N ), have a higher light resistance and 176

177 are primarily used for dying cellulose fibres (wool, viscose, flax, hemps, etc.) and polyamide fibres. Due to longitudinal joints occurring more often than cross joints and shear stress being of predominant importance, a test method of determining the shear strength of adhesivebonded joints in wood was selected. Their strength was determined following the PN-EN 302-1:2006 standard: Adhesives for load-bearing timber structures Test methods Part 1: Determination of bond strength in longitudinal tensile shear strength. The shear strength was determined for single lap joints samples with adhesive-bonded joints created between two rectangular bonded wooden elements which were subjected to longitudinal tensile stress. The samples were subjected to the stress after they had been soaked for 24 hours and until they were destroyed. Before the samples were bonded, the surfaces of the wood were stained twice by means of a cotton pad and then left in laboratory conditions for their moisture to level off and for the excess of water from the dye to evaporate. The moisture content of the wood to be bonded with the polyvinyl acetate adhesive amounted to 8%, whereas it stood at 15% for the wood bonded with the polyurethane adhesive because it was cured in the presence of moisture. The bonding parameters for the polyvinyl acetate adhesive were as follows: application 160 g m -2, open time 5 minutes, press time 25 minutes at 20 o C, press pressure 0.5 N mm -2. The polyurethane adhesive, in turn, had the following bonding parameters: application 220 g m -2, open time 5 minutes, press time 35 minutes at 20 o C, press pressure 0.7 N mm -2. Natural samples were bonded in the same conditions for the sake of comparison. Before the samples were cut out, the bonded material was conditioned in laboratory conditions for three weeks. For each version of wood being bonded and stained 40 samples were destroyed. RESULTS The results of the determination of the shear strength of adhesive-bonded joints for dry conditions are shown in Table 1, whereas Table 2 presents the results for wet conditions. Tab. 1. The longitudinal tensile shear strength of polyvinyl acetate adhesive and polyurethane adhesive bonds in natural pine wood and wood stained with synthetic dyes in dry conditions. Average shear strength of adhesive-bonded joints in dry conditions Dye Type of adhesive-bonded joints R [N mm -2 ] Polyvinyl acetate σ [N mm -2 ] v [%] R [N mm -2 ] Polyurethane σ [N mm -2 ] Metanil yellow Malachite green Hellion red Natural wood v [%] 177

178 Tab. 1. The longitudinal tensile shear strength of polyvinyl acetate adhesive and polyurethane adhesive bonds in natural pine wood and wood stained with synthetic dyes in dry conditions after it was soaked (24 hours). Average shear strength of adhesive-bonded joints in wet conditions Dye Polyvinyl acetate R σ [N mm -2 ] [N mm -2 ] Type of adhesive-bonded joints v [%] Polyurethane R σ [N mm -2 ] [N mm -2 ] v [%] Metanil yellow Malachite green Hellion red Natural wood The shear strength of the polyvinyl acetate adhesive-bonded joints in dry conditions in the pine wood stained with two kinds of dyes, i.e. acid and hellion ones, was higher than the strength of the polyvinyl acetate adhesive-bonded joints in natural wood. To be more specific, it was higher by about 7% for the wood stained with metanil yellow, and by about 18% for the hellion dye. The strength of adhesive-bonded joints in the natural and stained wood was similar for the one stained with a base dye malachite green. Similarly, the shear strength of polyurethane adhesive-bonded joints in dry conditions was higher for the wood stained with acid and hellion dye than the one in the natural wood. The shear strength of the polyurethane adhesive-bonded joints created in the wood dyed with metanil yellow was about 12% higher than the shear strength of polyurethane adhesive-bonded joints in the natural pine wood. The shear strength of the polyurethane adhesive-bonded joints created in the wood dyed with hellion red was about 17% higher. The respective rises may have been caused by the fact that pine wood surface was homogenised as a result of the application of a uniform layer of the dye. The samples were put in water at the temperature of 20 o C for 24 hours, which caused the strength of the adhesive-bonded joints to decrease compared to their strength in dry conditions in all versions of bonding; however, in the case of polyvinyl acetate and polyurethane adhesive-bonded joints in the wood stained with hellion red the fall was at the verge of statistical significance. After being soaked in water, polyvinyl acetate and polyurethane adhesive-bonded joints in the natural pine wood showed a decline of their strength by about 5% against the strengths of the joints tested in dry conditions. After being soaked in water the polyvinyl acetate adhesive-bonded joints showed the following falls in their strengths compared to dry joints: about 7% for samples being stained with metanil yellow and about 8% for samples being stained with malachite green. In the case of the polyurethane adhesive-bonded joints the falls in the strengths were as follows: about 7% for samples being stained with matanil yellow and about 11% for those stained with malachite green. When one compares the strength of adhesive-bonded joints after they were soaked in water as for the strength of adhesive-bonded joints in natural wood, it is possible to ascertain that the treatment merely caused a significant fall in the strength of the polyurethane adhesive-bonded joints in the wood stained with malachite green (about 10%). In the case of the other bonding options the shear strength of the joints in the stained wood was equal to or higher than the shear strength of the joints in the natural wood. 178

179 SUMMARY The figures obtained in the tests and supported by statistical calculations enable presenting the following conclusions: 1. The shear strength of polyvinyl acetate and polyurethane adhesive-bonded joints in pine wood tested in dry conditions and stained with three kinds of synthetic dyes, i.e. acid, base and hellion ones compared to the strength of the adhesive-bonded joints in the natural wood increases in varied degrees depending on the type of dye used. 2. The increase in the strength of adhesive-bonded joints in stained wood may have been caused by the surfaces of bonded wood having been homogenised. 3. A 24-hour-long soaking of the samples in water at 20 o C causes a slight fall in the shear strength of adhesive-bonded joints both in the stained and natural wood. REFERENCES 1. DANIHELOVÁ A., JABŁOŃSKI M., SEDLIAČIK J. RUŽINSKÁ E. 2010: Shear strength of urea-formaldehyde, phenol-formaldehyde and polyvinyl acetate glue bonds in fungi and insect-preserved pine plywood. Annals of Warsaw University of Life Sciences SGGW, Forestry and Wood Technology No 70, 2010 s GOS. B. 1996: Wybrane kleje polioctanowe do klejenia drewna warstwowego z tarcicy. Maat. Symp. Drewno I materiały drewnopochodne w konstrukcjach budowlanych. Szczecin-Międzyzdroje. s HLADIK V. 1976: Disperzni barviva. Teorie a praxe jejich aplikace. SNTL Nakladatelstvi Technické Literatury, Praha, s PROSZYK S., SEDLIAČIK J., KRYSTOFIAK T. 2002: Investigations of the strenght and durability of glue lines from PUR adhesives. Proc. 4ʼ th. Symp. Composite Wood Materiale, Technical University of Zvolen, s TYSZKA J. 1995: Barwienie drewna. Wydawnictwo Przemysłu Lekkiego i Spożywczego, Warszawa, s TYSZKA J. 1981: Powierzchniowe uszlachetnianie wyrobów z drewna. WN-T, Warszawa,

180 Streszczenie: Wpływ barwienia drewna wybranymi barwnikami syntetycznymi na sklejalność drewna sosnowego. W ramach pracy wykonano oznaczenia wytrzymałości spoin klejowych na ścinanie z klejów polioctanowinylowych i poliuretanowych w drewnie sosnowym wybarwionym różnymi rodzajami barwników syntetycznych używanych do barwienia drewna lub impregnatów przeznaczonych do ochrony drewna. Oznaczenia wytrzymałości spoin w drewnie wybarwionym porównywano z wytrzymałością spoin klejowych w drewnie naturalnym. Badania przeprowadzano na sucho i po moczeniu w wodzie. Corresponding authors: Piotr Borysiuk, Faculty of Wood Technology, Warsaw University of Life Sciences SGGW, Warsaw, 159 Nowoursynowska st., [email protected] Anna Danihelová, Faculty of Wood Research and Technology, Department of Physics, Electrotechnics and Applied Mechanics, Faculty of Wood Sciences and Technology, [email protected] Marek Jabłoński, Faculty of Wood Technology, Warsaw University of Life Sciences SGGW, Warsaw, 159 Nowoursynowska st., Poland, [email protected] Anna Policińska - Serwa, Building Research Institute, Warszawa, ul. Ksawerów 21 [email protected] Eva Ružinská, Faculty of Environmental and Manufacturing Technology, Department of Environmental Technology, Technical University in Zvolen, Slovakia, [email protected] 180

181 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Ignitability of wood impregnated with fireproof agent based on diammonium hydrogen phosphate, citric acid and sodium benzoate PIOTR BORYSIUK 1, WALDEMAR JASKÓŁOWSKI 2, PIOTR BORUSZEWSKI 1, IZABELLA JENCZYK-TOŁŁOCZKO 1, MAREK JABŁOŃSKI 1, DAWID BYLIŃSKI 1 Faculty of Wood Technology, Warsaw University of Life Sciences SGGW 2 The Main School of Fire Service Abstract: Ignitability of wood impregnated with fireproof agent based on diammonium hydrogen phosphate, citric acid and sodium benzoate. This paper examines the impact of pine and beech wood impregnation with fireproof agent, based on diammonium hydrogen phosphate, citric acid and sodium benzoate, to their ignitability. Retention of the product was 49 kg per 1 m 3. It was noted that impregnated pine wood, as well as beech wood did not sustain burning after removing the source of fire. At the same time, these materials require about 1.5 times higher oxygen index values to obtain the same effects of burning as unprotected samples. Keywords: pine wood, beech wood, fireproofing protection, reaction to fire, oxygen index INTRODUCTION Wood is a valuable material that people use in construction for many years. However, besides a number of beneficial characteristics, it is burdened with defects and one of them is lack of fire resistance. Wood ignites at temperatures of C, where ignition temperature largely depends on the species of timber and the heating conditions (Drysdale 2001, Osipiuk 2001, Krajewski and Witomski 2005). In order to reduce the ignitability, fireproof agents are used. Their application allows to extend the time of inflammation, reduce or eliminate flaming phase of burning, reduce the speed of fire spreading, or accelerate creating a layer of charcoal on wood surface resulting in limited heat transfer inside the material. At present, new wood preservatives reducing ignitability, based on ecological and non-toxic organic ingredients, which allows to use them in human environment, are available on the market. One of them is fireproof agent based on composition of diammonium hydrogen phosphate, citric acid and sodium benzoate (US ). In this work, the impact of pine and beech wood impregnation (with the use of aforementioned agent) for its ignitability was defined. MATERIAL AND METHODS Pine and beech slats without visible defects (nominal dimensions: 90 x 250 x 5 mm 3, density 516 kg/m 3 for pine and 716 kg/m 3 for beech) were protected with fireproof agent based on composition of diammonium hydrogen phosphate, citric acid and sodium benzoate. The product was used as a water solution having a concentration of 20%. Samples were pressure protected. They were immersed in preparation and put into the chamber, in which vacuum was produced. After 15 minutes, air was injected, which restored the atmospheric pressure. Then, tested samples were removed from the chamber and weighed in order to determine the amount of solution injected into each slat. Samples, which do not fulfill the assumed level of retention, were re-immersed in preparation for a time necessary to absorb assumed quantity of fireproof agent. For both, pine and beech slats, average retention was 181

182 49 kg per 1 m 3. After impregnation, slats were dried at C, to the moisture content of about 5%. Simultaneously, unprotected pine and beech slats were dried under the same conditions, to a moisture content of about 5%. For each variant 10 slats were prepared of which samples were produced for further study. Ignitability of wood was studied by two methods: 1. method of reaction to fire, according to EN ISO Samples dimensions were: 250 x 90 x 5 mm 3. As a measurement result it was noted: whether the ignition of the sample took place, whether the top of the flame reached a height of 150 mm above the location on which the flame work, what is the visual condition of the sample. 2. oxygen index method based on the standard ISO :1999. Oxygen index is the lowest content of oxygen in air mixture (expressed in percentage), which in laboratory conditions supports constant burning of the material. Dimensions of tested samples were 100 x 10 x 5 mm 3. Oxygen index measurement method is applied for comparison of the ignitability of different materials while assessing the modification of the same type of material, and the impact of additional fillers including various types of flame retardants. Oxygen index does not classify materials with respect to fire hazard. RESULTS AND DISCUSSION The results of reaction to fire tests are presented in Table 1. Generally, it can be stated that both, pine and beech slats impregnated with the tested product did not sustain burning after contact with flame for 30 seconds. At the point where the flame has been in contact with the sample, appeared a thin, compact layer of charred wood, which limited emissions of flammable compounds from wood to the environment. For unprotected samples, all pine slats and 1 of 3 beech slats were ignited. Flame height after 30 seconds was over 2 times lower in case of impregnated pine slats than for unprotected samples. For beech wood, the noted flame height after 30 seconds was similar for both, protected and unprotected samples. Examples of slats after reaction to fire test are presented in Figure 1. Fig. 1. Samples after test of reaction to fire: A - unprotected pine slat, B - impregnated pine slat, C unprotected beech slat, D - impregnated beech slat. 182

183 Table 1. The results of pine and beech wood study for reaction to fire Sample Sample Height of flame top No ignition achieved after 30 s [mm] Overall sample condition Unprotected pine slats P 1 Yes 179 Very bad, burning of sample P 2 Yes 155 Very bad, burning of sample P 3 Yes 163 Very bad, burning of sample Impregnated pine slats PI 1 No 66 Carbonization on the sample s surface PI 2 No 80 Carbonization on the sample s surface PI 3 No 69 Carbonization on the sample s surface Unprotected beech slats B 1 No 55 Bad, burning visible B 2 No 59 Bad, burning visible B 3 Yes 99 Very bad, burning of sample Impregnated beech slats BI 1 No 62 Carbonization on the sample s surface BI 2 No 66 Carbonization on the sample s surface BI 3 No 76 Carbonization on the sample s surface Table 2. The results of ignitability tests for pine and beech wood with the use of oxygen index - gray color indicates the lowest value of oxygen index for particular samples. Sample No Oxygen concentration (%) Observations Unprotected pine samples P After 57 sec. 22 mm of sample were burned P After 34 sec. 50 mm of sample were burned P After 46 sec. 50 mm of sample were burned P After 166 sec. 41 mm of sample were burned P After 180 sec. 48 mm of sample were burned Impregnated pine samples PI No sample ignition PI After 38 sec. 50 mm of sample were burned PI After 22 sec. 50 mm of sample were burned PI After 12 sec. 10 mm of sample were burned PI After 31 sec. 50 mm of sample were burned Unprotected beech samples B After 94 sec. 12 mm of sample were burned B After 15 sec. 50 mm of sample were burned B After 40 sec. 50 mm of sample were burned B After 56 sec. 15 mm of sample were burned B After 113 sec. 50 mm of sample were burned Impregnated beech samples BI No sample ignition BI After 89 sec. 34 mm of sample were burned BI After 34 sec. 50 mm of sample were burned BI After 61 sec. 50 mm of sample were burned BI After 123 sec. 41 mm of sample were burned 183

184 The results of ignitability tests for pine and beech wood with the use of oxygen index are presented in Table 2. While the research was conducted, time of burning and length of burned part were difficult to compare - they only let to determine, if the trial was successful or not. The test was considered as a success when the sample was burning for 180 seconds, or if the flame burnt 50 mm of sample. Oxygen index (the smallest percentage of oxygen in the air mixture needed for combustion of 50 mm of samples, or allowing to keep burning for 180 seconds) was the only characteristic possible to compare in this study. Tested pine and beech samples, which were not protected by agent, were burned (in the range tested) at the oxygen concentration around 28% in the air mixture. Protection of samples with tested product caused that in the studied conditions, they have been burnt (50 mm of sample) at a concentration of oxygen in the air at level of 41-42%. CONCLUSIONS On the basis of conducted research it can be stated, that impregnation of pine and beech wood, with the use of fireproof agent based on composition of diammonium hydrogen phosphate, citric acid and sodium benzoate, increases the fire resistance of these materials. None of the attempts of impregnated wood exposure to fire resulted in sustaining of the burning. Impregnated samples required about 1.5 times higher oxygen index values (higher oxygen content in the air) to meet the same conditions as burning of unprotected samples. REFERENCES 1. DRYSDALE D., 2001: Introduction to Fire Dynamics, J.Willey & Sons Inc. 2. EN ISO Reaction to fire tests - Ignitability of products subjected to direct impingement of flame - Part 2: Single-flame source test. 3. ISO Plastics - Determination of burning behaviour by oxygen index. 4. KRAJEWSKI A., WITOMSKI P., 2005: Ochrona drewna surowca i materiału. Wydawnictwo SGGW 5. OSIPIUK J., 2001: Trwałość zabezpieczenia drewna solnymi środkami ogniochronnymi. Wydawnictwo SGGW 6. United States Patent No: US Flame retardant chemical composition. Jun 15,

185 Streszczenie: Palność drewna zabezpieczonego środkiem ogniochronnym na bazie wodorofosforanu amonu, kwasu cytrynowego i benzoesanu sodu. W ramach badań określono wpływ impregnacji drewna sosnowego i bukowego preparatem ogniochronnym opartym na kompozycji wodorofosforanu amonu, kwasu cytrynowego i benzoesanu sodu na ich palność. Retencja preparatu wynosiła 49 kg na 1 m 3. Ustalono, że zaimpregnowane drewno zarówno bukowe jak i sosnowe nie podtrzymywało palenia po usunięciu źródła ognia. Jednocześnie materiały te wymagały ok. 1.5 razy wyższych wartości indeksu tlenowego do uzyskania tych samych efektów spalenia co próbki niezaimpregnowane. Corresponding authors: Piotr Borysiuk, Piotr Boruszewski, Izabella Jenczyk-Tołłoczko, Marek Jabłoński Faculty of Wood Technology, Warsaw University of Life Sciences SGGW, Warsaw, 159 Nowoursynowska st., Poland, [email protected], [email protected], [email protected] [email protected] Waldemar Jaskółowski The Main School of Fire Service Warsaw, 52/54 Słowackiego st., Poland, [email protected] 185

186 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Influence of the length of CFRP tape reinforcement adhered to the bottom part of the bent element on the distribution of normal stresses and on the elastic curve IZABELA BURAWSKA 1), ANDRZEJ TOMUSIAK 1), PIOTR BEER 1) Department of Construction and Technology of Final Wood Products, Warsaw University of Life Science, Nowoursynowska 159, Warsaw, Poland Abstract: Influence of the length of CFRP tape reinforcement adhered to the bottom part of the bent element on the distribution of normal stresses and on the elastic curve. The paper analyses the influence of reinforcements made of CFRP tape on the distribution of normal stresses and on the elastic curve of a wooden beam that is being bent. It was a numerical analysis made in the Solidworks Simulation environment. The local reinforcement of the element permitted to reduce the elastic curve by up to 20% and to reduce the maximum normal stresses by 80% in the proximity of the opening, by using a 50 cm long CFRP tape. It has been concluded that CFRP tapes may be useful for local reinforcement of the tensed areas of bent wooden beams that are weakened due to openings produced by knots that fell out or rotted. Keywords: bending, reinforcement, CFRP tape, normal stresses, elastic curve INTRODUCTION The intense development of technology creates new possibilities for designers and engineers. Lately, composite materials have become very popular, and especially the CFRP (carbon fibre reinforced plastic) tapes. This material started to be used in the construction in the 60s, with the development of the usage of resins. Composites have specific qualities that differentiate them from traditional construction materials, that is: low specific weight that goes together with very good physical parameters and high resistance. Table 1 shows the basic properties of chosen fibre types and steel. Table 1. Chosen properties of fibres and steel [German, 2005] Fibre type Parameter steel E-glass S-glass graphite kevlar 49 Boron Diameter [μm] Specific weight ρ [kn/m 3 ] Tensile strength R [GPa] Specific strength R/ρ [km] Young s Modulus E [GPa] Specific modulus E/ρ [km 10 3 ] Most composites consist of a continuous phase, called the matrix, which surrounds the dispersed phase, called the reinforcement. Hence, the properties of the composites, which have anisotropic character, depend on the share and on the properties of the phases that they consist of, as well as on the geometrical features and the manner of arrangement of the reinforcement within the matrix. Thanks to the anisotropy of the composites, there is a possibility of adjusting the resistance value and the anisotropy directions to the stress state of the material [Dąbrowski, 2002]. 186

187 Composite materials are used mostly to manufacture components of modern, light structures, sports and recreation equipment, as well as masts, posts, and above all reinforcements of constructions. Due to the above-mentioned advantages of composite materials, we decided to check whether it would be useful to locally reinforce a weakened, bent construction beam with a CFRP tape; the check was carried out numerically with the use of the Solidworks Simulation programme. It was also relevant to determine the optimum length of the local reinforcement of the weakened element. NUMERICAL ANALYSIS The CFRP tape was modelled as an orthotropic element, 1.2 mm thick, 50 mm wide and with a variable length 20 mm, 50 mm, 100 mm, 150 mm, 300 mm and 500 mm. The tape was adhered on the bottom part of the bent element, covering its whole width. The bent element was designed as a pine beam, also with an orthotropic model and the dimensions of 50x100x2000 mm. The characteristic values of the resistance parameters were assigned as for the class C22 timber. The Table no 2 presents the resistance parameters of the timber and of the CFRP tape, which were applied during the numerical analysis. Table 2. Chosen values of resistance parameters for the timber and for the CFRP tape C22 timber CFRP tape Longitudinal flexibility ratio E [MPa] Poisson s ratio ν [-] Transverse flexibility ratio G [MPa] E x E y E z ν xy ν xz ν yz G xy G xz G yz The glue layer was not modelled, because of its high resistance. Constant displacements were assumed at the place of contact between the layers. In order to carry out the simulation of reinforcement of the bent element, we prepared a model of real instruments applied during resistance tests. The virtual experimental workplace is in line with the recommendations of the PN-EN 408:2004 standard (Fig. 1.). The support and upper points of contact were designed as made of alloy steel. One of the support points of contact was defined as fixed, and the other one as mobile (Fig. 2.). Fig. 1. Experimental workplace view 187

188 Fig. 2. View of the layout of the support and upper points of contact We tested the bent element that was weakened by an opening left after a knot that fell out or rotted, whose diameter amounted to φ10, that was placed perpendicularly to the lateral surface of the beam and was located on its symmetry axis. Two positions of the opening were included in the assumptions (Fig. 3.): - the middle of the opening located on the bottom surface of the element; - the middle of the opening located 15 mm from the bottom surface of the element. Fig. 3. Opening location in respect to the bottom surface of the beam (2 positions) A load force amounting to P=6kN was applied to the beam, weakened by the φ10 opening in two positions. For the φ10 opening whose middle was located on the bottom surface of the element, the maximum normal stress was measured in point A (Fig. 4.), whereas for the opening placed 15 mm away, it was in point B, placed on the bottom part of the opening. Fig. 4. Location of the measurement points a) when l r, b) when l > r ; where l distance between the middle of the opening and the base surface, r opening radius 188

189 DISCUSSION OF RESULTS Figure no 5 presents a chart showing the maximum normal stresses reached for different lengths of the CFRP tapes, adhered to the bottom side of the element in accordance to the opening position, subject to a load force of P=6kN σmax [MPa] fi 10, 15mm from base surface fi 10, 0mm from base surface length of CFRP tape [cm] Fig. 5. Maximum normal stresses in the CFRP tape in accordance to its length and to the position of the opening in respect to the bottom surface of the beam The simulations that were carried out showed that when the tape used to reinforce the section was longer, the normal stresses that were reached in that section were higher. This is natural, because a longer tape transmits a bigger part of the section stresses. The only exception occurs when the φ10 opening is placed on the bottom surface of the bent beam: in the case of a 2 cm tape the maximum normal stresses reach higher values than in the case of a 5 cm long tape. This may be due to the fact that the tape is too short and it is not sufficiently anchored in relation to the opening type, which results in higher normal stress values reached within the tape. Figure no 6 shows the maximum normal stresses that were reached in the measurement points A and B of the openings, reinforced with the use of CFRP tape of different lengths fi 10, 15mm from base surface σmax [MPa] fi 10, 0mm from base surface fi 10, 15mm from base surface, without CFRP tape fi 10, 0mm from base surface, without CFRP tape length of CFRP tape [cm] Fig. 6. Maximum normal stresses in measurement points A and B in accordance to the length of the reinforcement 189

190 On the basis of the Figure no 6 it may be concluded that the maximum normal stresses in the measurement points A and B were reduced after applying a CFRP tape reinforcement to the section. The longer the tape, the more significant the reduction of normal stresses. In case of a 50 cm tape reinforcing the element weakened by a φ10 opening, whose middle was placed on the bottom surface of the beam, the stresses were reduced by up to 80%, while for an analogous tape, but in case of an opening placed at the distance of 15 mm from the bottom surface, the reduction amounted to 60%. Therefore, it is more effective to reinforce beams that are weakened by openings located far away from the neutral axis of the element. The value of normal stresses advances asymptotically to a certain value. Hence, it may be concluded that it is not economical to apply reinforcement to the whole length of the element. Moreover, in accordance to the Saint-Venant s principle [Orłoś, 1977], the disturbances caused in a uniform stress field and the increase of normal stresses, which goes together with the weakening, have a local character; and at a distance equal to several times the diameter of the opening, that disturbance is negligibly small. This fact also speaks in favour of the local reinforcement of weakened elements. Therefore, it seems that the length of the reinforcement applied in the proximity of the weak point should amount to 5-6 times the diameter of the opening. Figure no 7 shows the distribution of maximum normal stresses for a beam weakened with a φ10 opening, whose middle is placed on the bottom surface of the beam, reinforced with a 5 cm long CFRP tape. Fig. 7. Distribution of normal stresses for a test model example elastic curve [mm] fi 10, 15mm from base surface fi 10, 0mm from base surface fi 10 15mm and fi 10, 0mm from base surface, without CFRP tape length of CFRP tape [cm] Fig. 8. Elastic curve in accordance to the length of the reinforcement 190

191 Fig. 8. shows the relation between the elastic curve and the length of the CFRP tape reinforcement. On this basis it may be concluded that the higher the length of the reinforcement, the smaller the elastic curve of the bent element. A longer CFRP tape reduces the importance of the opening position for the elastic curve values. CONCLUSIONS: 1) The longer the tape, the higher the maximum normal stresses that are present in its section as a result of the operation of a constant force. 2) The longer the tape, the more significant the reduction of normal stresses that can be reached in the proximity of the opening. However, after exceeding a certain tape length, the reduction of normal stresses becomes very small. 3) The application of a CFRP tape provides a more significant reduction of normal stresses when the weak points are placed further from the neutral axis of the bent element. 4) The longer the reinforcing tape, the more significant the reduction of the elastic curve. 5) We have not observed any important influence of the position of the opening on the degree of elastic curve reduction as a result of the reinforcement. 6) CFRP tapes may be useful for local reinforcement of tensed areas of bent wooden beams that are weakened due to the presence of knots in their sections. REFERENCES: 1. DĄBROWSKI H., 2002: Wytrzymałość polimerowych kompozytów włóknistych, Oficyna Wydawnicza Politechniki Wrocławskiej, Wrocław 2. GERMAN J., 2005: Podstawy mechaniki kompozytów włóknistych, Politechnika Krakowska im. Tadeusza Kościuszki, Kraków 3. JASIEŃKO J., Czepiżak D., Nowak T., 2006: Wzmacnianie zginanych litych belek drewnianych taśmami CFRP, Problemy remontowe w budownictwie ogólnym i obiektach zabytkowych, DWE, Wrocław, ORŁOŚ Z., 1977: Doświadczalna analiza odkształceń i naprężeń, PWN, Warszawa Streszczenie: Wpływ długości wzmocnienia w postaci taśmy CFRP przyklejonej od dołu zginanego elementu na rozkład naprężeń normalnych oraz ugięcie. W pracy badano wpływ wzmocnienia w postaci taśm CFRP na rozkład naprężeń normalnych i ugięcie zginanej belki drewnianej. Analizę przeprowadzono numerycznie w środowisku Solidworks Simulation. Dzięki miejscowemu wzmocnieniu elementu uzyskano redukcję ugięć sięgającą nawet 20%, oraz 80% redukcję maksymalnych naprężeń normalnych w okolicy otworu przy zastosowaniu taśmy CFRP o długości 50cm. Stwierdzono, że taśmy CFRP mogą być przydatne do miejscowego wzmacniania stref rozciąganych zginanych belek drewnianych, osłabionych na skutek występowania otworów, jako pozostałości po sękach wypadłych lub zepsutych. Corresponding authors: 1) Izabela Burawska, Andrzej Tomusiak, Piotr Beer Department of Construction and Technology of Final Wood Products Faculty of Wood Technology, Warsaw University of Life Sciences SGGW, Ul. Nowoursynowska 159, Warsaw, Poland [email protected] [email protected] [email protected] 191

192 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Local concentration of stresses as a result of the notch in different positions to the bottom surface of bending solid timber beam based on numerical analysis in Solidworks Simulation environment IZABELA BURAWSKA 1), ANDRZEJ TOMUSIAK 1), MICHAŁ TURSKI, PIOTR BEER 1) Department of Construction and Technology of Final Wood Products, Warsaw University of Life Science, Nowoursynowska 159, Warsaw, Poland Abstract: Local concentration of stresses as a result of the notch in different positions to the bottom surface of bending solid timber beam based on numerical analysis in Solidworks Simulation environment. The study investigated the phenomenon of local concentration of stresses in the bent timber beams weakened by the opening. Weakness in the timber simulate knotholes or decayed knots. It was found that the value of local concentration of stresses and stress concentration factor depends, i.a., on the strength of the bending load, crosssectional dimensions of beams, as well as the size and location of the opening in relation to the bottom surface of bending beam. Keywords: bending, notch, normal stresses, numerical analysis INTRODUCTION Timber strength class directly depends on the quality of wood raw material from which it is harvested. Wood sawn from logs with a small diameter and from high parts is loaded with natural defects such as knots, which are the most important criterion, determining the grade of timber [Krzosek, 2009]. The adverse effect of knots manifests itself in reducing longitudinal tensile, bending and compression. Research shows that the impact of knothole made by decayed or loosed knot is comparable with the effect of a knot itself [Krzysik, 1975]. However, knotholes are even more negative since they act as a notch in structural elements. It was shown that all the discontinuities of geometry, which include openings, grooves, etc. cause the disorder of stress distribution [Stachurski, 2010]. The aim of this paper is to investigate the influence of size of the opening, as the remnant of the knot, and its position relative to the bottom surface of the bending beams on the normal stress distribution. NUMERICAL ANALISYS The model of wooden structural element and analysis of its behavior under the load was conducted using the finite element method in Solidworks Simulation. Considered element was modeled as a solid timber pine beam, as orthotropic elastic material with cross-section dimensions of 50x100x2000 mm and the characteristic values of the resistance parameters were specific to timber class C22 (table 1.). Table 1 Material parameters 5% modulus of elasticity parallel E x 6700 MPa Compression parallel 20 MPa Mean modulus of elasticity perpendicular E y 330 MPa Compression perpendicular 2.4 MPa Mean modulus of elasticity perpendicular E z 330 MPa Shear 3.8 MPa Mean shear modulus G xy 630 MPa Yield point 20 MPa Mean shear modulus G xz 630 MPa Poisson's Ratio ν xy 0.4 Mean shear modulus G yz 630 MPa Poisson's Ratio ν xz Tension parallel 13 MPa Poisson's Ratio ν yz 0.4 Tension perpendicular 0.4 MPa Density 340 kg/m 3 192

193 A model of real instruments applied during resistance tests was prepared with the recommendations of the PN-EN 408:2004 standard (Fig. 1.). The support and upper points of contact were designed as made of alloy steel, which was available in the software directory. Figure 2 shows the scheme of the supports and upper points of contact. Fig. 1. Experimental workplace view Fig. 2. View of the layout of the support and upper points of contact Points of weakness of wooden beams made by decayed of loosed knots were modeled as openings with a diameter of 10mm and 20mm, located perpendicularly to the side surface of the element. Openings in posterior tests were moved by 5mm (Fig. 3.). Middle of the φ10 opening was located 6,5mm and middle of φ20 opening was located 11.5mm from the bottom surface of the beam. In both cases to obtain the thickness of the stretched fibers of 1.5mm. Fig. 3. Location of φ10 and φ20 openings in respect to the bottom surface of the beam Beam weakened by φ10 and φ20 openings differently positioned was loaded by force P=6kN and P=8kN, to investigate the impact of load on the normal stresses distribution. For comparison and verification of the results beam without any openings was analyzed as well. 193

194 Measurement point of maximum normal stress depends on the distance of the middle of the opening to the bottom surface of the beam, further called as base surface. For φ10 and φ20 openings, for which the distance from the middle of the opening to base surface is less than their radius, the maximum normal stress was measured at A point (Fig. 4a.). However, for longer distances, point B was the place for measurement of maximum normal stress (Fig. 4b.). Fig. 4. Location of the measurement points a) when l r, b) when l > r ; where l - distance between the middle of the opening and the base surface, r- opening radius DISCUSSION OF RESULTS Figure no 5 presents a chart showing the dependence of the results of normal stress around the knothole from its position against the base surface. σ max fi 10, P=6kN fi 20, P=6kN fi 10, P=8kN fi 20, P=8kN , , distance between the middle of the opening and the base surface Fig. 5. Maximum normal stresses depending on the position of the center of the hole relative to the base area and loading force The simulations showed that the normal stress distribution in the cross section depends on the distance between the middle of the opening and the base surface, its diameter and the value of loading force. The highest value of normal stress for the beam loaded by force P=6kN and P=8kN was obtained for the φ20 opening, when distance between the middle of the opening and the base surface was 11.5 mm. Longer distances were less important for the distribution of normal stress values. The same trend occurred for the φ10 opening. Once the maximum normal stress was reached for the distance between the middle of the opening and the base surface 6.5 mm, along with approaching to neutral bending axis of the beam impact of the opening was decreasing. In both cases, the maximum normal stresses appeared at measuring point located 1.5 mm to base surface. This is related to takeover of the whole normal stress by lower fibers of a small total thickness. At a distance between the middle of the φ20 opening and the base surface 5 mm values of maximum normal stresses got precipitously high. This may indicate a greater impact 194

195 of measuring point on the maximum normal stress value than the degree of weakening of the cross. The value of maximum normal stresses for the distance between the middle of the φ20 opening and the base surface 5 mm was read into a point distant from it about 15 mm, while for the distance 10 mm, was read into a point 20 mm away from the base surface. The effect of loading on the normal stress distribution in the beam is clear. The greater the loading force, the larger values normal stresses gets.. Figure no 6 shows the location of the φ10 and φ20 openings that received the highest normal stress values while beams were loaded by force P=6kN. The most disadvantageous is a opening that is away at a small distance from the lower surface of the beam, although there are still stretched fibers. a/ b/ Fig. 6. Maximum normal stresses in openings a) φ10, b) φ fi 10, P=6kN fi 20, P=6kN fi 10, P=8kN fi 20, P=8kN σ max/σ max n-w , , distance between the middle of the opening and the base surface Fig. 7. The ratio of σ max / σ max n-w depending on the location of the middle of the opening relative to the base surface and loading force, explanation of the symbols in the text Figure no 7 shows the dependence between ratio of the maximum normal stress (σ max ) and the maximum normal stress occurring in the nonweakened beam (σ max, n-w ), located in the extreme tension fiber and the distance between the middle of the opening and the base surface and load values. Ratio of σ max and σ max,n-w, while moving toward the neutral axis, decreases. For φ10 and φ20 opening, whose center is located on the base surface, the ratio of normal stresses is similar for the load P=6kN and P=8kN. This indicates a comparable impact φ10 and φ20 opening positioned on the base surface on the distribution of normal stresses. The distance between the middle of the opening and the base surface increases until reaching the elevation 195

196 of middle equal to the radius increased by 1.5 mm. For a load P=8kN ratio of σ max and σ max n,w is 7.4. After reaching the maximum value, the value of ratio decreases. Fig. 8 Distribution of normal stresses to the φ10 opening (top) and φ20 opening (bottom) located in the middle of the span of beams Figure no 8 shows the normal stress distribution for the two corresponding openings - φ10 and φ20, whose middles are 30 mm from the base surface. A different course of normal stress distribution is noticeable for both beams. In surroundings of small openings there is a rapid increase of stress but in relatively small area covering almost only the opening. A short distance from the opening quickly compensates stress. Openings with a higher diameter cause less severe stress in their environment, in relation to smaller openings α k fi 10, P=6kN fi 20, P=6kN 0 5 6, , distance between the middle of the opening and the base surface Fig. 9. The shape factor depending on the position of the middle of the opening relative to the base surface To estimate stress amplification in vicinity of a geometric discontinuity can be used geometric stress concentration factors. Figure no 9 shows the distribution ratio of shape factor α k depending on the distance between the middle of the opening and the base surface. Shape factor can be described as the ratio of stress increased by existence of the notch (which in this case occurs as an opening), and the stress at the same point, but for non-weakened material. The value of the shape factor depends on the value of the load. Higher forces result in a greater ratio of maximum stress occurring around the opening to the stresses that occur without an opening. Also the dimension of the opening has a huge influence. For φ10 opening which middle was located in 5mm to the base surface ratio was 5.7, while for φ20 this ratio 196

197 was 7.8. The maximum value of the ratio of shape occurred in both cases, when the distance between the middle of the opening and the base surface was equal to the radius of the opening. CONCLUSIONS 1) The highest normal stresses around the top of opening occur whenever the opening is beyond the section. The highest normal stresses around the bottom of the opening is always present whenever the opening is completely in a cross-section. 2) The smaller the thickness of the stretched fibers below the opening, the greater the value of normal stresses occur around the opening. 3) The normal maximum stress depends on the size of the opening, as the opening has a larger diameter the stress gets higher. Changing the size of maximum stress is not proportional, and as it approaches the neutral axis it disappears. 4) The ratio of maximum normal stresses around the opening to the maximum stress occurring in the beam without weakness, located in the extreme tension fiber is dependent on the load. For the force P=6kN it ranges from 0.2 to 5.2 for φ10 and from 0.4 to 5.6 for φ20. For the force P=8kN it ranges from 0.3 to 6.9 for φ10 and from 0.6 to 7.4 for φ20. 5) Shape factor reaches the highest value for openings whose middle is located at a distance equal to the radius of the opening. May therefore be concluded that for these cases, levels of stress accumulation is the greatest. REFERENCES 1) de Moura M.F.S.F., Dourado N., Morais J. Crack equivalent based method applied to wood fracture characterization using the single edge notched-three point bending test. Engineering Fracture Mechanics 77 (2010). p ) Krzosek S.: Wytrzymałościowe sortowanie polskiej sosnowej tarcicy konstrukcyjnej różnymi metodami, Wydawnictwo SGGW, Warszawa ) Krzysik F. Nauka o drewnie, PWN, Warszawa ) Stachurski W., Maj M. Ocena poziomu naprężeń na powierzchni badanego elementu metodą elastooptyczną. In: XII Konferencja Odlewnicza TECHNICAL 2010;2010. p ) The University of Tennessee at Martin, Stress Concentration Factors and Notch Sensitivity, Lectore 4, Engineering 473, Machine Design 197

198 Streszczenie: Miejscowa koncentracja naprężeń jako skutek karbu o zmiennym usytuowaniu w stosunku do powierzchni dolnej zginanej belki na podstawie analizy numerycznej w Solidworks Simulation. W pracy sprawdzano wpływ otworu, jako pozostałości po sęku wypadającym lub zepsutym na rozkład naprężeń normalnych w zginanej belce drewnianej. Wpływ ten zależał głównie od wartości obciążenia, średnicy sęka oraz od położenia jego środka od powierzchni bazowej, którą stanowiła dolna powierzchnia belki. Wykazano, że najbardziej niekorzystny pod względem maksymalnych naprężeń normalnych jest otwór, który całkowicie mieści się w przekroju, i który powoduje pracę niewielkiej grubości włókien rozciąganych. Corresponding authors: 1) Izabela Burawska, Andrzej Tomusiak, Piotr Beer Department of Construction and Technology of Final Wood Products Faculty of Wood Technology, Warsaw University of Life Sciences SGGW, Ul. Nowoursynowska 159, Warsaw, Poland [email protected] [email protected] [email protected] 198

199 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) The preparation method of experimental studies of the wood sawing process D. CHUCHAŁA 1, K. ORŁOWSKI 1, S. KRZOSEK 2 1 Gdansk University of Technology, Faculty of Mechanical Engineering, Department of Manufacturing Engineering and Automation, Narutowicza 11/12, Gdansk, Poland 2 Warsaw University of Life Sciences, Forestry and Wood Technology, Nowoursynowska 159, Warsaw, Poland Abstract: The preparation method of experimental studies of the wood sawing process. The article presents methods of operation for preparing experimental studies of the wood sawing process on the narrow-kerf sash gang saw PRW15M. Preparation of studies process was divided into stages: preparation of samples, measurement of physical properties of wood (moisture content of wood, density of wood), measurement of structural properties of wood (average width of annual growth and average fraction of late wood). Keywords: experimental studies, wood, density of wood, annual growth, fraction of late wood. INTRODUCTION The process of experimental studies of the wood sawing induce destruction of samples (they are sawn into thin pieces). Therefore, it is important to examine the samples and to gather as much information as necessary for further analysis before sawing (destruction) of piles is. The preparation process of experimental studies of the wood sawing was divided into three stages: preparation of samples, measurement of physical properties of wood and measurement of structural properties of wood [1, 2]. The physical properties which measurement should be made, were taken: moisture content of wood and density of wood. The properties of wood structure proposed for the measurement before the experimental studies are then: average annual growth and an average fraction of late wood [2]. Nomenclature a sample thickness [mm] b sample width [mm] l sample length [mm] V sample volume [cm 3 ] m sample mass [g] ρ sample density [g/cm 3 ] MS measuring section (30 mm) AI annual growth [mm] WLW width of late wood [mm] SLW fraction of late wood [%] PREPARATION OF SAMPLES Dimensions of wood piles, depend on the operating parameters of the machine on which the study are going to be carried out (e.g. stroke of the saw frame, the number of blades in the gang, fastening system) [1, 5]. Samples for the narrow-kerf sash gang saw PRW15M were prepared with the following dimensions: height 80 mm, width 45 mm and length 600 mm. 199

200 Implementation of the samples was commissioned to sawmill plants which have a fleet of machines that ensures appropriate high quality prisms. For the study it was decided to use the same material that was previously used for endurance sorting by various methods [1]. MEASUREMENT OF PHYSICAL PROPERTIES The physical properties of samples prepared for experimental studies which were measured are: moisture content and wood density [2]. The measurement of moisture content of wood was made by using an electronic moisture content meter for wood WRD-100, with a compensation system which takes into account the effect of the ambient temperature for there measurement value [5]. The measurement was performed at random just before experimental sawing. The measurement of density of wood was performed by using the stereometric method [2]. This method consists in measuring the volume of the sample by measuring the various dimensions (length, width, height), and the determination of the sample mass. The dimensions of cross-sectional sample (width, height) were measured by using the caliper with the accuracy up to 0.05 mm, at six points, equally spaced on the length of the pile. The measure of the samples length was performed with a tape measure with the accuracy of 0.5 mm. On each of the sides of the piles there were made two measurements of length, which gave a total of 8 measurements per sample. The results of all the dimensions of the sample were checked by statistical method (Grubbs's test), in order to eliminate blunders (measurement errors) [3, 4]. After checking the results of measurements individual dimensions were calculated by using the arithmetic mean. The volume of the specimen was calculated with the accuracy of cm 3, from the relationship:, (1) The measurement of samples mass was made by using a RADWAG balance type WPT/R 1.5/3C, with the measuring range up to 3 kg and measurement accuracy of 0.5 g. The density was calculated by using the formula [2]:, (2) After receiving the density values of individual samples there were subjected to statistical analysis to eliminate the errors of measurement (blunders with the use of Grubbs's test) [3, 4], and then for each group of samples the average density (arithmetic mean) was calculated. MEASUREMENT OF STRUCTURAL PROPERTIES OF WOOD Important properties of wood that can be useful for subsequent analysis are: average annual increase of wood, and the average share of late wood. Measurement of these properties for the prepared samples was carried out by own methodology. Each sample was photographed at two ends of front planes. Photos were taken on the prepared stand, with a steady light. Afterwards, the pictures were imported into Autocad programme, then scaled to the dimensions of the actual sample. Using the tools in Autocad programme it was measured the width of annual growth and width of late wood in annual 200

201 growth over a 30 mm measuring section positioned perpendicularly to the tangent drawn to the ring determining the growth ring (Fig. 1). Fig. 1. The determination method of the width of annual growth and the width of late wood: MS measuring section, WLW width of late wood, AI annual growth For all samples from selected regions of origin as the average annual growth (arithmetic mean) has been calculated. The average fraction of late wood SWL is calculated from the relationship of the width of late wood WLW to the average annual growth AI (Eq. 3). CONCLUSIONS The preparation process of empirical studies of wood sawing presented in this paper allows us to obtain much more of valuable information on the test wood samples, which may be useful in the future for many additional analyses of obtained results of sawing wood. Gathering this information before the relevant experimental studies seems to be necessary, due to the nature of the research which results in destroying the samples. (3) 201

202 REFERENCES 1. KRZOSEK S., Wytrzymałościowe sortowanie polskiej tarcicy konstrukcyjnej różnymi metodami. Wydawnictwo SGGW, Warszawa, KRZYSIK F., Nauka o drewnie. PWN, Warszawa, KUKIEŁKA L., Podstawy badań inżynierskich. PWN, Warszawa NIKIEL G.: Opracowanie statystyczne wyników badań doświadczalnych z wykorzystaniem programu ReGreg. Opracowanie niepublikowane, Bielsko - Biała ORŁOWSKI K., Materiałooszczędne i dokładne przecinanie drewna piłami. Monografie Nr 40, Politechnika Gdańska, Gdańsk, Streszczenie: Sposób przygotowania badań doświadczalnych procesu cięcia drewna. W artykule przedstawiono sposoby działania, mające na celu przygotowanie badań doświadczalnych procesu przecinania drewna sosnowego na małogabarytowej pilarce ramowej PRW15M. Proces przygotowania badań podzielono na kilka etapów: przygotowanie próbek, pomiar własności fizycznych drewna (wilgotności drewna, gęstość drewna), pomiar własności strukturalnych drewna (średniej szerokości przyrostów rocznych oraz średniego udziału drewna późnego w słoju). Corresponding authors: Kazimierz Orłowski Gdansk University of Technology, Faculty of Mechanical Engineering, Department of Manufacturing Engineering and Automation, Narutowicza 11/12, Gdansk, Poland address: [email protected] [email protected] 202

203 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Straw briquette as an energy source MARIUSZ CYRANKOWSKI, JAN OSIPIUK, PAWEŁ BAREJ Department of Mechanical Woodworking, Warsaw University of Life Sciences - SGGW Abstract: Straw briquette as an energy source The paper presents essential information on straw briquettes, it describes straw as an energy material, and the briquette combustion process. Environmental aspects of straw briquette combustion are analysed as well, along with the comparison of straw briquette with traditional sources of energy. Keywords: briquette, straw, renewable sources of energy, biomass INTRODUCTION The growing demand on energy is now accompanied by diminishing natural resources used by the power sector (coal, natural gas, crude oil). The prices of energy are soaring higher and higher, which makes renewable energy sources at the centre of attention. Renewable energy offers some obvious advantages: it is environmentally-friendly and non-exhaustible. These advantages make the renewable energy distinct from the traditional energy sources, which are the main culprit of the alarming climate change. Global fossil fuel resources will be exhausted sooner or later. It is estimated that coal resources will last for another 220 years, whereas the resources of natural gas and crude oil will be exhausted in 60 and years, respectively. Facing the scarcity of fossil fuels and the environmental impact of the traditional energy sources, people are now looking for other ways to generate energy. Biomass combustion is one of alternatives, in which energy is produced of organic biodegradable substance made of agricultural, forestry and industrial by-products and waste materials. Straw briquette is one of biomass types which can be used to generate renewable energy. General specification of straw as a source of energy Straw is a by-product made of ripe or dry stalks of cereal plants, and also of dry leguminous plants, flax and rape. Like wood, straw is composed of cellulose, hemicellulose and lignin. In the past and today, straw is an agricultural by-product which has been mainly used for livestock bedding. The volume of straw produced has been on the increase with the introduction of modern agricultural production methods. As a result, new applications have been identified for the excessive amounts of straw produced in the agriculture, with energy production being one of them. The calorific value of dry straw is approx MJ/kg. As compared to coal (calorific value of approx MJ/kg), 1.5 ton of straw briquette corresponds to 1 ton of medium-quality coal. Straw is neutral for the environment, and its combustion in power plants has no impact on CO 2 emissions: the same amounts of CO 2 are produced in straw briquette combustion and in photosynthesis. Combustion of straw briquettes The combustion of straw briquettes as a substitute to coal offers significant reduction in CO 2 emissions. It is estimated that the same amounts of CO 2 are produced in straw briquette combustion and in the plant growth process (photosynthesis). Another advantage is the significant reduction of sulphur compound emissions. However, increased emissions of nitrogen compounds can be an issue, exhaust gas can also contain carbon monoxide (CO), polyaromatic hydrocarbons (PAH) and hydrogen chloride (HCL). These emissions are 203

204 directly dependant on the straw combustion process, which is essential in the effective utilization of briquettes in energy production. Sufficient air needs to be supplied to the straw combustion furnace to reduce dioxin emissions to the minimum levels. Dioxins are considered very dangerous for environment, and it is therefore essential to safeguard the proper combustion conditions. Like the combustion of any other fuels, briquette combustion can be complete or incomplete. Complete straw combustion needs to be accompanied by the supply of specific volume of air. In case of air deficiency, soot and non-combusted gases are produced containing pitch vapours. On the other hand, the same by-products are produced in conditions of excessive air supply, along with ashes and dust. As a rule, 25-50% air excess is supplied to the boilers to guarantee better combustion performance. Briquette is a universal fuel. It can be combusted in low-power boilers with manual and automatic feed, as well as in automated boiler rooms with computer-controlled combustion. It is also eligible for use in gasifying boilers. Briquette can be combusted alone or can be co-fired with other fuels, such as coal. Apart from the biomass parameters, another factor is the ash produced in the combustion process. Ash from straw briquettes can be used as a mineral fertilizer, however, the combusted biomass must be free from any impurities and additives. Straw vs. other fuels Table 1. Straw vs. other fuels (Chochowski, 2001) Parameters Unit Yellow straw Grey straw Coal Gas Wooden chips Humidity % by weight Ash content % by weight Carbon content % by weight Oxygen content % by weight Hydrogen content % by weight Chlorine content % by weight Nitrogen content % by weight Sulphur content % by weight Volatile matter % by weight Calorific value MJ/kg Heat of combustion MJ/kg Summary Non-renewable sources of energy will be gradually depleted, and the prices of traditional energy will be increasing. Biomass processing will become the mainstream. Straw combustion can be an important source of renewable energy. Straw briquettes are simple to make, no additives are typically required. Straw is processed with the use of briquetting machines: briquette presses, worm-type briquetting machines, and hydraulic ones, depending on the expected briquette parameters and the volume of straw processed. Moreover, the straw needs to have specific parameters, most notably humidity (up to 20%). Biomass combustion has a neutral environmental impact, and will contribute to preventing greenhouse effect and climate change in the long-term perspective. However, biomass as an energy source offers so much more than just reduced CO 2 and SO 2 emissions. Straw used for energy production can also contribute to the multifunctional development of rural areas. Small briquette plants will deliver inexpensive and environmentally friendly fuel to the local residents, and will create 204

205 more jobs. The production of straw briquettes as a renewable source of energy can be cofounded and supported by EU, which makes the establishment of professional production facilities of straw briquettes so much easier. REFERENCES Chochowski A., 2001: Technologiczne, ekologiczne i ekonomiczne aspekty energetyki odnawialnej, Wyd. SGGW, Warszawa Denisiuk H., Piechocki J., 2005: Techniczne i ekologiczne aspekty wykorzystania słomy na cele grzewcze. Wyd. Uniwersytetu Warmińsko-Mazurskiego w Olsztynie, Gradziuk P., 2003: Biopaliwa, Wyd. Wieś Jutra Sp. z o.o., Warszawa Gradziuk P., Grzybek A., Kowalczyk K., 2001: Słoma energetyczne paliwo, Wyd. Wieś Jutra Sp. z o.o., Warszawa Streszczenie: Brykiet ze słomy jako źródło energii. Praca zawiera informacje dotyczące brykietów ze słomy. Scharakteryzowana została w niej słoma, jako materiał energetyczny, ponadto w pracy opisano proces spalania brykietów. Poruszone zostały ekologiczne aspekty spalania brykietów ze słomy, a także porównanie ich z konwencjonalnymi źródłami energii. Corresponding authors: Mariusz Cyrankowski, Jan Osipiuk, Paweł Barej Wood Mechanical Processing Department, Wood Industry Mechanisation and Automation Institute, [email protected] [email protected] Warsaw University of Life Sciences - SGGW Warsaw,Nowoursynowska 159,Poland 205

206 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Implementation issues in visual systems for wood quality testing MARIUSZ CYRANKOWSKI, MICHAŁ KORZEMSKI Department of Mechanical Woodworking, Warsaw University of Life Sciences - SGGW Abstract: Implementation issues in visual systems for wood guality testing. The chosen problems in work were introduced during use of visional systems to investigation the quality of wood. It the problems were have the self - characterized was connected from wood material, with limited possibilities of devices how also with economy and the functioning the market. Keywords: machine vision, wood quality, forest industry FOREWORD Visual systems are more and more often used in various branches of industry due to a continuous development of automation, search for methods improving product quality and economic considerations. The process automation ensures higher production rates, cost reduction and better product quality. Visual quality control systems provide contact free, automatic control in a production, processing or assembly process. The systems provide real time monitoring, detection of parameters and defects, and data exchange with automatics enables elimination of defective products. A high quality control speed (up to several analyses per second) and 24 hour operation are two main merits of this solution. It provides near 100% accuracy, and significant reduction of unnecesary costs, as a consequence of production and sales of defective product. A possibility to use the system in locations, where people presence is required, in areas hazardous to health and where required by environmental protection considerations is also a great merit. Considering the benefits of the solution, a visual control of product quality is more often used also in the wood industry. TEST METHODS USING VISUAL SYSTEMS The visual systems are used mainly for quality control and verification of production line operation. The systems may be used for various tasks. Four main type tests are: 1. Verification of dimensions and validity. Verification of tolerance and shape. Comparison with reference standards. 2. Testing surface quality: cracking, roughness, texture, scratching, improving layer thickness, colour monitoring. 3. Verification of the assembly. Is the product assembled as intended and no components are missing? 4. Verification of product functions. Counting and 1D and 2D bar codes and ASCII characters reading systems. IMPLEMENTATION ISSUES IN VISUAL SYSTEMS FOR WOOD TESTING Related to wood materials The biggest issue with the coarse wood is its roughness. The falling light dissipates and casts shadows. For surface roughness measuring systems this effect is useful, and it presents 206

207 problems in other cases. The image analysing software may recognize shadows as defects or different wood tinge (if the feature is tested). There are also issues related to wood drying and storage that affect the image analysis process. The wood changes colour when dried and the stains from spacers may occur. The algorithm may treat it as a defect. Changes in sun exposure and humidity may affect wood tinge in improper storage conditions. Also a location of material in packages and stacks, where lower layers may become darker after prolonged storage is of significance. Keeping the boards clean is a condition necessary for accurate defect detection. At all production stages, the boards are subject to incidental soiling, e.g. with sawdust, bark etc. A wood internal structure is also important. The features, such as spring or summer wood, reaction wood, transverse direction etc. may affect the image analysis. Issues related to limited device capabilities The main issue is a complex wood structure. To create a general purpose knot detection system it is necessary to consider many species and create an extensive pattern data base using various algorithms depending on the type and kind of knot. The knots can be detected with various special filters, histograms, round area detection systems or density disturbances (X-ray). Each system must be adapted to specific production process, species and defect. Lighting, which present problems for each control method is still an unresolved issue. The layout of shadows in coarse material may affect image analysis, and is crucial at detection of shadows in wood and veneer, and suitable cameras and lighting are used to obtain reliable results by trial and error method. Issues related to economy and market operations The issue is related to the willingness of plant owners to install the visual systems. There are several foreign companies that specialize in implementation of devices in timber industry, including: Microtec measurement of quantitative, geometrical and structural features of wood, Inx Systems machines for sawmills and timber grading, Raute Wood general purpose equipment, Sicam Systems wood measurements at all production stages, Ultimizers, Inc process optimization. Microtec is the main distributor of the solutions in Poland. The first barrier is the cost. Prices from several thousand to a few hundred thousand Polish zlotys indicate that the solutions for different requirements and needs are available. The fear for misspending a large amount of money is greater than the prospective benefits. The second issue is the availability of the solutions. The offer of companies specializing in visual systems does not usually include the solutions tailored to wood industry. 207

208 Graph no. 1 Reasons for the increase in visual system popularity in Poland. (Source: Control Engineering Polska) SUMMARY Visual systems are widely used in wood industry, mainly as a method for wood quality control. Nowadays, to maintain competitiveness of products, the use of visual systems is indispensable. The wide range of devices and manufacturer s experience provide visual systems compatible with almost every control process available. From optimization of measuring processes in sawmills to detailed control of wood surface at various processing stages. The systems perform well in quality control of veneers, and in combination with automatic defect cutter, the timber can be graded by tinge with simultaneous knot and heartwood detection. They can also be used in complex assessment of wood including measurement of dimensions, detection of surface defects and X-ray tests for detection of hidden defects. Visual systems require continuous improvements and further studies. The main issue is the structure of tested materials. The wood as an anisotropic material is available in a wide range of species, it is characterized by a great diversity and is hard to analyse considering the quality. The other issue is a constant development of production automatics where the discussed systems are an essential component. 208

209 REFERENCES 1. Blicharski K., 2006: Systemy wizyjnej kontroli jakości przyszłością produkcji, wyd. Inżynieria i Utrzymanie Ruchu Zakładów Przemysłowych, 1 grudzień. 2. Thivakaran T.K., 2010: Machine Vision based Surface Roughness measurement with Evolvable Hardware Filter, wyd. ICGST-GVIP Journal, Volume 10, Issue 3, August. 3. Control Engineering Polska, : Raport: Systemy wizyjne na polskim rynku Streszczenie: Implementation issues in visual systems for wood quality testing. W pracy przedstawiono wybrane problemy podczas zastosowania systemów wizyjnych do badania jakość drewna. Scharakteryzowano problemy związane z materiałem drzewnym, z ograniczonymi możliwościami urządzeń jak również z ekonomią i funkcjonowaniem rynku. Corresponding authors: Mariusz Cyrankowski, Michał Korzemski Wood Mechanical Processing Department, Wood Industry Mechanisation and Automation Institute, [email protected] Warsaw University of Life Sciences - SGGW Warsaw,Nowoursynowska 159,Poland 209

210 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Plants as an alternative source of energy MARIUSZ CYRANKOWSKI, JAN OSIPIUK, DAWID ADAMCZYK Department of Mechanical Woodworking, Warsaw University of Life Sciences - SGGW Abstract: Plants as an alternative source of energy. This paper presents the opportunities to combust energy crop for its energy content, along with the advantages and disadvantages of this type of energy source. It also analyses benefits and losses associated with the cultivation of energy crop, and its potential utilization in the power industry. Keywords: energy crop, biomass, power industry. INTRODUCTION The renewable energy sector has been thriving in recent years: renewable energies have been at the core of large-scale concepts and environmentally friendly developments. This new phenomenon can be to some extent explained by the diminishing utilization options of fossil fuels, which will be exhausted sooner or later. The volume of fossil fuels still available is well documented, and it is estimated that the deposits of crude oil and coal will be exhausted within 30 and 200 years, respectively. The consumption of mineral energy resources is invariably associated with high emissions of greenhouse gases and the resulting adverse changes in the composition of atmospheric gases, which can lead to global climate changes. As a result of the greenhouse effect, temperatures have been increasing throughout the world. Temperature increase by merely C can be life-threatening to a multitude of plants and animals. It is also possible that people will have to face serious discomforts, especially in Africa and South Asia, where the area of arable land has noticeably decreased. Outline of renewable energy sources The contemporary world is almost entirely electricity-dependant. Electricity has been and will always be a crucial source of energy in the majority of human activities. It can have a variety of applications, most notably industrial production, transportation sector, heating, and lighting. Initially, electric energy has been produced by processing the natural resources: wood, brown coal, hard coal, crude oil, and gas. Facing the ever growing demand for electricity along with the diminishing natural resources as well as environmental and economic factors, people now have a new demanding challenge ahead. Within the last years, the focus has been on the development of the most efficient energy producing methods using renewable sources, such as solar radiation, water or the Earth s natural heat. The awareness has been changed as well, people now appreciate the highlights and benefits of this type of solutions. 210

211 Fig. 1. Renewable sources of energy ( Renewable energy sources can be typically divided into non-environmentally friendly (atomic energy, deep geothermal energy, and biofuels producing nitrogen dioxides and other by-products) and environmentally friendly (energy produced of water, wind, solar radiation, shallow geothermal energy, and biomass). YIELDING Yielding, which is defined as the production of specific biomass volume from crop cultivated within a specific area (Table 1) depends on a variety of factors, including the cultivation climate. Short periods of insolation are typically negatively affecting the volume of biomass produced. Soil richness is another yielding aspect: the higher the content of minerals and water in soil, the higher the yields. However, energy crop can be cultivated on Class 3 and Class 4 soils, and it is even unreasonable to cultivate it on better quality soils as it has a negligible effect on yield (and better quality soils can be used to cultivate more demanding plants). Agrotechnical measures can also significantly improve yielding. ( Table 1: Calorific values and yielding of energy crop (Lisowski, 2010) Name of energy plant Average calorific value per dry mass [MJ/kg] Dry mass per hectare of arable land [ton/ha) Miscanthus giganteus Spartina pectinata (prairie cordgrass) Multiflora rose Giant knotweed (Fallopia sachalinensis) Jerusalem artichoke (Helianthus tuberosus) Virginia mallow (Sida hermaphrodita) Common osier (Salix viminalis)

212 Fast growing shrubs (common osier and multiflora rose) can be considered the most appropriate for energy production purposes as they regrow quickly after being cut down. Perennials (virginia mallow, Jerusalem artichoke and giant knotweed) are less productive. Perennial grasses: miskanthus giganteus and spartina pectinata have the lowest energy potential. Advantages and disadvantages of energy crop and its utilization potential in the power sector Benefits associated with the cultivation of energy crop: contribution to environmental protection policy of the state. i.e. limited emissions of environmental pollutants affecting the climate, reduced environmental impact by limiting greenhouse gas emissions produced by traditional fuels, continuous and reliable supply of domestic energy medium, new jobs (especially important among rural population at high risk of unemployment), utilization of waste land, utilization of agricultural and production waste, generation of profits which are difficult to secure in conditions of over-production of crops, decentralized production of energy and improved security of energy supplies due to the increased number of energy providers. Disadvantages associated with the cultivation of energy crop: relatively low densities of raw materials, problems related to transportation, storage and proportioning, varied humidity values make it difficult to prepare the crop for energy production purposes, lower calorific values as compared to fossil fuels, seasonal biomass availability, high risk of drastic decrease of biodiversity if monocultures of energy crop are introduced, if the biomass is contaminated with pesticides, plastic waste and chloro derivatives, carcinogenic and toxic compounds can be released in its combustion. Utilization potential of energy crop The biomass resources made of energy crop can be evaluated in terms of its theoretical, technical and economic potential. Chart 1 illustrates the theoretical potential, i.e. values which cannot be translated into practice since they define only the potential of raw materials or biomass. Technical potential reflects the qualitative biomass value which can be taken into account for energy production purposes if technically feasible. Economic potential has a specific economic value and involves a share of technical potential. A market potential can also be estimated as the potential of biomass available on the market and ready for use (exchange, warehouse). million tons Technical potential Economic potential Market potential Chart 1: Estimated technical, economic and market potential of biomass for energy generation purposes (million tons]. (Gajewski, 2011) 212

213 SUMMARY Environmental protection objectives can be pursued by the progressive implementation of energy-efficient technologies, along with the replacement of traditional energy sources with renewable ones. There are plenty of species of energy crop which can be cultivated in Poland. At present, the development of energy production methods from energy crop has reached its turning point. However, in order to be introduced on an industrial scale, a few obstacles need to be dealt with, which can change the implementation process of this particular energy source. The conceptual assumptions need to be translated into technological solutions, both on farms which cultivate energy crop, and large business entities. Numerous large power plants have already made investments in the processing and utilization of biomass. It should be therefore assumed that the benefits associated with the development of biomass production from agricultural sources currently prevail. Let us therefore be hopeful that the tendency will continue to strengthen and that the energy production from renewable sources will reach the optimum levels. REFERENCES 1) Gajewski R., 2011: Potencjał rynkowy biomasy z przeznaczeniem na cele energetyczne. Czysta Energia,1/22-24, 2) Kieć J., 2007 : Odnawialne źródła energii. Wydawnictwo Akademii Rolniczej, Kraków, 3) Lisowski A., 2010.: Technologie zbioru roślin energetycznych. Wydawnictwo SGGW, Warszawa, Streszczenie: Plants as an alternative source of energy. W pracy przedstawiono możliwości przetworzenia surowców roślinnych na nośniki energii a także zalety i wady wpływające na produkcję tej energii. Omówiono korzyści jak również straty wynikające z uprawiania roślin energetycznych oraz potencjał ich wykorzystania w przemyśle energetycznym. Corresponding authors: Mariusz Cyrankowski, Jan Osipiuk, Dawid Adamczyk Wood Mechanical Processing Department, Wood Industry Mechanisation and Automation Institute, [email protected] [email protected] Warsaw University of Life Sciences - SGGW Warsaw,Nowoursynowska 159,Poland 213

214 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Eco-friendly method for paper dyeing with reactive dyes JACEK CZECHOWSKI, KAZIMIERZ BLUS* Institute of Papermaking and Printing, Technical University of Lodz * Institute of Polymer and Dye Technology, Technical University of Lodz Abstract: Eco-friendly method for paper dyeing with reactive dyes. The authors pre-evaluated possible application of kayacelon dyes (synthesized in the Institute of Polymer and Dye Technology, Technical University of Lodz) in paper dyeing combined with a polyelectrolyte - polycondensate of hexamethylene -1.6 diamine and guanidine. In the light of the research results presented here, the dye and retention agent dyeing method, which is to be patented, turned out to be very effective. The dye was practically entirely saturated on the pulp fibrous components, fines had good retention parameters contributing in this way to high purity of white water. It is particularly important in the environment friendly production of dyed papers in tightly closed water loops. Keywords: paper dyeing, kayacelon dyes, dye retention INTRODUCTION Environmental and economic aspects made the world s paper production change to coloured products manufactured from pulp with high content of recovered paper as well as mechanical pulp grades. The production of white papers demands significantly more raw materials per a finished product, apart from that more wastewater is produced. A colour catches the eye. Coloured paper products are used as advertising materials, newsprint, packaging as well as towels, serviettes, toilet rolls, etc. Aside from an aesthetic aspect, their advantages include also health aspects as the colour does not make the eyes feel tired. Recently coloured papers started to replace gray grades. Additionally, almost all paper grades are dyed to change their hue. The paper manufacture is a complex technological process consisted of the following stages: preparation and refining of fibrous semi-finished products, stock preparation, paper web consolidation in the sections of paper machines (forming, pressing and drying) as well as paper finishing. The most commonly used method for dyeing paper products is dyeing in the stuff in which a dye is added to the pulp suspension before paper web formation on the paper machine. In this method the dye is applied in the room temperature of ºC, within min, usually without any auxiliaries. The advantage of this method is adsorption of dye molecules on the entire surface of cellulose fibres. After paper web drying, an entirely dyed paper product is obtained. When working on the research project aimed at finding eco-friendly cellulose fibres useful for dyeing in neutral medium of reactive dyes, the authors turned their attention to Kayacelon React with a following structure: 214

215 CO 2 O 2 C + + N N Barwnik Dye Barwnik N H N N N Diamina N N N N H Barwnik Diamina Diamine The dyes of this type are able to react with cotton fibres in neutral medium in temperature of ºC, that is in the temperature of paper web drying. The aim of this study was to use the reactive dyes, derivatives of 3`-carboxypirydyno- 1,3,5-triazine in paper dyeing. EXPERIMENTAL For the testing purpose, a group of compatible 3`-carboxypirydyno-1,3,5-triazine reactive dyes was selected. Their synthesis was carried out in the Institute of Polymer and Dye Technology, Technical University of Lodz. The dyes are presented below(based on C.I.Reactive Red 221): CO 2 O 2 C SO 3 Na OH NH N N + + N N N NH NH N N N NH OH SO 3 Na N=N N=N SO 3 Na SO 3 Na C.I.Reactive Red 221 NaO 3 S SO 3 Na In the first stage of the test, paper samples were dyed with the reactive dye (Kayacelon React) and coagulant (polycondensate of hexamethylene diamine and guanidine). The second stage pre-evaluated an impact of the coagulant on purity of white water (defined by the fine content through measurement of absorbance of white water). Dyeing of papermaking pulp with the reactive dye (Kayacelon React type) and the coagulant (polycondensate of hexamethylene diamine and guanidine) In temperature of ºC, solution of 20 g/dm 3 of reactive dye containing 1% of dry dye in relation to absolutely dry papermaking pulp was added to papermaking pulp refined to 25 0 SR value and consistency of 0,3% (absolutely dry) and then the solution (20g/dm 3 ) of polycondensate of hexamethyleno diamine and guanidine, in the amount of 215

216 1% calculated into polymer in relation to absolutely dry papermaking pulp; ph of papermaking pulp was Adducts formed of the reactive dyes and the polyamide were adsorbed on the surface of fibres of refined pulp within 30 seconds. Retention of the dyes on the cellulose fibres (defined by measurements of absorbance) exceeded 90%. The remaining small amount of the dye was totally adsorbed on rapidly sedimenting molecules of the fines in the white water, and finally white water was completely colorless. The paper sheet for tests, formed on the wire of the Rapid Koethen apparatus, was dried in temperature of 130ºC. During paper web drying in temperature exceeding 100ºC covalent bonds are formed between reactive dyes and cellulose. The degree of bonding was determined by measurement of absorbance of solution from cooking paper sample in azeotropic mixture of pyridine and water (65% of pyridine) during 10 min in correlation with model curves. The determined degree of bonding between the paper and the dye was 96.7%. Dyeing results obtained with use of this method were characterized by vivid hue, high intensity of colour and very good resistance to wet conditions. For comparison, the tests regarding dyeing papermaking pulp with adducts of direct dye C.I. Direct Yellow 86 were performed. SO 3 Na N=N NH N NH N=N SO 3 Na N N SO 3 Na CH 3 NHCH 2 CH 2 OH C.I. Direct Yellow 86 CH 3 SO 3 Na It is a typical dye used commonly now for paper dyeing in combination with a coagulant being a product of polycondensation of hexamethyleno of 1.6 diamine and guanidine. Also in this case, the adduct was completely retained on cellulose pulp, however degree of bonding between the dye and paper was 73.6%. Effect of the amount of polyamide compound added to papermaking pulp on the amount of the fines in white water In the tests, bleached kraft hardwood pulp (SaBl) of different refining degrees was used. 1% of C.I. Reactive Red 221 was added to 0.3 % suspension of pulp beaten in the Valley laboratory beater to a few ºSR, and then 1 or 2% of condensate of hexametyleno of 1.6 diamine and guanidine in relation to dry papermaking pulp. From pulp prepared in this way, the small sheets of paper of 75 g/m 2 were formed on the Rapid Koethen apparatus (acc. to PN-EN :2001). The fine content in white water was determined by measurement of absorbance of white water. The pulp beating degree was described in terms of a Shopper Riegler ( 0 SR) numer. Measured absorbance values of white water for C.I.Reactive Red 221 are listed in Table 1. Table 1. White water absorbance Pulp beating degree Amount of addend polyamide compound [% in relation to a.d. pulp] White water absorbance value 1 11 ºSR ºSR

217 3 25 ºSR ºSR ºSR ºSR ºSR ºSR I should be noted that small amount of adducts that penetrated to white water during paper forming on the wire of the Rapid Koethen apparatus did not colour white water as it was entirely adsorbed on molecules of the fines that could be found in white water. CONCLUSIONS Presented here, the new method for paper dyeing in the manufacturing process with the adducts of the reactive dyes and the cationic polyamide compounds playing a role of a coagulant is tightly integrated with the paper production on the paper machine. Paper dyeing in the stuff is carried out in the water medium with ph close to natural in room temperature. In such conditions, the dyes are completely retained on the cellulose fibres. Some of the fines get through the wire. Their amount decreases along with the increased amount of added polyamide compound. The increase from 1% to 2% of added polycondensate of hexamethyleno diamine and guanine reduces the amount of the fines getting through the wire of the apparatus for forming paper sheets by 50% on the average. The fines from beaten pulp are adsorbed by the coagulant and then they are adsorbed along with the coagulant on the fibres in paper. During paper drying in temperatures exceeding 100ºC additional covalent bonding between the reactive dyes and the complex of 3`-carboxypyridino-1,3,5-triazine of hydroxyl groups of cellulose. Treatment of dyed papers with a buffer pyridine-water showed that it is permanently bonded with paper over 92% compared with 73.6% of the typical direct dye. It can be assumed therefore that at least 20% of the reactive dye is bonded by the covalent bonds with paper. The remaining amount of the dye may be bonded with paper by either covalent or ion bonds. Dyeing results achieved with this method are intensive with vivid hue and they are characterized by very high resistance to wet conditions. It is connected with the fact of forming ion bonds between sulfone monomolecules of the reactive dye and the cationic groups of a polymer. Owing to presence of large number of sulfone groups in the molecule, the reactive dyes are not aggregated in the water based solutions. The adducts formed are adsorbed on the surface of beaten cellulose fibres. In consequence, very intensive dyeing results are obtained. When concluding it has to be stressed that, in the light of preliminary test results, the paper dyeing method in the stuff with the reactive dyes of Kayacelon React type, adsorbed on the fibres and the fines of papermaking pulp with polyelectrolyte in a form of polycondensate of hexamethyleno diamine and guanidine, seems to be an effective process both economically and environmentally. Polycondensate of hexamethyleno-1.6- diamine and guanidine is highly effective retention aid both for the koyacelon dye and for the pulp fines. As e result we have obtained not only complete saturation of the dye of fibrous constituents of papermaking pulp but also high retention of the fines, owing to this fact white water appearing in the process of the web consolidation on the paper machine practically does not contain any dye and it has significantly reduced suspension content. This fact is very important for present eco-friendly paper production from wood based pulp in conditions of tightly closed loops of production water. 217

218 REFERENCES 1. SZWARCSZTAJN E., 1991: Przygotowanie masy papierniczej, WNT Warszawa. 2. DRZEWIŃSKA E., CZECHOWSKI J., STANISŁAWSKA A., 2006: Technologia wytwarzania tektury, Wydawnictwo Politechniki Łódzkiej. 3. PRZYBYSZ K., 1997: Technologia papieru, WNT Warszawa. 4. PALENIK., 1994: Przegl. Papiern., No 50, JACKSON A.C., 1995/1996: World Pulp & Paper Technology, HUNGER K., 2003: Industrial Dyes, Wiley-VCH, Weinheim. 7. ZOLLINGER H., 2003: Color Chemistry, VCH, Weinheim, New York. 8. BERRY T., 1998: Progress in paper coloration, Rev. Prog. Col., No 28, SHELLY J.K., 1990: J. Soc. Dyes Col. No 96, CZAJKOWSKI W., PALUSZKIEWICZ J., 2004: Przem. Chem., 83, 8, RENFREW A.H.M., PHILIPS D.A.S., BATES J., KAMPYL I., 2004: Dyes and Pigments 60, BLUS K., P ALUSZKIEWICZ J., CZAJKOWSKI W., 2005: Fibres and Textiles In Eastem Europe 13, 6, CZAJKOWSKI W., BLUS K., 2006: i inni Sposób barwienia włókien celulozowych barwnikami reaktywnymi pochonymi 3-karboksypirydyny,Zgł.Pat.Pol. P WIPO, Pat WO 2004/ A1; 15. BLUS K., CZECHOWSKI J., 2009: Sposób barwienia mas papierniczych w procesie wytwarzania papieru., Zgł. pat. P Streszczenie: Proekologiczna metoda barwienia papieru barwnikami reaktywnymi. Dokonano wstępnej oceny możliwości zastosowania w procesie barwienia papieru barwnika kayacelonowego (zsyntezowanego w Instytucie Technologii Polimerów i Barwników Politechniki Łódzkiej) w połączeniu z polielektrolitem będącym polikondensatem heksametyleno-1,6-diaminy z guanidyną. W świetle wyników badań zaprezentowanych w tej pracy, zgłoszony do opatentowania sposób barwienia papieru zaproponowanym układem barwnik środek retencyjny okazał się wysoce efektywny. Stwierdzono praktycznie całkowite wysycenie barwnika na składnikach włóknistych masy papierniczej, co w powiązaniu z dobrą retencją frakcji drobnej, zapewnia wysoką czystość wód podsitowych. Jest to szczególnie istotnym dla proekologicznej produkcji drzewnych papierów barwnych w warunkach silnie zamkniętych obiegów wodnych. This study was supported by the Polish Committee of Scientific Research (Grant No N N ) Corresponding authors: Jacek Czechowski, Institute of Papermaking and Printing, Technical University of Lodz, Wólczańska 223, Łódź Kazimierz Blus, [email protected] Institute of Polymer and Dye Technology, Technical University of Lodz, Stefanowskiego 12/16, Łódź 218

219 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Система модельно базированного автоматического управления процессом конвективной сушки пиломатериалов НЕНЧО ДЕЛИЙСКИ Кафедра Машинознания и автоматизации производства, Лесотехнический университет София, Болгария Abstract: System for model based automatic control of the convective drying process of lumber. This paper presents an electrical scheme and working algorithm of the created by the author system for model based automatic control of the temperature and relative humidity in convective drying chambers with inbuilt two specialized microprocessor programmable controllers. The first (main) controller based on mathematical model of the drying process computes the set-point values for the temperature and the relative humidity as a function of the wood specie, lumber thickness and the current average value for the wood moisture content. The second three channel controller ensures reliable and correct on line wood moisture measurement results for the set points calculation by the main controller. The individualization of the drying regimes according to the parameters of each consignment of different subjected to drying lumber ensures optimization of the quality and minimization of the energy costs of the whole process. Besides this, the implementation of the developed control system proves its high reliability. It is not only cheaper but also easier to tune service and apply in small woodworking companies. Key words: model based automatic control, programmable controller, wood drying process, moisture content ВВЕДЕНИЕ На международном рынке предлагаются разнообразные компьютеризированные системы для автоматического управления процессом конвективной сушки пиломатериалов. К сожалению, они слишком дороги для инвестиционных возможностей множества неболь-ших деревообрабатывающих и мебельных фирм в странах восточной и средней Европы. На основе накопленного в течение многих лет научного, научно-прикладного и практического опыта в области технологии, оборудования и микропроцессорного управления гидротермической обработкой древесины, нами совместно с фирмой «Дельта инструмент» - г. Софии разработаны специализированные программируемые логические контроллеры для автоматического управления процессом конвективнокамерной сушки пиломатериалов [3, 4]. Не уступая зарубежным аналогам в выполняемых функциях, эти контроллеры выгодно отличаются от них более низкой ценой и простотой обслуживания. В настоящей работе приводится электрическая схема и описывается действие разработанной автором и внедренной в индустрии в различнъх модификациях микропроцессорной системы модельно базированного автоматического управления процессом конвективной сушки пиломатериалов с участием в ней специализированных контролеров. ЭЛЕКТРИЧЕСКАЯ СХЕМА САУ КОНВЕКТИВНОЙ СУШКОЙ ПИЛОМАТЕРИАЛОВ На рис.1 показана принципиальная электрическая схема разработанной нами системы модельно базированного автоматического управления (САУ) процессом конвективно-камерной сушки пиломатериалов. В САУ участвуют два программируемые контроллера: 219

220 микропроцессорный контролер PLC1 (от англ. Programmable Logic Controller) для автоматического измерения влагосодержания и температуры древесины; Рис. 1а. Принципиальная электросхема САУ процессом конвективной сушки пиломатериалов Рис. 1б. Принципиальная электросхема САУ процессом конвективной сушки пиломатериалов (продолжение) 220

221 микропроцессорный контроллер PLC2 для модельно базированного управления процессом конвективной сушки расположенных в камере пиломатериалов [2]. К контроллеру PLC1 подсоединены три электросопротивительных датчика BMC1, BMC2 и BMC3 для измерения влагосодержания U подверженных сушке пиломатериалов, а также датчик BK для измерения текущей температуры древесины, чьи значения необходи-мы для вычисления этим контроллером температурной коррекции измеряемых значений U. К контроллеру PLC2 подсоединен электронный трансмитер с датчиками BK и BRH для измерения соответственно температуры T и относительной влажности RH сушильного агента. На зажимы контроллера PLC2 поступает информация о текущем средне арифметическом значении МС влагосодержания U, измеряемое и вычисляемое PLC1. Обзначение и предназначение остальных элементов САУ таково: SBM трехполюсный пакетный переключатель для подачи напрежения к САУ; QM1 и QM2 стартеры моторные для защиты двигателей вентиляторов камеры; KML и KMR контакторы, при помощи которых производится смена направления вращения электродвигателей МV1 и MV2 вентиляторов влево и вправо; KM1 и КM2 контакторы, управляющие электродвигателями МV1 и MV2; MP электродвигатель насоса для горячей воды, при помощи которой осуществля-ется обогрев калориферов сушильной камеры; MAL и MAR электродвигатели приводов открытия и закрытия соответственно левых и правых каналов для отвода отработавшего и ввода свежего воздуха в камеру; YAН электромагнитный вентиль для ввода увлажняющего флюида в камеру; FM, FТ, FC, FK, FAL, FAR, FH автоматические предохранители; НА звуковой сигнализатор; HLC, HL1 и HL2 лампы сигнальные. Действие показанной на рис.1а и рис. 1б САУ заключается в следующем. Поворотом ручки переключателя SBM подается электропитание к САУ. Тогда оператор при помощи кнопок и меню контроллера PLC2 вводит в него информацию о древесной породе, толщине и желаемом конечном влагосодержании пиломатериалов. На основе этих данных и непрерывно поступающей с контроллера PLC1 информации о моментном влагосодержании древесины контроллер PLC2 вычисляет по заложенной в его софтуере математической модели текущие задания для Т и RH сушильного агента. После старта процесса сушки контроллер PLC2 осуществляет полностью автоматичес-кое управление сушкой на основе непрерывного сравнивания вычисленных заданий Т и RH с их моментными измеренными значениями при помощи датчиков BK и BRH. Управление температурой сушильного агента в камере осуществляется при помо-щи реле KK контроллера PLC2. Оно предназначено включать и выключать монофазный двигатель МР насоса, подающего горячую воду к калориферам камеры. Когда измеренное датчиком ВK значение температуры сушильного агента ниже вычисленного контроллером ее режимного значения, тогда срабатывает реле KK и оно включает насос, обеспечивающий подачу горячей воды к калориферам камеры. При достижении температурой ее режимного значения реле KK выключается и подача горячей воды прекращается. Управление относительной влажностью сушильного агента в камере осуществля-ется при помощи реле KН, KAL и KAR контроллера PLC2. Реле KН предназначено включать и выключать электромагнит YAН вентиля, который обеспечивает подачу увлажняющего флюида в камеру. 221

222 Реле KAL и KAR управляют приводом реверсируемых монофазных электродвигателей МAL и МAR, которые открывают и закрывают соответственно левые и правые (входные и выходные) воздухообменные каналы сушильной камеры. Реверсируемое управление вентиляторами камеры осуществляется при помощи реле KVL и KVR контроллера PLC2. Реле KVL предназначено включать вентиляторы в условно левом направлении вращения, а реле KVL в условно правом направлении враще-ния. При помощи кнопок контроллера задается продолжительность паузы, необходимой для полной остановки электродвигателей вентиляторов перед автоматической сменой направления их вращения. Для сигнализации недопустимо больших (аларменных) отклонений измеренных значений температуры и относительной влажноти сушильного агента по отношению к вычисленным контроллером PLC2 их моментным режимным значениям изпользуются реле KKA и KHA. При возникновении таких отклонений соответствующее реле срабатывает и включает звуковой сигнализатор НА. При каждом аларменном выходе за заданные технологически допустимые пределы, а также при их последующем вхождении в них контроллер PLC2 производит архивирующую запись в собственной флэш-памяти. При помощи кнопок контроллера можно вывести на его дисплеи архивные записи и анализировать причины их возникновения. ЗАКЛЮЧЕНИЕ Внедрение описанной выше САУ на нескольких фабриках доказало эффективность заложенного в ней управляющего алгоритма, а также ее надежного функционирования при автоматическом управлении процессом конвективной сушки пиломатериалов в различных условиях. Впервые по сравнению с обычно применяемыми аналогичными алгоритмами, описанный в [1, 2] управляющий алгоритм обеспечивает следующие преимущества: вычисления режимных значений температуры и относительной влажности производятся не для определенной группы толщин пиломатериалов, а для конкретного, введенного оператором, значения (в mm) толщины подверженных сушке пиломатериалов; режимные значения температуры и относительной влажности вычисляются не константными для определенного интервала (напр. 5% или 10%) изменения влагосодержания древесины, а непрерывно изменяющимися для каждого его текущего значения. Такая индивидуализация режимов сушки сообразно с параметрами каждой порции подверженных сушке пиломатериалов обеспечивает оптимизацию качества и минимизацию энергопотребления для всего процесса сушки. ЛИТЕРАТУРА 1. ДЕЛИЙСКИ,Н., 2002: Алгоритм автоматического управления процессом конвективнокамерной сушки пиломатериалов при помощи программируемого контроллера. 3-rd international science conference Chip- and chipless woodworking processes. Starỳ Smokovec - Tatry, с ДЕЛИЙСКИ, Н., 2008: Алгоритм для вычисления режимных заданий в системе автоматического следящего управления процессом сушки пиломатериалов. Annals of Warsaw University of Life Sciences SGGW, Forestry and Wood Technology, No 63, с ПРОСПЕКТНЫЕ МАТЕРИАЛЫ И САЙТЫ в Интернете фирм Bollmann, Brunner, Hildebrand, Incomac, Incoplan, Ketres, Lignomat, Nardi, Mühlböck, Secal, Secea, Vanichek, etc. 222

223 4. YANKOV, E., N. DELIISKI, 2007: Programmable Control for Lumber Drying in Chambers. Proceedings of the 11 th WSEAS International Conference on SYSTEMS, Agois Nikolaos, Crete, Greece, p Streszczenie: System automatycznej kontroli suszenia konwekcyjnego tarcicy. Praca prezentuje schemat elektryczny oraz algorytm suszenia zaprojektowanego przez autora, opartego na dwóch dedykowanych programowanych mikrokontrolerach, systemu automatycznej kontroli temperatury I wilgotności w komorze suszenia. Pierwsz, główny kontroler bazuj na modelu matematycznym procesu suszenia i zadaje wartości temperatur i wilgotności w zależności od gatunku drewna, grubości tarcicy i akturalnych średnich parametrów materiału. Drugi kontroler przeprowadza pomiary wilgotności drewna w czasie rzeczywistym. Indywidualzacja schematów suszenia w zalezności od mierzonych i zadanych wartości zapewnia optymalizację jakości i zużycia energii, użyty system zapewnia ponadto wysoką niezawodność procesu, oraz łatwiejsze jego dostosowywanie dla małych przedsiębiorstw przemysłu drzewnego. Corresponding author: Nencho Deliiski, Faculty of Forest Industry, University of Forestry, Kliment Ohridski Bd. 10, 1756 Sofia, BULGARIA, [email protected] 223

224 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Вычисление удельной теплоемкости мерзлой древесины во время оттаивания льда в ней от адсорбционно связанной воды НЕНЧО ДЕЛИЙСКИ 1, ЛАДИСЛАВ ДЗУРЕНДА 2 1 Кафедра Машинознания и автоматизации производства, Лесотехнический университет София, Болгария 2 Кафедра Обработки древесины, Технический университет Зволен, Словакия Abstract: Calculation of the specific heat capacity of frozen wood during its defrosting in hygroscopic diapason. An approach for the calculation of the specific heat capacity c of frozen wood with ice in it, which is created from the freezing of hygroscopically bounded water, has been suggested. The approach takes into account the physics of the process of towing of this ice in the wood. It reflects for the first time the influence of the fiber saturation point of the separate wood species on the specific heat capacity of frozen wood c during u fsp wood defrosting in hygroscopic diapason and also the influence of the temperature on the u fsp and c. For the calculation of c according to the suggested approach a software program has been prepared, which has been input in the developed by Microsoft calculation environment of Visual Fortran Professional. With the help of the program computations have been made for the determination of c during towing of the mentioned above ice in oak wood with moisture content 0 u u at the temperature range between C and -0 0 C. fsp Keywords: specific heat capacity, ice from hygroscopically bounded water, defrosting of the wood, wood species ВВЕДЕНИЕ При технологических и других инженерных расчетах процессов тепловой и гидро-термической обработки древесных сортиментов необходимо располагать информацией о теплофизических характеристиках древесины и о влиянии многочисленных факторов на них. Важной такой характеристикой является удельная теплоемкость древесины с. Основными факторами, оказывающими влияние на с, являются влагосодержание древесины и агрегатное состояние воды в ней, а также температура. Влияние этих факторов на с охвачено в составленном ранее первым соавтором математическом описании с мерзлой и оттаявшей древесины (Deliiski 1990). Наши дальнейшие исследования показали, что более точное математическое описание с должно отражать еще и влияние микроструктурных особенностей отдельных древесных пород, выражаемое посредством их предела гигроскопичности ufsp (Делийски 2003), а также учитывать влияние температуры на ufsp. Целью настоящей работы является учет влияния температуры на u fsp в математичес-ком описании удельной теплоемкости мерзлой древесины в гигроскопическом диапазоне и вычисление при помощи улучшенного описания с такой древесины во время ее оттаивания. УЧЕТ ВЛИЯНИЯ ТЕМПЕРАТУРЫ НА u fsp В МАТЕМАТИЧЕСКОМ ОПИСАНИИ УДЕЛЬНОЙ ТЕПЛОЕМКОСТИ МЕРЗЛОЙ ДРЕВЕСИНЫ ВО ВРЕМЯ ЕЕ ОТТАИВАНИЯ 224

225 Удельная теплоемкость мерзлой древесины с в гигроскопическом диапазоне представ-ляет собой сумму удельных теплоемкостей самой древесины cw и льда cbw, образовавше-гося в древесине от замерзания адсорбционно связанной воды в ней (Чудинов 1968, Делийски 2003, Dzurenda & Deliiski 2010), т.е. (1) c c w c bw. cbw В (Deliiski 1990, 2003, 2004) выведены следущие уравнения для вычисления в гигроскопическом диапазоне, т.е при влагосодержании древесины u u : для содержащей лед древесины: fsp c w и (2) (3) (4) (5) 526 2,95T 0,0022T 2261u 1976unfw cw Kw, 1 u K w 0,00075 T 271,15 1,06 0,04u, u nfw u 0,12 exp 0,0567 T 271, 15 2 u nfw 0,12 T 271,15 K, c exp 0,0567 T 271,15 u 0,12 4 bw 1, nfw fsp 1 u u u u & T 271,15K, (6) c w для несодержащей лед древесины: 2097u 826 9,92u 2,55 0, T T, 1 u 1 u 1 u (7) c bw T 271, 15 K, где Т температура, K; u влагосодержание древесины, kg.kg -1 ; u влагосодержание древесины на пределе ее гигроскопичности, kg.kg -1 fsp ; u nfw количество незамерзающей воды в древесине при данной температуре, kg.kg -1. Для более точного определения c и c необходимо учесть и зависимость w от температуры. На основе результатов обширных экспериментальных исследований J. F. Siau (1984) предлагает следующее уравнение, которое отражает влияние температуры на влагосодержание несодержащей льда древесины на пределе ee гигроскопичности : u fsp bw ufsp 225

226 20 fsp u u 0,001( T 293,15), fsp (8) 20 где влагосодержание древесины на пределе ее гигроскопичности при 20 0 С, kg.kg - 1. u fsp В литературе отсутствуют сведения о влиянии Т на древесины, которая содержит лед, образовавшийся от замерзания адсорбционно связанной воды в ней. Единственно Б.С.Чудинов (1968) отмечает, что с понижением Т следует ожидать понижение такой древесины, так как та часть гигроскопически связанной воды, u fsp которая замерзает, перестает быть связанной и переходит в свободную. Поскольку уравнение (8) является общепринятым в специализированной литературе и относящимся ко всем древесным породам, то его можно использовать при вычислении удельной теплоемкости несодежащей льда древесины. Из-за отсутствия опубликованных сведений о влиянии Т на содержащей лед древесины, при вычислении удельной теплоемкости льда, образовавшегося от гигроскопи-чески связанной воды в древесине целесообразно использовать значения, которые получаются для соответствующей древесной породы по уравнению (8) u fsp после замещения в нем температуры окончательного оттаивания этого льда T T nfw, которая, как показано ниже, зависит от u. После решения уравнения (4) по отношению к Т получается следующее уравнение для определения температуры T Tnfw, при которой заканчивается оттаивание льда, образовав-шегося в древесине от замерзания гигроскопически связанной воды в ней: u fsp u fsp (9) unfw 0,12 ln ufsp 0,12 T nfw 271,15, 0,0567 На рис. 1 показано вычисленное по уравнению (9) с использованием и уравнений (4) и (8) изменение t T 273,15 дубовой древесины с = 0,29 kg.kg -1 (Dzurenda nfw nfw 20 u fsp & Deliiski 2010) в зависимости от влагосодержания древесины u при условии unfw u. 226

227 0-5 Температура t nfw, 0 C ВОДА ЛЕД ,15 0,2 0,25 0,3 0,35 t nfw Влагосoдeржание u, kg.kg -1 Рис. 1. Изменение в дубовой древесине с = 0,29 kg.kg -1 в зависимости от u На рис. 2 при помощи наклонной линии показано вычисленное по уравнению (8) 20 изменение u несодержащей льда дубовой древесины с = 0,29 kg.kg -1 fsp u fsp в зависимости от t и u при 60 t 0 0 C и 0,15 u ufsp. Горизонтальные линии на этом рисунке, соответствующие различным постоянным значениям u fsp const, пересекают наклонную линию при температурах t nfw, которые получаются по уравнению (9) для показанных в легенде рис. 2 значений влагосодержания u после замещения в (9) условия u. u nfw 20 u fsp Влагосoдeржание u fsp, kg.kg -1 0,35 0,34 ЛЕД ВОДА 0,33 0,32 0, Температура t, 0 C u = 0,15 u = 0,20 u = 0,25 u = 0,30 u = 0,312 kg/kg u fsp Рис. 2. Изменение дубовой дрeвесины с = 0,29 kg.kg -1 в зависимости от t и u 20 u fsp Как видно из рис. 2, получающиеся указанным способом значения u fsp const для содержаей лед древесины уменьшаются с увеличением u, что полностью соответствует отмеченному выше мнению Б.С.Чудинова (1968) о физике рассматриваемого процесса. 227

228 РЕЗУЛЬТАТЫ СИМУЛЯЦИОННЫХ ИССЛЕДОВАНИЙ УДЕЛЬНОЙ ТЕПЛОЕМКОСТИ МЕРЗЛОЙ И ОТТАЯВШЕЙ ДРЕВЕСИНЫ Для вычисления удельной теплоемкости древесины по уравнению (1) с использова-нием уравнениий (2) (9) нами изготовлена программа, которая введена в функциониру-ющей в Windows вычислительной среде Visual Fortran Professional. Программа позволяет вычислять c w и c bw, а также их сумму с при произвольных заданых величинах шагов изме-нения температуры и влагосодержания древесины в диапазонах 60 t 0 0 C и 0 u. u fsp На рис. 3 в качестве примера показано вычисленное при помощи программы изменение удельной теплоемкости дубовой древесины в зависимости от t и u в указанных диапазонах. Этой программой получены также и показанные на рис. 1 и рис. 2 результаты. Известно, что максимальное количество льда от замерзания гигроскопически связанной воды в древесине получается при u u. Как было отмечено выше, исследования Б.С.Чудинова (1968) показали, что оттаивание максимально возможного 0 количества такого льда заканчивается при t 2 C, т.е. при T T nfw 271, 15 K. После замещения этого значения Т в уравнение (8) определено максимальное значение u, при котором находящаяся в древесине вода является только связанной, т.е. в древесине отсутствует свободная вода. Таким образом установлено, что максимально возможное количество связанной воды в дубовой древесине равно u 0,312 kg.kg -1. До этого максимального значения u исследвано изменение с, которое показано на рис. 3. Удельная теплоемкость c, J.kg -1.K Температура t, 0 C fsp fsp u = 0 u = 0,05 u = 0,10 u = 0,15 u = 0,20 u = 0,25 u = 0,30 u = 0,312 kg/kg Рис. 3. Изменение удельной теплоемкости мерзлой и оттаявшей дубовой древесины с u 20 fsp 0,29 kg.kg -1 в зависимости от t и u На рис. 3 видно, что повышение t вызывает экспоненциальное нарастание удельной теплоемкости с содержащей гигроскопический лед и линейное увеличение с несодержащей такого льда древесины для всех исследованных значений u. Увеличение u при данном значении t обуславливает пропорциональное понижение с мерзлой древесины и повышение с оттаявшей древесины. На рисунке видно также, что когда u находится в диапазоне unfw u ufsp температура t t nfr, при которой заканчивается оттаивание льда от гигроскопически связанной воды в древесине, является критической. При этой температуре происходит скачок в сторону 228

229 понижения от достигнутого максимального для данного u значения с к значению с для оттаявшей древесины, так как при t t nfr больше нет льда в древесине. С уменьшением u при u nfw u u fsp скачок зависимостей c( t, u, ufsp ) перемещается к более низким значениям t nfw из-за обстоятельства, что при меньших значениях u полное оттаивание льда от гигроскопически связанной воды в древесине происходит при более низких температурах (Чудинов 1968). На рис. 3 видно, что скачок зависимостей c t, u, u ) для дубовой древесине ( fsp происхо-дит в соответствии с показанной на рис. 1 кривой t nfw ( u), а именно: при t 0 С для kg.kg -1 nfw 37,76 u 0, 15 ; при tnfw 18,93 С для u 0,20 kg.kg -1 ; при t 0 С для kg.kg -1 nfw 9,56 u 0, 25 ; при tnfw 3, 26 С для u 0, 30 kg.kg -1 и при tnfw 2,00 0 С для u 0, 312 kg.kg -1. ЗАКЛЮЧЕНИЕ В настоящей работе предложен метод для вычисления удельной теплоемкости мерзлой древесины, содержащей лед от замерзания гигроскопически связанной воды в ней. Метод учитывает физику процесса оттаивания этого льда в древесине. Он отражает влияние предела гигроскопичности u fsp отдельных древесных пород на удельную теплоемкость древесины во время ее размораживания, а также влияние температуры на u fsp. С изпользованием метода вычислены и графически представлены зависимости удельной теплоемкости для дубовой древесины в диапазонах 60 t 0 0 C и 0 u ufsp. Полученные результаты могут быть использованы в технологических и энергетических расчетах процессов оттаивания мерзлых древесных сортиментов и в модельно базированных системах автоматического управления этими процессами (Deliiski 2004). 229

230 ЛИТЕРАТУРА 1. ДЕЛИЙСКИ, Н., 2003: Моделиране и технологии за пропарване на дървени материали в автоклави. Дисертация за д.т.н., С., ЛТУ; 358 c. 2. ЧУДИНОВ, Б. С., 1968: Теория тепловой обработки древесины. Наука, М.; 255 c. 3. DELIISKI, N., 1990: Mathematische Beschreibung der spezifischen Wärmekapazität des aufgetauten und gefrorenen Holzes. VIII International Symposium Fundamental Research of Wood, Warszawa; DELIISKI, N., 2004: Modeling and automatic control of heat energy consumption required for thermal treatment of logs. Drvna Industria, Volume 55, 4; DZURENDA, L., DELIISKI, N.,: 2010: Tepelné procesy v technológiáh spracovania dreva. Vysokoškolska učebnica, TU-Zvolen; 266 s. 6. SIAU, J. F., 1984: Transport processes in wood, Springer-Verlag, NewYork Streszczenie: Pojemność cieplna zamorożonego drewna dębu podczas rozmrażania. Rozważano możliwość wyliczania pojemności cieplnej c zamarzniętego drewna wraz z lodem, powstałym wskutek zamrażania higroskopijnie związanej wody. Wzięto pod uwagę wpływ punktu nasycenia włókien róznych gatunków oraz temperatury na pojemność cieplną układu drewno-lód. Wykonano specjalne oprogramowanie na bazie Visual Fortran Professional fitmy Microsoft. Wyznaczono pojemności cieplne zamrożonego drewna dębu o wilgotności od zera do punktu nasycenia włókien, w zakresie temperatur od C do -0 0 C Corresponding authors: Nencho Deliiski, Faculty of Forest Industry, University of Forestry, Kliment Ohridski Bd. 10, 1756 Sofia, BULGARIA, [email protected] Ladislav Dzurenda, Faculty of Wood Technology, Technical University of Zvolen, T.G.Masarika 24, Zvolen, SLOVAKIA, [email protected] 230

231 Annals of Warsaw University of Life Sciences SGGW Forestry and Wood Technology No 73, 2011: (Ann. WULS-SGGW, Forestry and Wood Technology 73, 2011) Die Zukunft von Bandsägeanlagen mit Magnetführungen im Sägewerk HANS DIETZ 1) SŁAWOMIR KRZOSEK 2) 1) Institut für Werkzeugmaschinen Universität Stuttgart (IfW) 2) Lehrstuhl für Holzkunde und Holzschutz, Fakultät für Holztechnologie, Warschauer Naturwissenschaftliche Universität SGGW Abstract: Die Zukunft von Bandsägeanlagen mit Magnetführungen im Sägewerk. In dem Referat werden die realisierten Fortschritte beim praktischen Einsatz von Magnetführungen beschrieben und die Möglichkeiten zukünftiger Entwicklungen diskutiert. Es wurde eine 10 Jahre alt Quadrobandsägeanlage modernisiert. In Folge der Modernisierung erhöht man die Schnittgenauigkeit, Sägeblattspannung und Forschubgeschwindigkeit. Schlüsselwörter: Sägewerk, Bandsäge, Scanning, Bogenschnitt, Astigkeit, Ausbeute, Schnittwarentoleranz, Bandsägeführung, Regelung ÜBERBLICK In Forestry and Wood Technology No 71, 2010 wurde eine Methode beschrieben, wie man mit Hilfe geregelter Magnete eine Bandsägeführung realisieren kann. In Verbindung damit wurde auch gezeigt, dass die Belastung des Bandsägestahls durch Biege-Schwell-Belastung auf ca. 60 % reduziert wird, da die Biegebelastung an den bei konventionellen Maschinen eingesetzten Druckführungen vollkommen entfällt. Diese geringere Belastung eröffnet neue Möglichkeiten der Anlagengestaltung, da die geringere Belastung des Sägeblattes im umgekehrten Sinne wiederum eine stärkere Belastung durch Faktoren zulässt, die die Schnittleistung erhöhen. Das sind vorrangig die Sägeblattspannung und die Schnittgeschwindigkeit. Ausgehend von diesen Voraussetzungen wurden an einer ca. 10 Jahre alten Quadro- Bandsägeanlage für Vor- und Nachschnitt der Seitenbretter eine Magnetführung für die Bandsägeblätter 3 und 4 dieser Quadro-Bandsäge eingebaut (Bild 1). Außerdem wurde ohne Einbau weiterer neuer Elemente, allein durch Tuning der vorhandenen Frequenzumformer, erhebliche Veränderungen der Basisdaten der Anlage vorgenommen. 231

232 Bild 1: In einer Quadro-Bandsäge wurden die äußeren Seitenbrettsägen 1 und 2 weiter auf der Basis von Druckführungen für die Sägeblätter betrieben; die Modelsägen 3 und 4 erhielten die neue Magnetführung Typ FBS. KONSTELLATION VOR UMSTELLUNG DER ANLAGE AUF MAGNETFÜHRUNG Die technischen Daten der Anlage vor ihrer Veränderung waren wie folgt: Sägeblattführung mit konventionellen Druckführungen Maximale = reale Vorschubgeschwindigkeit 75 m/min Schnittgeschwindigkeit: 43 m/s Sägeblattspannung 150 N/mm² Einschnitt eines Zopfdurchmessers von 220 mm, 4 m lang zu einem Zentrum von 2x70x140 mit einem Seitenbrett 75 m/min Schnitthöhe im Vorschnitt 170 mm Sägezahnteilung 50 mm Spanraumquerschnitt 494 mm² Spanraumfüllung 50 % KONSTELLATION NACH DER UMSTELLUNG AUF ERHÖHTE SCHNITTLEISTUNG Die technischen Daten der Anlage nach ihrer Veränderung waren wie folgt: Sägeblattführung mit neuen Magnetführungen Typ FBS Maximale = reale Vorschubgeschwindigkeit 105 m/min Schnittgeschwindigkeit: 51 m/s Sägeblattspannung 200 N/mm² Einschnitt eines Zopfdurchmessers von 220 mm, 4 m lang zu einem Zentrum von 2x70x140 mit einem Seitenbrett 105 m/min Schnitthöhe im Vorschnitt 170 mm Sägezahnteilung 50 mm Spanraumquerschnitt 494 mm² Spanraumfüllung 59 % ERGEBNISSE NACH DER UMSTELLUNG AUF ERHÖHTE SCHNITTLEISTUNG Die Sägen 1 und 2 haben im Vor- und Nachschnitt eine geringere Schnitthöhe als die beiden Modelsägen 3 und 4. Das war praktischen Sägewerksbetrieb eine sehr Vergleich mit unerwartetem Ergebnis; denn die Sägen 1 und 2 wiesen im Vergleich mit den Sägen 3 und 4 stets mindestens die doppelte Abweichung von der geraden Schnittbahn auf (Bild 2). Es mussten deshalb keine weiteren Versuche mit gleicher Schnitthöhe gefahren werden. 232

233 Bild 2: Oben ist der Verlauf der Schnittbahn durch das Holz mit FBS-Technologie dargestellt; unten der Verlauf der Schnittbahn durch das Holz mit Druckführung. Die Amplitude der Abweichung des Sägeblattes mit Druckführung ist hier 3 x größer als mit FBS Durch Erhöhung von Sägeblattspannung und Schnittgeschwindigkeit konnte die Vorschubleistung einer ca. 10 Jahre alten Maschine um 40 % gesteigert werden. Wegen der Gegebenheiten der Grundauslegung konnten keine weiteren Steigerungen erzielt werden. Setzen wir jedoch voraus es kann eine neue Situation geschaffen werden, dann kann das Sägeblatt ohne etwas von seiner 8-stündigen Lebensdauer abgeben zu müssen, mit ca. 75 bis 80 m/s Schnittgeschwindigkeit betrieben werden. Das ergibt dann bei gleichen Schnittparametern eine Vorschubgeschwindigkeit von ca. 155 bis 165 m/min. Das ist dann die Vorschubleistung eines hochmodernen Profilierwerkes auf der Basis von Kreissägewerkzeugen. Damit ist bewiesen, dass die Bandsägetechnik mit ihrer ca. 5 % besseren Ausbeute im Vergleich zur Kreissägetechnik ihre frühere wirtschaftliche Überlegenheit wieder erreicht hat. LITERATUR 1. DIETZ H., KRZOSEK S., 2010: Entwicklungstendenzen bei Bandsägeführungen im Sägewerk. Annals of University of Life Sciences - SGGW. Forestry and Wood Technology, No 71, Seite DIETZ H., 2007; Vortrag bei CORMA (Corporation Chilena de la Madera), November 2007; Ausbeuteerhöhung durch bogenfolgendes Spanen. 3. DIETZ H., 2005; Vortrag auf dem 45. Internationalen Winterseminar in Rosenheim Ausbeuteerhöhung durch bogenfolgendes Spanen. 4. DIETZ H., 2004: Mehr Ausbeute durch aktive Bogenbearbeitung; Holzzentralblatt, 130. Jg., Nr. 61, Seite DIETZ H., KRZOSEK S., 2005: Roboquad idealna maszyna dla średniego tartaku. Gazeta Przemysłu Drzewnego, nr 6, str DIETZ H., KRZOSEK S., 2004: Vergleichende Untersuchung der Leistungsfähigkeit und Wirtschaftlichkeit von Band-und Kreissägen im Sägewerk. Annals of Warsaw Agricultural University. Forestry and Wood Technology, No 55, Seite

234 Streszczenie: Perspektywy rozwoju pilarek taśmowych z magnetycznymi prowadnicami w tartaku. W artykule zaprezentowano efekty modernizacji 10 letniego zestawu 4 pilarek taśmowych, polegającej na zamontowaniu magnetycznych prowadnic do dwóch wewnętrznych pił. W porównaniu do sytuacji przed modernizacją, czyli z konwencjonalnymi prowadnicami pił, uzyskano podwyższenie dokładności wymiarowej produkowanej tarcicy oraz zwiększenie prędkości posuwu. Corresponding authors: Hans Dietz, Institut für Werkzeugmaschinen Universität Stuttgart, Holzgartenstraße 17, D Stuttgart, e mail: [email protected] Sławomir Krzosek, Katedra Nauki o Drewnie i Ochrony Drewna, Wydział Technologii Drewna SGGW, ul. Nowoursynowska 159, Warszawa, e mail: [email protected] 234