ADVANCED ENGINEERING 1 st Year (2007) Volume 2 STRENGTH TESTING OF CORRUGATED TRANSPORT BOX IN DEPENDENCE OF MATERIAL AND CONSTRUCTION Lajić, B.; Babić, D. & Jurečić, D. Abstract: The purpose of this research was estimating the strength of the holand type boxes for packaging the fruit and vegetables, depending on the quality of the corrugated board from which the boxes were made, as well as of the construction of the box. To get as most as possible objective results, tested corrugated board was the corrugated board from which the boxes were made. Keywords: corugated board, construction of the box, holand type boxes, strength 1 INTRODUCTION All tests were carried out in accordance with prescribed standards for each type of testing at controlled atmosphere conditions. After the results were elaborated, the materials which do satisfy the quality requirements were included in further production, but the materials which did not satisfy the quality were discarded from further production. The boxes were made in two different construction type. Box cnstruction type A was formed by inserting, and construction type B was formed by glueing. All boxes were tested by standard method of box resistance to vertical pressure. The boxes of type A were made of two different quality five-layer corrugated board, and the boxes of type B were made also of two different quality five-layer corrugated board. 2 PROBLEM FORMULATION This work elaborates packaging of fruit and vegetables in corrugated board holand type boxes. Holand type boxes are open holders for fruit and vegetables which can be made of small wood boards, plastic and corrugated cardboard. The main characteristics of corrugated board holand type boxes are following: - greather attractiveness because of possibility of quality printing, - small weight, - the empty box is possible to transport in box blanx (if on the site the machine for glueing of the boxes is present) - easy process of impregnation, - low manufacturing expenses, - the possibility of manufacturing from recycling material, - good protection from contamination. - The insufficiencies of this box are following: - smaller ventilation than in small wood boards boxes, 199
- smaller strength than small wood boards boxes or plastic boxes (this insufficiency can be solved with edge fasteners) - this type of box is very sensitive to the humidity (this insufficiency can be solved by impregnation with water-tight mediums). The way from the producer of fruit and vegetables to final destination can be very long, and during transport various influences which can adversely affect this products are present. Because of that, fresh fruit and vegetables shall be protected with suitable packaging from mechanical damage, possible microbiological pollution, attack of insects, chemical influences, etc. Packaging intended for fresh fruit and vegetables shall be, before all, resistent to humidity and pressure. The most frequent way of transport of fresh fruit and vegetables is lorry-transport during which various loading of the packaging can appear. Because of vibrations of the vehicle and centrifugal force in the turns of the roads the box construction must ensure that the wares reach the consumer without damages. Before all, the boxes shall be resistent to pressure and squeezing, to which the lowerest boxes on the pallet are most exposed. To save the space, storage of the fruits in cold storage plants demands stacking of the boxes with fruits very high, one up on an other. The same problem appears by transport to great distances with the ship, train, or by the lorry, where controlled atmosphere contition with low temperature and increased relative humidity of the air are present, as well as smaller or greather vibration of the boxes. Moving of the boxes during transport is prevented because the boxes seat one up on an other very stable. Namely, the bulgings on the upper parts of the lower boxes enter in the recesses on the lower parts of the upper boxes. The streaming of the air and moisture is enabled on the openings on the bottoms of the boxes (Figure 1). 200 Fig. 1. Box blank of holand type box From above we can conclude that the gretest loadings appear during transport. Because of that, the box construction shall sustain all this loadings.
Fig. 2. The example of stacking packaged fruit and vegetables in cold storage plant Main characteristics which shall haveholand type boxes made from corrugated cardboard are following: - good resistance to pressure load, - good resistance to moisture, - maximal number of air openings, but this openings must not decrease mechanical properties of the box essentially, - the possibility of easy transport (non-formed box blanx), - easy handling, - dimensions adjusted to the fruits, - dimensions adjusted to stacking on euro-pallets, - non-toxic material, The purpose of this research was estimating the strength of the holand type boxes for packaging the fruit and vegetables, depending on the quality of the corrugated board from which the boxes were made, as well as of the construction of the box. To get as most as possible objective results, tested corrugated board was the corrugated board from which the boxes were made. All tests were carried out in accordance with prescribed standards for each type of testing at controlled atmosphere conditions. After the results were elaborated, the materials which do satisfy the quality requirements were included in further production, but the materials which did not satisfy the quality were discarded from further production. The boxes were made in two different construction type. Box cnstruction type A was formed by inserting, and construction type B was formed by glueing. All boxes were tested by standard method of box resistance to vertical pressure. The boxes of type A were made of two different quality five-layer corrugated board, and the boxes of type B were made also of two different quality five-layer corrugated board. 201
3 EXPERIMENTAL 3.1 Testing of corrugated cardboard testing of humidity in the corrugated cardboard, in accordance with the standard HRN H. N8.206, or the standard ISO 287 testing of the thickness of the corrugated cardboard, in accordance with the standard ISO 534 testing of the grammage of the corrugated cardboard, in accordance with the standard HRN H. N8.225, or the standard ISO 536 bursting test of the corrugated cardboard according to Mullen, in accordance with the standard HRN H. N8.211, or the standard ISO 2759 testing the resistance of the corrugated cardboard to the dynamic puncture, in accordance with the standard HRN H. N8.208 testing of the corrugated cardboard edge to compression (ECT;Edge Crush Test), in accordance with the standard ISO 3037 3.2 Testing of the boxes from corrugated cardbord testing the resistance ot the corrugated cardboard box to the compression (BCT; Box Commpression Test), in accordance with the standard ISO 12048 The construction of glued holand type box shall satisfy the demands of the glueing machine on the place of glueing (field or sorting plant). The testing models are strictly defined, which dimensions can differ in allowable tolerances only.beause there are a lot of different models, this work elaborates most present model on the market, represented as type B. The box is glued in eight points, and can not be flattened or disconnected any more. Because of that, the boxes are formed on the machine wich is placed very near to place of package, and this can be the field or sorting plant (for example, cold storage plant) only. Fig. 3. Holand type box B Fig. 4. Holand type box A formed by glueing formed by insertion Folding holand type boxes are more simple and convenient for use at smallet farms, where the purchase of glueing machine is not profitable. The dimensions of the box blanx for the same dimensions of the boxes formed by glueing or by insertion, are not the same. Folding holand type box formed by insertion is constructed on the way which enable to be formed manually very simply in a short time period. In distinction from glueing holand type boxes, folding type holand box can be decomposed in the 202
box blank after use easily, wich relieves the transport to the used paper recycling plant. Holand type box formed by insertion demands more human work at the forming, but there is not expenditure of the glue, which is at glueing type box significant. At forming of the boxes formed by insertion, the insertion tongues can be damaged, which makes the box useless. Because of that, we shall be very careful not to damage insertion tongues at forming of the boxes. Lateral tongues and lateral openings serve to fix the boxes at stacking the boxes one up on an other. 3.3 Testing of corrugated board types Five-layer corrugated board 2KŠ quality is made from 2 layers of testliner 140 g/m 2 as flat layers from front and back side of the corrugated board, from šrenac 120g/m 2 as medium flat layer, as well as from 2 waved layers of fluting 112 g/m 2. Five-layer corrugated board K2Š quality is made testliner 140 g/m 2 as flat layer from front side of the corrugated board, from 2 flat layers of šrenac 120g/m 2 as back side and as medium flat layer, as well as from 2 waved layers of fluting 112 g/m 2. 3.4 Types of tested boxes from corrugated bord In this research the basic division of holand type boxes for packaging of the fruit and vegetables was according to the box construction: - folded type boxes type A, boxes formed by insertion, - glued type boxes- type B, boxes formed by glueing Boxes type A-2KŠ holand type boxes for packaging of the fruit and vegetables made from five-layer corrugated board 2KŠ quality, formed by insertion Boxes type A-K2Š holand type boxes for packaging of the fruit and vegetables made from five-layer corrugated board K2Š quality, formed by insertion Boxes type B-2KŠ holand type boxes for packaging of the fruit and vegetables made from five-layer corrugated board 2KŠ quality, formed by glueing Boxes type B-K2Š holand type boxes for packaging of the fruit and vegetables made from five-layer corrugated board K2Š quality, formed by glueing 3.5 The devices used at testing of coruugated cardboard Fig. 5. Device for testing of humidity of corrugated cardboard Fig. 6. Device for testing of thickness of corrugated cardboard 203
Fig. 7. Digital scales for gramage testing Fig. 8. Device for bursting test according to Mullen Fig. 9. Device for testing dinamic puncture Fig. 10. Crush tester 3.6 The devices used at testing of coruugated cardboard boxes Fig. 11. Box compresion tester 204
4 RESULTS AND DISCUSION 4.1 Results of testing of corrugated cardbox Type of corrugated board Grammage [g/m 2 ] Thickness [mm] Dynamic Puncture [J] Mullen [ kpa] ECT [N/m -1 ] x σ x σ x σ x σ x σ 2KŠ 741,7 19,0 6,5 0,12 6,5 0,4 1068 96,3 7593 759,9 K2Š 737,2 11,7 6,6 0,13 6,48 0,4 986 88,79 6688 394,7 Tab. 1. Medium value, standard deviation, grammage, thickness, PT- test, Mullen-test and Ecttest for all kinds of corrugated boards for production od holand type boxes Here shall also be remarked that the materials which did not satisfy the quality requirements were discarded from further production of holand type boxes. Materials ECT [ J/m 2 ] PT [J] Mullen [kpa] Površinska masa 2KŠ 7593 6,5 1068 741,7 K2Š 6688 6,48 968 737,2 relation 12% 0,4% 9% 0,7% Tab. 2. Medium values results of ECT test, PT test, Mullen test and area mass test of corrugated board 2KŠ quality relating to corrugated board K2Š quality 4.2 Results of testing of the boxes made from corrugated cardboard x N x def. u mm x def. u % 2KŠ 2151,7 11,13 6,54 K2Š 1808,3 8,72 5,17 16% 22% 21% Tab. 3. Relations of BCT test medium values and during testing originated deformations (shown in milimeters and percents) for corrugated board quality 2KŠ boxes formed by inserting, and of the same type boxes made of corrugated board quality K2Š x N x def. u mm x def. u % 2KŠ 2793,3 8,55 4,94 K2Š 2492,7 8,40 4,85 11% 2% 2% Tab. 4. Relations of BCT test medium values and during testing originated deformations (shown in milimeters and percents) for corrugated board quality 2KŠ boxes formed by glueing, and of the same type boxes made of corrugated board quality K2Š. If the demands for box resistance to dynamic puncture are most important, regardless to the box price, we will choose five layer 2KŠ quality corrugated board box firstly, regardless to the box type. After this box follows five layer K2Š quality corrugated board box. - 2KŠ quality box is for 0,4% more resistant to dynamic puncture than K2Š quality box - 2KŠ quality box is for 7% more expensive than K2Š quality box. 205
TESTING TYPE MATERIAL QUALITY TYPE 2KŠ K2Š Thickness [mm] 6,47 6,57 Grammage [g/m 2 ] 741,74 737,24 Mullen [kpa] 1068 968 PT [J] 6,5 6,48 ECT [J/m 2 ] 7593 6688 BCT za konstr. A [N] 2151,7 1808,3 Deformation in mm 11,13 8,72 Deformation in % 6,54 5,17 BCT for constr. B[N] 2793,3 2492,7 Deformation in mm 8,55 8,4 Deformation in % 4,94 4,85 Price for box blank type A 2,77 2,58 Price for box blank type B 4,50 4,19 Tab. 5. Relations between corrrugated board characteristics, mechanical characteristics of the boxes type A and type B made of this corrugated boards with belonging box prices If the demands for box resistance to the pressure are most important, than the choice could be following: Most resistant is 2KŠ quality box type B, then K2Š quality box type B, hereafter 2KŠ quality box type A, and finaly K2Š quality box type A. 2KŠ quality box type B has the strength for 11% greather than K2Š quality box and for 23% greather strength from 2KŠ quality box type A, as well as for 35% greather strength from K2Š quality box type A. Regarding to the prices the relations are following: The box blank of the 2KŠ quality type B is for 7% more expensive than box blank of K2Š quality type B, for 38% more expensive than box blank of 2KŠ quality type A, and for 43% more expensive than box blank of K2Š quality type A. 5 CONCLUSION The quality of corrugated board determines also the qualityof the transportable holand type box for packaging the fruit and vegetables. When in the consideration is included the construction of the box type, regarding folded boxes (type A) and glued boxes (type B), it is possible to estimate exactly the influence of the construction to the strength, regardless to the material quality. References: [1] Hanlon, J. F.; Kelsey, R. J. & Forcinio, H. E. (1998). Handbook of Package Engineering (3 rd edition), CRS Press, ISBN 1-56676-306-1, London [2] Mark, R. E. (1993). Handbook of Physical and Mechanical Testing of Paper and Paperboard, Marcel Dekker, INC., ISBN 0-8247-1871-2, New York [3] Niskanen, K. (1998). Paper Physics, Book 16, Fapet Oy, ISBN 952-5216-16-0, Helsinki Author: Ph.D. Lajić Branka, Ph.D. Darko Babić, M.Sc. Jurečić Denis, Faculty of Graphic Arts, Department for projecting, packaging and printing finishing, Getaldićeva 2, Zagreb, Croatia, phone: +385 1 237 1080, fax: +385 1 2371 077, e-mail: denis@grf.hr 206