Determina)on of MDF fiber size distribu)on: Requirements and innova)ve solu)on

Transcription

1 Determina)on of MDF fiber size distribu)on: Requirements and innova)ve solu)on Benthien JT, Hasener J, Pieper O, Tackmann O, Bähnisch C, Heldner S, Ohlmeyer M Interna=onal Wood Composites Symposium 2013, April 03-04, 2013, SeaHle Abstract For all wood par=cle- based composite panels, par=cle size distribu=on and morphology are classified as crucial factors for the industrial produc=on process and the resul=ng product proper=es. Currently, par=cle size measurement of fibers for MDF produc=on is s=ll just done by skilled personnel (hap=c and visual), based on fiber mat density and an evalua=ng comparison of the actual produced MDF surface with samples of target quality. Such approaches seem to be limited in reproducibility and not op=mal for process control. Due to the large spectrum of par=cle size and the need of fiber separa=on for its determina=on, available fiber dimension detec=ng systems, e.g., from pulp and paper industry, cannot be applied adequately for the characteriza=on of MDF fibers. To determine the requirements of MDF manufacturers regarding fiber quality management, a survey was realized. All major companies worldwide were asked about their opinion on the effect of fiber size on panel quality and economic efficiency, as well as their demand regarding fiber size measurement. These results will be discussed in this conference contribu=on. Furthermore, the current state of an image analyzing based approach to measure the dimensions of dry- applied fibers will be presented. The system s efficiency will be shown in detail. Based on the characteris=cs of each individually analyzed par=cle, property profiles of three differently defibrated MDF fibers will be presented.

2 Determina)on of MDF fiber size distribu)on: Requirements and innova=ve solu=on J. Benthien, J. Hasener, O. Pieper, O. Tackmann, C. Bähnisch, S. Heldner, M. Ohlmeyer Thünen Ins=tute of Wood Research Sea>le, April April Int Wood Comp Sym 2013

3 About the Thünen Ins)tute scien=fic policy advice Federal Ministry of Food, Agriculture and Consumer Protec=on Rural Areas Organic Farming Market Analysis Agricultural Technology Forestry Forest Ecosystems Forest Economics Wood Research Fisheries Fisheries Ecology Sea Fisheries Bal=c Sea Fisheries University of Hamburg Department of Wood Science THÜNEN Ins=tute of Wood Research Slide 3

4 1. Fiber quality survey Mo=va=on and Results O. Pieper, O. Tackmann, M. Ohlmeyer Thünen Ins=tute of Wood Research Sea>le, April April Int Wood Comp Sym 2013

5 Fiber quality survey Aim Relevance of fiber quality for MDF produc=on? State of the art in quality control? Approach Worldwide survey in 2011 Response rate 300 ques=onnaires Response rate 10% n = 29 Europe America Asia Australia Africa Slide 5

6 Which type of fiberboard do you produce? 100% 75% 50% 25% 0% Furniture grade Molding/ 3D surface Direct prin=ng Flooring Pigmented MDF Others Slide 6

7 Fiber quality survey 100% 75% Q: Is fiber quality a crucial factor in your process? A: Yes (90%) Q: Do you asses fiber quality for QC? A: Yes (90%) 50% 25% 0% Yes Slide 7

8 Which method is applied to evaluate fiber quality? 100% 75% 50% 25% 0% Hap=cal and visual evalua=on by operator Various sieving methods Op=cal evalua=on by instrument Pulmac shive analyzer Bulk density aler mat forming Slide 8

9 Which board proper)es are affected by fiber quality? 100% 75% 50% 25% 0% Internal bond Thickness swelling Other Direct prin=ng or lacquering quality Moulding quality Coa=ng quality Surface soundness Physical and mechanical proper=es Surface quality Slide 9

10 How is the fiber quality adjusted during produc)on? 100% 75% 50% 25% 0% Slide 10

11 How does the fines content affect the process? 75% 50% posi=ve neutral nega=ve 25% 0% Note The fines content was mostly classified to affect the process nega=vely Slide 11

12 How does the fiber content affect the process? 75% 50% posi=ve neutral nega=ve 25% 0% Note The fibers content was nearly always classified to have a posi=ve or no effect on the process. Slide 12

13 How do shives affect the process? 75% 50% posi=ve neutral nega=ve 25% 0% Note Beside some clear cases, the effect of shives was classified to be nega=ve and posi=ve on the process at the same =me. Slide 13

14 Fiber quality survey Summary Fiber quality is of worldwide interest for MDF produc=on MDF proper=es are affected by fiber quality In prac=ce, fiber quality is adjusted by various process parameters Fibers are the most wanted structures The acceptable amount of fines and shives depends on the intended MDF type Conclusion A measuring device is needed, which allows an individual characteriza=on of MDF fibers for process control Slide 14

15 2. MDF fiber characteriza)on Opera=on principals and test results J. Benthien, J. Hasener, S. Heldner, C. Bähnisch, M. Ohlmeyer Thünen Ins=tute of Wood Research Sea>le, Benthien et al. 03. A pril April 2013 Int Wood Comp Sym 2013

16 Limita)ons of currently available fiber analyzers Problem MDF fiber composi=on spreads from small dust par=cles up to several cen=meter- sized fiber bundles Current limita)ons Low sample size; fiber bundles may block the system Sieve analysis capture fiber width only Limited reproducibility Solu)on Image analyzing system, based on dry- separated fibers Developed by the Thünen Ins=tute and Grecon Slide 16

17 Opera)on Principal by D. Schmidt Slide 17

18 Measuring Device 0.5 g fibers 82 images per minute Image size: 93 x 62 mm Pixel size 23.2 µm 1094 dpi (ppi) 8 minutes per run 650 images per run 250,000 fibers per run 3 replica=ons per fiber Benthien et al. Slide April 2013 Int Wood Comp Sym 2013

19 Image analysis (3) (1) and (2) (1) Gray scale image Processed image Image processing Flow line tracing (1) and separa=on of overlapping fiber (2) Image moment method (3) Special treatment, if (1) and (3) are not applicable Slide 19

20 Fiber material Fiber A High temperature/ long =me 16 bar (200 C)/ 8 min Fiber B Standard 8 bar (170 C)/ 4 min Fiber C Low temperature/ short =me 4 bar (143 C)/ 1 min Benthien et al. Slide April 2013 Int Wood Comp Sym 2013

21 Rela)ve frequency 100% 75% 50% 0-1 mm 1-3 mm 3-6 mm >6 mm 25% 0% Fiber A 16 bar/ 8 min Fiber B 8 bar/ 4 min Fiber C 4 bar/ 1 min Seite 21

22 Double length- weighted rela)ve frequency 2% Fiber A Fiber B Fiber C 1% 0% Fiber length (mm) Seite 22

23 Double length- weighted rela)ve frequency 100% 75% 50% 0-1 mm 1-3 mm 3-6 mm >6 mm 25% 0% Fiber A 16 bar/ 8 min Fiber B 8 bar/ 4 min Fiber C 4 bar/ 1 min Seite 23

24 Characteris)c values Fiber A B C Cooking condi)ons 16 bar/ 8 min 8 bar/ 4 min 4 bar/ 1 min 0-1 mm 10.3% 7.4% 7.9% Double length- weighted rela=ve frequency 0-3 mm 59.0% 53.9% 46.7% 3-6 mm 27.5% 33.7% 35.7% > 6 mm 3.2% 5.1% 9.6% Double length- weighted fiber length 2.6 mm 2.9 mm 3.3 mm Longest detected fiber 16.3 mm 18.4 mm 32.8 mm Seite 24

25 Data treatment Line chart 655 length classes (width: 0.05 mm) Weigh=ng number of fibers two =mes by the fiber length average of each length class (n*l 2 ) Calcula=on of the (double length- weighted) rela=ve frequency Characteris)c values and bar chart 4 length classes (width: 0-1 mm; 1-3 mm; 3-6 mm; >6 mm) Further procedure like for graph pain=ng Double length- weighted fiber length Data from characteris=c value calcula=on L w = n*l 3 / n*l 2 Slide 25

26 Conclusion and outlook Conclusion A new approach for MDF fiber characteriza=on is needed The presented measuring device fulfills the requirements for MDF fiber characteriza=on The effect of varying cooking temperature and =me on the fiber quality was shown Outlook Characteriza=on of differently manufactured MDF fibers (Grinding gap distance, wood specie, ) Correla=on of fiber characteris=cs and fiberboard proper=es Slide 26

27 Acknowledgement Co- authors ins)tu)ons and companies Fagus- GreCon Greten GmbH & Co. KG (Grecon), Dr. Jörg Hasener University of Hamburg (UHH), The Cogni=ve Systems Laboratory (KOGS), Chris=an Bähnisch Department of Wood Science, Mechanical Wood Technology, Olaf Tackmann Further project partners, Clemens Seidl Sonae- Industria SGPS S.A. c/o Glunz AG, Dr. Alfred Pfemeter Ins=tut für Holztechnologie Dresden ggmbh (IHD), Dr. Detlef Krug, Christoph Wenderdel Kind support from colleagues Chris=na Waitkus, Thünen Ins=tute, Scien=fic Informa=on Centre Doerthe Schmidt, Thünen Ins=tute for World Forestry Slide 27

28 Thanks for your kind a>en)on! Sea>le, April April Int Wood Comp Sym 2013 Jan T. Benthien Thünen Ins=tute of Wood Research Leuschnerstr. 91c Hamburg Germany Phone Fax