Sensitivity Analysis of Internal Mat Environment during Hot-Pressing
Keywords:
Wood composite, hot-pressing, modeling, flakeboard, simulationAbstract
The effect of several hot-pressing parameters on the internal mat environment was investigated by using a hot-pressing simulation model. The results were compared to experimental data from laboratory-produced flakeboard. The pressing parameters included initial mat moisture content, final panel density, press platen temperature, and press closing time. The variation of temperature and total gas pressure during the press cycle at six points in the vertical mid-plane of a single layer, random mat structure was predicted with the heat and mass transfer model using the different pressing conditions. Twenty-four boards were manufactured according to the same specifications, and the temperature and internal gas pressure were measured with thermocouples and gas pressure probes at the same six locations. The model consistently predicted the major trends during the hot-pressing operation.
The hot-pressing simulation model used in this study was developed based on fundamental engineering principles. The material physical and transport properties were the best available values from the literature or best estimates based on engineering judgment. A sensitivity study assessed the relative importance of the different transport properties during the hot-pressing process. The sensitivity analysis of the model parameters revealed that the thermal conductivity and gas permeability of the mat have the greatest influence on model results. The assessment of these transport properties experimentally, as a function of mat structure, is highly desirable and can considerably improve future model predictions.
References
Bhagwat, S. 1971. Physical and mechanical variations in cottonwood and hickory flakeboards made from flakes of three sizes. Forest Prod. J.21 (9): 101-103.nBrumbaugh, J. 1960. Effect of flake dimension on properties of particleboard. Forest Prod. J.(5):243-246.nDai, C., B. Knudson, and R. Wellwood. 2000. Research and development in oriented strandboard (OSB) processing. Proc. 5th Pacific Rim Bio-Based Composites, December 10-13, 2000, Canberra, Australia, Pp. 556-563.nGeimer, R. L., H. M. Montrey, and W. F. Lehman. 1975. Effects of layer characteristics on properties of threelayer particleboard. Forest Prod. J.25(3): 19-29.nGeimer, R. L., J. W. Evans, and D. Setiabudi. 1999. Flake furnish characterization: Modeling board properties with geometric descriptors. USDA For. Serv. Res. Paper FPL-RP-577. USDA For. Prod. Lab., Madison, WI.nHeebink, B. G., and R. A. Hann. 1959. How wax and particle shape affect the stability strength of oak particle boards. Forest Prod. J.9(7): 197-203.nHoglund, H., U. Sholin, and G. Tistad. 1976. Physical properties of wood in relation to chip refining. Tappi59(6): 144-147.nKamke, F. A., and L. J. Casey. 1988a. Gas pressure and temperature in the mat during flakeboard manufacture. Forest Prod. J.38(3):41-43.nKamke, F. A., and L. J. Casey. 1988b. Fundamentals of flakeboard manufacture: internal mat conditions. Forest Prod. J.38(6):38-44.nKelley, M. W. 1977. Critical literature review of relationships between processing parameters and physical properties of particleboard. USDA. Forest Serv., For. Prod. Lab., Gen. Tech. Rep. FPL-10.nMaku, T., R. Hamada, and H. Sasaki. 1959. Studies on the particleboard. Report 4: Temperature and moisture distribution in particleboard during hot-pressing. Wood Research, Kyoto University Report 434-46.nSchajer, G. S., M. A. Stanish, and F. Kayihan. 1984. A computationally efficient approach to drying of hygroscopic and non-hygroscopic porous materials. Proc. ASME Annual Meeting, 84-WA/HT-13, New Orleans, LA.nSharma, V., and A. Sharon. 1993. Optimal orientation of flakes in oriented strandboard (OSB). Exp. Mech.32(2): 91-98.nSiau, J. F. 1995. Wood: Influence of moisture on physical properties. Department of Wood Science and Forest Products, Virginia Polytechnic Institute and State University, Blacksburg, VA.nSmith, D. C. 1982. Waferboard press closing strategies. Forest Prod. J.32(3):40-45.nStrickler, M. D. 1959. Effects of press cycle and moisture content on properties of Douglas-fir flakeboard. Forest Prod. J.9(7):203-215.nWang, K., and F. Lam. 1999. Quadriatic RSM models of processing parameters for three-layer oriented flakeboards. Wood Fiber Sci.31(2): 173-186.nWang, S., and P. M. Winistorfer. 2000a. Consolidation of flakeboard mats under theoretical laboratory pressing and simulated industrial pressing. Wood Fiber Sci.32(4): 527-538.nWang, S., and P. M. Winistorfer. 2000b. Fundamentals of vertical density profile formation in wood composites. Part II. Methodology of vertical density formation under dynamic conditions. Wood Fiber Sci.32(2):220-238.nWinistorfer, P. M., and D. Dicarlo. 1988. Furnish moisture content, resin nonvolatile content, and assembly time effects on properties of mixed hardwood strandboard. Forest Prod. J.38(11/12):57-62.nZombori, B. G. 2001. Modeling the transient effects during the hot-pressing of wood-based composites. Ph.D. Dissertation, Virginia Polytechnic Institute and State University, Blacksburg, VA.nZombori, B. G., F. A. Kamke, and L. T. Watson. 2001. Simulation of the mat formation process. Wood Fiber Sci.33(4): 564-580.nZombori, B. G., F. A. Kamke, and L. T. Watson. 2002. Simulation of the internal mat conditions during the hot-pressing process. Wood Fiber Sci.35(1):2-23.n
Downloads
Published
Issue
Section
License
The copyright of an article published in Wood and Fiber Science is transferred to the Society of Wood Science and Technology (for U. S. Government employees: to the extent transferable), effective if and when the article is accepted for publication. This transfer grants the Society of Wood Science and Technology permission to republish all or any part of the article in any form, e.g., reprints for sale, microfiche, proceedings, etc. However, the authors reserve the following as set forth in the Copyright Law:
1. All proprietary rights other than copyright, such as patent rights.
2. The right to grant or refuse permission to third parties to republish all or part of the article or translations thereof. In the case of whole articles, such third parties must obtain Society of Wood Science and Technology written permission as well. However, the Society may grant rights with respect to Journal issues as a whole.
3. The right to use all or part of this article in future works of their own, such as lectures, press releases, reviews, text books, or reprint books.
