A Model to Predict the Density Profile of Particleboard
Keywords:
Particleboard, density profile, simulation modelingAbstract
Certain mechanical properties of particleboard panels depend on the density variations that occur through the panel thickness (density profile). Particleboard density profiles result from the felting and hot pressing operations. Repeatedly altering a commercial particleboard manufacturing process to produce a predetermined density profile is undesirable from economic and production standpoints. An analytical tool to predict density profile as a function of the manufacturing processes was needed. Computer simulation modeling was employed to satisfy this need. A multilayer description of the density and moisture gradients resulting from the felting process provides input for this model. Inputs for the pressing process include platen temperature and press closing rate.
The model simulates the physical and mechanical processes that occur in the press and mat system. Heat conduction, gas transport, layer compaction, and water phase changes were included in the model. Thermal properties were taken from the literature, and gas transport properties required approximation.
A steeper density gradient with increasing platen temperature was predicted by the model. This result conforms to general expectations. Changes in press closing rates resulted in model-predicted density profiles that contradict the expected pattern. The probable reason for this effect is that the core layers remained at or near the ambient temperature, and the maximum mat resistance increased as closing rate increased. Simulation of an initially uneven moisture gradient resulted in increased heat penetration, as expected.
References
Engels, K. 1978. Latest European developments in blending. In T. Maloney, ed. Proceedings of Washington State University International Symposium on Particleboard, April 4-6, 1978. Washington State University, Pullman, WA.nHarpole, G. H. 1979. Economic models for structural flakeboard production. Forest Prod. J. 29(12):26-28.nKieser, J., and E. F. Steck. 1978. The influence of flake orientation on MOR and MOE of strandboards. In T. Maloney, ed. Proceedings of Washington State University International Symposium on Particleboard, April 4-6, 1978. Washington State University, Pullman, WA.nLaufenberg, T. L. 1984. Measurement of reconstituted wood products using gamma radiation. Presented at the Technical Forum of the 38th Annual FPRS International Meeting. June 24-28, 1984. St. Louis, MO.nLaufenberg, T. L. 1986. Using gamma radiation to measure density gradients in reconstituted wood products. Forest Prod. J. 36(2):59-62.nLewis, W. C. 1967. Thermal conductivity of wood-base fiber and particle panel materials. U.S. Forest Serv., Forest Prod. Lab., Res. Rep. FPL 77.nMcCarthy, E. T., and C. E. Steffens. 1980. Non-contact on-line precision thickness measurements offer new profitability. In T. Maloney, ed. Proceedings of Washington State University International Symposium on Particleboard, April 2-5, 1980. Washington State University, Pullman, WA.nMcMillin, C. W. 1969. Specific heat of some ovendry loblolly pine wood. Wood Science 2:52-53.nNearn, W. T., and K. Bassett. 1968. X-ray determination and use of surface-to-surface density profile in fiberboard. Forest Prod. J. 18(1):73-74.nPlumb, O. A., P. C. Malte, and R. W. Cox. 1980. A numerical study of optimum operating conditions for convective wood particle dryers. In T. Maloney, ed. Proceedings of Washington State University International Symposium on Particleboard, April 2-5, 1980. Washington State University, Pullman, WA.nShen, K. C., and M. N. Carroll. 1969. A new method for evaluation of internal strength of particleboard. Forest Prod. J. 19(8):17-21.nShen, K. C., and M. N. Carroll. 1970. Measurement of layer-strength distribution in particleboard. Forest Prod. J. 20(6):53-55.nSiau, J. 1971. Flow in wood. Syracuse, New York, Syracuse Press. 131 pp.nSmith, D. 1980. Consideration in press design for structural boards. In T. Maloney, ed. Proceedings of Washington State University International Symposium on Particleboard, April 2-5, 1980. Washington State University, Pullman, WA.nSteiner, P. R., S. Chow, and D. Nguyen. 1978. Improving mill waferboard properties by x-ray-densitometer evaluation methods. Forest Prod. J. 28(12):51-55.nStlvens, R. R. 1978. Slicing apparatus aids in determination of layer-density of particleboard. Forest Prod. J. 28(9):51-52.nStrickler, M. D. 1959. Properties of Douglas-fir flakeboard. Forest Prod. J. 9(7):203-214.nSuchsland, O. 1967. Behavior of a particleboard mat during the press cycle. Forest Prod. J. 17(2):51-57.n
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