Veneer Surface Roughness and Compressibility Pertaining to Plywood/LVL Manufacturing. Part II. Optimum Panel Densification

Authors

  • Brad Jianhe Wang
  • Simon Ellis
  • Chunping Dai

Keywords:

Compressibility, compression ratio, contact area, density, dimensional stability, gluebond, laminated veneer lumber (LVL), material recovery, performance, plywood, surface roughness, trembling aspen, veneer

Abstract

In Part I of this series, a novel method was proposed to assess surface roughness/quality and compressibility of wood veneer, and the wood compression theory was revised to include the first stage of "progressive contact." Based on this revised theory, the minimum compression required can be established for achieving adequate contact of veneer-to-veneer (or plate), and true veneer yield displacement can be determined. Owing to the variation of veneer compressibility and random veneer placement in the panel assembly, this study aimed to apply the revised theory to establish the optimum panel densification for performance plywood and laminated veneer lumber (LVL) manufacturing. Using 3.2-mm-thick rotary cut trembling aspen (Populus tremuloides) veneer as an example, the correlation between the contact area and panel compression ratio (CR) was first established in terms of veneer surface roughness. Then, the required aspen panel CR and density were identified for achieving a target 80% contact area of veneer-to-veneer (or plate). Meanwhile, through the compression tests of 30- x 30-mm aspen veneer specimens, within-sheet and between-sheet variations in density, thickness, and compressibility were revealed. Furthermore, based on the frequency distribution of the minimum compression required and yield displacement for aspen veneer, the optimum range of aspen panel densification was identified with a CR ranging from 11.3% to 18.0%. Finally, through the manufacturing of aspen panels, such densification range identified was validated for improved panel quality, material recovery, and dimensional stability while achieving superior panel bending and gluebond performance.

References

Dullien, F. A. 1992. Porous media: Fluid transport and pore structure. 2nd ed. Academic Press, New York, NY.nFaust, T. D., and J. T. Rice. 1986. Effects of veneer surface roughness on the bond quality of southern pine plywood. Forest Prod. J.36(4):57-62.nFaust, T. D., and J. T. Rice. 1987. Effects of a variable glue application rate strategy on bond quality and resin consumption in the manufacture of southern pine plywood. Forest Prod. J.37(7/8):64-70.nNeese, J. L., J. E. Reeb, and J. W. Funck. 2004. Relating traditional surface roughness measures to gluebond quality in plywood. Forest Prod. J.54(1):67-73.nNield, D. A., and A. Bejan. 1998. Convection in porous media. 2nd ed. Springer-Verlag, New York, NY.nWang, B. J., and C. Dai. 2005. Hot-pressing stress graded aspen veneer for laminated veneer lumber (LVL). Holzforschung59(1):10-17.nWang, B. J., X. Zhou, C. Dai, and S. Ellis. 2006a. Air permeability of aspen veneer and glueline: experimentation and implication. Holzforschung60(3):304-312.nWang, B. J., C. Dai, and S. Ellis. 2006b. Veneer surface roughness and compressibility pertaining to plywood/LVL manufacturing. Part I. Experimentation and implication. Wood Fiber Sci. (3):535-545.n

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Published

2007-06-05

Issue

Number 4 / October 2006

Section

Research Contributions

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