Based on extensive results from laboratory and mill studies, this report focuses on the characterization of green veneer moisture content (MC) and development of a mathematical model for green veneer MC variation, establishment of the optimum clipping width and Forintek’s improved green veneer sorting method for common softwood and hardwood species. Further, the economic benefits of improved green veneer clipping and sorting were analyzed. Finally, a computer simulation program, VSort, was developed to assist mills in performing optimum green veneer clipping and sorting.
The key results show that:
the MC distribution appeared to be a dual-peak pattern for common softwood and hardwood species: one for heartwood veneer and the other for sapwood veneer, characterized by means and standard deviations of the two normal distributions. The position of the first peak (heartwood) was more consistent whereas the second peak (sapwood) varied more among logs;
the green veneer clipping should be based on the green veneer sorts with each of them having a target clipping width, which can be determined based on the shrinkage measurement of sapwood and heartwood of each species and the minimum allowable clipping width in the mill;
the green veneer sorting should be based on peak veneer MC and the size of wet spots on each veneer sheet instead of average veneer MC used currently in the mill;
with improved clipping strategy, veneer recovery can be improved by 1.0 to 2.0%, which can translate to an annual savings varying from $200,000 to $400,000 per mill;
with improved green veneer sorting strategy using Forintek’s new light transmission method, veneer drying productivity can be improved by 4.0 to 8.0% for green Douglas-fir veneer. The improvement in drying productivity also depends on the species and mill situation. Further, the improved veneer sorting helps significantly reduce the amount of overdried veneer. The improved green veneer sorting will translate to an annual savings varying from $400,000 to $800,000 per mill;
the VSort model can successfully characterize the MC distribution for common softwood and hardwood species and the relationship between peak veneer MC and average veneer MC in terms of clipping width. It can also assist mills perform optimum green veneer clipping, and establish the optimum cut-off MC levels of each sort for improved veneer drying and reduced energy consumption.