Performance Evaluation of the Least-Cost Lumber Grade-Mix Solver


  • Urs Buehlmann
  • Xiaoqiu Zuo
  • R. Edward Thomas


Rough mill, least-cost lumber grade-mix, performance evaluation, response surface


The least-cost lumber grade-mix problem is of high economic interest to industry. Finding the minimum grade or grade-mix for a given cutting bill can save a company large sums without incurring additional costs. To academia, the least-cost lumber grade-mix problem is of significance due to its complexity and the difficulty to obtain near optimal or optimal results.

An earlier study used a new statistical approach to solving the least-cost lumber grade-mix problem. A five-factor mixture design was used to create a lumber grade-mix response surface, on which the minimum cost point is determined. However, this model's merit has never been assessed so far. This study compares the performance of the new statistical model with solutions derived from the widely used OPTIGRAMI 2.0 least-cost lumber grade-mix program.

Results revealed that the statistical optimization approach provides better overall solutions for both raw material and total production cost scenarios. For 9 of 10 cutting bills tested, the statistical model found lower-cost solutions compared with those provided by OPTIGRAMI 2.0. The maximum savings found was $70/m3 of raw material (cost savings of 9%) and $105/m3 when processing costs were included (cost savings of 10%). Thus, the new model has the potential to help wood products manufacturers decrease their material and processing costs. This model has been incorporated into ROMI, the USDA Forest Service's rough-mill simulation tool.


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Research Contributions