RIP-X: decision software to compare crosscut-first and rip-first rough mill systems

RIP-X is software which was developed to simulate the rough mill cutup of lumber. It determines the yields of the current and least-cost grade mixes for both the crosscut-first system and the rip-first system. A statistical comparison of the crosscut-first and rip-first current yields is made. The least-cost grade mix is determined by a linear programming model incorporated into the software. Validation of the RIP-X linear programming model was performed by comparing its results to results from an existing model. When the parts' lengths were restricted to the existing model's constraints, the RIP-X results did not differ significantly from the existing model's results. Comparison of current available model results with the unrestricted RIP-X model, indicated that previous models have provided sub-optimal solutions because of maximum parts' length restrictions in some lumber grades. Field tests were conducted to determine the accuracy of the crosscut-first and rip-first simulations in rough mills. The yield estimates from the crosscut-first and rip-first simulations did not differ significantly from the actual rough mill yields.