A mathematical approach for the optimal planning of drying operation

Abstract

Lumber drying is an important stage in sawmills since lumber charateristics required by the market are achieved through this operation. Generally, it is a batch process that is carried out in drying kilns that operate in parallel out of phase. This work presents a mixed integer linear programming model (MILP) for the optimal planning of this process stage. The model determines how board packages are processed in dryers and the start and end times of each drying cycle in each kiln. This approach combines concepts of both multidimensional bin packing ‒to plan the load of kilns‒ and parallel machine scheduling ‒to sequence drying cycles. The model is tested with different objective functions that represent different work criteria related to sawmills.