Scheduling production for a sawmill: A comparison of a mathematical model versus a heuristic

Sawmill production scheduling is complex. It involves determining which logs to process taking into account the diameter, length, and grade of each log, on one hand, and the finished products that are needed to fulfill the orders, on the other. The cutting pattern determines which products are generated and also the yield, which is how much of the volume of the log ends as finished products. We used two approaches to solve the problem: a mathematical model, which calculates the volume and the schedule of various types of logs, and a heuristic that solves the problem by systematically applying the criteria used by a sawmill programmer in southern Chile. We compare the results of using both approaches under various scenarios in a 6 week planning horizon, with the mathematical model showing a superior performance in almost all instances except two, were both found the optimal solution. The proposed mathematical model can be solved in a relatively short time, which makes it a suitable basis of a practical optimization-based decision support system.