SEQUENCING HEURISTICS FOR DEPENDENT SETUPS IN A CONTINUOUS PROCESS INDUSTRY

ln this paper we address the scheduling of Biaxially Oriented Polyprop ylene (BOPP) film production, which belongs to the plastics industry a nd is a continuous process. Scheduling problems in BOPP film productio n involve processing different thickness settings of films on a common facility. Customer orders of the same thickness setting are usually g rouped together as a production batch and a setup time is incurred whe never the batch is switched. However, there is usually more than one b atch for the same thickness setting because of the due date constraint s of the orders. Therefore, there is a need to develop a hatching and sequencing scheme that minimizes the total setup time, or equivalently the makespan, under the due date constraint. In this paper heuristics are developed to generate a near-optimal solution for the problem. Th e heuristics are evaluated by an optimal solution procedure and are te sted by using the actual data from a plant making the BOPP film. Compa rison of the heuristics with the results of the current system has dem onstrated a significant reduction in total setup time. Copyright (C) 1 996 Elsevier Science Ltd.