Operations scheduling for an advanced flexible manufacturing system with multi-fixturing pallets

Abstract

This study addresses a new operations scheduling problem for an advanced flexible manufacturing system with multi-fixturing pallets that can load multiple parts for the purpose of facilitating system productivity and flexibility. The problem is decomposed into four sub-problems: palletizing that selects the set of parts loaded on each pallet; pallet input sequencing that determines the sequence of loaded pallets initially released into the system; pallet routing that determines the route of each pallet among machines while selecting the machine to process each operation of the parts loaded on each pallet; and pallet process sequencing that determines the sequence of pallets to process their loaded parts on each machine. Practical constraints such as central buffer capacity, limited number of pallets, pallet setup worker availability and re-palletizing for identical parts are also considered. A fast heuristic approach is proposed that uses a combination of priority rules for palletizing/pallet input sequencing, pallet routing and pallet process sequencing. To test the performance of various rule combinations, simulation experiments were done on a number of test instances and the best ones are reported for each of the makespan measure that maximizes the system throughput and the total tardiness measure that meets the due-dates of parts.