Production planning for ̄exible ̄ow systems with limited machine ̄exibility

A ̄exible manufacturing system (FMS) is highly capital-intensive and FMS users are concerned with achieving high system utilization. The production planning function for setting up an FMS prior to production should be developed in order to make the most of the potential bene®ts of FMSs. We consider two production planning problems of grouping and loading a ̄exible ̄ow system, which is an important subset of FMSs where the routing of parts is unidirectional. We show that considering this routing restriction as well as limited machine ̄exibility strongly a€ects both the solution techniques and the quality of the solutions. Because of the complexity of the problem, we present a heuristic approach that decomposes the original problem into three interrelated subproblems. We show that the proposed approach usually ®nds a near-optimum solution and is superior to an approach that exists in the literature of FMS production planning. We also introduce e€ective heuristic methods for two new subproblems that arise because of the unidirectional ̄ow precedence and ̄exibility constraints. Computational results are reported and future research issues are discussed.