ANALYSIS OF FLEXIBLE MANUFACTURING SYSTEMS WITH DISTINCT REPEATED VISITS - DRQ

This article examines the performance effects caused by repeated part visits at the workstations of a flexible manufacturing system (FMS). S uch repeated part visits to the same workstations are commonly associa ted with fixture changes for machining complex parts, reclamping, and remounting or reorienting them. Since each of the repeated visits to a workstation may require different processing requirements, the result ing queueing network does not have a product form solution. We therefo re develop an approximate mean value analysis model for performance ev aluation of an FMS that may produce multiple part types with distinct repeated visits. We provide numerical examples and validate the accura cy of our solution algorithm against simulation. These examples show t hat the proposed model produces accurate throughput and utilization pr edictions with minimal computational efforts. These examples reveal th at increasing the total pallet population may result in a reduction of the aggregate throughput, and that the FMS's performance could be mor e sensitive to the mix of pallets and part routes than to the total nu mber of pallets. Our model will be of use, in particular, when manager s wish to control individual operations (e. g., to adjust individual o peration times to achieve economic savings in tool wear and breakage c o sts) or to investigate the performance implications of route changes due to alternate assignments of particular manufacturing tasks to cer tain workstations.