Dynamic layout strategies for flexible manufacturing systems

In this paper the authors are concerned with a key element for the effective utilization of flexible manufacturing systems (FMS), namely the design of the physical layout. This problem involves finding which processing modules should be adjacent to each other and how they should be connected with the transfer links of the material handling system to minimize the material handling requirements. These requirements also impact on in-process storage space, work-in-process inventories, the cost of control, and throughput time. The authors first characterize mathematically the static problem where all part attributes are constant over time. They then proceed to analyse the dynamic problem, where changes in system characteristics (such as the part mix manufactured by the FMS), can cause a substantial increase in material handling requirements, thereby indicating a need to consider a relayout. The authors examine the influence of a number of system parameters on several relayout strategies and derive guidelines for FMS relayout based on a series of experiments with realistic size problems. The present results indicate that a decrease of up to 36% in performance capability occurs for some relayout strategies when compared to the best strategy. Much of this substantial loss in effectiveness can be avoided by minimal, yet timely, machine rearrangement. The present findings can guide decision makers vis-à-vis their own systems where actual system relayout costs can be used. The paper concludes with directions for further research.