Evaluation of Scheduling Strategies on the Performance of a Flexible Manufacturing Cell:a Simulation Study

The current trend in semiconductor manufacturing is characterized by expanding product variety, decreasing lead times from order to delivery, exacting standards of quality, and competitive prices. One possible means of achieving this is in the form of increased flexibility. Providing flexibility is typically an expensive proposition so, industrial engineers aim to provide more economic approaches to enable flexible manufacturing cells and related equipment to operate appropriately in an efficient manner. It is essential to characterize these tools in detail before the production plans are finalized. Using state-of-the-art computer simulation, a generic model of photolithography tools has been developed. The model examines the impact of changing product volumes, buffer size, product sequence and product-mix on performance criteria, e.g. throughput time. The high investment cost of flexible manufacturing cells justifies the use of computer simulation support to maintain high system performance and reduce risk by predicting the system behavior under any feasible production schedule. Simulation results presented in a Taguchi experimental design framework offer a robust methodology to gain quick insights into the behavior of selected parameters within flexible manufacturing system environments. The developed model has been evaluated and found to be relatively more effective than simplified deterministic approaches when measured against actual production.