A Hybrid Dispatching Rules in Wafer Fabrication Factories

Even though having gained further insight into dispatching problems involving wafer fabrication, previous research cannot optimize the three global performances (Throughput, Cycle Time and Work-In-Process) simultaneously. To overcome the conflicts among these three performance factors, we present a dispatching decision method for the wafer fabrication factory based on Theory of Constraints (TOC), which uses different ways to manage the bottleneck and the non-bottleneck machines. The proposed method consists of four categories of dispatching rules: (1) default/normal condition, (2) low WIP level in the bottleneck machine, (3) high WIP level in the non-bottleneck machines, and (4) batch machine. Also, a simulation model with real world data is established to examine the performance of the proposed method. Simulation results in this study indicate that the proposed method will not only significantly maximize the system throughput, but also minimize the cycle time and the work-in-process (WIP) inventory.