A Simulation-Based Closed Queueing Network Approximation of Semiconductor Automated Material Handling Systems

Queueing networks have been used to model material handling in flexible manufacturing systems. We explore the use of a closed queueing network model to approximate an intrabay automated material handling system (AMHS) in semiconductor manufacturing. A simulation-based approach is proposed to obtain estimates of system performance measures. Current simulation models in the industry are very complex, require significant development time, and take a long time to run. The proposed simulation-based queueing network approximation can be used as an easy and fast alternative or as a precursor to a full-fledged modeling exercise depending on the type of decision being made and the level of granularity required in the output. Using a simple intrabay configuration, we compare estimates from the approximation approach and a more detailed modeling approach to characterize the performance of the approximation. In addition, a simulation information model is used to compare AMHS models based on the amount and types of information needed to model the system, and to obtain desired output. This classification aids modelers in determining the level of detail to incorporate in a model based on the objectives of the simulation study.