Modeling and Simulation of a Re-entrant Manufacturing System Using Colored Petri Nets

This paper describes the use of Colored Petri Nets (CPNs) in the simulation and analysis of re-entrant manufacturing systems with inspections. Inspection stations in a manufacturing system are designed to enhance product quality and process performance. An example is the semiconductor manufacturing process, especially the wafer fabrication line. We consider a model in which there are three possible outcomes at the end of each inspection: accept, reject, or re-enter the system at a previous stage. The performance measures of interest are cycle time, queue length at each buffer, and utilization of each work cell. We use CPN Tools, a graphical software tool and interface used to create, edit, simulate, and analyze CPN models. In this paper we give a brief overview of CPNs and the advantages of using them in the modeling of manufacturing systems. We also present the execution of the CPN model and analysis of a representative system.