Empirical evaluation of exponential and independence assumptions in queueing models of manufacturing systems

This paper presents actual data (processing times, interarrival times, cycles-between-failures, and time-to-repair) from two automotive body welding lines. The purpose is twofold. First, to help researchers focus their work on realistic problems, we exhibit the nature of randomness actually found in two industrial manufacturing systems and provide a data source for realistic probability distributions. Second, we assess the validity of two common assumptions regarding this randomness in automotive manufacturing. Many queueing network models assume that certain random variables are independent and exponentially distributed. Though often reasonable, the primary motivation for the independence and exponentiality assumptions is mathematical tractability.