Performance evaluation of flexible manufacturing systems with station breakdowns, material handling system delay, and general processing times

Scope and method of study. This research examines the problems of modeling and performance evaluation of Flexible Manufacturing Systems (FMS's) with station breakdowns, material handling system (MHS) delay, and general processing times. The open queueing network models are used to model the FMS, assuming the blocked jobs will be recirculated. The method of moments is used to fit multiple parameter distributions to the moments of the stations' effective processing times. Computer simulations are used to verify the analytical results.;Findings and conclusions. A new methodology for obtaining the output (throughput) rate of FMS's without blocking has been introduced. A convenient and powerful approach is developed to transform a general FMS into a equivalent system without MHS delay and station breakdowns. The only data needed to conduct this transformation are the first several moments of the processing and repair times, and the mean time between breakdowns, that are easy to obtain from collected operation data. Then an iterative procedure is devised to obtain the FMS's major performance measures, such as the output rate, sojourn time, and station utilizations.