Performance evaluation of flexible manufacturing systems using factorial design techniques

The authors present the results of a simulation study of a flexible manufacturing system (FMS). The FMS considered includes ten machining centers capable of performing a variety of tasks, an automated guided vehicle (AGV) based material handling system, and an automated single-input-single-output storage-retrieval system connected to the manufacturing system by conveyors. The system manufactures a large part mix and the parts are transported within the system by the AGV on pallets. Alternate part routing, which is an integral feature of most present day FMS, has been included in the model of this system. The model for the present study accounts for uncertainties such as stochastic part arrival patterns, variable machining times, and machine breakdowns. The performance of the system has been investigated under difficult AGV availability conditions, operation time levels, scheduling rules, and layouts of the system using factorial design techniques. The time spent by parts in the system is considered one of the main criteria of system performance. Statistical methods are used to analyze the effects of these parameters on the system performance.