Performance Analysis of a Flexible Manufacturing System under Planning and Control Strategies
Résumé
A typical Flexible Manufacturing System (FMS) has been studied under Planning, Design and Control (PDC) strategies. The chief objective is to test the impact of design strategy (routing flexibility) on system performance under given planning strategy (alternate system load condition) and control strategies (sequencing and dispatching rules). A computer simulation model is developed to evaluate the effects of aforementioned strategies on the make-span time, which is taken as the system performance measure. Shortest Processing Time (SPT), Maximum Balance Processing Time (MBPT) are the sequencing rules for selecting the part from the input buffer whereas for machine selection the dispatching rules are Minimum Number of parts in the Queue (MINQ), and Minimum queue with Minimum Waiting Time of all parts in the Queue (MQMWT). In this paper, the same manufacturing system is modeled under two different system load conditions. These load conditions are Full Balanced Load (FBL) and Unbalanced Load (UBL) with respect to machine load and processing time. The result of the simulation shows that there is continuous reduction in make-span with increase in routing flexibility when both machine load and processing times are unbalanced i.e., under UBL system condition. Modeling of FMS shows that each strategy causes a flow process for each part inside the system. The co-ordination and integration of flexible resources to guide these processes in a desirable direction (lesser conflicts) is important. An FMS can then become a platform for studying interoperability between the various potentially conflicting processes where flexibility helps to reduce these conflicts. The improved performance can then become a measure of this phenomenon.