ANALYSIS OF SIMULATED PERFORMANCE OF SOME PREVENTIVE MAINTENANCE POLICIES IN A MANUFACTURING SYSTEM

Abstract

This research is directed to analyze the simulated performance of some selected time-based maintenance policies as applied to a manufacturing system by using simulation. A simulation model is constructed for a job shop type. This job shop contains a certain number of groups of similar machines (process layout). The modeled system can receive any number of different batches where each batch may have different processing routes. The simulation model is programmed using the SIMSCRIPT II. 5 simulation language. In this research four maintenance policies are selected to study their performance , and are compared by using some time-based measures of performance. The selected policies are no preventive maintenance (NOPM) policy(if a machine fails it is repaired) CYCLE(t) policy(Schedule a PM task after t multiples of MTBF of the machine) , GROUP policy(if a machine failed it is repaired and PM tasks are performed on the remaining machines in its group) , and CRIT policy(if a critical machine failed it is repaired and PM tasks are performed in the remaining machines in its group). Five factors were taken into consideration to study their effects on the maintenance policies performance. These factors are system complexity(COMP) , system loading (LOAD) , job scheduling rule(RULE) , service ratio(SR) , and PM interval(INT).