ANALYSIS OF CELLULAR AND FUNCTIONAL MANUFACTURING SYSTEMS IN THE PRESENCE OF MACHINE BREAKDOWN

The paper reports a comprehensive study performed to compare the perfo rmance of cellular and functional layouts by extending the previous re search to cumulatively include two significant environmental factors: machine breakdown and batch size. The factors included in the study ar e demand, run time, type of material handler, batch size and repair po licy. Two different repair policies are considered in the study. The f irst policy (RP1) assumes that machines will be repaired as and when t hey breakdown. The second policy (RP2) is based on a new rule proposed in the study for performing preventive maintenance, which combines th e ideas of both condition-based maintenance and opportunistic maintena nce. Two performance measures, namely the mean work-in-process invento ry and mean throughput time are used in the comparison. A simulation m odel has been developed and implemented to compare 32 different shop c onfigurations each, with functional and cellular layouts. The processi ng sequence for parts assumed in this study depicts a pure flow line w ithout any backtracking of parts and no intercellular part transfers w hich can be regarded as a conducive arrangement for cellular layouts. Although none of the previous research cumulatively included repair po licy and batch size as environmental factors, the findings from this r esearch reconciled with those previously reported with respect to spec ific environmental factors. Several managerial implications that emerg e from this study are presented when mean work-in-process inventory an d mean throughput time are used as performance measures.