Extended economic production quantity models with preventive maintenance

Abstract

This paper generalizes the Economic Production Quantity (EPQ) model in the process manufacturing industry by incorporating regular Preventive Maintenance (PM) activities into classic EPQ model. The PM program improves the conditions of production to an acceptable level and avoids potential stops and disruptions. Therefore, it is a vital task in every production process. However, the EPQ model does not consider PM activities and thus, it is not applicable to real-world situations. A manufacturer that produced a product under the EPQ setting with a defective production process was considered in which every production cycle involved a number of sub-production cycles. Two models were developed based on the disposal time of defective items to determine the optimal number of subproduction cycles. In Model I, the disposal of defective items was performed once per cycle at the end of each production cycle, while in Model II, the disposal of defective items was performed multiple times per cycle at the end of each sub-production cycle. The total cost functions were derived for each model separately and then, simple solution algorithms were designed. A numerical example was dealt with to evaluate the proposed models. The results illustrated that Model II was more cost eective than Model I.