A constrained integrated imperfect manufacturing-inventory system with preventive maintenance and partial backordering

In this paper, a multi-product single-machine economic production quantity model with preventive maintenance, scraped and rework is studied. Shortages are permitted and a fraction of them is backlogged. Capacity and service level are limitations of the production system. It is assumed that preventive maintenance can be performed when the inventory level is positive or negative. Indeed two different scenarios are modeled and according to the comparisons between their costs, a new scenario according to the best time of preventive maintenance is investigated and modeled. The aim of this research is to determine the best time for preventive maintenance, production and back-ordered quantities of each item and common cycle length, such that the expected total cost is minimized. The objective function of the final proposed model is proved to be convex and closed-form optimal solutions are derived. Two numerical examples based on a real application of the proposed model in a turning manufactory with only one computer numerical control machine applied to lathe metal plates to different sizes are used to illustrate the applicability of extended model and proposed solution method.