Joint optimization of imperfect condition-based maintenance and lot sizing via an availability-cost hybrid factor

Abstract

This article develops a joint model of condition-based maintenance (CBM) and economic production quantity (EPQ) for a single-unit manufacturing system. The degradation process of the system is described by a random coefficient growth model, where the mean and variance may increase with time. The condition of the system is monitored after each lot size. Three types of actions are considered, preventive maintenance (PM), preventive replacement, and corrective maintenance (CM), which are performed according to multilevel thresholds. PM is imperfect, and the system lies between two states, that is, it is as good as new or as bad as old after PM with a certain probability. Different actions lead to different calculations to determine the optimal PM strategy based on the renewal reward theory. An availability-cost hybrid factor is proposed to balance the cost per unit time and the availability of the system. Numerical simulations are provided to illustrate the method, and then a sensitivity analysis is conducted by a real case study. A comparison with single-level threshold strategies demonstrates the effectiveness of the proposed approach.