A Mathematical Model for Dynamic Scheduling of Production and Maintenance Activities in a Flexible Job-Shop System

Simultaneous maintenance scheduling and production scheduling play an essential role in manufacturing systems. Most studies investigated maintenance scheduling as a series of activities and ignored their macro policy effects. Based on a dynamic approach proposed by Do et al. [1], this paper presents a mathematical model that considers the impact of long-term maintenance policies in addition to short-term conditions. This model attempts to minimize preventive (PM) and corrective maintenance (CM) costs and various production costs such as setup costs, tardiness costs, and safety stock, penalty costs. The model considers essential assumptions such as 1) initial inventory, 2) assembly activities, 3) batch-sizing with unequal/variable sizes, 4) sequence-dependent setup times, 5) safety stock levels, 6) dispatch of maintenance teams and 7) the limited number of maintenance teams. Due to the non-linearity of the average number of corrective maintenance activities, a linearization method has been used to solve this problem. Finally, the validity and efficiency of the model are analyzed by implementation in a numerical experiment.