An Integrated Model for Production and Preventive Maintenance Planning in Multi-State Systems

This paper integrates preventive maintenance with tactical production planning in multi-state systems. The proposed model coordinates the production with the maintenance decisions, so that the total expected cost is minimized. We are given a set of products that must be produced in lots on a multi-state production system during a specified finite planning horizon. Planned preventive maintenance, and unplanned corrective maintenance can be performed on each component of the multi-state system. The maintenance policy suggests cyclical preventive replacements of components, and a minimal repair on failed components. The objective is to determine an integrated lot-sizing and preventive maintenance strategy of the system that will minimize the sum of preventive and corrective maintenance costs, setup costs, holding costs, backorder costs, and production costs, while satisfying the demand for all products over the entire horizon. We model the production system as a multi-state system with binary-states, and s-independent components. A method is proposed to evaluate the times and the costs of preventive maintenance and minimal repair, and the average production system capacity in each period. We show how the formulated problem can be solved by comparing the results of several multi-product capacitated lot-sizing problems. For large-size problems, a genetic algorithm is developed to deal with the preventive maintenance selection task in the integrated planning model.