Integrated Optimization Research on Preventive Maintenance Planning and Production Scheduling

Most of papers that deal with the production planning problems assume that the equipments are always available during the scheduling horizon, however, preventive maintenance activities cost time that could otherwise be used for production, but delaying preventive maintenance for production may increase the probability of equipment failure. In order to resolve the conflict between preventive maintenance planning and production scheduling and find a balance point between the two, an integrated optimization strategy is proposed in this paper. Firstly, a preventive maintenance model and a production scheduling model are developed independently to minimize the total cost of the manufacturing system, then an integrated model is presented with the same objective. In this paper, we assume that the effect after preventive maintenance is not ´as-good-as-new´ but imperfect which can be described by an improvement factor. Finally, a numerical example of system optimized with adaptive genetic algorithm is discussed, the results show that this optimal integrated policy is much more practical than the optimal maintenance planning and sequence decision given by the independent models, and it can provide decision support for the two.