Multi-objective optimization of parallel machine scheduling integrated with multi-resources preventive maintenance planning

Many studies on the integration optimization of production scheduling and preventive maintenance usually only consider one resource, i.e., machine. However, in real-world manufacturing, multiple dependent resources (e.g., human, tools and machines) are needed at the same time to avoid mismatch of multi-resource usage, which makes it highly important to jointly schedule production and maintenance tasks of multiple resources in order to improve system availability and system throughput simultaneously. In this paper, a multi-objective parallel machine scheduling problem with two kinds of resources (machines and moulds) and with flexible preventive maintenance activities on resources are investigated. The objective is to simultaneously minimize the makespan for the production aspect, the unavailability of the machine system, and the unavailability of the mould system for the maintenance aspect. A multi-objective integrated optimization method with NSGA-II adaption is proposed to solve this problem. The extensive computational experiments are conducted. The results show that the integrated optimization method of production scheduling and preventive maintenance outperforms the method with periodic preventive maintenance for this problem, in terms of multi-objective metrics, and the results also show the effects of different flexibilities of resources for job processing.