Joint optimization of multi-window maintenance and spare part provisioning policies for production systems

Advanced asset management emphasizes the collaborative schemes of maintenance and spare part resources driven by asset health status. This paper formulates a joint optimization model of maintenance-spare part provisioning policy for a production system with observable defect information and postponed spare part supplies. Three levels of state-based maintenance windows, (a) regular inspection window (RIW); (b) defect removal window (DRW), and (c) pre-specified overhaul window (POW) are integrated to promote the timeliness and robustness of maintenance decision-makings, and mitigate production downtime due to spare part delays. In particular, a spare part order is induced upon defect identifications at DRW and the system continues production until being replaced as soon as the order arrives at the maintenance base, or being renewed at POW when the system attains a specified age. As such, spare part replacement is delayed, so as to leave enough time for resource preparation, and prolong the remaining useful lifetime. The system net profit is maximized through the interval optimization of RIW and DRW. A numerical experiment on maintenance engineering of a steel convertor plant is used to demonstrate the proposed methodology.