Opportunistic maintenance of production systems subject to random wait time and multiple control limits

A variety of production systems experience unavoidable production wait time due to the exhaustion of raw materials or lack of demand, which provides extra opportunities for the execution of maintenance activities. In this article, we propose a novel condition-based maintenance strategy for a production system whose production waits arrive according to the homogeneous Poisson process. The system undergoes gradual degradation, which ultimately results in soft failures (capacity reduction). To ensure a flexible and cost-effective maintenance allocation, opportunistic maintenance (during production waits) and regular maintenance are schemed simultaneously along with two separate control limits. The applicability of the proposed strategy is validated by a case study on a crystallizer casting machine. The result illustrates that the proposed maintenance strategy is more cost-effective compared with several classic/advanced strategies.