Coordinated production and opportunistic-preventive maintenance control policy in deteriorating hybrid manufacturing–remanufacturing systems

This paper addresses a multi-mode production planning and control (PPC) problem in operation-dependent deteriorating systems evolving within dynamic and stochastic environments (DSE). These systems alternate between manufacturing and remanufacturing modes to meet demand. The proposed solution introduces a novel integrated production, switching, preventive maintenance (PM), and opportunistic preventive maintenance (OPM) policy to minimize long-term total costs. The policy optimizes production rates, switching between modes, and maintenance activities. We combine optimal control theory and numerical methods to characterize the optimal control structure, which includes a hedging point production-switching policy and state-based preventive and opportunistic maintenance strategies. OPM is conducted during inventory-dependent switching downtimes if the scheduled PM is imminent, enhancing system performance. A simulation-based optimization framework refines control parameters to minimize total costs across diverse system settings. The results indicate that incorporating OPM into the proposed control policy can reduce total operational costs by up to 10% compared to policies with only PM and exceed 30% compared to policies without PM, while also providing valuable insights for managing production downtimes through the coordinated integration of multi-mode production and PM strategies.