Joint production and repair efficiency planning of a multiple deteriorating system

This paper presents an integrated model for the simultaneous production and repair activity planning of a manufacturing system whose performance output is subject to progressive deterioration. In this context, an appropriate joint control strategy is critical to reduce costs and remain competitive. The obtained control policy balances the amount of maintenance activities needed to increase the availability and reduce defects against the increase in the total cost from downtime and deterioration. The production system consists of an unreliable machine that produces one product type and where unmet demand is backlogged. The rate of defects of the machine depends on its level of deterioration, which is defined through a set of multiple operational states and the age of the machine. Additionally, an intensity control model is adapted to define the repair efficiency applied to the system, aiming to mitigate the effect of deterioration that is mainly observed on the failure intensity of the system. The solution is obtained numerically through the formulation of a Hamilton-Jacobi-Bellman equation. A numerical example is provided and an extensive sensitivity analysis is conducted to validate the obtained results.