Joint Optimization of Condition-Based Maintenance and Spare Parts Orders for Multi-Unit Systems with Dual Sourcing

Efficient coordination of maintenance scheduling and spare parts management for critical components can reduce overall operational costs for companies. When sourcing spare parts from more than one supplier, planners can balance response times and prices provided by different suppliers to further reduce operational costs. We develop a joint condition-based maintenance and spare parts provisioning policy for a multi-unit system with dual sourcing. We use a Markov decision process to formulate the sequential-decision problem, which considers degradation states of multiple components and spare parts inventory information from two suppliers. An exact value iteration algorithm is adopted to derive the optimal joint maintenance-and-ordering policy. Interestingly, we find that a replacement will be delayed to judge which component will be replaced first in a two-component system when the degradation level of one component approaches the level of the other one. Numerical results show that our proposed policy with dual sourcing can reduce the expected cost by as much as 42%, compared to the traditional (s,S) policy with single sourcing.