Multi-criteria optimization for joint maintenance and spare part provisioning: a simulation study

In today’s industries, optimal spare parts provisioning performs a critical role towards sustaining the asset’s operational capabilities. This is often achieved through mitigating the impact of unnecessary downtime associated with sub-optimal replenishment lead times. In this regard, spare parts provisioning is mentioned as an important mitigation strategy, more so for repairable components where spare part demand is initiated by equipment failure. Moreover, the repairable systems presume the possibility for component reconditioning thereby influencing the demand for new parts. Invariably, this influences the stocking policy implemented by the organization. Depending on the echelon the spare part is sourced, different transshipment policies may be adapted, though with varying cost impacts. In addition to the implemented policy, several maintenance aspects may influence spare part demand. The aspects may include the component reliability, spare part quality and the repair efficiency. To realistically model such complexities associated with spare part replenishment, simulation approaches are often explored. In this study, a simulation modelling approach for spare part replenishment is proposed. The model evaluates the impact of alternative provisioning systems that may be applicable for repairable components. Moreover, the model mimics the effect of equipment maintenance aspects on system availability and defines several performance measures, i.e. system reliability and replenishment cost. In addition, different replenishment strategies are implemented, e.g. regular and emergency replenishment. Of course, varying replenishment costs are incurred depending on the replenishment strategy adapted and the echelon the part is sourced from. The performance measures are weighted and ranked using the Analytic Hierarchy Process approach where the perceived importance of the measures is taken into account. In this way, the salient aspects, e.g. supplier reputation and/or choice of maintenance policies are factored in the simulation results. The simulation approach is implemented in the empirical case of thermal power plant engines. The results highlight the important influence of component reconditioning on the spare parts replenishment policy. Moreover, the component quality influences the feasible reconditioning cycles, thus impacting the spare part stocking policy and replenishment policy implemented by the organization. Finally, the usefulness of the model for decision support is highlighted, more so in the context of joint maintenance and repairable inventory systems.status: publishe