An optimal joint maintenance and spare parts inventory model

Abstract

Optimised maintenance of plant machineries is one of the important tasks to reduce plant operating cost. To carry out these maintenance tasks smoothly, development of spare parts inventory policy is the most prioritised issue. This research aims at the derivation of a joint maintenance and spare parts inventory model for a multi-component system. The decision variables are the order quantity and the ratio of ordering interval to preventive maintenance interval. We used block-based maintenance policy and periodic review inventory policy in this study. At first, a cost function is developed assuming that failure occurrences follow Poisson process with a constant failure rate and machine failures are non-repairable. Second, the model is further expanded for the case when failure occurrences follow non-homogeneous Poisson process and machine failures are repairable. The applicability of the developed models is demonstrated by numerical examples. Sensitivity analysis is also conducted to examine the effects of input parameters.