Optimal schedules of two periodic preventive maintenance policies and their comparison

Abstract

In this paper, we propose two types of PM actions among which one type of PM actions effect on the relative wear-out since the last PM action (local PM action) while another PM actions are effective in restoring global wear-out since equipment started operating (global PM action). Based on the proposed local and global PM actions, we develop two periodic PM policies which are called the type I PM policy and the type II PM policy, respectively. For each PM policy, we derive formulas to compute the expected cost rates of the system during its life cycle and investigate the optimal PM schedules, which are to minimize the expected cost rates. We also compare the local PM policy and the global PM policy under the assumption that the cost for the global PM action is higher than or equal to the cost for the local PM action. For the purpose of illustration of our results, we investigate numerically the sensitivity of optimal schedules.