Condition based maintenance in the context of opportunistic maintenance

TLDR

Condition‑based maintenance predicts failures from component operating conditions and typically offers higher availability and lower costs than age‑based replacement, but its advantage in multi‑component serial systems—where opportunistic maintenance can group repairs to reduce downtime—is uncertain. The study examines how opportunistic maintenance affects the effectiveness of CBM. The authors simulate a three‑component serial system, varying the number of components under CBM, the size of the opportunistic maintenance zone, the cost savings from grouping, and the probability of failure during a preventive maintenance interval. Under the tested conditions, CBM remains cost‑effective in the serial system but is less effective than age‑based replacement for grouping maintenance; when failure probability is low and the opportunistic zone is large, ABR can outperform CBM if line productivity is critical.

Abstract

Condition based maintenance (CBM) uses the operating condition of a component to predict a failure event. Compared to age based replacement (ABR), CBM usually results in higher availability and lower maintenance costs, since it tries to prevent unplanned downtime and avoid unnecessary preventive maintenance activities for a component. However, the superiority of CBM remains unclear in multi‐component systems, in which opportunistic maintenance strategies can be applied. Opportunistic maintenance aims to group maintenance activities of two or more components in order to reduce maintenance costs. In a serial system, this may also result in less downtime of the production line. The aim of this paper is to examine the impact of opportunistic maintenance on the effectiveness of CBM. We simulate a small system consisting of three components in series and vary the number of components under a CBM policy, the length of the opportunistic maintenance zone, the cost benefits of grouping maintenance activities, and the chance of a failure occurrence within a preventive maintenance (PM) interval. The results show that within the current experimental settings, CBM remains cost effective in the multi‐component serial system, but is less effective than ABR in grouping maintenance activities. When the chance of failure is small and the length of the opportunistic maintenance zone is large, ABR may even be a better option if line productivity is important.