The purpose of this paper is to explore whether or not a preventive replacement model always gives a solution with a specified preventive effect and looks at the relationship between the preventive effect and cost saving.
The age and block replacement policies with the Weibull failure distribution are considered. Measures of the preventive effect associated with specific maintenance policies are derived.
The sufficient condition to achieve a given preventive effect is represented graphically as a function of the system's aging intensity and the cost ratio of failure and preventive replacements.
The models developed in the paper will help maintenance engineers to know whether a system is aged or not and then they can make a decision on replacement.
The optimal replacement models considered in this paper give a solution with a good preventive effect only if the maintained system is sufficiently aged. The criterion whether or not the system is sufficiently aged is set by the decision‐maker based on specific maintenance situations or maintenance objectives.
