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HeA new machine will not fail easily in the early stage of its useful life. This phenomenon is consistent with the fact that the optimal sequential preventive maintenance (PM) policy which has longer PM intervals in its earlier stage of lifetime. In this paper, we propose a failure-rate-reduction periodic PM model with delayed initial time in a finite time span. Then, the optimal periodic PM policy is developed by minimizing the expected total maintenance cost, which can have smaller expected total maintenance cost than the optimal policy of the original failure-rate-reduction periodic PM model. The algorithm of finding the optimal PM policy for the proposed PM model is developed. Finally, examples are illustrated to verify the optimal policies of the proposed new PM model.

In practice, a system or equipment has a finite useful life. When an aged system is replaced by a new system, the new system seldom has exactly the same characteristics, functions, investment cost, maintenance expenses, etc., as those of the aged system. However, the literature has shown that most researchers are devoted to studying maintenance problems in an infinite time span, which assumes that the replaced system in each replacement cycle (or period) has the same conditions and costs. Apparently, the assumption might not be practical, since the useful operating life of most systems is finite in the real world. Therefore, the purpose of this research is to develop an optimal preventive maintenance (PM) policy having failure rate reduction within a finite time span under a warranty consideration by minimizing the expected total maintenance cost. The PM cost is assumed to be a linear function of each PM effect. Two cases are studied and compared; one is with no warranty provided and the other is with a g...

It has been shown that the incorporation of the Total Productive Maintenance (TPM) into the manufacturing machine is a success in that: the decrease of the machine failure rate and the improvement of the machine reliability. The major subject of the TPM system is focused on the Daily Maintenance Service (DMS) of the manufacturing machine such as cleaning and inspection performed by in-line operators. The DMS is classified as a preventive maintenance policy and has significant contribution in practical applications. However, little research has been devoted to modeling the Daily Maintenance Service. This research assumes that the machine failure rate will be improved if the DMS is performed for a long period of time. If DMS is performed, the machine will at least be restored to “as bad as old” state but can not reach the “as good as new” state. Thus, the DMS is categorized as an imperfect maintenance according to its characteristics. The emphasis of this research is to model the DMS for high preci...