Designing warranty and maintenance policies for products subject to random working cycles

The extensive application of digital technologies makes it possible for reliability managers to track in real time the product working cycles over the life cycle. Tracked working cycles belong to a type of reliability management factor because they can more accurately measure the product reliability in real time. By integrating tracked working cycles into reliability management over the product life cycle, the present paper designs two categories of random maintenance policies. The first category includes two random warranties to manage product reliability over the warranty period, where refund and limited maintenance service are two key methods to maintain warranty fairness. Each random warranty is evaluated and analyzed from the viewpoint of cost. The second category is a random maintenance policy to manage the product reliability over the post-warranty period, where preventive maintenance and random periodic replacement are combined. In such a policy, preventive maintenance can improve the reliability of the product through its warranty at a limit that occurs last, and the intention of such an action is to lower the failure frequency over the post-warranty period. By analyzing the parameters, such a policy is simplified as some special maintenance policies to manage product reliability over the warranty period. The devised random maintenance policy is modeled and optimized to minimize the expected cost rate. Sensitivities on the devised warranties and random maintenance policy are explored numerically. The results show that the designed random maintenance policy is capable of reducing failure frequency over the post-warranty period.