: Warranty is a contractual obligation that manufacturer gives to buyer on selling of every special product in a specified time frame. When a product failure occurs, according to warranty policy that is already considered, manufacturer should repair or replace the defective product. Type and degree of repairs during the period of warranty by the manufacturer that the product is made is effective on the cost of the warranty. In most warranty policy manufacturer performs some repairs at specified intervals. This strategy of repair, preventive maintenance (PM) is called. According to the aim off majority of businesses in maximize their profits, this issue that the reduction in warranty costs due to perform PM be greater than the cost of doing it, is important for manufacturer. Due to the complexity of products, when the basic warranty period at the time of product sales supplied, ends, customers prefer to for a certain period after the completion of this course, purchase the extended warranty. Previous studies have shown that warranty policy, on a two-dimensional framework based on the age and usage of the product, in order to increased competitive advantage and customer satisfaction must be developed. A closer examination of the issue, shows a research gap to link the basic and extended warranty. In this study, the effect of PM to reduce intensity of repairable products, is investigated. According to the upside of function of intensity of product failure to time and its usage and approaching to time and usage of two-dimensional warranty coverage, increase the risk of failure in fixed distance between two actions of PM and this occurrence can effect on producer cost. Therefore a mathematical relationship presented to variable intervals to perform PM, and we detected that this new strategy has better results to minimize the expected cost of the warranty, compared with periodic PM. It also follows that with the increasing marginal cost of PM, the expected cost of the warranty will be increased and in return the less number of PM actions done on products. On the other hand, the better repair on the product due to less PM actions and therefore increase the expected cost of the warranty.
