| Summary: | Unreliable conditions and process deterioration of machines are the major issues in several manufacturing systems. These issues not only affect the production schedules but also affect the product quality significantly. A process warm-up production and amalgamation of the preventive and corrective maintenance are important for the smooth functioning of production activities and improving the product quality. The management needs to handle the product shortages carefully and raise the backorders to upgrade the business economy. To accomplish all these objectives, we develop two production inventory models in this paper by considering a process warm-up production run, hybrid maintenance schedule, anticipated shortages during the maintenance period, and rework of imperfect items. Two different rates are used to distinguish the production of imperfect items in the warm-up and standard production periods. We use fixed and variable lengths to represent the warm-up production period in the two models respectively. The maximum customer waiting time for receiving the backorders is calculated under the consideration of finite replenishment policy and simultaneous regular demand satisfaction. Numerical examples and sensitivity analysis are provided to illustrate the models. The two models are compared based on their annual variable costs. The results suggest that a trade-off between the rework and holding costs of defective items is necessary for better inventory decisions. Determining the optimal value of the length of the warm-up production period is necessary to minimize the annual variable cost.
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