Joint Inventory and Scheduling Control in a Repair Facility
102 Pages Posted: 18 Feb 2021 Last revised: 18 Apr 2023
Date Written: February 11, 2021
Abstract
We study inventory and repair scheduling decisions of a maintenance service provider for repairable capital goods. Due to high downtime costs, the service provider keeps spare parts on stock to replace broken parts quickly. The service provider should determine the inventory level of spare parts for each component and the repair scheduling policy. Furthermore, in case of a stock-out, the service provider should decide whether to backorder the demand or execute an emergency repair, which is an urgent but expensive repair operation for a broken part followed by a fast form of installation. The objective is to minimize the long-run average inventory holding, backorder, and emergency repair costs. We formulate the repairable network as a closed queueing system and consider an asymptotic regime in which the repair facility is in the conventional heavy-traffic regime. Then, we formulate and solve a Brownian control problem (BCP). From the optimal BCP solution, we derive a simple and intuitive decision rule stating whether emergency repairs are necessary or not to achieve a close-to-optimal system performance. Moreover, we propose a simple, intuitive, and easy-to-implement heuristic control policy and demonstrate its close-to-optimal performance via numerical experiments.
Keywords: Spare parts, inventory control, scheduling, asymptotic analysis
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