Abstract

This article investigates spare parts service contracts for capital goods. We consider a single-item, single-location inventory system that serves one customer with multiple machines. During the contract execution phase, the true demand rate is observed. It can differ from the estimated demand rate because of two factors: increased demand variation in finite horizon settings and a shift in the mean utilization of the machines by the user during the contract. When the true demand rate is higher than the estimated demand rate, the Original Equipment Manufacturer (OEM) is faced with higher-than-expected costs for the execution of the contract, and the asset user is generally faced with a higher number of extreme long downtime events. Therefore, we introduce the flexible-time contract, which ends after a predetermined number of demands. Using a Markov decision process, we prove that a state-dependent base stock policy is optimal under a flexible-time contract. Using simulation, we compare the flexible-time contract with the standard fixed-time contract. Our results show that the flexible-time contract reduces the costs for the OEM by up to 35% and prevents not meeting the agreed-on service level. We obtain similar results in a multi-item setting.

摘要

本文研究资本货物的备件服务合同。我们考虑一个单一项目、单一地点的库存系统，该系统为一个客户提供多台机器。在合同执行阶段，观察真实的需求率。由于两个因素，它可能与估计的需求率不同：有限范围设置中需求变化的增加以及用户在合同期间机器平均利用率的变化。当真实需求率高于估计需求率时，原始设备制造商 (OEM) 面临着高于预期的合同执行成本，而资产使用者则普遍面临更高数量的极长停机事件。因此，我们引入了弹性时间合同，该合同在达到预定数量的需求后结束。使用马尔可夫决策过程，我们证明了依赖于状态的基础储量策略在弹性时间合同下是最优的。使用模拟，我们将弹性时间合同与标准固定时间合同进行比较。我们的结果表明，弹性工时合同可将 OEM 的成本降低多达 35%，并防止无法达到约定的服务水平。我们在多项目设置中获得了类似的结果。