Condition-based maintenance is a proactive maintenance strategy where the condition of machinery is monitored. A machine is preventively maintained when it shows signs of degradation, in which case the necessary spare parts are provided from stock. However, machines may occasionally suffer from sudden shocks, or they may fail before showing any signs of deterioration. Having stock-outs in case of failures leads to costly downtimes. To avoid such downtimes, we propose a condition-based critical level policy. In this policy, preventive maintenance can be carried out such that spare parts can be consumed when the stock level is not below the critical level. In order to assess the potential impact of this policy, we develop a conceptual model for which we establish a simple numerical procedure that allows to select the optimal base-stock and critical level thresholds. We compare the operational cost under the optimal critical level policy to that under the optimal base-stock policy. The results indicate that the proposed critical level policy can indeed reduce the operational cost significantly as compared to the base-stock policy.

基于状态的维护是一种主动的维护策略，可以监控机器的状态。当机器显示出退化迹象时，要对机器进行预防性维护，在这种情况下，必须从库存中提供必要的备件。但是，机器有时可能会遭受突然的冲击，或者在出现任何劣化迹象之前可能会发生故障。发生故障时缺货会导致昂贵的停机时间。为了避免此类停机，我们提出了基于条件的关键级别策略。在此策略中，可以进行预防性维护，以便在库存水平不低于关键水平时可以消耗备件。为了评估此政策的潜在影响，我们开发了一个概念模型，为此我们建立了一个简单的数值程序，可以选择最佳的基础库存和临界水平阈值。我们将最优临界水平策略下的运营成本与最优基础库存策略下的运营成本进行了比较。结果表明，与基本库存策略相比，拟议的关键级别策略确实可以显着降低运营成本。