中文摘要：

部件重要度是指当一个部件发生故障时,对其顶事件发生概率的贡献程度,是系统中各分系统或部件重要程度的一种数量体现。根据数控机床中各部件对顶事件发生的重要性大小进行系统设计的改进是十分有用的。部件重要度计算就是在某种意义下将系统各部件按其重要性大小排列出来,根据部件重要度大小来辅助系统设计,用较少的人力、物力提高原有系统的可靠性指标,建立优化维修检测法规等[1]。

英文摘要：

Parts importance refers to the contributions to the probability of top event when a part is in failure. It＇s useful to improve the system design according to the parts importance of the machine tools. Through calculating, parts importance is listed according to the values. We can improve the reliability index of the systems through system design with less human resources and material resources.