Abstract: In practical production, multistage process usually contains series and parallel structures, the multistage manufacturing process with series and parallel hybrid structure is the most common form in practice, and in the parallel structure with different modes, the effect of the quality variation in the upstream process on the downstream process and the total process capability is different. According to the characteristics of the multistage process with parallel structure, process capability in the parallel multistage process with parallel, disperse, and convergence three basic patterns is analyzed. Based on the perspective of variation decrease, the influence of the variation of each sub-process on the overall process capability in multistage manufacturing is studied. The effect of quality improvement is evaluated according to the “difficulty”and“utility ratio”of reducing quality variation of each sub-process.Then the basis for selecting the strategy of multistage process capability improvement is given and an example is provided to illustrate it. The results show that the method can identify the different influences of the quality variation reduction of each process on process capability of this process and total process capability, determine the priority of quality improvement, and then realize the economic quality improvement and optimization of the multistage manufacturing process.

Key words: multistage manufacturing process, parallel structure, process capability, utility ratio

摘要： 多工序制造过程通常包含串联和并联两种结构,具有串并联混合结构的多工序制造过程是实践中最为常见的形式,而不同模式的并联结构其上游工序质量波动对下游工序及总过程能力的影响不同。针对多工序制造过程并联结构特点,本文从波动减少的角度重点对多工序并联制造过程中并行、分散和收敛三种基本模式进行过程能力分析,研究多工序制造过程中各子过程波动对整体过程能力的影响,并根据各子过程质量波动减少的“困难度”和“效用比”评价质量改进的效果,给出多工序并联过程能力改进策略选择依据。通过实例表明,本方法能较好地识别各工序质量波动减少对本工序过程能力和总过程能力的不同影响,确定质量改进的优先顺序,实现多工序制造过程的经济性质量改进和优化。

关键词: 多工序制造过程, 并联模式, 过程能力, 效用比