Variation transmission analysis and diagnosis of multi-operational machining processes

In a Multi-operational Machining Process (MMP), final product variation is an accumulation, or stack-up of variations generated at all the manufacturing operations. In this paper, variation transmission in the MMP is analyzed by relating part variations to operational errors from machine tools, fixtures and datums. At each operation, total part variation is separated into several components corresponding to different variation sources. The result can be applied in both process design and diagnosis. A methodology is developed to identify faulty operations. Process diagnosability is also discussed. A case study is provided to illustrate the developed diagnostic methodology.