AOQ Metric for Sequential Systematic Sampling with Screen Right Response Plan

The smart manufacturing movement of Industry 4.0 has led to major changes to modern manufacturing practices. However, challenges around time and resource constraints in manufacturing settings also have highlighted a concurrent need for advancement in quality control methodology. Traditional batch-based acceptance/rejection inspection schemes, while effective when properly implemented, tend to be resource intensive, imposing an operational burden in systems in which where the process quality level is insufficient to avoid regular triggering the full lot inspection. In some cases, the inspection-induced bottlenecks render the traditional screening response plan unfeasible, resulting in operational deviations from the theoretical sampling scheme and/or response plans of the quality metrics being used. The misalignment of actual inspection behavior and the assumed inspection behavior of quality metrics can lead to incorrect—and potentially anticonservative—assessments of outgoing quality.A potential alternative to the traditional random sampling and full inspection scheme is the sequential systematic sampling with the screen right response plan (SEQSSR) method. This paper derives quality metrics for average outgoing quality level (AOQ) and average total inspections (ATI). Characterizations of the risk metrics provide insight into appropriate use cases for the SEQSSR method.