Optimal yield improvement in multi-stage manufacturing systems

Multi-stage manufacturing systems producing some non-conforming items still present economic operational problems. A decomposition approach is presented to model multi-stage manufacturing systems with inspection stations. The concept of process improvement as developed is expressed in terms of a step-wise yield improvement path, along which the most profitable improvement stages are identified. It is shown that the model selects an ever increasing set of stations to improve, once the profitability of the best station-candidates reaches a level similar to that of some other station-candidates. The approach also extends the concept of an event (naturally connected to a time frame) by relating it to a dynamic profitability frame. From an operational perspective the findings suggest that a quality improvement project, initially undertaken by a cross-functional team at a multi-stage level, may be continued through concurrent projects, focusing on improving the quality of specific manufacturing stages. The research results may be directly extended to include integrated economic improvement-inspection decisions.