Quality Improvement of Work-in-Process in Manufacturing System Based on Opportunistic Rework Strategy

Machine maintenance usually leads to disruptions in the manufacturing process, resulting in production losses. To fully utilize the unavoidable downtime caused by machine maintenance, a quality improvement method of work-in-process (WIP) based on opportunistic rework strategy for serial manufacturing system with multiple rework loops is proposed. The calculation methods for the upstream opportunistic rework window (UORW) and downstream opportunistic rework window (DORW) were provided, and based on UORW and DORW, advanced and dynamic qualified quality limit (QQL) adjustments were made to perform additional opportunistic reworks, so as to improve the quality of WIPs. The effectiveness of proposed method was verified through a single rod manufacturing case of shielding components.