Application of the Integrated SPC/PI Strategy in Discrete Manufacturing Systems

In order to improve the ability of on-time deliveries, the PI (proportional integral) control algorithm is put forward in discrete manufacturing systems so as to maintain lower and steadier WIP (work-in-progress ). For long-term process improvement, the integrated strategy of SPC/PI (statistical process control, SPC) is further proposed. To evaluate the control effects of this kind of integrated scheme, an implementation and monitoring model are proposed, based on which, a case study is carried out in the production line of certain motorbike engines´ crankcases. Shewhart control chart is used to evaluate the control effects of unique PI and integrated SPC/PI when both drift/shift errors exist in WIP mean. Simulation results indicate that the integrated SPC/PI outperforms unique PI with regard to WIP control in discrete manufacturing systems.