Direct closed-loop quality control for injection molidng

In this study, an online quality control system has been proposed and developed. A quality index, part weight, is measured in each cycle. The difference between this measurement and a quality target is used to adjust mold separation, a process variable. In a cascading fashion, the mold separation is controlled via switchover point and holding pressure, two machine variables, in cycle-to-cycle and within-cycle control. Compared to conventional cavity pressure-based control, the present implementation results in a significant improvement in both long-term and short-term consistency in part quality. In addition, direct quality feedback control has numerous benefits, such as 100% quality inspection and automatic process tuning.