Influence of V/P switchover point, injection speed, and holding pressure on quality consistency of injection‐molded parts

During the injection molding of molten polymers, the control strategy is switched from speed control to pressure control at the filling‐to‐packing (V/P) switchover point. V/P switchover influences part quality and process stability. V/P switchover timing traditionally depends on the degree of volumetric filling of molten polymer in the cavity and is limited to obtain a smooth and repeatable pressure curve for each injection, indicating consistent part quality. Repeatability is affected by the V/P switchover point, injection speed, holding pressure, and holding time. This study clarifies the effect of the injection speed, V/P switchover point, and first‐stage holding pressure setting on cavity pressure curves and injection molding quality. These factors were optimized and verified through the injection molding of integrated circuit trays. The experimental results indicate that adjusting the rear speed of filling stage, V/P switchover point, and first‐stage holding pressure, can yield the ideal pressure curve and improve process stability. Compared with the initial process parameter setting, part warpage was reduced by 40% from 0.042 to 0.025 mm, deviation of part width at the end of the filling pattern was reduced by 54% from 0.024 to 0.011 mm, and width range was reduced by 50% from 0.006 to 0.003 mm.