A control system for an injection molding machine performs a molding cycle. The molding cycle includes a filling process for controlling an advancing motion of a screw of the injection molding machine, and a hold press process for controlling a pressure of a molten resin after the filling process. The control system includes retracting speed limit means for limiting a retracting speed of the screw to a predetermined retracting speed limit value after a pressure control in the hold press process begins.

The injection molding machine control system plays a critical role in ensuring high-quality production by managing the molding cycle, which includes the filling process and hold press process. During the filling process, the screw advances to inject molten resin into the mold cavity, while the hold press process maintains optimal pressure to prevent defects. A key innovation in modern systems is the retracting speed limit means, which restricts the screw’s retracting speed to a predefined limit after pressure control begins. This enhances stability, reduces material waste, and improves part consistency.