What Is a Precision Injection Molding Machine and How Closed-Loop Control Improves Accuracy

A precision injection molding machine is an injection molding machine equipped with closed-loop control for the molding process. In most cases, the machine uses closed-loop control to regulate injection pressure and injection speed. Closed-loop control, also called feedback control, works by detecting the actual output of the system through sensors, sending that signal back to the controller, and allowing the controller to compare the real output with the target value. The system then automatically adjusts the process so that the output stays as close as possible to the desired setting and overall deviation is minimized.

In simple terms, closed-loop control is an automatic correction method that keeps the molding process closer to the required value. When injection molding machines use closed-loop injection control, the repeatability and stability of molding performance are significantly improved. This helps reduce part size variation and improves both dimensional accuracy and dimensional stability of the finished product.

For hydraulic injection molding machines, closed-loop control is usually achieved through the use of servo valves, which allow precise regulation of hydraulic system pressure and flow. In ultra-precision injection molding machines, servo control boards and computer control systems are also used to further improve output repeatability and make hydraulic pressure and flow control more accurate, enabling higher precision molding performance.

Compared with hydraulic machines, all-electric injection molding machines have greater advantages when it comes to achieving full closed-loop control. In an all-electric machine, a computer motion controller drives the servo motors and processes feedback signals from sensors through the control system. This makes it possible to control injection, plasticizing, mold opening and closing, and ejector actions with high precision.

With full closed-loop control, position accuracy can reach 0.01 mm, resulting in higher dimensional accuracy for molded parts. At the same time, the overall stability and repeatability of the machine are also greatly improved, making all-electric injection molding machines especially suitable for precision and ultra-precision molding applications.