The screw must ensure that the material is melted and homogenized. This process can be adjusted with back pressure to avoid overheating. The mixing element does not produce excessive flow rates which would otherwise cause degradation of the polymer. Each polymer has a different maximum flow rate, and if it exceeds this limit, the molecules will stretch and the polymer backbone breaks. However, the focus remains on controlling the forward axial movement of the screw during injection and holding. Subsequent cooling processes, including intrinsic stress, tolerances, and warpage, are important to ensure product quality.
This is all determined by the quality of the mold, especially when optimizing the cooling channels and ensuring effective closed-loop temperature regulation. The system is completely independent and does not interfere with mechanical adjustments. Mold movements such as closed mold and ejection must be accurate and efficient. A velocity profile is usually used to ensure that the moving parts are in close proximity. Contact maintenance can be adjusted. Therefore, it can be concluded that the product quality is mainly determined by the system that controls the forward movement phase of the screw without considering the energy consumption and mechanical reliability, and the same additional conditions (such as mold quality). On hydraulic injection molding machines, this adjustment is achieved by detecting oil pressure. Specifically, the oil pressure activates a set of valves through the control plate, and the fluid acts through the manipulator and is regulated and released.
Injection speed control includes options such as open loop control, semi-closed loop control, and closed loop control. The open loop system relies on a shared proportional valve. The proportional tension is applied to the desired proportion of fluid so that the fluid creates pressure in the injection barrel, allowing the injection screw to move at a certain forward speed. The semi-closed loop system uses a closed loop proportional valve. The loop is closed at the position where the closed port is located, and the closed port controls the flow ratio of the oil by movement within the valve. The closed loop system closes at the screw translation speed. A speed sensor (usually a potentiometer type) is used in the closed loop system to periodically detect the drop in tension.
