When a screw injection machine is used, the pressure on the top of the screw when the screw rotates and retreats is called plasticizing pressure, also known as back pressure. The magnitude of this pressure can be adjusted by the relief valve in the hydraulic system.
Ejector: The ejector pushes the ejector plate to move the ejector wire cylinder fixed on the ejector plate, and pushes the plastic parts (products) and wastes out of the mold cavity or core to achieve the effect of demoulding. The ejector rod is generally ejected. The structures that can be used for ejection also include push plates, jacking pipes, etc. Push tube: The push tube is also used to push out the product. It is generally used in places such as screw holes and pillars to help demolding.
Push tube: The push tube is also used to push out the product. It is generally used in places such as screw holes and pillars to help demolding.
Ejector: The surface damage of the ejector is smaller for the plastic part, and it is suitable for the situation where the ejection part has precision and surface requirements.
In injection, the size of the plasticizing pressure needs to be changed with the design of the screw, the requirements of product quality and the type of plastic. If these conditions and the rotational speed of the screw remain unchanged, increasing the plasticizing pressure will strengthen the shearing. The effect is to increase the temperature of the melt, but it will reduce the efficiency of plasticization, increase the reverse flow and leakage flow, and increase the driving power.
In addition, increasing the plasticizing pressure can often make the temperature of the melt uniform, the mixing of the colorant is uniform, and the gas in the melt can be discharged. In general operation, the decision of plasticizing pressure should be as low as possible on the premise of ensuring the quality of the product. The specific value varies with the variety of plastics used, but usually rarely exceeds 20 kg/cm².