⒈Plasticizing pressure: (back pressure) When using a sc […]
⒈Plasticizing pressure: (back pressure) When using a screw injection machine, the pressure on the top of the screw when the screw rotates and retreats is called plasticizing pressure, also known as back pressure. The size of this pressure can be adjusted by the overflow valve in the hydraulic system. In injection, the size of the plasticizing pressure needs to be changed with the screw design, product quality requirements and the types of plastics. If these conditions and the screw speed are the same, increasing the plasticizing pressure will strengthen the shear Function, that is, it will increase the temperature of the melt, but it will reduce the efficiency of plasticization, increase the reverse flow and leakage, and increase the driving power.
In addition, increasing the plasticizing pressure can often make the temperature of the melt uniform, the mixing of the pigments and the discharge of the gas in the melt. In general operation, the decision of plasticizing pressure should be as low as possible under the premise of ensuring good product quality. The specific value varies with the variety of plastics used, but usually rarely exceeds 20 kg/cm².
⒉Injection pressure: In the current production, almost all the injection pressure of the injection machine is based on the plunger or the top of the screw to the plastic
The applied pressure (converted from the oil pressure) shall prevail. The role of injection pressure in Dongguan injection molding is to overcome the flow resistance of the plastic from the barrel to the cavity, to give the molten material the rate of filling the mold and to compact the molten material.