How to control the pressure in two-color injection molding process

The two most important processes of two-color injection molding are filling and pressure-holding, below, we will tell you how to control the pressure in two-color injection molding process.



1. Injection pressure

In the current two-color injection molding process, almost all injection pressures are based on the pressure applied to the plastic by the top of the plunger or screw (converted from the oil circuit pressure). The role of injection pressure in injection molding is to overcome the resistance of plastic flow from the barrel to the cavity, to give the rate of molten material filling and to compact the molten material.

2. Plasticizing pressure

In injection, the amount of plasticizing pressure is required to change according to the design of the screw, the quality of the product and the type of plastic. If these conditions and the speed of the screw are constant, increasing the plasticizing pressure will strengthen the shearing effect, i.e., it will increase the temperature of the melt, but it will reduce the efficiency of plasticization, increase the backflow and leakage, and increase the driving power.

In addition, increasing the plasticizing pressure often leads to uniform temperature of the melt, uniform mixing of the color and discharge of gas from the melt. In general operation, the decision of plasticizing pressure should be in the premise of ensuring the excellent quality of the product the lower the better, the specific value is different with the variety of plastic two-color mold used, but usually rarely exceed 20 kg / cm2.