How to Solve the Process Pressure of Injection Molding Parts Processing?

Injection molding parts processing process will produce pressure, if not properly solved, often lead to injection molding products quality problems, understand which process pressure for the injection molding plant to produce qualified goods is very important.

First, the pressure of injection molding

Plasticizing pressure refers to the rotation of the screw, pushing the plasticizing liquid to the head of the screw, and the melt of the head of the screw produces reverse pressure on the head of the screw at the same time. When the reverse pressure is greater than the friction between the screw and the inner wall of the cylinder and the sum of the oil return resistance of the cylinder piston in the reverse direction, the screw begins to reverse, and the reverse pressure of the screw is the rotating dynamic plasticizing pressure of the screw on the raw material, also known as the screw back pressure. By adjusting the oil return pressure of the cylinder, different plasticizing pressure of the screw can be obtained.

The adjustment of plasticizing pressure has a great influence on the plasticizing quality and production efficiency of raw materials for injection molding products. With the increase of plasticizing pressure, the mixing and plasticizing quality of raw materials can be improved, and the volatiles in raw materials can also be discharged, thus ensuring the quality of injection molded products. The disadvantage is that after increasing the plasticizing pressure, the plasticizing time of raw materials in the barrel will be extended, and the plasticizing rate will be reduced. The extension of plasticizing time will increase the possibility of raw materials decomposition.

The plasticizing pressure of plastics with different properties should also be properly controlled. For heat-sensitive raw materials (PVC, POM), in order to prevent it from staying in the barrel for too long and decomposing, low plasticizing pressure should be used; For plastics with low viscosity of raw material melt (PET, PA), a smaller plasticizing pressure should be used to reduce the leakage flow during the plasticizing process. For plastics with good thermal stability (PE, PP, PS), a higher plasticizing pressure can be obtained, which can improve production and is conducive to improving the plasticizing and mixing quality of raw materials.

2, injection pressure

Injection pressure refers to the pressure exerted by the screw head on the plasticized melt. During the injection process, the pressure of the screw head on the molten material makes the molten material overcome the friction resistance flowing into the mold cavity in the cylinder and enter the mold cavity at a certain speed, so that the molten material is compacted.

Simply speaking, the plasticizing pressure and injection pressure during the processing of injection parts have a profound impact on the quality of products, especially for injection molding operators, who should always pay attention to the various parameter changes of the injection machine in the process of injection molding production.