Barrel temperature:

The temperature to be controlled during injection molding includes barrel temperature, nozzle temperature and mold temperature. The first two temperatures mainly affect the plasticization and flow of plastics, and the last two temperatures mainly affect the flow and cooling of plastics. Each plastic has a different flow temperature. For the same plastic, the flow temperature and decomposition temperature are also different due to different sources or brands. This is due to the difference in average molecular weight and molecular weight distribution. The plasticizing process of plastics in different types of injection molding machines is also different, so the temperature of the barrel is also different.

Nozzle temperature:

The nozzle temperature is usually slightly lower than the maximum temperature of the barrel. This is to prevent possible "salivation" in the through nozzle of the melt. The nozzle temperature should not be too low, otherwise the nozzle will be blocked due to premature solidification of the melt, or the product performance will be affected due to premature solidification of the material injected into the cavity.

Mold temperature:

Mold temperature has a great influence on the internal performance and apparent quality of products. The temperature of the mold depends on the crystallinity of the plastic, the size and structure of the product, performance requirements and other process conditions (melt temperature, injection speed and injection pressure, molding cycle, etc.).

pressure control

The pressure in the injection molding process includes plasticizing pressure and injection pressure, which directly affects the plasticization of plastics and the quality of products.

Plasticizing pressure:

(back pressure) when using the screw injection machine, the pressure at the top of the screw when the screw rotates and retreats is called plasticizing pressure, also known as back pressure. This pressure can be adjusted by the overflow valve in the hydraulic system.

In injection, the plasticizing pressure needs to change with the design of screw, the requirements of product quality and the type of plastic. If these conditions are the same as the screw speed, the increase of plasticizing pressure will strengthen the shear and increase the melt temperature, but it will reduce the plasticizing efficiency, increase countercurrent 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 pigments and the discharge of gas in the melt.