Injection molding is the nature of the injection molding machine using plastic heating to a certain temperature can melt into a liquid, the molten liquid with high pressure injection into a closed mold cavity, after cooling and shaping, after opening the mold to get the required plastic body products. In the use of injection molding machine, special attention should be paid to temperature control and pressure control.
1. Temperature control
The temperature that needs to be controlled in the injection molding process includes cylinder temperature, nozzle temperature, mold temperature, etc. The former mainly affects the plasticization and flow of plastics, while the latter mainly affects the flow and cooling of plastics. In order to prevent possible "drooling" in the straight-through nozzle, the nozzle temperature is generally slightly lower than the maximum temperature of the barrel. The temperature of the nozzle should not be too low, otherwise it will lead to premature solidification of the melt, clogging the nozzle, or affect the performance of the product due to the injection of condensation in the mold cavity. Mold temperature has an important impact on the internal performance and appearance quality of the product, so it should be adjusted to the appropriate mold temperature according to the requirements of the product.
2. Pressure control
The injection pressure is divided into two types: plasticizing pressure and injection pressure, which directly affects the plasticization and product quality of plastics. When the screw injection machine is used, the pressure generated by the melting material on the top of the screw when the screw rotates backward is called plasticizing pressure, also known as reverse pressure, and the size of the pressure can be adjusted by the relief valve in the hydraulic system. In general, under the premise of ensuring product quality, the decision of plasticizing pressure should be as low as possible.
