The process conditions of injection molding have been explained on the official website of Huanke Precision. Today, Huanke Precision will continue to talk about another important factor affecting the quality of injection molding parts: action time, that is, the molding cycle of plastic products.
Injection molding cycle refers to the time needed to complete an injection molding process, which includes all the time in the injection molding process. The molding cycle directly affects the production efficiency and equipment utilization rate.
In the whole molding cycle, injection time and cooling time are the most important. They are not only the main component of the molding cycle, but also have a decisive impact on the quality of plastic parts. In injection molding time, the filling time is inversely proportional to the filling rate, and the filling rate depends on the injection rate. In order to ensure the quality of plastic parts, the filling speed should be controlled correctly. For the plastic parts with high melt viscosity, high glass transition temperature and fast cooling rate, glass fiber reinforced plastic parts and low foaming plastic parts, rapid injection or high-pressure injection should be used.
In production, the mold filling time generally does not exceed 10s. The pressure holding time in the injection time accounts for a large proportion in the whole injection time, which is generally about 20~120s(thick wall plastic parts can reach 5~10min). The length of holding time is determined by the structure size of plastic parts, material temperature, main channel and gate size. Under the condition of normal process conditions and reasonable size of main channel and gate, the best pressure holding time is usually the smallest time within the fluctuation range of shrinkage of plastic parts.
The cooling time is mainly determined by the wall thickness of the plastic, the temperature of the injection mold, the thermal properties of the plastic and the crystallization properties. The length of the cooling time should be to ensure that the plastic parts do not cause deformation when demoulding as the principle. The cooling time is too long, not only prolongs the molding cycle, reduces the production efficiency, but also sometimes causes the difficult situation of the demoulding of the complex plastic parts.
