(4) Problems that should be paid attention to in the injection molding process (including the requirements of injection molding machines)
In order to reduce internal stress and surface quality defects, the following aspects should be noted in the injection molding process.
a) Special screw and injection molding machine with separate temperature control nozzle should be used;
b) The injection temperature should be higher than the plastic resin without decomposition;
c) Injection pressure: generally higher to overcome the defect of large viscosity of the melt, but the pressure is too high, which will cause internal stress and cause deformation and deformation;
d) Injection speed: in the case of filling the mold, it is generally low, and it is better to use slow, fast and slow multi-stage injection;
e) Holding time and molding cycle: in the case of satisfying the product filling, no dents or bubbles; it should be as short as possible to minimize the residence time of the melt in the barrel;
f) screw speed and back pressure: under the premise of satisfying the quality of plasticizing, it should be as low as possible to prevent the possibility of depreciation;
g) Mold temperature: The cooling of the product is good or bad, which has great influence on the quality. Therefore, the mold temperature must be able to accurately control the process. If possible, the mold temperature should be higher.