1. In the case of inconsistent molding conditions or improper injection molding, various process parameters such as temperature, pressure and time must be controlled in strict accordance with the process requirements, especially the molding cycle of each plastic part must be consistent and cannot be changed at will.plastic molding size  If the injection pressure is too low, the pressure holding time is too short, the mold temperature is too low or uneven, the temperature at the barrel and the nozzle is too high, and the plastic part is not cooled enough, all of which will lead to the unstable size of the plastic part.

Under normal circumstances, using higher injection pressure and injection speed, appropriately extending the mold filling and pressure holding time, and increasing the mold temperature and material temperature are beneficial to overcome the dimensional instability failure.

2. Improper selection of molding raw materials The shrinkage rate of molding raw materials has a great influence on the dimensional accuracy of plastic parts. If the precision of molding equipment and molds is high, but the shrinkage rate of molding raw materials is large, it is difficult to ensure the dimensional accuracy of plastic parts.

In general, the greater the shrinkage rate of the molding material, the more difficult it is to ensure the dimensional accuracy of the plastic parts. Therefore, when selecting a molding resin, the influence of the shrinkage rate of the raw material after molding on the dimensional accuracy of the plastic part must be fully considered. For the selected raw materials, the variation range of the shrinkage rate cannot be greater than the requirements of the dimensional accuracy of the plastic parts.

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