During injection molding, the cross-sectional size of the gate should be small rather than large. When determining the gate size, it should be smaller first, and then in the process of mold testing, it should be corrected according to the cavity filling situation, especially for the the first mock examination with multiple cavities, through the correction, all cavities can be filled evenly at the same time. In order to avoid deformation caused by stress, it is generally advisable to take a thin gate; To avoid shrinkage marks, the gate should be thick; If the filling is insufficient, it is advisable to take a wider width and within the allowable range of the mold. The length of the gate and runner should be shorter, with fewer twists and turns being better; The gate that affects the appearance of injection molded parts should be as small as possible: for products with large mass stars, large body shapes, and large shrinkage, the gate should be as large as possible.

During injection molding, a small gate can increase the flow rate of the molten material, increase the friction of the molten material, and increase the temperature of the molten material. The result is a decrease in the viscosity of the molten material, which is beneficial for mold filling. However, due to the high resistance of the small gate, there is a significant loss of injection pressure, which is not conducive to melt filling, especially for the thin structure of the remote injection molded parts. Due to the rapid solidification of the small gate and its unfavorable effect on the pressure retention and shrinkage of plastic products, the shrinkage marks generated by the injection molded parts are large, but the internal stress generated by the injection molded parts is relatively small; At the same time, it can shorten the injection molding cycle and facilitate the cleaning of the condensate at the gate. Some products should not have a gate that is too small, such as some thick walled products. During the injection process, it is necessary to perform at least two additional presses to meet the requirements of plastic products. A gate that is too small can cause premature solidification at the gate, making it difficult to fill the material and causing product defects.

The form of the gate and the size of the cross-section can affect the deformation of the injection molded part, and different shapes of injection molded parts should adopt different gate shapes and cross-sectional sizes. The internal stress generated by various gate forms and cross-sectional sizes during injection molding is also different, and the internal stress of injection molded parts is also one of the main factors that cause deformation of injection molded parts.