The design of the gate is related to the size and shape of the plastic part, the mold structure, the injection process conditions and the performance of the plastic part. However, according to the above two basic functions, the gate section is small and the length is short, because only this can satisfy the increase. Large flow rate, rapid cooling and sealing, easy to separate plastic parts and minimum gate residue.
The main points of the gate design can be summarized as follows:
(1) The gate is opened in a thick section of the plastic part, so that the molten material flows into the thin section from the thick material section to ensure complete filling;
(2) The choice of gate location should minimize the plastic filling process to reduce pressure loss;
(3) The choice of gate location should be beneficial to exclude air in the cavity;
(4) The gate should not be allowed to flush the melt directly into the cavity, otherwise a swirling flow will occur, leaving a spiral mark on the plastic part, especially the narrow gate is more prone to such defects;
(5) The choice of gate location should prevent the formation of stitching lines on the plastic surface. Especially in the ring or cylindrical plastic parts, the cold material should be added at the melt casting of the surface of the gate. well;
(6) The gate position of the injection mold with the elongated core should be far from the forming core, and the forming core should not be deformed by the flow;
(7) When forming large or flat plastic parts, a double gate can be used to prevent warpage, deformation and lack of material;
(8) The gate should be opened as far as possible without affecting the appearance of the plastic part, such as the bottom of the edge;
(9) The size of the gate depends on the size, shape and plastic properties of the plastic part;
(10) When designing multiple cavity injection molds, consider the balance of the flow channels to consider the balance of the gates, and try to make the molten materials uniformly charge at the same time.