The position of the gate has a great influence on the deformation of the injection molded part and has a direct impact on the quality of the injection molded part. Improper selection of the gate location will cause deformation of the injection molded part and many other defects. The choice of the gate position mainly depends on the shape and requirements of the injection molded part, and there are usually the following principles
1. The principle of large wall thickness and consistent flow. The gate location should be selected at the maximum wall thickness of the product, so that the plastic melt flows from the thick wall to the thin wall; it is also necessary to keep the flow from the gate to the cavity basically the same .
2. The principle of downstream flow The gate position should be set at the top of the plastic product so that the material flow fills down from the top of the product. It must not be set at the middle end of the injection molded part, let alone at the lower end of the injection molded part, so that the material flow can be filled countercurrently from the middle and lower end of the injection molded part.
3. The principle that the material flow flows from the open cavity to the narrow place. The gate position should be set in the open cavity of the mold, and it should also avoid the direct impact of the material flow on the core to cause flocculation and flow marks on the outer surface of the injection molded part.
4. The principle of preventing material loss and stable flow. Plastic product manufacturers should prevent jetting at the polyester mouth, which can produce serpentine flow or collection flow during the filling process.
5. In principle, the gate position should be set in the main force direction of the injection molded part, because the tensile stress and compressive stress are the largest in the flow direction of the injection material, especially the reinforcement with additives plastic.
6. The principle of avoiding weld marks where the strength of injection molded parts is relatively high. When selecting positions for plastic products, the size and accuracy of the injection molded parts, the shape and shrinkage directionality, the position of the weld marks and the fiber directionality of the injection molded parts should be considered, because the plastic will affect the body The flow direction and the shrinkage perpendicular to the flow direction are not the same, and the deformation, shrinkage and fiber directionality are also different. The strength of the weld line and the place where the injection molded parts are subject to greater force should avoid weld lines, and the number of weld lines The less the better.
7. The principle of short process flow and low kinetic energy and pressure loss. The gate position should make the flow of the material flow short, which is beneficial to the discharge of cavity gas and minimizes the change of the direction of the material flow. It is also necessary to avoid the material flow directly impacting the core or insert.
8. Appearance and the principle of easy removal of gate aggregates The surface of injection molded parts with high appearance requirements should not be provided with gates, and gate aggregates are easy to remove.
Post time: Nov-26-2021