How to choose the correct injection mold gate location?
1. 5 requirements for gate location
1)appearance requirements (gate marks, welding wiring)
2)product functional requirements
3)mold processing requirements
4)warping deformation of products
5)gate capacity is not easy to remove
6) the molding process is easy to control
2. Impact on production and function
1) length determines injection pressure, clamping force, and length of product filling can reduce injection pressure and clamping force.
2) the location of the gate will affect the pressure holding, the size of pressure holding and whether the pressure holding is balanced. Keep the gate away from the stress position of the product (such as the bearing) to avoid residual stress. Exhaust gas must be considered in the location of the gate to avoid wind accumulation.
3. Tips for selecting gate location
The gate is a short groove with a small cross-section area that connects the runner to the cavity. The cross section area should be small so as to achieve the following effects:
1)soon after injection, the gate is cold knot
2)easy to remove nozzle
3)after dewatering, only a few marks are left
4)make the packing of multiple cavities easier to control
5) reduce overpacking
Gate location and size. injection mold
1)placing the gate at the thickest part of the product, pouring from the thickest part can provide better filling and pressure retaining effect. If the pressure is not enough, the thinner area will solidify faster than the thicker area. Avoid placing the gate on the sudden change of thickness to avoid hysteresis or short shooting.
2)if possible, pouring from the center of the product, placing the gate in the center of the product can provide equal length of flow, the size of flow will affect the required injection pressure, the central pouring makes the pressure in all directions uniform, can avoid uneven volume contraction.
3) when the plastic flows into the flow channel, the plastic near the mold surface is the first to reduce heat (cooling) and solidify. When the plastic flows forward, it just flows through the layer of solidified plastic. And because plastic is a low heat transfer material, solid plastic formed absolutely green layer and retaining layer can still flow. Therefore, in an ideal situation, the gate should be located in the cross runner layer to allow the best plastic flow effect. This is most often seen in circular and hexagonal crosswalks. However, trapezoidal crosswalks do not achieve this effect because the sprue cannot be placed in the middle of the runner.
When determining gate location, the following principles should be adhered to:
1)the rubber materials injected into each part of the cavity should be as average as possible;
2)the rubber material injected into the mold should maintain a uniform and stable flow front at all stages of the injection process;
3)the possible occurrence of welding marks, bubbles, pits, virtual positions, insufficient injection of glue and glue spraying shall be considered;
4）try to make the operation of the dewatering port easy, preferably automatic;
5) the location of gate shall be coordinated with all aspects.
There are no hard and fast rules for gate design. Most gate design methods are based on experience, but there are two basic elements to be considered: injection mold
1）the larger the area of the cross section of the gate, the better, and the shorter the length of the groove, so as to reduce the pressure loss when the plastic passes through.
2) the gate should be narrow to facilitate cold junction and prevent excessive plastic backflow. Therefore, the gate should be in the center of the runner and its cross section should be as round as possible.However, the gate switch is usually determined by the module switch.