3. Tips for choosing a gate location
(1) Place the gate at the thickest part of the product, and the pouring from the thickest part can provide better filling and pressure holding effect. If the holding pressure is insufficient, the thinner area will solidify faster than the thicker area, avoiding the gate being placed at a sudden change in thickness to avoid hysteresis or short shots.
(2) If possible, pouring from the center of the product, placing the gate in the center of the product can provide the same length of flow, the length of the flow will affect the required injection pressure, and the central pouring will make the pressure in all directions uniform. Can avoid uneven volume shrinkage.
(3) Gate: The gate is a short groove with a small cross-sectional area for connecting the flow channel and the cavity. The cross-sectional area is small, so as to obtain the following effects:
1) soon after the mold hole is injected, the gate is cold-knotted;
2) The water removal port is simple;
3) Only a few traces are left after the water removal is completed;
4) making the filling of multiple cavity points easier to control;
5) Reduce the excessive amount of filler.
There are no hard and fast rules for designing gates. Most of them are based on experience, but there are two basic elements that need to be compromised:
(1) The larger the cross-sectional area of the gate, the better, and the shorter the length of the channel, the better, to reduce the pressure loss when the plastic passes.
(2) The gate shall be narrow so as to be easy to cold and prevent excessive plastic from flowing backwards. Therefore, the gate is in the center of the flow channel, and its cross section should be as circular as possible. However, the gate switch is usually made of a module. The switch to decide.
(3) Gate size: The size of the gate can be determined by the cross-sectional area and the length of the gate. The following factors can determine the optimal size of the gate:
1) rubber flow characteristics;
2) the thickness of the module;
3) the amount of rubber injected into the cavity;
4) melting temperature;
5) Tool temperature.
When determining the location of the gate, the following principles should be followed:
(1) The rubber injected into each part of the cavity should be as even as possible.
(2) The rubber compound injected into the mold shall maintain a uniform and stable flow front at all stages of the injection process.
(3) It should be considered that there may be weld marks, bubbles, pockets, imaginary position, insufficient shot glue and glue spray.
(4) It should be as easy as possible to make the water removal operation easy, it is best to operate automatically.
(5) The position of the gate should be compatible with all aspects.