4. Balance of the gate
If a balanced runner system is not available, the following gate balancing method can be used to achieve the goal of uniform injection molding. This method is suitable for molds with a large number of cavities.
There are two ways to balance the gate: changing the length of the gate channel and changing the cross-sectional area of the gate. In another case, when the cavity has different projected areas, the gate needs to be balanced. In this case, to determine the size of the gate, first determine the size of one of the gates and find the corresponding one. Comparing the ratio of the cavity volume, and applying this ratio to the comparison of the gate and the corresponding cavity, the size of each gate can be successively obtained. After the actual test, the gate can be balanced. operating.
5. The position of the gate in the runner
When the plastic flows into the flow channel, the plastic first heats down (cools) and solidifies near the die face. When the plastic flows forward, it only flows through the solidified plastic layer. And because the plastic is a low heat transfer material, the solid plastic is formed. The green layer and the retaining layer are still flowable. Therefore, in the ideal case, the gate should be placed in the cross-flow layer position to make the best plastic flow effect. This is most common in circular and hexagonal cross-flow channels. However, the trapezoidal cross flow can not achieve this effect, because the gate can not be placed in the middle of the flow channel.