How to determine plastic molding problems and finished product deformation?

Two of the biggest possibilities are:

The plastic parts are unevenly thick or the corners are not round enough, so the cooling shrinkage cannot be averaged, resulting in warping deformation.

For some flat plastic parts, for the appearance of the surface, the runner gate is located at the corner of the gate. When the glue is injected, the molten plastic can only be injected into the cavity at a high speed from one end, so the plastics solidified in the cavity are straightened to the same direction (called orientation), at which time the plastic is inside. The stress is very large; when the mold is released, the pieces are pulled back to the original state, and thus the deformation occurs.

In order to make the molten plastic fill the cavity smoothly, the design should avoid the following three points:

1. The thickness difference between the same plastic parts is too large.

2. There are excessive sharp angles.

3. The buffer zone is too short, making the difference between thickness and thickness very different.

From the gate analysis, the design of the mold should ensure that the plastic can enter the cavity smoothly. Therefore, the split runner should avoid the use of right-angle turning. The turning point is more suitable for the curved transition zone. Therefore, the short and thick runners are ideal. Reduce fluid resistance and fluid orientation. However, the problem to be considered is that an oversized gate will increase the flow path waste and also affect the appearance of the plastic part. In addition, if you are worried that the gate is too large and the scrap is increased, you can consider adding a certain proportion of Kaijie silicone powder to increase the fluidity of the raw material to reduce the fluid resistance, ensure the gate discharge is normal, and prevent the deformation of the finished product.

In addition, in order to avoid the tightness of the plastic filling, the demoulding is difficult and the deformation is caused, and adding a certain proportion of the releasing lubricant can improve the success rate of the demolding of the finished product. The cross-sectional shape of the runner is determined by the amount of shot and the shape of the product. After the product is more difficult to form part of the runner, the main channel should be relatively enlarged, so that the cross-sectional area of ​​the main channel is equal to the total cross-sectional area of ​​the channel.

Process solution:

1. The product has not been cooled when it is ejected → reduce the mold temperature → extend the cooling time → reduce the temperature of the raw material

2. The shape and thickness of the finished product are asymmetrical → fixed by a fixed frame after demoulding → changing the forming design

3. Too much filler → reduce injection pressure, speed, time and dose

4. Several gates are not evenly fed → change gate

5. Ejection system imbalance → improved ejection system

6. Uneven mold temperature → adjust mold temperature

7. The material near the gate is too loose and too strong → increase or decrease the injection time