How To Deal With Bubbles In TPU Products

How To Deal With Bubbles In TPU Products

Date:Jul 29, 2019

During the molding process of injection molded TPU products, there are sometimes many bubbles, which not only affect its strength and mechanical properties, but also affect the appearance of the products. Generally, when the product is uneven in thickness or when the mold has protruding ribs, the cooling rate of the material in the mold is different, resulting in uneven shrinkage and easy formation of bubbles, so special attention must be paid to the mold design. In addition, the raw material is not sufficiently dried, and still contains a part of water, which is decomposed into a gas by heat when it is melted, and easily enters into the cavity to form bubbles. Therefore, when bubbles appear in the product, the following factors can be checked and processed.

Cause:

1. The raw materials are wet

2. Insufficient injection

3. The injection speed is too fast

4. The raw material temperature is too high

5. Low back pressure

6. The finished section, rib or column is too thick

7. The sprue overflow is too small

8. Mold temperature is not average

9. The screw retreats too fast


Approach:

1. Completely toasted

2. Check temperature, injection pressure and injection time

3. Reduce the injection speed

4. Reduce the melt temperature

5. Improve back pressure to appropriate

6. Change the design of the finished product or the location of the spill

7. Increase the sprue and entrance

8. Adjust the mold temperature to uniform

9. Reduce the screw back speed


B03


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