Causes and solutions for bubbles in injection molded PP

Update:23-12-2020
Summary:

  Causes and solutions for bubbles in injection mo […]

 

Causes and solutions for bubbles in injection molded PP. Injection molded PP products have bubbles:

PP bubble solves problem one:

1 Increase the mold temperature and reduce the injection time and cycle "Because PP bubbles are formed by internal shrinkage due to excessive cooling time"

2 Increase back pressure and extend injection time Use high pressure and low speed

PP materials generally do not have bubbles (because of low moisture absorption), which may be caused by the filling of PP materials during granulation. If the solution to the process is: 1. Add a spare gang to bake the material; 2. Increase the back pressure of the injection molding and slow down the injection speed; 3. The barrel temperature should not be too high.

Originally PP material is a very good material, 1 first consider your mold structure, where the bubbles are formed, second, the temperature of the bubble tube should not be too high, 3 the thickness of the product, 4 do not draw the glue and try/or draw less glue . In fact, injection molding efficiency adjustment should not only look at the parameters, it is boring, and more analysis of the problem is the right way. Sometimes, the adjustment of the machine is not based on the top 5 of the molding.

PP bubbles solve problem two:

1. The storage speed is too fast, add some back pressure appropriately

2. The raw material is not dry enough and contains moisture

3. The plastic stays in the barrel for too long

4. The screw injection is too long

5. Poor mold exhaust

6. The injection pressure is too small and the injection speed is too high

7. The melt temperature is too high and the mold temperature is too low

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