Causes Of Bubbles In Plastic Injection Parts

Bubbles will appear in the processing of our Plastic Injection Parts.  How do we need to solve such problems?

Bubbles will appear in the processing of our Plastic Injection Parts.  How do we need to solve such problems?

Now let's analyze in detail the causes of this problem and the relevant solutions.

First, when the wall thickness of plastic products is large, the cooling speed of the outer surface is faster than that of the central part. Therefore, as the cooling progresses, the resin in the central part shrinks and expands toward the surface, resulting in insufficient filling of the central part.  This condition is called vacuum bubble.

The main solutions are as follows.  According to the wall thickness, determine the reasonable gate and runner size.  General gate height should be 50% ~ 60% of the product wall thickness;  A certain amount of supplementary injection material is reserved until the gate is sealed.  The injection time should be slightly longer than the gate sealing time.  Reduce injection speed and increase injection pressure;  Materials with high melting viscosity grade are adopted.

Second, bubbles caused by the generation of volatile gases.

The main solutions are as follows: fully pre-drying, and after drying, detecting whether the moisture content of the dried material meets the injection molding requirements;  Reduce resin temperature to avoid decomposition gas.

  1. Bubbles caused by poor fluidity can be solved by increasing the temperature of resin and mold and increasing the injection speed.

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