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The solution of bubble issue during injection molding process

 According to the causes of bubbles, the countermeasures are as follows:


(1) When the wall thickness of the product is large, the cooling speed of its external surface is faster than that of the central plastic part. Therefore, as the cooling goes on, the resin at the central part shrinks and expands towards the surface, resulting in insufficient filling at the central part. This condition is called a vacuum bubble. Solutions mainly include:
A) Determine the reasonable gate and gate size according to the wall thickness. Generally, gate height shall be 50% ~ 60% of the wall thickness of the product.
B) Until the gate is sealed, a certain amount of supplementary injection material is left.
C) The injection time should be slightly longer than the gate sealing time.
D) Reduce the injection speed and increase the injection pressure;
E) Use materials with high melt viscosity.

2) The bubbles caused by the production of volatile gases are mainly solved as follows:
A) Sufficient pre-drying.
B) Reduce the resin temperature to avoid the generation of decomposition gas.


(3) Bubbles caused by poor fluidity can be solved by raising the temperature of mold and increasing the injection speed.

We are engaged in a variety of industries mold and injection molding parts for more than 25 years.​
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