Depending on the cause of the bubbles, the countermeasures are as follows

1. When the wall thickness of the product is large, the cooling rate of the outer surface is faster than that of the center, therefore, with the cooling progress, the plastic resin in the center expands to the surface while shrinking, so that the center part is underfilled. This situation is known as a vacuum bubble solution, and the main solutions are:

a. According to the wall thickness, determine the reasonable gate and sprue size, and the general gate height should be 50%~60% of the wall thickness of the product.

b. Until the gate is sealed, a certain amount of supplementary injection 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 grades.　　

2. The bubbles caused by the generation of volatile gases, the main solutions are:　

a. Pre-dry thoroughly.　　

b. Reduce the temperature of the resin to avoid the generation of decomposition gas.　　

3. Air bubbles caused by poor fluidity can be solved by increasing the temperature of resin and mold and increasing the injection speed.