The thick part of the plastic product processed by injection molding is easy to produce bubbles, and the reason for the formation is exactly the same as that of the depression of the molded product. The cavity formed in the thick wall of the shaped product is a bubble. According to the cause of the bubbles, the countermeasures taken are: when the product wall thickness is large, the cooling rate of the outer surface is faster than the cooling rate of the center part. Therefore, as the cooling progresses, the plastic in the center part shrinks and expands to the surface, resulting in insufficient filling of the center part. This is called a vacuum bubble.

The main solutions are:

1. Determine the reasonable gate and gate size according to the wall thickness. Generally, the gate height should be 50%-60% of the product wall thickness.

2. Before adding the injection gate, a certain amount of sealing material will be reserved.

3. The injection time should be slightly longer than the gate sealing time.

4. Reduce the injection speed, increase the injection pressure, and use materials with high melt viscosity.

5. Due to the generation of volatile bubbles, the main solutions are: (1) Fully pre-drying. (2) Lower the resin temperature to avoid decomposition of gas. Increasing the temperature of the resin and the mold and increasing the injection speed can solve the problem of air bubbles caused by poor fluidity.

6. Warpage deformation of injection molded parts is a very difficult problem. It should be solved mainly from the aspect of mold design, but the effect of adjusting the forming conditions is very limited. When the deformation is caused by the residual stress caused by the molding conditions, the stress can be eliminated by reducing the injection pressure, increasing the mold temperature, making the mold temperature uniform, increasing the resin temperature, or using annealing methods.

Green Vitality Industry Co .,Ltd specializes in injection mold and injection molding.

Please feel free to contact us if you have new mould projects.