Causes of Air Bubbles in Injection Molded Parts

Air bubbles refer to small bubbles present within plastic parts. What are the causes of air bubbles in injection molded parts?

Firstly, in terms of the injection molding process:

Excessive injection speed:

If the injection speed is too high, it can trap air within the molten plastic.

Overly high melt temperature:

High melt temperatures can cause the plastic to degrade, releasing gases that form bubbles.

Excessive screw decompression:

If the screw retracts too much, it can draw air into the melt.

In terms of mold design:

Improper gate quantity or location: 

Incorrect gate placement can hinder proper venting, trapping air.

Significant structural variations:

Parts with large steps or drastic curved surfaces may trap air during filling.

Excessive holes or grids:Complex designs with numerous holes or grids can make it difficult to vent air effectively.