appearance of bubbles

The appearance of bubbles or cavities in the side wall of the preform
Many manufacturers of preform injections suffer from the appearance of many problems, including bubbles or cavities that appear on both sides of the preform. This problem is due to many reasons, which are:
• Air entry during preform formation due to insufficient melting pressure of the material
• Excessive pressure relief leads to air intake during injection
• Early melting of the material due to increased temperature in the external feeding zone
Therefore, to solve this problem, follow the following steps
• Increase the back pressure of the screw.
• Check the plastic plug in the feeding area
• Reduce the temperature of the feeding area
• Reduce stress by reducing withdrawal time.