How can bubbles be avoided in the extrudate?

This fault points to various possible causes:

1. Moisture

Remedy:
Predry material

2. Inadequate venting

Remedy:

• Examine vacuum (at least 100 mbar) - Increase temperature before vent zone
• Lower screw speed

 
3. Output too high

Remedy:
Decrease screw speed (recommendation: do not exceed peripheral screw speed of 0.3 m/s)

4. Melt temperature too high (material decomposition)

Remedy:
Reduce processing temperatures or screw speed

5. Contamination with foreign material

Remedy:
Pay attention to cleanliness

6. Die temperature too high

Remedy:
Reduce die temperature

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