How can porous, eroded surfaces be avoided on extrudates?

This fault points to various possible causes:

1. Poor contact with calender rolls

Remedy:

• Clean calender rolls
• Increase roll temperature
• Increase contact pressure of calender rolls

2. Inadequate degassing

Remedy:

• Check vacuum (at least 100 mbar)
• Increase temperature before vent zone
• Reduce screw speed

3. Moisture

Remedy:
Predry material

back