How can streaks be avoided in the direction of extrusion?
This fault points to various possible causes:
1. Moisture
Remedy:
Predry material or examine drying process (see under "Predrying")
2. Inadequate venting
Remedy:
- Examine vacuum (at least 100 mbar)
- Increase temperature before the vent zone
- Reduce screw speed (recommendation: do not exceed peripheral screw speed of 0.3 m/s)
3. Output too high
Remedy:
Reduce screw speed
4. Melt temperature too high (material decomposition)
Remedy:
Reduce processing temperatures or screw speed
5. Die lips and / or calibrating unit damaged
Remedy:
Grind and polish affected parts
6. Material deposits on die lips
Remedy:
Remove with copper or wooden rod, clean with cloth and polishing paste
7. Previous processing of plastic with higher molecular weight
Remedy:
Clean unit, especially screw
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