Inconsistent melting and pigmentation.
A homogeneous melt is crucial for maintaining part quality.
A inconsistent melt may be evident by poor melting of the granules or poor colour dispersion.
1. Barrel temperatures too low, particularly at rear zone.
2. Increase screw speed.
3. Increase back pressure.
4. Check for proper screw compression ratio.
5. Check for wear of the screw or barrel.
6. Check for proper screw flight depth.
7. Increase the plasticising capacity of the machine - use a larger screw / barrel combination.