| Bubbles, Voids | |
| Possible Cause | Suggested Remedy |
| Nozzle temperature too hot | a. Reduce nozzle temperature b. Decrease melt temperature c. Reduce back pressure d. Increase screw decompression e. Use enough screw RPM’s to allow screw to recover using approximately 90% of the cooling time |
| Wrong nozzle design | Use reverse taper nozzle |
| Moisture in material | a. Review material handling to eliminate moisture pick up b. Dry material prior to moulding c. Use hopper dryers |