Mold-Masters Hot Runner - Dimensional Irregularities

20.6.6 Dimensional Irregularities
The nished product is of a di󰀨erent dimensional value than originally
designed or previous production.
Probable Cause:
1. Molding Machine
• Low injection pressure
• Short hold pressure time
• Damaged backow / check ring valve
• Short cycle time
• Cylinder clearance too big
• Nozzle heaters malfunctioning
2. Mold
• Temperature setting too high
• Small gate size resulting in wrong pressure
• Incorrect gate location
• Incorrect mold conguration / size
3. Material
• Generally not a material related issue unless excessive regrind is
used
Solution (in sequence):
1. Increase injection pressure
2. Increase cooling time
3. Increase mold temperature
4. Ensure cycle time is consistent
5. Monitor molding machine for irregularities
6. Balance regrind ratio
7. Increase gate size
8. Decrease gate land length
9. Balance the runner and / or gate system
10. Decrease cavity quantity
20-10
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