- molds and plastics  injection troubleshooter -

• Blisters - plastic injection troubleshooter

• Description:

Small air-or gas-filled hollows in the moulding, cooling voids.

• Causes:
machine · injection pressure too low
· inadequate functioning of back flow valve
· suck-back too long
· plasticizing too fast
· air trap in the hopper feed
· improper feed
mould · volatiles and trapped gas
· mould temperature too low
· thin to thick transition
material · melt overheating

• Actions:

1st. control holding / injection pressure
2nd. increase back pressure
3rd. increase mould temperature
4th. check back flow valve
5th allow for adequate venting
6th enlarge gate
7th shorten land length

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