- molds and plastics  injection troubleshooter -

• Sticking in Cavity - plastic injection troubleshooter

• Description:

At end of cycle, the moulding does not release from the mould but sticks in the cavity (female mould side).

• Causes:
machine · injection pressure too high
· injection speed too high
· holding time too long
· too much material feed
mould · cavity too hot – release is better from hot mould (20°C below HDT)
· mould too cold
· poor mould finish
material · melt too hot

• Actions:

1st. check cycle time: cooling
2nd. decrease injection pressure
3rd. decrease injection hold time
4th. decrease injection speed
5th decrease second pressure time
6th reduce and adjust feed for constant cushion
7th check for poor mould finish or corrosion on mould surface
8th increase mould opening time
9th decrease material temperature by lowering cylinder temperatures and/or nozzle
10th lower mould temperature
11th adjust the cavity temperature to a 20°C differential between mould halves
12th check mould for undercuts and/or insufficient draft and taper
13th use proper mould release

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