Troubling shooting common moulding problems

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Everyday information the injection moulder requires from Invotec Solutions.

The below article can be used for machine setters and machine operators of injection moulding machines.

View our other articles form our setter and operators guide for injection moulders. Taken from our moulders catalogue (Toolbox Edition)

Below are a list of observations commonly see on injection moulded part and some suggested areas for further investigation.

Short Mouldings

Not enough material
Insufficient venting
Injection speed slow
Cylinder temperature low
Mould temperature low
Injection pressure low
Runners or gates too small

Sinking or Dimples

Injection speed too fast
Holding pressure low
Holding time too low
Gates too small or in wrong location
Shot too small
Cooling time short
Mould temperature too high
Runners or gates too small

Splay/Splash Marks

Material not dried properly
Melt too hot
Injection too fast
Gates too small

Expanding/Ballooning of Thick Parts

Material not dry
Melt too hot
Cooling time short
Mould temperature too high

Un-melted Granules

Barrel temperature profile wrong. Cold in the rear and middle zones
Cold spots in the nozzle or nozzle adaptor
Cold spots in the hot runner

Foamy Appearance in Product

Melt too hot
Material not dry