| Possible Cause |
Possible Solution |
| Material is oriented during injection process |
Decrease injection velocity for slower
filling.Increase mold temperature.
Adjust velocity profile to provide
homogeneous melt.
|
| There is a difference in packing density |
Increase hold pressure.
Increase injection fill speed to
fill mold faster.
Increase screw RPM. |
| Material flow into mold is not uniform. |
With multi-cavity molds, make sure
flow is balanced. |
| Part is too hot during ejection. |
Reduce melt temperature. Increase cooling time.
Reduce mold temperature |
| Molded part has stresses. |
Increase melt temperature.
Prevent overpacking at gate by reducing
hold pressure or reducing hold time.
Lengthen cooling time.
Delay knockout actuation.
Increase injection forward time.
Reduce temperature differential in mold. |
Knockout is operating improperly.
|
Knockout engaging too fast, slow down
ejectionNon-uniform operation of pins
Bearing area of knockout pins is too small.
Increase diameter and number of knockout pins.
Relocate knockout pins to strong area of part.
With delicate parts, change to air blow-off. |
Part design is incorrect.
|
Make sure part contains no sharp variations in cross sections. Correct
taper or draft insufficiencies. |
