|
Abnormal
|
reason
|
process
|
| Vacuum foam |
Insufficient capacity from the lack of shrinkage caused by quenching around thick wall section
Unsuitable mold temperature
Unsuitable cylinder temperature
Insufficient injection pressure and pressure keeping |
Eliminate thickness deviation
Modify gate position to meet at right angles at thick wall section
Raise mold temperature
Lower cylinder temperature
Raise injection pressure and pressure keeping |
| Weld mark |
Unsuitable cylinder temperature
Lack of injection pressure
Unsuitable mold temperature
Lack of degassing in the cavity |
Raise cylinder temperature
Raise injection pressure
Raise mold temperature
Add air vent |
Sink mark |
Caused by the shrinkage that results from slow cooling of the surface of thick wall parts
(unsuitable thickness
Insufficient injection pressure
Insufficient injection capacity
Mold temperature is too high or lack of cooling
Insufficient pressure maintained
Insufficient gate dimension |
Reduce thickness deviation
Raise injection pressure
Increase injection capacity
Increase cooling time if mold temperature is suitable
Extend holding time
Increase gate dimension |
Burning
(whole or partial change
in color) |
Unsuitable cylinder temperature
Retention occurs partially in cylinder
Seepage into the screw joint between cylinder and nozzle
Inclusion of check valve and ring
Decomposition from insufficient pellet drying
Excessive capacity of molding machine |
Lower the cylinder temperature
Eliminate dead angles
Eliminate gap around screw jointEliminate detention by redesigning
Provide pre-drying as recommended
Change to a suitable capacity machine |
| Silver streak |
Unsuitable cylinder temperature
Long detention time
Unsuitable injection speed
Unsuitable gate dimension
Insufficient pellet drying
Unsuitable injection pressure |
Lower cylinder temperature
Eliminate retention
Slow injection speed
Enlarge the gate size
Provide pre-drying as recommended
Reduce injection pressure |
Wave around gate
(devitrifying) |
Unsuitable injection speed
Unsuitable pressure holding interval
Unsuitable mold temperature
Unsuitable gate dimension |
Slow injection speed
Shorten pressure holding interval to avoid the presence of molten materials in the cavity after filling
Raise mold temperature
Enlarge the gate size |
| Jetting and flow marks |
Unsuitable mold temperature
Unsuitable injection pressure
Unsuitable gate dimension |
Raise temperature
Reduce injection pressure
Enlarge the gate size |
Defective ejection
(defective mold release) |
Lack of gradient in core and cavity
Unsuitable cycle
Unsuitable cylinder temperature
Unsuitable position and number of knock pins
Vacuum with molded products in mold release
from core
Unsuitable mold temperature
Injection pressure is too high and filling capacity is too large |
Add a draft
Cooling time is too short or extremely long
Lower molding temperature to reasonable value
Examine reasonable position and number
Often occurs when the surface of the core is smooth. Eject with plate not with pin, and add vent pin
Lower the mold temperature and lengthen the cycle
Reduce injection pressure and reduce weight of materials |
