VARIETY of DEFECTIVE MOLD and CAUSE

Condition FILLING MISS

Cause Molding Machine :
1.Low material temperature
2. Low injection pressure
3. Material feed shortage
4. Too small nozzle hole diameter
5. Cylinder nozzle clogging
Cause Mold :
1. Small gate or runner
2. Inadequate gate position
3. Inadequate position of or no air vent
4. Low mold temperature
5. Cold slag clogging in runner or gate
Cause Material :
1. Low fluidity
2. Low lubricity


Condition F I N

Cause Molding Machine :
1. Weak clamping force
2. High injection pressure
3. Material over feed
4. High material temperature
Cause Mold :
1. Flaw or foreign body on parting plane
2. Wide project area to the machine
3. High mold temperature
Cause Material :
1. Excessive fluidity


Condition SHRINKAGE CAVITY

Cause Molding Machine :
1. Low injection pressure
2. Slow injection
3. High material temperature
4. Short pressure retaining
5. Material feed shortage
Cause Mold :
1. High mold temperature
2. Products thickness uneven
3. Small gate
4. Cooling time shortage
5. Inadequate ejection
Cause Material :
1. Material too supple
2. High contraction coefficient


Condition WELD LINE

Cause Molding Machine :
1. Low material temperature
2. Low injection pressure
3. Slow injection
Cause Mold :
1. Small gate or runner
2. Low mold temperature
3. Inadequate gate position
4. Inadequate air vent
Cause Material :
1. Rapid curring
2. Insufficient drying
3. Low lubricity


Condition NO GOOD LUSTER/HAZE

Cause Molding Machine :
1. Nozzle clogging or small diameter
2. Material feed shortage
Cause Mold :
1. Inadequate air vent
2. Small gate or runner
3. Insufficient measures for corrosion
4. Excessive mold release agent
Cause Material :
1. Insufficient drying
2. High volatility
3. A foreign body mixed


Condition FLOW MARK

Cause Molding Machine :
1. Low material temperature
2. Low injection pressure
3. Slow injection
4. Too small nozzle diameter
Cause Mold :
1. Low mold temperature
2. Products thickness uneven
3. Small gate or runner
4. Small or no slag well
Cause Material :
1. Low fluidity
2. Low lubricity


Condition SILVER STREK/BUBLE

Cause Molding Machine :
1. Fast injection
2. Low injection pressure
3. Small injection capacity
4. Short pressure retaining
5. High material temperature
Cause Mold :
1. Inadequate air vent
2. Small gate or runner
3. Products thickness uneven
4. Small or no slag well
Cause Material ;
1. Insufficient drying
2. High volaticity


Condition BLACK STREAK/BURNED

Cause Molding Machine :
1. High material temperature
2. Long stay inside cylinder
3. Flaw inside cylinder
Cause Mold :
1. Inadequate position of of no air vent
2. Small slag well
3. Oil or something inside cavity
Cause Material :
1. Excessive lubricant
2. Insufficient drying


Condition BAD RELEASE of SPUE or PRODUCTs

Cause Molding Machine :
1. High injection pressure
2. Material overfeed
Cause Mold ;
1. Dislocation of nozzle hole and sprue hole
2. High mold temperature
3. Low sprue gradient
4. Undercut on or low gradient of cavity
Cause Material :
1. Insufficient lubricant


Condition WARPAGE/DEFORMATION

Cause Molding Machine :
1. High injection pressure
2. Long pressure retaining
3. Insufficient annealing
Cause Mold ;
1. No good ejection mechanism
2. High mold temoperature
3. Big gate
4. Uneven cooling
Cause Material :
1. Low fluidity
2. High contraction coefficient
3. Low material rigidity.


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