Gaseous components in the plastic appear at the molding surface and collapse.
| Appearance |
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| Characteristics |
Thin,radial lines
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- Relatively few occurrences over a wide area
- Random occurrence at points removed from the gate
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- Thin,long sparkler-type pattern
- Thermal decomposition and deterioration
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| Cause /
Countermeasures |
Insufficient drying
More Details |
Inclusion of air
More Details |
Degradation
More Details |
| Appearance |
|
| Characteristics |
- Willow-shaped and elongated.
- Immediately after passing the gate, it occurs in the entire molded product.
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| Cause /
Countermeasures |
Insufficient drying
More Details |
| Appearance |
|
| Characteristics |
- Relatively few occurrences over a wide area
- Random occurrence at points removed from the gate
|
| Cause /
Countermeasures |
Inclusion of air
More Details |
| Appearance |
|
| Characteristics |
- Thin,long sparkler-type pattern
- Thermal decomposition and deterioration
|
| Cause /
Countermeasures |
Degradation
More Details |
Insufficient Drying
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Silver streaking form the center gate
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| Characteristics |
Occurs over the complete molding immediately after passage through the gates.
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| Cause |
- Problems with drying equipment and drying conditions
- Inappropriate drying temperature and time
- Low volume of warm air in the dryer
- Inadequate hopper capacity (i.e., short drying time) - Faulty temperature regulator
- Blocking of the air filter
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| Countermeasures |
Review the drying conditions
- Optimization of drying conditions
- Adjustment of the dryer's warm air volume
- Cleaning of the air filter
- Optimization of the hopper capacity
- Repair of the temperature regulator
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* Please also refer to our grade search and product design guide .
Inclusion of air
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Silver streaking form the center gate
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| Characteristics |
- Relatively few occurrences over a wide area
- Random occurrence at points removed from the gate
|
| Cause |
Molding
conditions |
Die Conditions |
Molding conditions |
- Insufficient mixing of ground matter
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- Cold flow mixing
- No cold slag well
- Too few sprues, runners, and gates
- Gate gas mixing (i.e., tunnel gate restrictions)
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- Low nozzle and cylinder temperatures
- Excessive metal cooling
- Entry of air into the cylinder
- Excessive metal cooling
- Entry of air into the cylinder
- Excessively high molding temperature, injection pressure, and injection speed
- Poorly-balanced cylinder temperature settings
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Insufficient back pressure
- Excessive amount of pull back
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| Countermeasures |
Examine the material surface
- Correction of the mixing of ground matter
- Elimination of dust
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Examine the die
- Installation of a cold slag well
- Repair of sprues, runners, and gates
- Correction of gate height and angle
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Examine the molding conditions
- Modification of the cylinder temperature setting
- Correction of the screw speed
- Correction of the back pressure
- Correction of the surge back volume
- Correction of the die temperature
* Please also refer to our grade search and product design guide .
Degradation
 |
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Silver streaking from the center gate
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| Characteristics |
- Thin, long sparkler-type pattern.
- Occurs over the complete molding immediately after passage through the gates
|
| Cause |
If bubbles are formed during blank purging
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If bubbles are not formed during blank purging
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- Faulty heater band(i.e., localized heating by the nozzle heater)
- Excessively high nozzle temperature, cylinder temperature, injection speed, or screw speed
- In-cylinder retention
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- Poor nozzle contact
- Too few sprues, runners, and gates
- Bad gate positioning
- Retention inside hot runners
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| Countermeasures |
- Heater band repair
- Optimization of the balance between molding machine capacity and molded component capacit
- Optimization of the nozzle temperature, cylinder temperature, injection speed,or screw speed
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- Examination of nozzle contact
- Repair of sprues, runners, and gates
- Correction of gate positions
- Review of hot-runner temperature setting and injection speed
|
* Please also refer to our grade search and product design guide .
