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Molding Defects


Silver Streaks (Degradation)

Silver streaking from the center gate


Characteristics
  • Thin, long sparkler-type pattern.
  • Occurs over the complete molding immediately after passage through the gates

 
If bubbles are formed
during blank purging
If bubbles are not formed
during blank purging
Causes
  • 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
  • Poor nozzle contact
  • Too few sprues, runners, and gates
  • Bad gate positioning
  • Retention inside hot runners
Counter-
measures
  • 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
  • Examination of nozzle contact
  • Repair of sprues, runners, and gates
  • Correction of gate positions
  • Review of hot-runner temperature setting and injection speed

Please see our grade-specific molding condition sheet.


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 Customers are requested to independently determine the suitability of our materials for their products. We also request that sufficient attention also be paid to laws, regulations, and industrial rights.


molded part cracking
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