Material Drying
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POM surface streaks and silver threads
Fenómeno do problema
Irregular streaks and silver threads appear on the product surface, worsening during periods of high barrel temperature and improving after purging and cooling.
Análise das causas
Excessively long material residence time causes slight degradation producing gas, or the pellets contain trace moisture; degradation gas is stretched into streaks during filling and adheres to the surface.; during on-site troubleshooting, verify item by item according to this mechanism, and avoid blindly adjusting the machine based only on experience
Solução
①Lower the barrel temperature and shorten residence time; ②clean the barrel to remove degraded material; ③pre-dry at 80℃ if necessary; ④stabilize production cycle to avoid long material storage.
Conclusão principal
Streaks and silver threads mostly originate from degradation or trace moisture; troubleshoot from the three aspects of temperature, residence time, and drying, starting with the easiest adjustment, cooling.; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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