Material Drying
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PA66 drying temperature upper limit 90℃
Fenómeno do problema
Pellets turn yellow and agglomerate after drying, injection molded products yellowish and more brittle
Análise das causas
Drying temperature exceeding 90℃ causes surface oxidation yellowing of PA66 pellets and even sticking; oxidation products also become triggers for subsequent degradation and color difference, over-drying damage is likewise irreversible
Solução
①Hot air dehumidifying drying strictly controlled at 80-90℃; ②yellowed pellets are judged over-dried and scrapped; ③if drying is not completed after 8 hours, lower to 70-80℃ for heat preservation while waiting for production
Conclusão principal
PA66 drying temperature upper limit 90℃ is stricter than PA6; what over-temperature brings is not more dryness but oxidative degradation, over-dried material can only be scrapped; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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