Material Drying
3 Aufrufe
Silver streaks caused by moisture in EVA processing
Problembeschreibung
White silver streak marks appear on EVA injection molded product surface
Ursachenanalyse
Raw material moisture >0.05% vaporizes during high temperature processing forming bubbles stretched into silver streaks; insufficient drying or hopper condensed water vapor
Lösung
1) Dry raw material at 80°C for 3-4h to moisture <0.02%; 2) Increase back pressure 0.5-1MPa for venting; 3) Reduce injection speed to avoid air entrapment; 4) Heat hopper to prevent condensed water vapor
Wichtigste Erkenntnis
Silver streaks are caused by moisture vaporization and stretching; drying and venting are the main countermeasures
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