Material Drying
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EMA Processing Moisture Causes Silver Streaks
Problem Phenomenon
White silver streaks appear on the surface of EMA injection molded products
Cause Analysis
Raw material contains moisture >0.05%, which vaporizes during high-temperature processing to form bubbles that are stretched into silver streaks; insufficient drying or condensed water vapor in the hopper
Solution
1) Dry the 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 the hopper to prevent condensed water vapor
Key Takeaway
Silver streaks are caused by moisture vaporization and stretching; drying and venting are the main countermeasures
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