Material Drying
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PMMA Insufficient Drying Bubbles and Silver Streaks
Fenómeno do problema
Bubbles appear inside transparent products, silver streaks are distributed along the flow direction on the surface, moisture content test exceeds the standard, and defects disappear after sufficient drying.
Análise das causas
After PMMA absorbs moisture, the moisture content rises, and the moisture vaporizes during melting to form bubbles and silver streaks; transparent parts are extremely sensitive to trace moisture, and the moisture content must be reduced to below 0.05% or even 0.02%.
Solução
①Dehumidifying drying 80~90℃×3~4 hours; ②moisture content controlled below 0.05%, below 0.02% for optical parts; ③sealed conveying after drying; ④extend drying time in humid environments.
Conclusão principal
Drying is the first quality gate in PMMA processing; eighty percent of bubbles and silver streaks on transparent parts originate from moisture, and drying verification should be the first choice in abnormality troubleshooting.; After confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence.
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