Material Drying
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Haze and blooming on PPO surface
Problem Phenomenon
Haze (blush) and uneven gloss appear on the surface of PPO products, with some areas hazy and some areas shiny, and appearance parts are judged unqualified.
Cause Analysis
Material moisture, excessive injection speed, or excessive melt temperature cause surface microscopic abnormalities; improper mold temperature and cooling overheat the surface layer during the filling stage; mismatched surface treatment processes amplify the visual difference.
Solution
①Strictly pre-dry to exclude the moisture factor; ②optimize mold temperature and cooling to avoid surface overheating; ③optimize back pressure and injection speed to avoid air entrapment; ④unify the cavity surface treatment grade.
Key Takeaway
PPO haze is the surface mapping of multiple factors of moisture, temperature, and speed; item-by-item investigation starts from drying; cavity surface consistency is the basic guarantee.; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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