Material Drying
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PBT product bubbles (degradation)
Problem Phenomenon
Bubbles still exist after full drying, reduced after lowering temperature.
Cause Analysis
Excessive melt temperature or too long residence causes PBT thermal degradation gas generation; shear overheating also produces it.; when troubleshooting on site, verify item by item according to this mechanism, and avoid blindly adjusting the machine based only on experience
Solution
①Lower melt temperature; ②shorten residence time; ③reduce screw speed; ④clean the barrel.; after adjustment, continuously sample to verify the effect, and resume mass production only after confirming stability
Key Takeaway
Distinguish moisture and degradation for bubbles; if drying is ineffective, check the temperature history.; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence; include this case in the defect archive as a troubleshooting reference for similar problems in the future
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