Material Drying
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PET moisture content measurement
Problem Phenomenon
Relying on drying time experience to start the machine, the white haze defect rate fluctuates greatly between batches
Cause Analysis
Different batches of chips have different initial moisture contents, and a fixed drying time cannot guarantee a consistent drying endpoint; during on-site troubleshooting, verify item by item according to this mechanism, and avoid blindly adjusting the machine based only on experience
Solution
Equip a rapid moisture meter to test each batch, judging by 50 ppm for bottle grade and 200 ppm for injection grade; test records are associated with the production batch; after adjustment, take consecutive samples to verify the effect, and resume mass production only after confirming stability
Key Takeaway
The drying endpoint must be judged by actual measurement, and experience-based time is unreliable; 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 subsequent similar problems
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