Processing Machinery
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PVDF Back Pressure and Shear Heat Accumulation
Problem Phenomenon
【Problem phenomenon】When plasticizing PVDF with high back pressure, the actual melt temperature exceeds the set value, and products discolor and lose strength
Cause Analysis
PVDF is shear-sensitive; shear heat generated by high back pressure and high screw speed superimposes on external heating, making the actual melt temperature exceed the limit; the CS-Seal guide explicitly specifies low back pressure to prevent shear heat accumulation
Solution
Take a low back pressure value and reduce screw speed; calibrate settings based on measured melt temperature; when plasticization is insufficient, prioritize raising external heat rather than adding shear; After adjustment, take consecutive samples to verify the effect, and resume mass production only after confirming stability
Key Takeaway
Shear heat is an invisible overtemperature source; PVDF requires low back pressure and low screw speed for plasticization; After confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence; Include this case in the defect archive as a reference for troubleshooting similar problems in the future
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