Processing Machinery
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PVC Back Pressure and Screw Speed
Problem Phenomenon
After increasing back pressure, plasticization improved but product discoloration intensified and metering time also lengthened
Cause Analysis
PVC back pressure of 3-10MPa is sufficient; too high causes shear heat accumulation and degradation; screw speed 20-60rpm, high-speed friction heat also exceeds the limit; plasticization relies on temperature rather than shear
Solution
①Back pressure 5-10MPa for rigid, 3-8MPa for soft; ②screw speed 20-60rpm; ③for insufficient plasticization, prioritize fine-tuning temperature rather than back pressure
Key Takeaway
PVC plasticization management takes low shear as the guideline; both back pressure and speed are low, and temperature is the main adjustment means; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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