Extrusion & Post
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PVC Extrusion Melt Pressure Abnormality
Problem Phenomenon
Die head pressure continuously high or fluctuating, unstable output, product dimensions and appearance fluctuate accordingly.
Cause Analysis
Poor plasticization makes melt viscosity high, screen pack blockage, too low temperature; insufficient formula lubrication causes high internal friction; abnormal pressure is a comprehensive reflection of plasticization and lubrication state; during on-site troubleshooting, verify item by item according to this mechanism, avoid blindly adjusting the machine based solely on experience.
Solution
①Increase temperature and plasticization degree; ②Replace screen pack and monitor pressure differential changes; ③Check internal/external lubrication system balance; ④Stabilize feeding (forced feeding/stirring to prevent bridging); ⑤Check screw and die head flow channel condition.
Key Takeaway
PVC 'abnormal pressure = mirror of plasticization and lubrication': pressure is the comprehensive health indicator of the extrusion system; continuously high or fluctuating, don't expect stable products — first straighten out plasticization and lubrication.
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