Processing Machinery
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LLDPE film screw shear heat
Problem Phenomenon
Measured melt temperature is higher than the set value; the bubble is unstable and the film surface yellows.
Cause Analysis
LLDPE's high viscosity makes screw shear heating significant; at high speed, shear heat can make the melt temperature exceed the set value by tens of degrees.; During on-site troubleshooting, verify item by item according to this mechanism, avoiding blindly adjusting the machine based only on experience.
Solution
①Reduce screw speed; ②optimize screw compression ratio; ③calibrate the process with measured melt temperature; ④water-cool the screw when necessary.; After adjustment, continuously sample to verify the effect, and resume mass production only after confirming stability.
Key Takeaway
Shear heat is an invisible variable in LLDPE temperature control; measured melt temperature should be used as the process benchmark.; After confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence.
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