Injection Molding
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Uneven and Fluctuating Melt Temperature in PE '2079851475616104452
Problem Phenomenon
Gloss and shrinkage are inconsistent in some areas of products from the same mold, or melt temperature fluctuation causes unstable quality.
Cause Analysis
Uneven plasticization and large melt temperature differences; insufficient back pressure or poor screw mixing capability leads to non-uniform melt; shear heat generated by excessive screw speed/back pressure makes the actual melt temperature far exceed the set value.
Solution
①Appropriately increase back pressure to improve mixing uniformity; ②Check the screw mixing section, and replace with a mixing-type screw if necessary; ③Use temperature measurement means to actually measure the melt temperature and calibrate the process; ④Reduce excessive speed/back pressure to control shear heat; ⑤Stabilize the melt temperature curve.
Key Takeaway
PE melt quality = 'uniformity + temperature control': back pressure and screw mixing determine uniformity, and shear heat determines the actual temperature; the set temperature does not equal the melt temperature — actual measurement is the truth.
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