Extrusion & Post
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Uneven wall thickness of low density polyethylene extruded pipes
Problembeschreibung
Pipe wall thickness is uneven in the circumferential direction, showing eccentric wall phenomenon.
Uneven wall thickness affects pipe pressure resistance; the thin-wall side ruptures first under pressure, seriously affecting pipe use safety.
Ursachenanalyse
(1) Die and mandrel not concentric, uneven gap
(2) Uneven melt temperature; large temperature difference around the die circumference
(3) Uneven extruder output, melt pressure fluctuation
(4) Unstable haul-off speed or haul-off center not concentric with the die
(5) Pipe sizing sleeve worn or improperly installed
Lösung
(1) Adjust the concentricity of die and mandrel; circumferential gap error not exceeding ±0.05mm
(2) Check die heater band distribution, ensure circumferential temperature difference not exceeding ±3°C (160-220°C range)
(3) Check extruder plasticizing stability, ensure uniform output
(4) Align the haul-off device centerline with the die center
(5) Check the sizing sleeve; replace if severely worn, ensure concentric installation
Wichtigste Erkenntnis
Uneven wall thickness is caused by uneven die gap or uneven temperature; it needs to be solved from mold accuracy and temperature uniformity.
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