Processing Machinery
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Rough inner wall of linear low density polyethylene extruded products (Variant: mass production scenario)
Fenómeno del problema
The inner wall of pipes or profiles is rough and uneven, with visible stripes or particles.
Rough inner wall affects pipe fluid resistance and hygienic performance, and may breed bacteria in water supply pipes.
In particular, in continuous mass production, this problem is more prominent and requires key attention.
Análisis de la causa
(1) Mandrel temperature too low; stick-slip flow of melt on the mandrel surface
(2) Insufficient mandrel surface finish or wear
(3) Insufficient compressed air pressure (during internal pressure sizing)
(4) Melt temperature too low, poor flowability
(5) Insufficient screw plasticization, unmelted particles in the melt
(6) In continuous mass production, process parameter fluctuations or equipment status changes have aggravated this problem
Solución
(1) Appropriately increase mandrel temperature, match with die temperature (190-250°C range)
(2) Polish mandrel surface to Ra≤0.2μm, chrome plating when necessary
(3) Check the compressed air system, ensure stable pressure
(4) Appropriately increase barrel temperature to a reasonable value within the 190-250°C range
(5) Optimize screw design and rotation speed, ensure full plasticization
(6) And establish standardized work instructions, paying special attention to parameter stability in continuous mass production
Conclusión clave
Rough inner wall is caused by low mandrel temperature or poor surface condition; it needs to be solved from temperature control and mold maintenance.
Targeted preventive measures need to be taken in different production scenarios.
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