Processing Machinery
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Rough inner wall of heat-resistant polyethylene extruded products (Variant: mass production scenario)
Problem Phenomenon
The inner wall of the pipe or profile is rough and uneven, with visible streaks or particles.
Inner wall roughness affects the fluid resistance and hygienic performance of the pipe, and may breed bacteria in water supply pipes.
Especially in continuous mass production, this problem is more prominent and requires key attention.
Cause Analysis
(1) Mandrel temperature too low, melt stick-slip flows on the mandrel surface
(2) Mandrel surface finish insufficient or worn
(3) Compressed air pressure insufficient (during internal pressure sizing)
(4) Melt temperature too low, poor fluidity
(5) Screw plasticization insufficient, unmelted particles in the melt
(6) In continuous mass production, process parameter fluctuations or equipment state changes aggravate this problem
Solution
(1) Appropriately increase mandrel temperature to match die temperature (190-230°C range)
(2) Polish mandrel surface to Ra≤0.2μm, chrome plate if necessary
(3) Check the compressed air system to ensure stable pressure
(4) Appropriately increase barrel temperature to a reasonable value within 190-230°C
(5) Optimize screw design and rotation speed to ensure full plasticization
(6) And establish standardized work instructions, paying special attention to parameter stability in continuous mass production
Key Takeaway
Inner wall roughness is caused by low mandrel temperature or poor surface condition, and 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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