What are the strategies to improve dimensional and geometric accuracy in profile production?

In production, addressing defects with significant dimensional and shape deviations requires a balanced approach. Common countermeasures typically include:
① Adjust the screw speed to match the feeding rate;  
② Adjust the extrusion pressure—typically, for a twin-screw extruder producing standard profiles, the die pressure drop should be 25–32 MPa;  
③ Adjust the temperature—the temperature settings across different zones of a twin-screw extruder generally follow a "high-low-high-low-high" pattern, with higher temperatures set at the die section;  
④ Adjust the vacuum suction force to ensure appropriate adhesion across all parts of the parison. If the shaping vacuum is too low, insufficient material adhesion may lead to severe deformation or failure to form properly, compromising product appearance and dimensional accuracy, resulting in defective products. Conversely, excessive shaping vacuum increases traction load, may cause traction difficulties, and shorten the service life of the vacuum pump;  
⑤ Adjust cooling efficiency—for dry-wet combined negative-pressure vortex water tanks, maintain good tank sealing and install vacuum holes at the outlet to remove cooling water from the profile surface;  
⑥ Adjust the traction machine pressure—within the premise of maintaining regular profile shape, slightly increase traction pressure to prevent conveyor belt slippage and mold jamming caused by resistance in the sizing die;  
⑦ Adjust the traction speed—set it slightly higher than the extrusion speed;  
⑧ Clean and repair the mold promptly.
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