Material Drying
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PA66 extruded rods and plates
Fenómeno del problema
Extruded PA66 rods have center bubbles and surface ripples, and internal looseness after machining
Análisis de la causa
Rods have large wall thickness, the outer layer cools first and center feeding is insufficient, forming shrinkage voids and bubbles; micro-bubbles from insufficient drying also remain in the center; extrusion temperature fluctuation causes surface ripples; during on-site troubleshooting, verify item by item according to this mechanism, avoiding blindly adjusting the machine based only on experience
Solución
①Fully dry the raw material to moisture content ≤0.15%; ②Sizing sleeve slow cooling to reduce inner-outer temperature difference; ③Extrusion temperature stable within ±2℃ fluctuation; after adjustment, take continuous samples to verify the effect, confirm stability before resuming mass production
Conclusión clave
The internal quality of PA66 rods relies on dual control of drying and slow cooling; once center shrinkage voids form they cannot be remedied, prevention is the only means; after confirming effectiveness, fix the parameters and practices into the work instructions to prevent recurrence
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