Material Drying
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Internal Pores and Bubbles in PEEK
Fenómeno do problema
PEEK extruded rods, pipes, or thick-wall injection molded parts have pores and loose cross-sections inside, with decreased mechanical strength and pressure-tightness, detectable by X-ray or section inspection.
Análise das causas
Moisture in the raw material vaporizing, gas entrained in the melt, and insufficient packing pressure jointly cause pores; rapid surface solidification prevents internal gas from escaping, leaving it trapped in the product core as a permanent defect.
Solução
①Fully dry at 150℃×3 hours or more and verify; ②Heat up slowly to let entrained gas fully escape; ③Increase molding pressure to enhance melt packing; ④Optimize the cooling rate to avoid premature surface freeze-off.
Conclusão principal
PEEK pores are the result of the superposition of the three factors of drying, venting, and packing; thick-wall parts and extruded profiles carry the highest risk; porosity should be included in the non-destructive testing items for critical parts.
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