Processing Machinery
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Black Specks and Carbonized Particles in PEEK
Fenómeno do problema
Black particles and black streaks appear on the surface or inside PEEK products; the number of black specks increases as production time extends, with short-term improvement after purging followed by recurrence.
Análise das causas
Melt accumulates in dead spots of the barrel, screw, and nozzle, residing long-term at high temperatures above 380℃, carbonizing and flaking off; the fiber friction shear heat of glass fiber reinforced PEEK aggravates local overheating and degradation.
Solução
①Regularly and thoroughly clean dead spots of the screw, barrel, and mold hot runner; ②Optimize the runner to eliminate stagnation areas; ③Lower the processing temperature and screw speed; ④Displace PEEK with a dedicated purging compound before shutdown.
Conclusão principal
Tracing PEEK black specks requires combining metallographic analysis to locate the carbonization source; equipment dead spots are the root cause; the high material cost makes the cost of black-speck scrap far exceed that of ordinary plastics, so preventive purging is the most economical.
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