Processing Machinery
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Shutdown Carbonization Failure of PEEK
Problembeschreibung
When PEEK production resumes after a mid-run shutdown of more than 15 minutes, the first batch of products shows a concentrated outbreak of yellowing, black specks, and silver streaks, requiring multiple shots to return to normal.
Ursachenanalyse
During the shutdown, the PEEK in the barrel continuously thermally degrades above 380℃, the melt carbonizes, discolors, and generates gas; the longer the residence time, the thicker the degraded layer, and the degraded material is gradually mixed into the products after restarting.
Lösung
①If a shutdown of more than 15 minutes is expected, immediately lower the barrel temperature to a safe range; ②For long shutdowns, displace and drain with a dedicated purging compound; ③Fully discharge material and extend purging shots before resuming production; ④Establish shutdown operation specifications.
Wichtigste Erkenntnis
The core of PEEK shutdown management is dual control of time and temperature; 15 minutes is the empirical red line; the cost of discharging material at shutdown is far lower than batch scrap caused by degraded material mixing in.
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