Processing Machinery
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POM residence time red line
Fenómeno do problema
Small parts produced on a large machine: the products gradually discolor, and yellow spots and bubbles appear on the sprue
Análise das causas
POM is highly heat-sensitive: it decomposes after 60 minutes at 200°C or 30 minutes at 210°C; POM-H can stay 35 minutes at 215°C while POM-K only 20 minutes at 205°C, so a small shot size in a large barrel inevitably exceeds the time limit
Solução
①Melt residence in the barrel shall not exceed 20 minutes; ②match the shot size to the machine capacity; ③when molding is interrupted, purge the barrel plastic and lower the temperature; after adjustment, take continuous samples to verify the effect, and resume mass production only after confirming stability
Conclusão principal
Residence time and temperature jointly determine POM's thermal fate; 20 minutes is the general upper limit at '2079851475616104452 temperature, and purging is required upon interruption; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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