Material Drying
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POM product bubbles
Fenómeno do problema
Bubbles appear inside or on the surface of the product, holes are visible on sectioning, and bubbles decrease after drying the pellets and lowering the melt temperature.
Análise das causas
Moisture in the pellets vaporizes in the melt, or decomposition gas is not discharged and is trapped inside the product; vacuum voids formed by insufficient feeding in thick-walled areas also appear as bubbles.; during on-site troubleshooting, verify item by item according to this mechanism, and avoid blindly adjusting the machine based only on experience
Solução
①Fully dry at 80~90℃ for 3~4 hours; ②lower the melt temperature to reduce decomposition gas; ③strengthen holding pressure feeding; ④improve mold venting.; after adjustment, continuously sample to verify the effect, and resume mass production only after confirming stability
Conclusão principal
POM bubbles must be distinguished among three sources: water vapor, decomposition gas, and vacuum voids; drying and temperature control come first, feeding and venting follow, verify item by item to locate.; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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