Material Drying
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PA66 bubbles
Problem Phenomenon
Bubbles inside products, more frequent at thick walls.
Cause Analysis
Moisture vaporization; or thick-wall vacuum voids; overheating decomposition gas; the three mechanisms need to be distinguished; during on-site troubleshooting, verify item by item according to this mechanism, and avoid blindly adjusting the machine based solely on experience.
Solution
①Strengthen drying and verify moisture content compliance by moisture determination; ②add holding pressure at thick walls; ③control melt temperature within the grade-recommended window to prevent overheating degradation; ④open or clean vent grooves at the corresponding positions to ensure smooth gas discharge; ⑤core out and reduce material at thick walls to reduce shrinkage from the source.
Key Takeaway
PA66 bubbles follow the 'water, vacuum, decomposition' three-way classification: moisture is the primary cause in high-temperature nylon; drying verification comes first, holding pressure and temperature control follow; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence.
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