Molds & Tooling
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PA6 Low-Viscosity Drooling and Flash
Problem Phenomenon
Nozzle drooling and stringing contaminate the mold surface, flash appears at product edges, and the mold parting line is frequently crushed and damaged
Cause Analysis
PA6 melt has very low viscosity and excellent flowability, penetrating into even tiny gaps to form flash; the melt drools and strings under its own weight at the nozzle, and the mold expands as soon as the cavity pressure is slightly high; during on-site troubleshooting, verify item by item according to this mechanism, avoiding blind machine adjustment based only on experience
Solution
①Use a needle-valve nozzle to prevent drooling; ②Reduce holding pressure and final-stage injection pressure to prevent flash; ③Improve parting line fitting accuracy, and control the vent groove depth within 0.02mm
Key Takeaway
The low viscosity of PA6 is a double-edged sword; drooling prevention relies on the needle-valve nozzle, flash prevention relies on pressure control and mold precision, both ends must be blocked; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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