Injection Molding
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POM flow lines and flow marks
Problem Phenomenon
Ripple-like flow marks centered on the gate appear on the product surface, and the flow marks are reduced after increasing melt temperature and mold temperature.
Cause Analysis
The melt front cools quickly, and the subsequent melt pushes the front to form ripples; low melt temperature or mold temperature and slow injection speed aggravate front cooling, making flow marks more obvious.; during on-site troubleshooting, verify item by item according to this mechanism, and avoid blindly adjusting the machine based only on experience
Solution
①Appropriately increase melt temperature; ②increase mold temperature; ③increase injection speed; ④enlarge gate and runner dimensions.; after adjustment, continuously sample to verify the effect, and resume mass production only after confirming stability
Key Takeaway
Flow marks reflect a melt front temperature management problem; POM has good flowability and can be improved by appropriately increasing temperature and speed, but care must be taken not to exceed the decomposition temperature upper limit.; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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