Injection Molding
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Low Weld Line Strength in PU '2079851475616104452
Problem Phenomenon
PU injection molded multi-gate products have weld line strength only 30-40% of the whole
Cause Analysis
Temperature of the two melt fronts already dropped, causing small molecular chain diffusion depth and insufficient entanglement; dispersed phase orientation discontinuous at the weld line
Solution
1) Increase injection temperature by 10-15°C to increase diffusion depth; 2) Increase injection speed to keep the front temperature high; 3) Increase holding pressure to ensure weld area compaction; 4) Set an overflow well at the weld line and cut it off afterward
Key Takeaway
Low weld line strength is caused by insufficient molecular entanglement; high-temperature high-speed injection and overflow well are effective countermeasures
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