Injection Molding
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Low weld line strength in EVA '2079851475616104452
Problem Phenomenon
Strength at weld line of EVA injection molded multi-gate products is only 30-40% of the whole
Cause Analysis
The two melt fronts have cooled causing small molecular chain diffusion depth and insufficient entanglement; dispersed phase orientation discontinuous at weld line
Solution
1) Increase injection temperature by 10-15°C to increase diffusion depth; 2) Increase injection speed to keep front temperature higher; 3) Increase holding pressure to ensure weld compaction; 4) Set overflow well at weld line and cut off afterwards
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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