Injection Molding
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Low weld line strength in PVA '2079851475616104452
Problem Phenomenon
Strength at the weld line of PVA injection molded multi-gate products is only 30-40% of the whole
Cause Analysis
Temperatures of the two melt fronts have 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 front temperature higher; 3) Increase holding pressure to ensure compaction at the weld; 4) Set overflow groove at the weld line and cut it off afterwards
Key Takeaway
Low weld line strength is caused by insufficient molecular entanglement; high-temperature high-speed injection and overflow groove are effective countermeasures
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