Injection Molding
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ASA weld line visible and low strength
Problem Phenomenon
ASA dark-colored product weld line marks are clearly visible, strength insufficient at convergence of multi-gate parts, cracks along weld line after assembly stress.
Cause Analysis
When the convergence temperature of two melt fronts is insufficient, interfacial bonding is weak; ASA dark formula makes weld line visual contrast strong; Plastribution points out that high injection speed obtains the strongest weld line, low speed the opposite.
Solution
①Raise melt temperature and use the highest possible injection speed to strengthen weld line; ②raise mold temperature to 50~80℃ range; ③strengthen venting in convergence area; ④gate layout moves weld line out of appearance surface and stressed area.
Key Takeaway
ASA weld line governance counter-conventionally requires high-speed filling; weld lines on dark parts can only be relocated and are hard to eliminate; high speed must be matched with good venting.; After confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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