Molds & Tooling
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ABS weld line (bonding line)
Problem Phenomenon
Visible line marks appear behind hole positions, inserts, or on multi-gate products; the strength is weak, and cracking easily occurs along the weld line under load.
Cause Analysis
When two or more melt fronts converge, the temperature is insufficient, the venting is poor, the molecular chains are not fully entangled, forming a dual defect of appearance and strength; the weld line is weaker when the ABS mold temperature is low.
Solution
①Increase melt temperature, mold temperature, and injection speed so that the fronts converge at high temperature; ②open vent grooves at the confluence; ③adjust the gate position/number to move the weld line to a non-appearance low-stress area; ④set overflow wells to improve front quality; ⑤reduce the number of gates when necessary.
Key Takeaway
For ABS weld lines, 'if it cannot be eliminated, transfer it + raise temperature + vent': treating it as a structural design problem and avoiding it to a non-load-bearing area in advance is more effective than hard adjusting on the machine afterwards.
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