Injection Molding
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PA6 '2079851475616104452 Jetting Marks
Problem Phenomenon
Snake-shaped marks, obvious when the gate faces an empty cavity.
Cause Analysis
High-speed jetting through a too-small gate; high initial speed; the melt does not hit the wall and folds and piles up; during on-site troubleshooting, verify item by item according to this mechanism, and avoid blindly adjusting the machine based only on experience; during troubleshooting, confirm item by item around key factors such as jetting marks and gates to avoid misjudgment.
Solution
①Change the gate direction so that the melt hits the cavity wall first after entering the cavity and then spreads;②decelerate at the injection start section, pass through the gate at low speed, and then increase speed;③appropriately enlarge the gate to reduce shear rate and pressure loss;④appropriately increase mold temperature to improve the melt's replication and fit to the cavity surface;⑤switch to a lap joint gate to avoid direct jetting of the melt into the cavity.
Key Takeaway
PA6 jetting marks = 'hit the wall first after entering': gate direction cooperates with the speed curve; let the front spread against the wall, and the snake-shaped marks disappear; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence.
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