Injection Molding
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Jetting flow marks on POM product surface
Problem Phenomenon
Snake-shaped jetting marks appear in front of the gate, and the marks disappear after reducing the initial stage of injection speed.
Cause Analysis
Excessively high injection speed causes the melt to enter the cavity in a jetting manner, and the snake-shaped strands overlap to form jetting marks; it is more likely to occur when the gate is small and the cavity is open.；During on-site troubleshooting, verify item by item according to this mechanism, and avoid blindly adjusting the machine based only on experience
Solution
①Adopt slow-fast-slow multi-stage injection with low speed in the initial stage; ②enlarge the gate size; ③adjust the gate position so that the melt impinges on the core; ④increase the material temperature.；After adjustment, take continuous samples to verify the effect, and resume mass production only after confirming stability
Key Takeaway
Jetting marks can be effectively controlled with the speed profile alone; low initial speed lets the melt spread out before speeding up, balancing appearance and cycle time.；After confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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