Injection Molding
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PVC Injection Flow Marks
Problem Phenomenon
Dark flow marks appear on product surface, uneven gloss, poor appearance.
Cause Analysis
Uneven plasticization, large melt temperature gradient; PVC melt has high elasticity, unstable flow shows marks on the surface; uneven melt temperature or poor plasticization makes local melt state inconsistent, forming visible flow marks.
Solution
①Improve plasticization uniformity; ②Stabilize the melt temperature curve, avoid quality drift caused by temperature fluctuation; ③Optimize the injection speed curve; ④Enlarge gates and runners; ⑤Increase mold temperature to improve flow front contact.
Key Takeaway
PVC flow marks = a 'plasticization uniformity' problem: uneven plasticization is the root; PVC melt has high elasticity, any slight flow instability leaves marks on the surface — uniformity of plasticization and temperature control is fundamental.
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