Injection Molding
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Melt fracture of PP injection molded parts
Problem Phenomenon
The surface near the gate is rough and wavy, with poor gloss.
Cause Analysis
The shear rate of the melt passing through the gate is too high and surface layer fracture occurs; low melt temperature and a small gate aggravate this phenomenon.; during on-site investigation, verify item by item according to this mechanism to avoid blindly adjusting the machine based only on experience
Solution
①Appropriately increase the melt temperature; ②enlarge the gate size; ③optimize the injection speed curve; ④increase the mold temperature to improve surface replication.; after adjustment, continuously sample and verify the effect, and resume mass production after confirming stability
Key Takeaway
PP melt fracture is mostly seen with high-speed filling through small gates; coordinated adjustment of temperature, gate, and speed can eliminate it.; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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