Injection Molding
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PP Flash
Problem Phenomenon
Thin-sheet flash appears at the parting line and ejector pins, requiring manual trimming after demolding.
Cause Analysis
PP melt has low viscosity and good flowability, easily penetrating parting line gaps under high pressure; excessive injection pressure, insufficient clamping, and parting line wear all cause it.
Solution
①Reduce injection/holding pressure; ②calculate clamping force; ③appropriately lower melt temperature to raise viscosity; ④repair parting line and ejector pin fit clearances.
Key Takeaway
For flash of low-viscosity materials, pressure restraint comes first.
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