Injection Molding
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PC Injection Flash
Problem Phenomenon
Thin flash appears at the parting line and ejector pins, often accompanied by clamping alarms, more obvious in individual cavities of multi-cavity molds.
Cause Analysis
PC requires high injection pressure, and cavity pressure easily exceeds the clamping force and pushes the mold open; parting line wear, insufficient clamping tonnage, and excessive holding pressure all induce it; PC's high-pressure process characteristic makes its flash risk higher than low-viscosity general-purpose materials.
Solution
①Reduce injection and holding pressure, lowering 5%~10% each time and observing; ②Calculate and increase the clamping force, leaving sufficient high-pressure process margin; ③Repair the parting line and moving part fits; ④Advance the holding pressure switchover point to avoid over-filling; ⑤Investigate filling imbalance in multi-cavity molds.
Key Takeaway
PC flash = 'high-pressure process meets insufficient clamping': PC is born to need high pressure, and the clamping margin must be left sufficient; first reduce holding pressure, then increase clamping, and finally repair fits, do not take high pressure as the only solution for flash.
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