Injection Molding
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ABS injection flash (burrs)
Problem Phenomenon
Thin sheet-like excess material appears at the parting line, ejector pin holes, and slider mating areas, affecting assembly and appearance; multi-cavity molds often show flash in individual cavities.
Cause Analysis
The cavity pressure exceeds the clamping force, causing the parting line to be pushed open; too high injection/holding pressure, too high melt temperature and low viscosity, insufficient clamping force, parting line wear, or foreign matter can all cause it, and it is more easily triggered under the ABS high-pressure process.
Solution
①Reduce the injection/holding pressure by 5%~10% each time and observe; ②calculate the clamping force according to the projected area; ③appropriately lower the melt temperature; ④clean and repair the parting line, check the mating of moving parts; ⑤check filling imbalance in multi-cavity molds.
Key Takeaway
For ABS flash, first reduce the process pressure, then check the mechanical clamping and mating: reversing the order easily crushes the venting and accelerates mold wear; flash in individual cavities requires checking the filling balance rather than adjusting the overall pressure.
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