Extrusion & Post
4 조회수
General-purpose polyethylene injection molded products flash/burrs
문제 현상
Flaky overflow material, i.e. flash or burr, appears at the product parting line, ejector pin holes, slider seams, etc.
Flash affects appearance and dimensional accuracy, increases post-processing workload, and in severe cases causes the product to stick in the mold and makes demolding difficult.
원인 분석
（1） Clamping force insufficient, the mold is pushed open by melt pressure during injection producing a gap\
（2） Injection pressure too high or holding pressure too large, exceeding the mold clamping force\
（3） Mold parting line worn or poorly fitted, with gaps\
（4） Barrel temperature too high, melt viscosity low and flowability too good, easy to overflow\
（5） Mold vent grooves too deep, melt overflows into the vent grooves forming flash
해결 방법
（1） Check and increase the clamping force, ensure the clamping force is greater than 1.2-1.5 times the melt pressure in the cavity\
（2） Appropriately reduce injection pressure and holding pressure, use the lowest pressure under the premise of ensuring quality\
（3） Lower the barrel temperature to the lower value within the 160-260°C range, increase melt viscosity\
（4） Check the mold parting line, re-lap the mold closing surfaces, ensure the gap is less than 0.02mm\
（5） Check the vent groove depth, polyolefin material vent groove depth not exceeding 0.03mm
핵심 요약
Flash is a manifestation of mismatch between mold clamping force and injection pressure, requiring control from three aspects: clamping force, injection pressure and mold precision.
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