Summary for hard coating halo spot Discussion
Hard coating halo spot on 6061-T6 aluminum was questioned after a part showed 2.0 mil overall hardcoat, but a lighter area with only 1.5 mil and a silver halo. Paul Buckley said the defect resembled something he had seen before on plug- or weld-repaired parts, though he stated that was not the case here. Willie Alexander replied that it “sure looks like a plug,” pointing to visible hand sanding in the area as if someone had tried to blend the repair. The thread does not confirm the exact cause, but the discussion strongly suggests a localized repair or blended area beneath the hardcoat as the likely explanation for the color change and halo effect.
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Q. Hello,
I was wondering if anyone has seen a spot like this after a hard coating. The Part has 2.0 mil of Hardcoat, the spot has 1.5 mil of Hardcoat but it appears to be lighter in color with a silver halo around it. The only time that we have seen something like this happen before is when a part had been plug or weld repaired. But this did not happen.
Thanks
Paul
Paul Buckley
– Stoughton Massachusetts
February 14, 2024
A. Paul,
It sure looks like a plug. Note the hand sanding in its location in what appears to be an attempt to blend it in.
Willie Alexander
– Green Mountain Falls, Colorado
February 17, 2024
Hi Willie,
I appreciate your response. We will be getting the part back from the plater and will do a deeper inspection to see if a similar mark is on the inside. What is weird as far as we know the machinist did not have any issues turning or any welding/plug being done. Aluminum was extruded.
Paul
Paul Buckley [returning]
– Stoughton Massachusetts
February 20, 2024