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IndustryArena Forum > MetalWorking > Mass finishing equipment/media/strategies > Strange textue after anodizing 6082 aluminum, appears galvanized
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  1. #1
    Join Date
    Mar 2013
    Posts
    7

    Strange textue after anodizing 6082 aluminum, appears galvanized

    Hello,
    I received CNC turned parts made of 6082 T6 aluminum, or at least that was what I specified, which came out of a 32mm round rod.

    I took it to the local (cheap) anodizing company, which uses the sulfuric acid bath technique. The quality they produce is not so great, and the dimensions usually come out slightly smaller, but the other parts I've sent them for anodizing are good enough, which are also 6082, but cut from hollow tubes or plates.

    However, these turned parts all come back with a strange texture like galvanized, while the other parts look uniform. Have a look at this photo. The texture appears on the circumference, in the long direction, but in every part there is always a small arc section of about 30 degrees out of the 360 which is completely uniform and doesn't show the texture. Meanwhile, the cross sections come out very rough.
    Does anyone know what could cause this and how to prevent it?

    The anodizing company doesn't give straight answers, but they mentioned something like they would need phosphorus but it's too toxic for them to dispose of, so they don't use it. I tried to ask the company that turned the parts, but they haven't replied. I wonder if they actually used 6082 T6 or if they used something else. I read on some other threads that this texture sometimes occurs on materials that are extruded and the texture follows stress lines, or that it occurs mainly on 7075.

    Thanks
    Attachment 198312

  2. #2
    Join Date
    Jan 2013
    Posts
    19
    Hard to say what happened with this part. Black is the hardest color to do. I do anodizing at home and there are just so many things to factor in. Could be bad etching, not enough or too much current, weak acid bath, poor electrical connection... the list goes on. Is the finish in the picture exactly as you got it back from the anodizer? Just looks like a poor job all around. Also, could have been bad surface prep. Parts need to be really clean before anodizing and any defects in surface finish will show even more after anodizing.

    Jeremy
    Jeremy

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