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Anodized Aluminum

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  • monte55
    started a topic Anodized Aluminum

    Anodized Aluminum

    Is there a way to tell for sure if aluminum IS anodized?

  • fun4now
    replied
    aluminum gets clear coats all the time, look at bike side covers. it is also painted, just like steel you can do what you want to it. anodizing is not the cheapest process and needs to be dipped in several tanks ( electrically charged as said) to get done. the parts need to be attached to a rack oe some form of hanger then submerged. larger parts might be painted or even powder coated if its a cheaper option and meets the makers needs. i did some anodizing in MN for a wile. we had big tanks but most stuff was smaller and lots of it. aluminum also gets a chromate covering instead of anodized some times to help the paint process stick.
    its a nice material, its light and can be finished in many options, unlike painted steel i scratch in painted aluminum dose not result in a growing rust mass.
    do what it takes to get it conductive then take a torch to some, see if its a clean melt or lots of burn smoky off. i

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  • kcstott
    replied
    Aluminum can have just about any surface coating from paint to powder-coat to chrome. An anodized surface is kind of hard to describe. It is simply part of the metal and not a surface coating so if it flakes peals or chips it's not anodized, and if you can remove it with a solvent it's also not anodized. Paintball guns are anodized even the ones with splashed on colors. Most aluminum baseball bats are also anodized and some are then pad printed with the logo but still have an anodized layer as a foundation.
    Most aluminum bicycle parts are anodized. aluminum arrows for archery are all anodized. I'm trying to give you examples so you can find something and compare the two. just try to find something colored anything but black because a black anodized part may be hard anodized and is very different then type two anodize which is the most common anodize and is the only anodize you can color just about any color under the sun. Hard anodize come in two colors: black and clear(which is not really clear it's more of a muted dull gray)
    An easy way to tell if it's hard anodize is to scratch the part with a scribe. if it sounds like you are cutting glass and produces a white-ish powder it's hard anodize.

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  • monte55
    replied
    One more question.........could aluminum also have a coating other than anodize like a clear coat, that one would think is actual anodize? They both
    would not be conductive so how do you know which is anodize?

    Thanks guys for the input

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  • welderman23
    replied
    Originally posted by kcstott View Post
    . this is why a stainless wire brush will cut through it and allow a good weld.
    If you were able to clean the part with acetone and got conductivity then it was for sure NOT anodized. you have to scratch through the anodize layer to raw aluminum to get a continuity reading.
    good to know ....thanks

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  • kcstott
    replied
    fun4now is correct. Since an anodized part is non conductive it needs to be removed before welding. Anodize has good dielectric properties but it will not insulate against a welder. It will however hinder the welding process a lot.
    And if you removed the coating with acetone then it was paint not anodize.
    Anodizing is an electro chemical process that changes the surface to aluminum oxide and can be colored in a separate step before the anodize process is finished. The color in anodize can be as simple as Rit clothing dye.

    Oxidized aluminum is nearly the same but not as thick as anodize and will present less of a problem when welding but I prefer to do all my aluminum welding on as clean a part as possible.

    Aluminum by it's nature is oxidizing as soon as it come in contact with oxygen and it will build up a layer of oxide and then stop. this is why a stainless wire brush will cut through it and allow a good weld.
    If you were able to clean the part with acetone and got conductivity then it was for sure NOT anodized. you have to scratch through the anodize layer to raw aluminum to get a continuity reading.
    Last edited by kcstott; 02-29-2008, 11:19 PM.

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  • fun4now
    replied
    its easy-er to weld with the anodized off it. if ya do a search on it you will find some recommend pulse to help break up the anodize layer. most prefer to take it off if they can. it acts like a thick oxide layer...well it really is one.

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  • monte55
    replied
    Thanks for the info...........I took a piece I believe to be anodized and the Fluke said infinity. I was given a receiver dish..large one with a black finish and after removal of the finish with acetone I had a circuit. What about oxidized aluminum. Will it conduct a path? Some say to remove the anodize before tigging and others say don't bother. This dish was about 10 ft diameter and provides a fair amount of project stock..extruded.

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  • kcstott
    replied
    Anodize in non conductive so if you try to read Ohms across an anodized part without scratching into the surface it should read very high resistance or infinite resistance. I used to do anodizing in my garage. type II only not hard anodize.
    Kerry

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