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Discussion Starter #1
Does anyone know if anodizing really significantly diminishes electrical conductivity? I'm thinking about having some aluminum '92 GM f-body alternator-a/c brackets anodized, but I don't know if this might diminish the performance of the accessories (through poor ground?). Anyone have any idea? Is a good ground through the brackets even necessary for a CS130 alt or radial a/c compressor?
 

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It does. It's common practice to plug the holes before a part gets anodized. Along with preventing build-up in the holes, it provides for a good electrical interface.
Chassis ground bond tests call for <1 ohm resistence to the frame. Bonding to an anodized surface can show >10 ohms. Often a part doesn't get anodized around the screw hole when a ground lug is attached there.
 

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Anodization is a dielectric oxide based compound. It acts as an insulator. A good coating of anodization should have a very high resistance. Therefore, it will be a very poor conductor of electrons. The anodization is very thin and using a star type locking washer would break the coating and allow you to conduct electricity through the piece.

It is amazing what you learn working in the semiconductor industry. We had a process that would deteriorate the anodization until it was gone. At that point, we would have big problems and have to replace the part. We used the anodization as an insulator between the cathode and anode for 13.56 Mhz RF at 1100 watts.
 

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Very interesting... :eek:

I went and talked to an anodizing shop today. The guy said that often cast aluminum parts don't turn out too nice (discoloration, mottled effects etc.) so now I'm having second thoughts.
 

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The Aluminum grain alignment and consistency is not the same on Cast as a part that was milled from a billet. If it is cast, I would look into possibly a tinted clear coat or powdercoating. Anodizing will not look right and I doubt that you would be happy with the results.
 

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Scott, Think about Powder coating…. Many different colors… Including “Translucent Colors” that look like anodize finishes.
Just a thought…
Mark (A.K.A. Z28 Mark)
 
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