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Posted by jppickett on January 6, 2008, 9:30 pm
Please log in for more thread options Years ago when I was a Aircraft welder in the Navy we would take an
oxy-acetylene torch and with a highly carboizing flame and blacken the
aluminum then adjust to a neutral flame and heat till the carbon black was
gone then clean with a stainless steel wire brush... seemed to work well...
John
> Are any of those aluminum cleaners suitable for use in cleaning aluminum
> before Tig welding?
>
> Seems like sanding oxidixed aluminum gets some of the grunge but grinds
> the rest of the oxide into the surface of the metal - is it better to try
> and etch it off with acid first or on the other hand are there Al cleaners
> that work or fluxes designed to help with getting the bead to wet when
> metal is oxidized on the surface?
>
> I've seen more experienced Tig welders welding some pretty crummy looking
> aluminum (old propellors etc.) so there must be some tricks to it.
>
> Apparently more electrode positive time (indicated as lower "% negative
> balance" on Miller machines) accelerates the Ar ions so they bombard and
> clean the surface - any other tips?
>
> We used to clean telescope mirror plates under low pressure argon with
> high voltage so that we could aluminize them - same principle (the low
> pressure allows the Ar to accelerate even more before they get slowed down
> bumping into another gas molecule)
>
> Maybe I should be giving my old aluminum pieces that need to be welded a
> bath in Ar with a few kV applied to really clean them.
>
> Graham P
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> before Tig welding?
>
> Graham P