[DMCForum] Question about aluminum

["Farrar Russell Carroll Hudkins" <fhudkins@xxxxxxx>]

Checksix3:
(Sorry I don't know your real name.)
You know a lot about aluminum so I thought I'd ask you: Does it take
gold electroplate? And if so, how well is it compared with brass?
Thanks,
--Farrar

      -----Original Message----- 
      From: checksix3 [mailto:jetjock11@xxxxxxxx] 
      Sent: Wed 4/28/2004 12:27 AM 
      To: DMCForum@xxxxxxxxxxxxxxx 
      Cc: 
      Subject: [DMCForum] One more thing...
      
      


      ...The guy was talking about soldering aluminum, not welding
it.
      Welding by definition is the melting and fusion of the base
      materials. This doesn't happen with soldering or brazing.
      
      Aluminum can easily be soldered or even brazed with the proper
flux
      and technique. Don't use normal solder though, there are
special
      alloys made just for A/C repairs. Search on the net to find
them or
      ask at www.aircondition.com. I answer questions over there as
I'm
      also a licensed automotive A/C tech, among other things.
However, I'd
      take the other guy's advice and let an experienced A/C shop do
it.
      
      Aluminum doesn't oxidize when welding, it develops an oxide
layer in
      contact with the air. This "alumina" layer melts at a very
high temp
      and is why you need to remove it with AC current or other
means. Try
      puttin an arc on a thin piece of AL with normal (electrode
negative)
      DC GTAW current, it'll just shrug off the arc. Using electrode
      positive will break up the oxides but very little heat is
tranfered
      to the work and the tungten will melt. It's why you need a
larger
      diameter tungsten when GTAW welding with AC or to weld
aluminum or
      magnesium. It's also why the tungsten "balls" when welding
with A/C.
      It has to do with the physics of the arc, I won't bore you
with the
      details unless you really want to know.
      
      It's also why you can't cut aluminum well with a torch. A
cutting
      torch doesn't simply "burn" ferrous metals like steel, it
oxidizes
      them. Since AL contains no iron it can't be oxidized at the
temps a
      torch develops. A plasma cutter is a much better way to deal
with non
      ferrous metals. Fwiw, welding is much more science (and art)
than
      people think. It's far more involved than simply making sparks
and
      melting stuff.
      
      
      
      
      Yahoo! Groups Links
      
      
      
      
      
      



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