> Would someone please tell me the difference between MIG, TIG and heliarc
> welders?
Heli-arc is basically the same thing as TIG, it was an early brand name that
has endured as a synonym.
MIG stands for Metal-Inert-Gas, while TIG is Tungsten-Inert-Gas. The
distinction is the type of electrode, MIG uses a metal electrode that also
melts and provides the filler metal. TIG uses a tungsten electrode that
doesn't melt, the filler metal is provided separately.
> What is the purpose of using inert gas (CO2 or Argon)
> when welding?
When metals get hot enough to weld in the presence of oxygen(air), they also
corrode (rust) instantly, which prevents them from welding. The shielding
gas is one way of keeping oxygen away from the weld while it's molten.
> What type is best all around for restoration work: welding
> frames, body sheet metal etc.?
IMO, TIG comes close to being the best all-round, however it's quite
expensive and more difficult to learn. MIG is a close second for doing
sheet metal work and is easier to use and much less expensive. However,
it's more difficult to get a good weld on things like frames, and requires a
bigger, more expensive unit, multiple passes, etc.
My plan is a 'stick' welder (flux coated electrode, no shielding gas) for
heavy welds like frames, and a MIG for sheet metal and aluminum. Well,
someday anyway.
Randall
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