MIG - Metal Inert Gas (commonly called wirefeed)
TIG - Tungsten Inert Gas (commonly called Heliarc)
Heliarc and TIG are the same thing. Basically you have a tungsten electrode
that is the arc point. This arc is what melts the base melt and you "fuse"
the metals together. You use filler rod to fill in the gaps. The tungsten
is not what is "melted" into the weld, just an arc point. It is referred as
"Heliarc" because Helium is generally used as the "inert gas" or shield gas.
In MIG welding the wire that is "melted" into the base metals is the
electrode. This wire is consumed and is generally supplied in large spools.
No need for filler rod, because the electrode IS the filler rod.
The inert gas is a "shielding" gas to keep oxygen from the "melted" metals.
Oxygen results in "oxidation" or brittle, porous welds. It also keeps other
impurities such as moisture away from the fresh weld. You have to keep the
O2 away from the weld. That is what the coating on the stick rod (arc)
welding does. Keeps the O2 away (and generates a lot of smoke) Same with
the "flux" in "flux core" wire. CO2 is a good cheap versatile gas and you
can use it to weld mild steel and galvanized. Argon/CO2 mix is a better gas
and it welds "flatter" but it is more expensive.
MIG is definitely the easiest to learn and most versatile. A good machine
that is NOT flux core can weld light gauge such as sheet metal, and heavier
metals such as the frame, etc. I would recommend MIG.
That being said, a good TIG person can make the most beautiful welds you
have ever seen, weld very thin metals together without any warpage (think
even as thin as foil), and also weld aluminum, stainless steel, and steel
with basically the exact same set up.
Real welders may correct me, but that is the gist.
-Bill
-----Original Message----
Would someone please tell me the difference between MIG, TIG and heliarc
welders? What is the purpose of using inert gas (CO2 or Argon) when welding?
What type is best all around for restoration work: welding frames, body
sheet
metal etc.?
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