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Hello! My name is Mac and on behalf of expertvillage.com I am here to discuss MIG welding. Today we
will be talking about the different gases that are used in MIG welding. The purpose
of the gas is to provide a shielding cloud around the molten puddle of metal. This shielding
gas effect excludes oxygen and nitrogen from the atmosphere that will contaminate the weld
if it is exposed to oxygen and nitrogen. There are many different kinds of shielding gases
and they all have different effects on the weld. For instance, if you are welding in
short arc mode you can just use straight CO2, then it will give you a perfectly adequate
shielding gas effect. The advantage of CO2 is that it is very cheap and bottle of it
lasts for a very long time. If you however want to achieve a spray arc weld from your
machine you need to use a bottle of argon CO2 mixture with a maximum amount of 20% CO2.
You will get an extremely fine looking weld that is very, very cosmetically good looking,
deep penetration and a very high deposit rate. For welding aluminum for instance you would
use pure argon gas, you might use a mixture of argon and some other rare gases for welding
stainless steel. These gases have one drawback of course is that they do not support life
so one must be careful not to weld in an enclosed space where you could become asphyxiated by
these inert gases.