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.