Why do you need shielding gas for a mig welder?

 I am new to welding and have many questions. Is the gas held in a separate container or held in the welder itself?

lemonie6 years ago
It's to prevent / reduce oxidation / burning. The gas is usually held outside the welding unit - Argon, or on the cheap carbon dioxide.

gmxx6 years ago
 usually the gas is held in an outside tank. the gas is thiwer to create a bubble around the weld to protect the joint as you are working. it is imperative that the joint be "clean" when you weld, so they use the bubble to protect it.