The inner diameter of the contact tip should be matched to the diameter of the wire.
One shows how much gas is still in the tank, and the second shows your gas flow rate.
The first one can be used for almost all purposes whereas the second one is especially used over metals with excessive rust on it.
Use the chart below to set the wire speed based on the wire size.
It welds stainless steel grades 304 through 310 when needed or welds dissimilar metals together where needed.
Picture 08 — Characteristics of Argon as shielding gas.
MIG Welding Gas Chart Settings Charistics of MIG Welding Gasses Different gasses produce different types of weld penetration and arc characteristics.
The process then becomes GMAW or Gas Metal Arc Welding.