I'd like to add to what Oldred and Redsdad already posted...
(man..if Oldred is already old, then Redsdad must be ancient...J/K, I've been waiting a long time to used both of your names in a sentence like that...hahahahahaha)
OK..MIG welding is one of the easiest methods to master, and TIG is one of the hardest.
MIG welding allows the operator to set the machine for voltage,(heat) and wire speed. Once set, and the trigger is pulled, the machine will lay the same bead all day long, providing that the joint design is the same, and the metal thickness is the same. This is especially useful for production work on ferrous metals, as well as production work on aluminum. You can vary the amount of wire that you put into the joint, which lets joints that are not fitted up very well still be welded without a great loss in strength...That makes MIG welding a good choice for hotrodders, because things that need welding don't always fit together the way they do in the magazines...You can weld anyplace that you can fit the torch, and once proficient, you can even weld by ear and feel without even seeing the joint...
The speed that you can weld up a joint is also one of the highest, I would think it's faster than stick, when you take into cosideration the chipping of slag and changing electrodes.
The drawbacks are that the weld bead is usually harder than the surrounding metal, and the bead can become inconsistant if you are trying to weld parts that have varying thicknesses, or vastly different thicknesses. Thin metal can be hard to weld, as the heat builds up and you get burnthrough.
TIG welding requires the most skill, as the current is operator controlled by a foot pedal,(the machine lets you set a maximum current and the pedal controls the amount of current available under that setting),the arc length, bead width and position is controlled by the operator, and the filler metal deposition rate and position is operator controlled as well. :sweat: TIG welding is about 1/2 as fast as MIG, even slower...Filling poorly fitted joints is a chore, and slows the process even more. Because you need 2 hands, welding in inaccessable places is harder to do than with a MIG...
2 hands and a foot, all going at the same time...Lots of hand eye coordination as well. It takes a bunch of time to become proficient with TIG. (I'll be proficient ...someday...maybe)
The TIG can weld most anything that can be welded, given the right rod, electrode and shielding gas...Steel, stainless steel, Chrome moly steel, aluminum, titanium, magnesium can all be welded with a minimum of setup. (I can change the settings and electrode on my TIG to go from steel to aluminum in less than a minute, a MIG welder requires a gas change as well as a wire change to switch materials.). It can also be used to braze which will join a variety of formed as well as cast materials.
The weld is usually the same hardness as the surrounding metal, provided you use the right rod, which makes it possible to hammer the weld flat on body panels instead of grinding. This also makes cracking at the edge of the weld less likely to occur, like happens with a MIG weld sometimes, if the bead is piled up... ..
You only put as much heat into the part as you need to, to "wet" or melt the surface, before adding filler rod, this makes it easier to control burnthrough on thin materials. You can also fuse metal together with a TIG, not using any filler rod at all, provided the metal is thin enough, and the joints are closely fitted. Putting a gas shield behind your weld is also possible, (gas purge ), and deeper weld penetration as well as a pure backside of the weld is possible...very useful when welding process tubing and vacuum chamber construction.
The TIG weld , if executed properly, looks very cool too.
Hope that helps,
Mikey