MIG welding is accomplished with few starts and stops, allowing for longer welds. Welds are clean, requiring little post-weld cleanup. In TIG welding, a weld can be accomplished with filler metals or without filler metals. MIG welds require filler metals. Unlike MIG welding, there is absolutely no spatter produced during TIG welding.
Shielding gases form arc plasma, allowing for more controlled welds in welding. In MIG welding, argon gas is used alone or in combination with oxygen, carbon dioxide or helium to form a shielding gas. TIG welding employs either argon, argon and hydrogen or argon and helium gases to provide shielding gas.
Both welding methods can result in excessive melt-through, incomplete joint penetration or incomplete fusion. Both methods can also present difficulties in producing a starting arc. TIG welding has lower deposition rates than MIG welding. MIG welds can leave heavily oxidized deposits.