Metal Inert Gas (MIG) welding, (sometimes refered to as wire welding), is a semi-automatic or automatic arc welding process in which a continuous and consumable wire electrode and a shielding gas are fed through a welding gun. A constant voltage, direct current power source is most commonly used with MIG welding, but constant current systems, as well as alternating current, can be used.  A related process, flux cored arc welding, often does not utilize a shielding gas, instead employing a hollow electrode wire that is filled with flux on the inside.

 

MIG welding is the most common industrial welding process, preferred for its versatility, speed and the relative ease of adapting the process to robotic automation.  See images below for examples of MIG welding.