Definition
An electric arc welding process in which a continuously fed metal wire serves as both the electrode and the filler material, while a stream of inert gas (such as argon or helium) flows around the arc to shield the molten weld pool from contamination by the surrounding air. Now more commonly called Gas Metal Arc Welding (GMAW).
Plain English
A welding method that feeds a metal wire into an electric arc to join two pieces of metal, while blowing a non-reactive gas around the weld to keep air from spoiling it.
Context Anchor
Seen in aircraft maintenance and repair discussions involving welded metal parts, welding methods, or shop procedures.
Derivation
The name describes the process directly: a metal wire electrode is used, and an inert (chemically non-reactive) gas shields the weld. 'Inert' comes from the Latin 'iners,' meaning inactive or unable to react — the gas is chosen precisely because it will not combine with the hot metal.
Why Pilots Care
Correct Metal Inert Gas welds maintain airframe structural integrity; faulty welds can create weak points that compromise safety in flight.
Intuition Check
Do not read the gas as the fuel or heat source. In Metal Inert Gas welding, the electrical arc makes the heat; the gas mainly protects the hot weld from the air.
Example Sentence 1
The repair shop used a Metal Inert Gas welder to join the aluminum patch to the damaged fuselage skin.
Example Sentence 2
Mechanics often choose Metal Inert Gas welding for quick, clean repairs on steel brackets in the engine compartment.