Gas metal-arc welding (GMAW) also called as metal inert-gas (MIG) welding, In Gas metal-arc welding process the weld area is shielded by an effectively inert atmosphere of argon, helium, carbon dioxide or various other gas mixtures. The consumable bare wire is fed automatically through a nozzle into the welding arc by a wire-feed drive motor. In addition to using inert shielding gases, de-oxidizers usually are present in the electrode metal itself in order to prevent oxidation.
The temperatures generated in Gas metal arc welding are low, GMAW method is suitable only for thin sheets and sections of less than 6 mm, otherwise incomplete fusion may occur. GMAW operation is easy to perform is commonly used for welding ferrous metals in thin sections. Pulsed-arc systems are used for thin ferrous and nonferrous metals. GMAW process is used for welding most ferrous and nonferrous metals and is used extensively in the metal fabrication industry. Because of the relatively simple nature of the process, the training of operators is easy. This process is versatile, quick, economical and welding productivity is double that of the Submerged-arc Welding process.
- The maximum size of electrodes used in Gas Metal-arc welding is less than or equal to 4mm.
- Spatter loss in this process is high.
- To keep the spatter loss within the limits of 10%, the maximum thickness of plate which can be joined by using MIG welding with single pass welding up to 30mm thickness only.