GMAW

Gas Metal Arc Welding (GMAW), commonly known as MIG welding, is a welding process that joins metals by heating them with an arc formed between a continuously fed consumable wire electrode and the workpiece. The weld pool is protected from the atmosphere by an externally supplied shielding gas.

In GMAW, a constant-voltage power source supplies electricity to a spool of filler wire that is fed through a welding gun. The wire acts as both electrode and filler material, melting to form the weld joint. The workpiece is typically grounded, and the process can weld a range of metals from thin sheets to thicker sections, including ferrous and nonferrous materials.

Shielding gas composition plays a key role in arc stability and weld quality. Gases used include inert argon for nonferrous metals, or active mixtures such as carbon dioxide or argon-CO2 for steel. The shielding gas protects the molten weld from atmospheric contamination and influences the transfer mode of the arc.

GMAW offers several transfer modes. Short-circuit transfer is common for thin sections and positions requiring low heat input; spray transfer provides high deposition rates on thicker sections with a steady arc; pulsed-spray combines features to control heat input and reduce spatter. The choice depends on material, thickness, and welding position.

Typical equipment includes a MIG welding gun, a power supply, a wire feeder with consumable wire, and a shielding gas supply with regulators. Proper setup involves selecting wire diameter and gas, adjusting voltage and wire feed, and preparing the workpiece.

Applications span automotive, construction, and manufacturing. Advantages include high welding speeds, suitability for automation, and clean welds with minimal post-weld cleaning. Limitations involve equipment and shielding gas costs, as well as sensitivity to wind and drafts. Safety measures include adequate ventilation and protective equipment to mitigate fumes and radiation.