A close up of GMAW.
Gas metal arc welding (GMAW) is an automatic or semi-automatic welding process. Shielding gas and a continuous consumable wire electrode are fed through a welding gun. GMAW uses a constant power source, such as direct current or voltage, to weld materials such as steel and aluminum. GMAW is popular in industries like car manufacturing due to its speed and versatility.
GMAW is commonly used for sheet metal fabrication.
GMAW was first developed in the early 19th century when carbon was used. In the late 19th century, metal electrodes were invented, and in 1920, General Electric invented the first predecessor to GMAW. In 1953, the use of carbon dioxide for welding was developed. It quickly gained popularity as it made welding cheaper.
GMAW is widely used by the sheet metal industry. Arc spot welding has replaced resistance or rivet welding. It is also used in robotic welding, where robots operate the welding gun and sheet metal to save time and money. GMAW is generally not suitable for outdoor use as changes in the atmosphere can cause the shielding gas to dissipate and degrade weld quality. It is also not suitable for underwater welding for the same reasons.
A shielding gas protects the seam from contamination as it forms and cools during GMA welding.
The equipment used in GMAW is a welding gun, wire feed unit, electrode wire, and shielding gas supply. When the control switch on the wire feeder is turned on, electrical power and gas flow are started. This causes an electrical arc to open. The gas nozzle is used to direct the welding gas evenly to the welding area.
The basic technique used in GMAW is quite simple. The operator carefully guides the welding gun and guides it along the area to be welded. It is important to maintain a constant distance between the tip and the work, as the electrode can overheat or waste shielding gas. The correct angle of the weapon is also important; it should be kept at 45° when welding at an angle and 90° when welding on a flat surface.
GMAW requires safety equipment, including special goggles and leather gloves.
GMAW can be extremely dangerous if proper precautions are not taken. Welders must wear protective clothing, including long-sleeved jackets capable of withstanding heat and flame. Leather gloves should also be worn when handling the welding gun. The electric arc can also cause burns to the retina of the eye, so helmets with protective plates should be worn to avoid exposure. GMAW should never be attempted without all proper safety procedures in place.