Spot welding (RSW) is a process in which contacting metal surfaces are joined by heat from resistance to electric current flow. Work pieces are held together under pressure exerted by electrodes.
Projection welding is a modification of spot welding in which the weld is localized by means of raised sections, or projections, on one or both of the work pieces to be joined. Heat is concentrated at the projections, which permits the welding of heavier sections or the closer spacing of welds.
Resistance seam welding is a typically automated process that produces a weld at the faying surfaces of two similar metals. The seam may be a butt joint or an overlap joint. The process differs from butt welding, however, in that butt welding typically welds the entire joint at once, while seam welding forms the weld progressively, starting at one end and moving the length of the material to create a seam weld.
Gas metal arc welding (GMAW), sometimes referred to by its subtypes, metal inert gas (MIG) welding or metal active gas (MAG) 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.
Plasma arc welding (PAW) is a process similar to gas tungsten arc welding (GTAW). The electric arc is formed between an electrode and the work piece. The key difference between PAW and GTAW is that, in PAW, by positioning the electrode within the body of the torch, the plasma arc can be separated from the shielding gas envelope. The plasma is then forced through a fine-bore copper nozzle, which constricts the arc, causing the plasma to exit the orifice at a velocity approaching the speed of sound and temperature approaching 20,000 °C.
Electric resistance welding (RW) refers to a group of welding processes, such as spot and seam welding, that produce coalescence of faying surfaces where heat to form the weld is generated by the resistance of the welding current through the workpieces. Some factors influencing heat or welding temperatures are the proportions of the workpieces, the electrode materials, electrode geometry, electrode pressing force, weld current, and weld time.
Laser beam welding (LBW) is a technique that uses a laser to join multiple pieces of metal. The beam provides a concentrated heat source, allowing for narrow, deep welds and high welding rates. The process is frequently used in high volume applications, such as in the automotive industry.
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