Spot welding 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 work pieces to be joined. Heat is concentrated at the projections which permits welding of heavier sections or closer spacing of welds.
Resistance Seam Welding
Resistance seam welding is a typically automated process that produces a weld at the faying surfaces of two or more sheets of metal. Seam welding can be broken down to mash seam or overlap welding.
Gas Metal Arc Welding
Gas metal arc welding (GMAW), sometimes referred to by its subtypes, or metal inert gas (MIG) 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
Plasma arc welding (PAW) is a process similar to gas tungsten arc welding (GTAW). The electric arc is formed between an electrode and work piece. The key difference between PAW and GTAW is that, in PAW, by positioning the electrode within the body of the torch, plasma arc can be separated from 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 speed of sound and temperature approaching 20,000 °C.
Autogenous Laser Welding
Austenitic stainless steels and carbon steels love autogenous laser welding and no filler metal is required for strength or corrosion concerns. Sheets can be seamed together without any edge preparation with full weld penetration from one side.
Laser Hybrid Welding
Laser hybrid welding is useful for very specific applications when filler metal is required. The laser beam is combined with MIG welding puddle to push molten filler metal deep into weld joint. This process adds more heat and distortion than autogenous laser welding. Laser hybrid welding can also be used to increase weld speed or depth of penetration and provides more tolerance of joint fitup.