WELDING PROCESSES
Submerged Arc Welding The Submerged Arc Welding process is a type of arc welding. The formation of the arc is made from an electrode, acting as the filler material. The weld zone is entirely covered with a layer of granulated flux, hence the term ‘submerged’ in the name. This flux is made from carbon
and silicate material. The flux generates a gas shield and facilitates electrical conduction when molten. During the welding process, the flux is continuously delivered by a tube attached to a flux hopper. The entire welding process is
mechanised and is buried under the granular flux, so it can’t be seen from the outside. This type of arc welding process can
and pipe-to-plate joints, for which high-quality single-side welds and double-side formed welds can be achieved using laser welding. In shipbuilding, welding thick
plates (with added filler metal) using laser welding yields joint performance superior to conventional arc welding, reducing product costs, enhancing component reliability, and contributing to the extended service life of ships. Laser welding is also applied in
the welding of stator laminations for electric motors, the production of engine casings, wing spars, and other aircraft components, as well as in the repair of aviation turbine blades.
Thermite Thermite Welding, or exothermic welding, is a welding process that uses molten metal to permanently join the metals to be welded. The process needs thermite - a mixture of metal oxide and aluminium powder. The process is an exothermic
reaction of the thermite composition that heats the metals and fuses them together. An external heat source ignites the thermite and starts the chemical reaction. This type of welding is commonly used to weld cracks in railways and make heavy, strong joints for large pieces of machinery.
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have a high metal deposition rate of up to 20 kg/hour. It also has a capacity for welding metals with thicknesses up to 100 mm. This type of welding is often used in heavy fabrication industries. The aviation industry, shipbuilding, railroads, and bridge- building also use this type of welding.
Plasma Arc Welding (PAW) PAW is a type of arc welding similar to Gas Tungsten Arc Welding. The similarities lie in the arc created between a tungsten electrode and the object being welded. However, in PAW, the plasma arc is isolated from the shielding gas. Isolation is done by putting the electrode inside the torch’s body. The arc is also constrained by
plasma pushed through a fine-bore copper nozzle. The electronics industry often uses this type of welding. It’s also found application in the aerospace industry.
Electroslag Welding (ESW) Electroslag is a vertical process of bonding heavy metal pieces for use in machines and industrial equipment. This advanced technique is specifically designed to vertically join thin metal plates edge-to-edge. Unique to ESW, the welding action occurs directly between the edges of the plates rather than being applied externally to a joint. The process begins by positioning
consumable metal guides between the two plates, setting them up for the welding operation. A copper electrode, which doubles as the filler material for the joint, is then introduced through these guides. The welding arc is initiated by applying an electrical current, and the weld begins at the start of the seam, progressively moving across the designated weld area. This movement is meticulously controlled by a machine, rendering the process fully automated once the plates and guides are set up. Electroslag Welding is
predominantly used for joining low-carbon steel plates that are exceptionally thick. It can also be aptly applied to structural steel, provided certain precautions are considered.
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