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Metal WeldingMetal welding is the joining of two metals through coalescence, which is accomplished through heating the metals enough to melt into one another. Since joining parts, plates and edges together is an essential part of the fabrication process, welding is nearly always used in metal fabrication processes. Types of welding differ by heat source, pressure and filler metals. Heat and filler metals are used to connect metal surfaces in brazing and soldering operations. These joining processes do not melt the base materials as welding does. In addition, metal welding differs from metal brazing and soldering because unlike brazing, welding does not require a filler material in order to create the actual bond. Metal parts may also be joined by applying adhesives and then curing or setting the adhesive. Used to form a variety of metal parts, such as snow blades, connectors, MRI trailers, shelving, lockers, cabinets, storage cages, heat exchanger shrouds and microwave antenna receiver brackets, metal welding has nearly unlimited applications. A broad range of industries benefit from metal welding processes including microelectronics, automotive, commercial, medical, industrial, defense, marine, aerospace, petrochemical and construction. Aluminum welding and steel welding are the two most common types of metal welding; steel welding includes stainless steel welding and carbon steel welding. Often an industrial process, metal welding can take place in environments such as open air, underwater and outer space. The main disadvantage to metal welding is that it is a dangerous process and safety equipment and other precautions must be used to avoid electric shock, burns, eye damage and poisonous fumes There are many different energy sources that are used during metal welding processes, including an electric arc, friction, ultrasound, a gas flame, a laser and an electron beam. The type of energy source that will be used depends on the type of metal welding being used. There are many different metal welding processes, six of the most common including spot welding, electric arc welding, gas metal arc welding (GMAW), ultrasonic welding, energy beam welding and explosion welding. Spot welding involves joining together overlapping pieces of metal at small points, or spots, through the application of great pressure as well as an electric current. Electric arc welding uses a welding power supply, typically either a direct current (DC) or an alternating current (AC), to create an electric arc between an electrode, which can be consumable or non-consumable, and the base material in order to melt the metals at the welding point. During GMAW, a shielding gas, which can be either an inert gas or an active gas, and a continuous, consumable wire electrode are fed through a welding gun. This process is typically powered by a DC power source, but can also be powered by an AC power source. Ultrasonic welding utilizes high frequency sound energy in order to soften or melt the metal at the joint. Metals that are being joined are first held together under pressure and then subjected to ultrasonic vibrations. Energy beam welding includes laser beam welding and electron beam welding. While they are very similar processes, electron beam welding differs from laser beam welding because electrons are focused instead of photons. Explosion welding is accomplished during a solid state through using chemical explosives to accelerate one of the metals at an extremely high velocity.
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