Welding is the process that joins metals or thermoplastics together by fusion. Most often, this is done by melting the pieces together and adding a filler material that forms a strong joint. There are a variety of different tools that can be used for welding, including lasers, electron beams, friction, electric arc and gas flames. Arc welding creates an electric arc between the electrode and the base material to create an intense heat. This heat melts the metals, creating a fusion at the welding point. Two types of arc welding are metal inert gas welding, or MIG welding, and tungsten inert gas welding, or TIG welding. A MIG welder utilizes a semi-automatic or automatic welding process that feeds a consumable wire electrode and a shielding gas (typically argon) through the welding gun. This process creates the necessary heat to weld two pieces of metal together. In MIG welding, there are four main ways that metal transfers: spray, pulsed-spray, globular and short-circuiting. A TIG welder uses non-consumable tungsten electrodes to create the weld between two metals. Typically, a filler metal is used as well. Welding can be dangerous, and there are certain precautions that need to be taken to prevent electric shock, severe burning and overexposure to ultraviolet lights. Welding should only be carried out in an area that has proper ventilation because of the toxicity of some metals. It is also important to wear a safety shield, fire-resistant clothing, long sleeves, a fire-resistant skull cap and fire-resistant gloves. A helmet with a filter lens should also be worn in front of the face.
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