Welding joins materials by causing coalescence. Many different energy sources can be used for welding, including a gas flame, an electric arc, a laser, an electron beam, friction, and ultrasound.
A cutting torch head is similar to a welding torch but can be identified by the oxygen blow out lever or trigger. Once the metal is heated to a bright red, oxygen is supplied to the heated parts by pressing the trigger. This forms an oxide with a melting point that is around half that of the metal. Plasma cutting is an additional method.
Photographers: Luke Sharrett, Norm Betts, Brent Lewin, Adeel Halim, Dado Galdieri, Daniel Acker, Ty Wright, Prashanth Vishwanathan, Meg Roussos, Aaron M. Sprecher/Bloomberg
