A Welder, or Brazer, is responsible for assembling pieces of metal together or repairing damage in metal components using heavy machinery that emits high heat, melting the metal into shape. Their duties include reviewing blueprints, cutting metal into the appropriate shape and smoothing molten metal to remove creases. Welding is a joining process in which metals, or sometimes plastics, are heated, melted and mixed to produce a joint with properties similar to those of the materials being joined. There are three main components needed to create a weld. These are: A heat source such as an electric arc, a flame, pressure, or friction.