metal. TIG welding is an electric welding process that uses a non-consumed tungsten electrode to provide heat, with the filler rod added manually. This is more like gas welding as a process, but with a different heat source. Hardfacing A specialist use for filler metal is where a deliberately different metal is to be deposited. This is often done for hardfacing excavating tools or digger bucket teeth. A hard, but more expensive and sometimes brittle, facing alloy is deposited onto the wear surfaces of mild steel tools. Four types of filler metals exist—covered electrodes, bare electrode wire or rod, tubular electrode wire, and welding fluxes. Sometimes non-consumable electrodes are included as well, but since these metals are not consumed by the welding process, they are normally excluded. Usage Covered electrodes Covered electrodes are used extensively in shielded metal arc welding and are a major factor in that method's popularity. Bare electrode wires Bare electrode wires are used in gas metal arc welding and bare electrode rods are used in gas tungsten arc welding. Tubular electrode wires Tubular electrode wire is used in flux-cored arc welding. Welding fluxes Welding fluxes are used in submerged arc welding. See also Amorphous brazing foil Autogenous welding, welding processes without filler References Cary, Howard B. and Scott C. Helzer (2005). Modern Welding Technology. Upper Saddle River, New Jersey: Pearson Education. . Welding