A filler metal is a metal added in the making of a joint through welding

Welding

Welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, with pressure sometimes...

, brazing

Brazing

Brazing is a metal-joining process whereby a filler metal is heated above and distributed between two or more close-fitting parts by capillary action. The filler metal is brought slightly above its melting temperature while protected by a suitable atmosphere, usually a flux...

, or soldering

Soldering

Soldering is a process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, the filler metal having a lower melting point than the workpiece...

. Four types of filler metals exist—covered electrode

Electrode

An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...

s, bare electrode wire or rod, tubular electrode wire and welding fluxes. Sometimes nonconsumable electrodes are included as well, but since these metals are not consumed by the welding process, they are normally excluded.

Covered electrodes

Covered electrodes are used extensively in shielded metal arc welding

Shielded metal arc welding

Shielded metal arc welding , also known as manual metal arc welding, flux shielded arc welding or informally as stick welding, is a manual arc welding process that uses a consumable electrode coated in flux to lay the weld...

 and are a major factor in that method's popularity.

Bare electrode wires

Bare electrode wires are used in gas metal arc welding

Gas metal arc welding

Gas metal arc welding , sometimes referred to by its subtypes metal inert gas welding or metal active gas welding, is a semi-automatic or automatic arc welding process in which a continuous and consumable wire electrode and a shielding gas are fed through a welding gun...

 and bare electrode rods are used in gas tungsten arc welding

Gas tungsten arc welding

Gas tungsten arc welding , also known as tungsten inert gas welding, is an arc welding process that uses a nonconsumable tungsten electrode to produce the weld...

.