Arc welding heats metals by making a high-current electric arc between pieces of metal to be joined and an electrode . One of the most common types of arc welding is shielded metal arc welding ( SMAW ) ; it is also known as manual metal arc welding ( MMA ) or stick welding . Electric current is used to strike an arc between the base material and consumable electrode rod , which is made of steel and is covered with a flux that protects the weld area from oxidation and contamination by producing carbon dioxide ( CO2 ) gas during the welding process .