A welding wire is smoothly fed from the torch and continuously melted in the electric arc. The molten wire material mixes with the molten material being joined, creating a liquid weld pool. After the arc recedes, the weld pool solidifies, creating a permanent joint. A shielding gas is continuously supplied through the welding torch and its gas nozzle, protecting the molten metal from atmospheric exposure and cooling the torch (liquid-cooled torches are also used).

Voltage is applied to the welding wire via a current cable extending from the power source (semi-automatic welding machine) and then transferred via a copper contact tip.