Welding current is the term used to describe the electricity that jumps across the arc gap between the end of the electrode and the metal being welded. An electric current is the flow of electrons. The resistance to the flow of electrons (electricity) produces heat.

The greater the electrical resistance, the greater the heat and temperature that the arc will produce. Air has a high resistance to current flow, so there is a lot of heat and temperature produced by the SMA welding arc. Electrons flow from negative (–) to positive (+).

What three units are used to describe any electrical current?

Three units are used to describe any electrical current.
The three units are voltage (V), amperage (A), and wattage (W).
• Voltage, or volts (V), is the measurement of electrical pressure in the same way that pounds per square inch is a measurement of water pressure. Voltage controls the maximum gap that the electrons can jump to form the arc. A higher voltage can jump a larger gap. Welding voltage is associated with the welding temperature.

• Amperage, or amps (A), is the measurement of the total number of electrons flowing, in the same way that gallons are a measurement of the amount of water flowing. Amperage controls the size of the arc. Amperage is associated with the welding heat.

• Wattage, or watts (W), is a measurement of the amount of electrical energy or power in the arc. Watts are calculated by multiplying voltage (V) times amperes (A), Watts are associated with welding power or how much heat and temperature an arc produces.