Welding electrodes send an electric current or arc across two pieces of metal, creating extreme heat and causing the two metals to fuse. A welding electrode can be an anode, a cathode, or the electrode can have an alternating current. Depending on the type of welding, the electrode can be consumable or non-consumable.

Chemistry of Arc Welding

In arc welding, the exchange of electrons between two metals, known as the arc, creates heat that can meld metals. The arc's electrons pass through the charged metal surface and a welding electrode. In most cases, the arc must be protected with gases, such as Helium or Argon, or flux. Depending on the type of welding, the high heat created by the arc either melts two metals together or uses a filler metal to conjoin two surfaces.

Consumable Electrodes

Some types of arc welding, such as shielded metal arc welding (SMAW), flux-cored arc welding (FCAW), and gas metal arc welding (GMAW), use a specially fabricated welding electrode that breaks down from the heat of the arc, creating a protective gas or flux. These electrodes are called consumable electrodes.

Non-Consumable Electrodes

An electrode encased within a gas nozzle that emits a protective gas is a non-consumable electrode. The gas flows around the electrode and over the metal surface, protecting the arc. Examples of welding using non-consumable electrodes are plasma arc welding (PAW) and tungsten inert gas (TIG) welding.

Resistance Welding

Resistance welding, such as resistance spot welding (RSW) and resistance seam welding (RSEW), uses the heat produced between two electrodes and pressure to fuse two metal surfaces.

Certification and Caution

Welding classes are available through many community colleges. Although certification is not necessary for most welding jobs, it is possible to receive certification through the American Welding Society. Welding involves many dangerous phenomena, including heat, electricity, and off-gassing. Be sure to wear protective gear and work in a well-ventilated area.

Source:

"Architectural Graphic Standards;" John Hoke; 2000

More Information:

welding.com

American Welding Society