ARC WeldingTechniques

Arc welding roots go back to 1800's when an English scientist discovered that an electric current would form an "arc" when forced across a gap of steel plates. Electric was not used for "arc welding" until 1880's when DeMeritans, a French inventor, used it to join plates in a storage battery with a "carbon arc." The procedure was improved on and it was discovered that a bare metal rod, now named an "electrode," would melt off by the heat of the arc and act as filler metal in the weld.

Using the bare electrode was hard to control and caused a weld that is porous, brittle, and weak. By the early 1900's an important development was the discovery that welds are stronger and easier to make when a chemical coating was placed on the metal electrode. The coating was called "flux." The flux was baked on the electrode and was renamed."

World War I and II placed a high demand on manufactures and builders so the "arc welding" process was further developed and honed. For example, riveting used in the building industries was replaced with welding. Many companies sprang up in America to manufacture welding machines and electrodes to meet the new demands. The perfection of welding processes continued at a rapid rate.

Other techniques such as Gas Metal Arc Welding, aka "MIG," and Gas Tungsten Arc Welding aka "TIG" were perfected. An arc is struck between a "nonconsumable tungsten" rod and the base metal. The heat of the arc causes the edges of the plates to melt and flow together. A filler rod can be manually applied, if needed A patent was granted for a "TIG" process and was named "Heliarc®."

MIG welding is identified by the American Welding Society and uses a " . . . continuous solid wire electrode for filler metal and an externally supplied gas (typically from a high-pressure cylinder) for shielding. The wire is usually mild steel . . . " (Lincoln Electric). The wire is fed through a "gun." The MIG process is widely used in aircraft and automobile manufacturing. MIG is easy to learn, it speeds up production and produces high quality welded joints. One drawback is that it can't be used in vertical or overhead positions.

"Plasma arc welding" was introduced in the Unites States. The atomic/nuclear energy ushered in "electron beam" welding. Other systems such as "inertia friction welding" followed.

Laser welding or "fusion" is one of the newest processes. "Laser welding is a high production welding process that produces deep penetration welds with minimum heat effective zones" (Laser Fusion, www.laserfusionwelding.com.) Because of the tremendous concentration of energy in a small space, it proved to be a powerful heat source. The laser welding process is still finding welding applications in aircraft industry and other metalworking operations.