If, as in MIG welding, a flat characteristic power source is used, any contact with the workpiece surface would damage the electrode tip or fuse the electrode to the workpiece surface. This could happen either deliberately during arc starting or inadvertently during welding. A constant current power source is essential to avoid excessively high currents being drawn when the electrode is short-circuited on to the workpiece surface. TIG welding must be operated with a drooping, constant current power source - either DC or AC. When filler metal is required, it must be added separately to the weldpool. Because the electrode is not consumed during welding, the TIG welder does not have to balance the heat input from the arc as the metal is deposited from the melting electrode. The small intense arc provided by the pointed electrode is ideal for high quality and precision welding. In the TIG welding process the arc is formed between a pointed tungsten electrode and the workpiece in an inert atmosphere of argon or helium. Click here to see our latest technical engineering podcasts on YouTube. TIG has played a major role in the acceptance of aluminium for high quality welding and structural applications.
Using an inert gas shield instead of a slag to protect the weldpool, the process was a highly attractive replacement for gas and manual metal arc welding. Tungsten inert gas (TIG) welding became an overnight success in the 1940s for joining magnesium and aluminium. Tungsten Inert Gas (TIG) welding, also known as Gas Tungsten Arc Welding (GTAW) is an arc welding process that produces the weld with a non-consumable tungsten electrode.