ArtMetal

TIG stands for Tungsten Inert Gas. Another common name for it is Heli-Arc, which is really a brand-name at this point.

TIG may be compared to gas welding but using electricity. The heat source is an electric arc off of a rod of tungsten. The tungsten is held within a copper collet in the torch body. The tungsten is considered a non-consumable electrode. This means that it is not used up in the welding process.

An inert gas (Argon or Helium) is provided by the torch in order to cover the molten weld pool. This protects the molten metal from contamination by the atmosphere.

The power source used is normally set for DCEN (Direct Current, Electrode Negative) to weld all metals except Aluminum. Aluminum used AC (alternating current).

Filler rod may or may not be added, depending upon the type of joint and the thickness or the metal. The filler rod is usually one that matches the base metal in composition and strength. But there are some applications in which the filler rod needs to differ from the base metal to obtain an optimum weld. (an example would be the different types of aluminum: 1XXX aluminiums area best welded with 4043 rod)

Most power sources use a foot pedal or thumb switch to provide variable amperage (heat) while welding. Similar to the gas pedal on an automobile, this pedal or switch allows the welder real-time control of the amperage needed. It's great!

The technique used to do the welding is similar to that of oxyfuel welding. The torch provides the heat and the filler rod is added by the welder into the molten puddle. In TIG, however, the torch angle is about 20 degrees off of the vertical (oyfuel it is 45 degrees). And the filler rod is added pretty much flat, almost parallel to the base metal.

TIG takes more manual skill to master than the other welding processes. But the welds are of extreme high quality: there is no splatter, smoke, slag.

This process is great for bronze castings, stainless steel, aluminum, titanium, tool steels.