TIG welding stands for Tungsten Inert Gas welding process.

. It is also known as Gas Tungsten Arc Welding or GTAW. This is basically an arc welding method rather similar to MIG (wire) welding. However in this case a non-consumable tungsten electrode provides the arc. Filler rod feeders add from a filler metal outside of the arc either manually, or automatically.

The tungsten electrode provides electric current to the arc, creating a very precise and concentrated and localized heat zone. Therefore the TIG welding process is most favorable for jobs where it is not necessary to weld over a large area.

To protect the integrity of the weld and the molten metal, a shield of Helium or Argon gas, which is inert gases, is used. Since these gases are inert, they are ideal for shielding the weld puddle and heat zone. The torch performs the function of providing the electric current as well as the shielding inert gas to the weld zone.

The power source for TIG welding is an AC/DC welder with a high duty cycle. A minimum of 60% is recommended. The welder also needs a high frequency generator, which is essential to maintain a stable arc during the "zero" voltage conditions in the alternating current power supply. 

To regulate the current or amperage during welding, you can employ remote amperage control devices or simple push button controls. This is required from both safety and welding control point of view, as it would allow you to control the current and also prevent you from accidentally striking an arc.

Grades of electrodes used in the TIG welding process are: pure tungsten, 1% thoriated, and 2% thoriated. While pure tungsten electrodes are good for general-purpose use, thoriated electrodes provide a much better arc, and have a longer life. While tungsten electrodes are popularly used for steel, Thoriated tungstens are for non-ferrous metals such as aluminum. Electrodes are available in several diameters: .040", 1/16, 3/32, 1/8, 5/32. 3/16, and also as large as 1/4".

TIG filler metals are numerically categorized and filler rods are 36" long and available in 1/16, 3/32, 1/8 diameters.

While a detailed discussion of the steps of welding are beyond the scope of this article, here are some of the important considerations in TIG welding

·         To get a good joint, cleaning the weld area is of paramount importance.

·         Both parts to be welded should then be arranged. For butt welds it is necessary to have a gap equal to the diameter of the electrode.

·         Keep a clean copper backing plate, which would ensure a clean atmosphere behind the puddle.

·         Choosing the electrode of the right diameter for the job and grind the end of the electrode to a point. This is also called dressing and is useful to creation of the proper arc.

·         Ensure to adjust the inert gas flow in the welding torch such that the shielding flows after the arc is stopped. This will prevent contamination of the electrode during the cooling down process.