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TIG Welding Basics

Swapnil Srivastava Jan 27, 2019
TIG welding is very popular because of its durability and arc stability. The following write-up describes the basics related to this type of welding.
Tungsten Inert Gas (TIG) welding is a process that works with the help of a tungsten electrode. This electrode is used to produce the weld and a shielded gas like argon, which protects the weld area from atmospheric contamination.
A constant electric power supply is provided for this process. It was initially named Heliarc, as helium was used when it was invented. Proper cleaning of the weld joint area and the filler metal is necessary for the removal of oil, grease, dirt, paint, etc. Such contaminants may result in arc instability and lead to a poor weld.
TIG welding process can be used on Stainless steel types like 304 and 321, 1010 carbon steel, Nickel alloys, Aluminum alloys like 6061 and 5052, Titanium alloys like 6al4v, Copper alloys like Nibral bronze, etc.
The power source should be an AC/DC welder with a high duty cycle, and a high frequency. This frequency feature enables arc stability during zero voltage conditions in the alternating current cycle.
With technological advancements in the field of power source, the use of pure tungsten has decreased. The main reason for this is the low melting temperature of tungsten, which causes the formation of a rounded ball at the tip. With the growth of the ball, it becomes more difficult to see the weld puddle, causing instability of the arc.
Ceriated tungsten provides a better alternative because of its ability to withstand higher temperatures. It can also be used on both AC and DC polarities, and it increases the welding amperages by 25 to 30 percent as compared to pure tungsten.
Thoriated tungsten is also available in the market, and is popular for its higher current capacity. It also allows easier arc starting and greater arc stability for the basic welding process.
The most important component of TIG welding is the TIG torch, which delivers electric current and shielding gas to the weld joint. Nowadays, there is a huge variety of such torches that are available in the market. One should use a torch that fits comfortably in one's hand and stays cool.
Air cooled and water cooled torches are also available. The former ones are rated at 150 percent of the welder's rating, and they serve a good purpose. The latter ones are good for professionals, but are impractical for the hobbyist.
The filler metals that are used are categorized in a similar way as the arc welding electrodes. Commonly these filler rods are 36 inches long, and their diameters are available in 1/16, 3/32, and 1/8 diameters. Oxy-acetylene welding rods are not compatible with the TIG welding characteristics.
It is advisable to use tungsten of the smallest possible diameter, and match the size of the electrode with that of the collet. Premium quality torches and work leads should be used, and while welding, they should be kept as short as possible. Before beginning, one should also ensure that the stick electrode holder is detached from the machine.