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Understanding tungsten inert gas welding (TIG)

Today I will be discussing  the definition, applications, diagram, machine, working, advantages and disadvantages of tungsten inert gas (TIG) welding. You’ll also know the difference between TIG and MIG welding.

Read more: Understanding stud welding

What is TIG Welding?

Tungsten inert gas (TIG) welding is also known as gas tungsten inert arc welding (GTAW). It is an arc welding process that uses a non-consumable tungsten electrode. The electrode is protected from atmospheric contamination or oxidation by an inert shielding gas (a mixture of argon or helium). Filler metal may be and may not be added for those autogenous welds.

Electrical energy transfers current through a Colum of highly ionized gas and metal vapors, which is known as plasma. This welding process became successful in the 1940s for joining aluminum and magnesium. It uses an inert gas shield to protect the weld, unlike other arc welding process that uses slag.

Read more: Understanding arc stud welding and its techniques

Applications

The followings are the applications of TIG welding:

  • It is widely used in aerospace industries
  • Industries use TIG welding on a thin workpiece, especially nonferrous metals
  • It is used in the manufacturing of space vehicles
  • TIG welding is suitable on small diameter, thin wall tubing, making it applicable in bicycle industries
  • It is used to repair and manufacture works
  • The process is used to repair tools and die, especially ones made of aluminum and magnesium.

Some material applications of TIG welding include:

Stainless steel, alloy steel, aluminum, titanium, copper, magnesium, nickel alloys

Diagram of TIG welding:

TIG welding

Read more: Understanding electric arc welding

Tungsten inert gas welding Machine

TIG welding machine consist of the following component:

  • AC or DC power supply
  • Non-consumable tungsten electrode
  • Inert gas supply
  • Welding head

tig welding machine

Read more: Understanding gas welding process

Working principle of TIG welding

Tungsten inert gas welding TIG

The working of tungsten inert gas welding is less complex and can be easily understood. It operate under similar principle with MIG welding; the base metal and bonding materials are melted by the heat generated by an electrical current. it then cools and form a solid joints. Although there is still huge difference between the welding despite the similarities.

Read more: Understanding metal inert gas welding (MIG)

Watch the video below to learn the working of gas tungsten arc welding (GTAW):

Read more: Understanding flux cored arc welding (FCAW)

Differences between MIG and TIG welding

The table below shows the difference between TIG and MIG welding:

MIG Welding TIG Welding
Metal inert gas (MIG) welding utilizes a consumable electrode that is continuously fed into the welding zone from a wire pool. Tungsten inert gas (TIG) welding utilizes a non-consumable electrode (so it remains static and intact during welding).
The electrode itself melts down to supply necessary filler metal required to fill the root gap between base metals. So electrode acts as filler metal (no additional filler is required). If required, filler metal is supplied additionally by feeding a small diameter filler rod into the arc. So filler metal is supplied separately.
Composition of electrode metal is selected based on parent metal. Usually, metallurgical composition of electrode metal is similar to that of base metal. Electrode is always made of tungsten with small proportion of other alloying elements (like thorium).
It is suitable for homogeneous welding. It cannot be carried out in autogenous mode welding as filler is applied inherently. It is particularly suitable for autogenous mode welding. However, it can also be employed for homogeneous or heterogeneous mode by supplying additional filler.
The electrode-cum-filler for MIG welding comes in the form of a small diameter (0.5 – 2 mm) and very long (several hundred meters) wire that is wound in a wire-pool. TIG welding filler typically comes in the form of small diameter (1 – 3 mm) and short length (60 – 180 mm) rod.
Due to very large length, the filler electrode can be fed for a longer duration without replacement. Due to short length, frequent replacement of filler is required. This interrupts the welding process unintentionally.
MIG welding is commonly carried out either in AC or in DCEP polarity so that electrode can be melted and deposited at a faster rate. TIG welding is commonly carried out either in AC or DCEN polarity to increase electrode life.
Filler deposition rate is very high, so the process is highly productive. Filler deposition rate is low. In this sense, it is not very productive.
MIG welding usually produce spatter. This causes loss of costly filler metal. TIG welding is mostly free from spatter.
Quality and appearance of weld bead are not very good. It can easily produce defect-free reliable joint with good appearance.
It does not lead to tungsten inclusion defect. TIG welding sometimes leads to tungsten inclusion defect (occurred when a melted/broken part of the tungsten electrode gets embedded into weld bead).

Read more: Understanding plasma arc welding

Advantages and disadvantages of TIG welding

Advantages

The following are advantages of TIG welding.

  • It produces high quality welds
  • It is protected by the inert gas during the process
  • TIG welding does not produces slag
  • It can be performed in any welding position

Disadvantages

Despite the great benefits of TIG welding, some limitations also occurs. The followings are the disadvantages of TIG welding

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  • Offers a slow welding process
  • High skilled labour is needed
  • Operation cost is much expensive
  • Welders exposure to high intensities of light

Read more: Understanding electroslag welding

That is all for this article, where the definition, applications, diagram, machine, working, advantages and disadvantages of gas tungsten arc welding (GTAW), tungsten inert gas welding (TIG). We also discussed the difference between MIG and TIG welding. I hope you got a lot from the reading, if so, kindly share with other students. Thanks for reading, see you next time!

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