What is TIG Welding : Principle, Working, Equipment’s, Applications, Advantages and Disadvantages

TIG stands for tungsten inert gas welding or sometimes this welding is known as gas tungsten arc welding. In this welding process, the heat required to form the weld is provided by a very intense electric arc which is the form between a tungsten electrode and a workpiece. In this welding, a non-consumable electrode is used which does not melt. Mostly no filler material is required in this type of welding but if it required, a welding rod fed into the weld zone directly and melted with the base metal. This welding is mostly used for welding aluminum alloy.

TIG Welding:

Principle:

TIG welding works on the same principle of arc welding. In a TIG welding process, a high-intensity arc is produced between the tungsten electrode and the workpiece. In this welding, mostly workpiece is connected to the positive terminal and the electrode is connected to the negative terminal. This arc produces heat energy which is further used to join metal plate by fusion welding. Shielding gas is also used which protect the weld surface from oxidization.

Equipment’s

Power Source:

The first unit of equipment is the power source. A high current power source needed for TIG welding. It uses both AC and DC power sources. Mostly DC current is used for stainless steel, Mild Steel, Copper, Titanium, Nickel alloy, etc. and AC current is used for aluminum, aluminum alloy, and magnesium. The power source consists of a transformer, a rectifier, and electronic controls. Mostly 10 – 35 V is required at 5-300 A current for proper arc generation.

TIG Torch:

It is the most important part of TIG welding. This torch has three main parts, tungsten electrode, collets, and nozzle. This torch is either water-cooled or air-cooled. In this torch, the collet is used to hold the tungsten electrode. These are available in varying diameter according to the diameter of the tungsten electrode. The nozzle allows the arc and shielded gases to flow into the welding zone. The nozzle cross-section is small which gives high intense arc. There are passes of shielded gases at the nozzle. The nozzle of TIG needs to replace in the regular interval because it wears out due to the presence of an intense spark.

Shielding Gas Supply System:

Normally argon or other inert gases are used as shielded gas. The main purpose of shielded gas to protects the weld from oxidization. Shielded gas does not allow coming oxygen or other air into the welded zone. The selection of inert gas depends upon metal to be welded. There is a system that regulates the flow of shielded gas into the welded zone.

Filler Material:

Mostly for welding thin sheets no filler material is used. But for thick weld, the filler material is used. The filler material is used in the form of rods which are directly fed into the weld zone manually.

Working:

Working on TIG welding can be summarized as follow.

• First, a low voltage high current supply supplied by the power source to the welding electrode or tungsten electrode. Mostly, the
  electrode is connected to the negative terminal of the power source and workpiece to the positive terminal.
• This current supplied form a spark between the tungsten electrode and the workpiece. Tungsten is a non–consumable electrode, which gives a highly intense arc. This arc produced heat that melts the base metals to form a welding joint.
• The shielded gases like argon, helium is supplied through pressure valve and regulating valve to the welding torch. These gases form a shield which does not allow any oxygen and other reactive gases into the weld zone. These gases also create a plasma which increases the heat capacity of electric arc thus increases welding ability.
• For welding thin material no filler metal is required but for making thick joint some filler material used in the form of rods which fed manually by the welder into welding zone.

Application:

• Mostly used to weld aluminum and aluminum alloys.
• It is used to weld stainless steel, carbon base alloy, copper base alloy, nickel base alloy, etc.
• It is used to welding dissimilar metals.
• It is mostly used in aerospace industries.

Advantages and Disadvantages:

Advantages:

• TIG provides a stronger joint compare to shield arc welding.
• The joint is more corrosion resistant and ductile.
• A wide verity of joint designs can form.
• It doesn’t require a flux.
• It can be easily automated.
• This welding is well suited for thin sheets.
• It provides good surface finish because of negligible metal splatter or weld sparks that damage the surface.
• The flawless joint can be created due to the non-consumable electrode.
• More control on the welding parameter compare to another welding.
• Both AC and DC current can be used as a power supply.

Disadvantages:

• Metal thickness to be weld is limited to about 5 mm.
• It required high skill labor.
• Initial or setup cost is high compare to arc welding.
• It is a slow welding process.