28 June 2017

Tungsten inert gas welding

Tungsten inert gas welding is also known as gas tungsten arc welding.

In this process, an inert gas shielded arc welding process using a non-consumable electrode. The electrode may also contain 1 to 2% thoria mix along with the core tungsten or tungsten with 0.15 to 0.40% zirconia. The pure tungsten electrodes are less expensive but also it will carry less current. The thoriated tungsten electrodes carry high current and more desirable because they can strike and maintain a stable at with relative ease. The zirconia added tungsten electrode better than pure tungsten but inferior to thoriated tungsten electrodes.

The process set up :

Tungsten inert gas welding setup is shown in figure it consists of a welding torch at centre electronic inert gas is supplied to the welding zone through the Anil apart surrounding the tungsten electrode to effectively displays the atmosphere Around The World Patel the smaller world tours may not be provided with Anni cooling device for the electrodes but larger ones are provided with circulating cooling water 30 welding process can be used for joining a number of materials through the more aluminium magnesium and stainless steel.

Components used :
  • Power Supply (A.C or D.C)
  • Filler Rod
  • Non-consumable Tungsten electrode
  • Welding Head
  • Inert Gas Supply

Tungesten intert gas welding

Working principle :

TIG welding process is relatively difficult to perform out of another welding process because it normally requires two hands for the process to be performed while other processes require that the welder manually feed a filler metal into the weld area with one hand.

In this process, first of all, strike the welding arc that can be produced by torch. A high-frequency generator provides an electric spark. This spark is a conductive path for the welding current through the shielding gas and it allows the arc to be initiated while the electrode and the workpiece are separated. The inert gas forms a gas shielding around the weld. It protects the weld from the external atmosphere. 

Once the arc is struck, the welder moves the torch in a small circle to create a welding pool, the size of that depends on the size of the electrode and the amount of current then torch moves back and filler metal is added manually to the front end of the weld pool as it needed.
The arc current is often gradually reduced to allow the weld crater to solidify and prevent the formation of cracks at the end of the weld. Thus, this process can be done.

Advantages of TIG welding :
  • It produces high quality and clean welds.
  • No slag is produced so welds are not weakened.
  • The weld is automatically protected by the inert gas during the welding process so welds are corrosion resistance, more ductile, and stronger.
  • This process can apply for any position of welding like wise horizontal, vertical or flat.
  • It can be performed by both automatic and manual technique.
  • It easily applied to thin material and used for a wide range of metal thickness.
  • There is less distortion of work piece because the small heat affected zone.
  • Only the necessary amount of filler metal is added to the welding puddle so there is no spatter or sparks are produced.
  • Use one shielding gas mainly Argon for all applications.
  • In this process finishing process required little or less. Sometimes grinding or preparation before it can be painted.
  • It is the preferred choice in most of the intricate works, where shape of each and every weld joint counts.
Main most common limitations of TIG welding is low deposition rate of the filler and metal per pass so that time increased to completed the welds that's why it is mostly used for thinner metal. More than that it has certain disadvantages we can check it below :

Disadvantages of TIG welding :
  • As we seen it is slow process.
  • More complicated process so that highly skilled labour is required.
  • Less economical than consumable electrode for sections thicker than 3/8 inch.
  • Tungsten inclusion.
  • Welder is exposed to the huge intensities of light.
  • This process is also more expensive.
  • Sensitive to drafts.
Tungsten Inert Gas Welding offers several advantages that account for its popularity and its use in agriculture and many other industries. 
Applications of Tungsten Inert Gas Welding :
  • Stainless steel
  • Alloy steel
  • Aluminium
  • Titanium
  • Copper
  • Magnesium
  • Nickel alloys