ASHOKA INSTITUTE OF TECHNOLOGY & MANAGEMENT AKTHA, SARNATH VARANASI MECHANICAL ENGINEERING DEPARTMENT

“TUNGSTEN INERT GAS WELDING(TIG)” SEMINAR PRESENTATION ON “TUNGSTEN INERT GAS WELDING(TIG)” Presented by Arvind Kumar Maurya B.Tech. ME 5th Semester Roll Number-1064140007 SESSION-2012-2013 Under the guidance of- Mr. Arvind Kumar Maurya Assistant Professor Mechanical Engineering Department

Contents What is TIG TIG Process TIG Operation Non-Consumable Electrodes Types of Electrodes TIG Torch Shielding Inert Gases Advantages and disadvantages of TIG Applications of TIG Safety

What is TIG Tungsten Inert Gas (TIG) or Gas Tungsten Arc (GTA) welding is the arc welding process in which arc is generated between non consumable tungsten electrode and workpiece. The tungsten electrode and the weld pool are shielded by an inert gas normally argon and helium.

Diagram of TIG Welding System Fig : Schematic Diagram of TIG Welding System

TIG Process.... In TIG welding process, the arc is maintained between a non-consumable tungsten electrode and the workpiece in a protective inert gas atmosphere. Any filler metal needed is supplied externally. The possible currents available are Direct Current (DC) and Alternating Current (AC).

...TIG PROCESS.... Normally a DC arc is used with tungsten as the negative pole.

...TIG PROCESS.... This is not possible for the metals such as Al and Mg, where the oxide layer persists if the workpiece is used as the anode. This layer prevents the formation of the weld pool.

...TIG Process When the tungsten electrode is used as the anode excessive heat is generated. So an AC arc is used for such materials. To avoid the melting of the electrode, Thorium or Zirconium is added to tunstun to increase its melting point.

TIG Operation First of all the material surface is cleaned clearly which is to be weld. Then the power source is applied. Nozzle valve is also opened before the welding operation . After that the torch is contacted to that surface due to which the welding starts with no fumes. Any filler metal needed is supplied externally.

Non-consumable Electrodes Electrodes are not consumed in the weld puddle. Inert gas provides a shield to protect the electrode. Usually 7” in length – common diameters are 1/16”, 3/32” & 1/8”.

Non-Consumable Electrodes.. Fig: Tunstun holder

Types of Electrodes

Thoriated Tungsten red band is 2% thorium, yellow band is 1% thorium. Used on all steels with DC polarity. Does not contaminate as easily as pure tungsten. Better arc stability and runs better at low amps.

TIG Torch.... Parts of the Torch Head- Torch body Collet for holding electrode Electrode cap Ceramic nozzle Water inlet and outlet pipes for cooling Shielding gas pipe Current Cable

TIG TORCH Fig: TIG Welding Torch

Shielding Inert Gases.... The shielding gases used for TIG welding are mostly argon, helium, and mixtures of argon and helium. A brownish-yellow fume from the weld zone indicates that the shielding gas cover has been lost and that oxides are forming .

...Shielding Inert Gases... The most commonly used gas because it is cheaper and 10 times heavier than helium. Argon is 1.4 times heavier than air and gives better control of the arc and weld puddle because it is a heavier gas than helium. Helium shielding gas is used for welding thick sections of metal and when higher arc voltages and higher weld zone temperatures are needed.

Advantages of TIG... Weld non-ferrous metals. Deep penetration. Weld in all positions. Clean weld – no slag. Weld light to heavy gauge metals.

...Advantages of TIG.... Welds made are- more corrosion resistant more ductile and Stronger The welding process is easier than other methods because the weldor can clearly see the welding zone.

...Advanteges of TIG The finished weld requires little, if any, grinding or preparation before it can be painted. Less distortion of the workpiece because of the small heat affected zone. Minimal amount of smoke, fumes, and sparks created.

Disadvantages of TIG More user skill is required. Cost of equipment may be higher than other processes. Metal must be clean.

Application of TIG The TIG process can be used to join most metals. It welds aluminum and magnesium and their alloys, alloy steels, carbon steels, stainless steels, copper, nickel and nickel alloys, titanium, tin, silicon, aluminum bronzes, and cast iron.

Limitations of TIG One limitation of the TIG welding process is the low deposition rate of the filler and metal.

Safety Make sure “ALL” skin is covered. Light will burn your skin if exposed. Use proper eye protection. Turn off power to set-up or take the torch head apart. You can get shocked if you accidentally push the foot rheostat. You are a better conductor of electricity than metal is. Turn the machine off the make changes on it.

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