A process of welding that makes use of non-consumable tungsten electrode and inert gas (usually argon) is known as TIG welding. The inert gas is used as a shield to prevent atmospheric contamination in the process of welding. The actual welding takes place by means of metal vapors and highly ionized gas known as plasma.
The plasma is produced as a result of energy generated from a constant current power supply in this process. This technique is used for welding light metals, such as magnesium, aluminum, and alloys of copper. The thin sections of stainless steel are generally welded with the help of this technique.
The Welding Process
- This process requires very high skills and protection.
- The welder has to hold the welding torch in one hand, while he feeds the metal filler with the other.
- To strike an arc is the most important thing in the process of welding.
- A high frequency generator facilitates an arc formation by creating a path through a shielding gas.
- The arc is struck when the distance between the welding area and electrode is 1.5-3 mm.
- After striking the arc, a welding pool is created by circling the welding torch around the welding area.
- Once the weld pool is created, the torch is tilted at an angle of 10-15 degrees while maintaining the distance between the electrode and welding area.
- Filler metal is then added to the weld pool.
TIG Welding Techniques
- This technique is used to increase the accuracy of welding.
- In this method, a cold filler wire is used for feeding, and it is dabbed or oscillated into the welding area.
- This method is used for welding nickel, titanium, tool steels, and various alloys.
- Milling cutters, seals in jet engines, mower blades, and drill bits are the common applications where the dabber technique is used.
- In the pulsed-current technique, the current used in welding alternates between two levels, i.e., the pulse and background current.
- The pulse-current denotes a higher current, while the background current means a lower current.
- In this technique, the weld area gets heated, and the fusion takes places during the pulse-current or higher current period.
- During the period of lower or background current, the weld area solidifies due to cooling.
- Some of the advantages of using the pulsed-current method is that the amount of warpage or distortion in welding is reduced considerably.
- Weld speed and weld penetration increases, while the quality of welding is improved if this technique is used.
- The hot wire technique of welding is slightly different than the previous mentioned techniques.
- In this method, filler metal to be added during welding is 'resistance heated'.
- The heating is done till the filler metal reaches its melting point.
- The deposition rate of the machine is increased because of prior heating of the filler metal. This technique is mostly used in 'hard-facing' operations.
The process of TIG welding is a type of arc welding. Unlike the MIG welding techniques that are easy to learn, TIG is difficult to carry out. Professionals or experts are required to successfully carry out the process.