There are always some details that go unnoticed when comes to understanding of tig welding. Most welders are familiar with this process, however as it is pretty specific, takes a lot of time and it is not very efficient at a larger scale, not many welders are actually using it.Copy HTML Copy text
Let’s start by taking a closer look on how it works. In the TIG process, the electrical arc is established between the workpiece and a non-consumed tungsten electrode. The pool of fusion and the electrode are protected against the effects of atmospheric air by an inert gas, whose flow is directed by a nozzle that surrounds the electrode, and when necessary, metal is added.
Approximately 70% of the heat generated is concentrated in the positive end of the process.
The TIG process was introduced in the 1930s in the aeronautical industry, directed to the military area for welding aluminum and its alloys. At the time of its development, the importance of shielding gas to prevent the appearance of defects in the weld bead was already well known. Used in the welding of the main metals in all industrial sectors, the TIG process has high quality and high structural resistance.
Advantages of the TIG welding process
• • Better finishing between processes;
• • Excellent quality of mechanical welding properties;
• • Watertightness and sanitary finish;
• • Does not require additional metal in certain thicknesses and preparations;
• • Weldable in any position ;
• • It allows controlling the heat input in the part to be welded:
Disadvantages of the TIG welding process
• • Low productivity;
• • The high cost of implementation;
• • Requires skilled labor.
TIG welding forms
Autogenous welding: it is one where no added metal is used. Used in overlapping joints, roots without opening, joints with an outer angle, and thin thickness.
Welding with filler metal: all welding is carried out, regardless of the type of joint or purpose, with the addition of metal.
Note: Some steels require welding with filler metal due to their chemical composition, thus excluding the possibility of autogenous welding.
Variables of the TIG welding process
• • Electric arc voltage;
• • Current intensity;
• • Welding speed;
• • Tungsten electrode ;
• • Sharpening the electrode;
• • Shielding gas and nozzles;
• • Additional material.
Arc voltage
The arc voltage is directly linked to the arc length. It is a result of the union of many variables inherent to the operation, they are:
• • The distance between the electrode and the part;
• • The welding current;
• • Type of shielding gas;
• • Sharpening the electrode.
The arc tension also influences the width of the fusion pool and the penetration, which directly results in the cord’s characteristics.
Current types
Direct current (DC): Used in the welding of carbon steel, stainless steel, copper, nickel, and titanium.
Alternating current (AC): Used in welding aluminum and its alloys.
Tig welding speed
This is probably the biggest drawback of this welding method. It is relatively slow process and that’s why is not very popular for a bigger projects.
TIG welding torch applications
All elements can be welded either manually or automatically with a TIG welding torch. TIG torches are especially suitable where alloyed steels, special metals (e.g., nickel), or light metals are used, such as titanium or magnesium.
Sharpening the electrode
The sharpening of the tungsten electrode varies according to the type of current that will be used. For direct current (DC) welding, the electrode must be sharpened like a pencil. For alternating current (AC) welding, the tip must be rounded.
Gas Lens
For welding stainless steels, titanium, and tool steels, a special gas diffuser known as the gas lens system has been developed to improve the gas protection in the weld region. In this system, micro gas bundles offer better protection with the same flow used in the conventional system.
Manual TIG welding method
1) Once the arc is started, the electrode is moved circularly until the welding puddle is established.
2) The torch must be tilted moved along the joint to merge the surfaces gradually. The addition metal must be added at the beginning of the puddle.
Conclusion
The tig welding process is widely used today, as it is versatile and allows to join a wide variety of metals. However, it requires a lot of attention and is probably the slowest of all commonly used welding methods.
This article was written by Jim Richard Dalton, a welder with over 20 years of experience in TIG welding and a manager at Welding Superstore, distributor of top quality welding boots https://www.weldingsuperstore.com.au/safety-and-workwear/welding-boots/