This method has become one of the most popular and productive, but it is also the most complex because it must be carried out according to specific rules.
The TIG welding method was developed during the Second World War for military purposes and is currently one of the most used procedures. Arc welding with infusible tungsten electrode under inert gas protection, commonly known with the abbreviation TIG (Tungsten Inert Gas), is a more complicated process than standard manual welding with MMA coated electrode and requires good experience and coordination to ensure satisfying results.
The advantage of this particular process, however, is to provide high-quality joints with a high degree of tightness; Furthermore, TIG welding is also characterized by high productivity and by the possibility of being used on different types of metal alloys, including those of aluminum, magnesium, and titanium.
These characteristics have meant that the TIG methodology has spread exceptionally rapidly at all levels, especially in the hobby and craft sector, despite its difficulty in execution. Among the various versions available on the market, the best-selling TIG welder is precisely the medium-low power one, and this is enough to give a general idea of how much the range of hobby and artisan users that make use of this has expanded particularly type of system.
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The conditions and cleanliness of the working environment
Returning to the discussion on the complexity of the method, it arises from the particular conditions required for its correct execution; to guarantee high quality and tight joints the welding bath must, first of all, be isolated from the surrounding atmosphere to avoid contamination from slag and oxidation due to contact with oxygen.
Consequently, the work environment where TIG welding is carried out must be kept very clean, and the same applies to the operator’s equipment, especially gloves and protective helmet, given their proximity to the welding bath.
Furthermore, as far as possible, it is good to shield the welding area from air currents, which could easily blow away the inert gas intended to protect the bathroom, with the risk of contaminating the molten metal and irreparably compromising the quality. Welding.
The choice of the most suitable gas
To protect the weld pool, an inert gas is used to create a sort of “shirt” on the point where the arc is created; the type of gas to be used varies according to the temperature, and consequently, the type of alloy and the thickness to be welded. The inert gases used for TIG welding are argon, helium, and mixtures of argon-helium and argon-hydrogen, which, apart from the specific characteristics possessed, also differ in cost.
Argon gas, for example, is cheaper and is especially suitable for welding thin thicknesses, which is why it is used primarily in the hobby field; helium is more expensive instead, and being lighter than air it requires use in higher doses, but since it favors an arc with a temperature higher than that generated in argon, it is characterized by productivity and superior efficiency.
The correct use of gas
Once you have chosen the gas, make sure you use it correctly. Even if the new TIG torches are equipped with a specific nozzle for automatic delivery during welding, it is still necessary to take the required precautions, starting right from the nozzle size.
This must always correspond to the diameter of the electrode; otherwise, the protective jacket would end up presenting “leaks” and frustrate its primary purpose; if the wire has to be replaced with a different one, the nozzle will also have to be changed accordingly.
The gas outlet pressure must be adjusted appropriately; there are TIG welding systems equipped with the appropriate pressure reducer that allows you to adjust the gas flow directly from the system, thus allowing the use of cylinders without a pressure circuit.
The alternative, on the other hand, consists of purchasing a specific pressure circuit to be applied to the cylinder, so that it can be used safely with welding systems without a reducer. Apart from the latter component, the pressure circuit must also have a pressure gauge, and a solenoid valve, which, once connected to the torch will allow you to open and close the gas flow directly from it and according to the operator’s needs.
The importance of “keeping the right distances.”
It seems almost a joke, but another essential aspect of paying attention to guarantee the complete success of a TIG welding is the right distance to keep between the arc and the piece to be welded.
There are two reasons, and the first is related to temperature. In essence, any changes in the arc distance, even minimal, generate variations in the heat of the bath, which translates into a non-homogeneous cord. The second relates to the consequences of a possible contact of the electrode with the piece to be welded, with consequent “gluing” or release of slag in the weld pool, which compromises the quality and seal of the joint.
This is why the TIG welding process is more complex and requires a considerable hand and experience to guarantee the best results, especially in cases where the use of filler rods is needed.
Coordination in movement
To perform a proper TIG welding, therefore, a good coordination of movement must be developed. This is especially required when thicknesses greater than three millimeters must be welded because, in these cases, the use of filler rods is needed, as mentioned above.
In this case, the operator is forced to use both hands, one to use the torch and the other to bring the rod close to the welding arc; if you add to this the need to always keep the arc distance and the forward movement along the joint line constant, you can easily imagine the degree of expertise required to obtain perfect welds.
These “rules” must not discourage novice welders at all; on the contrary, they want to be a stimulus in practicing, performing as many “training” welds as possible before tackling more demanding jobs.