TIG Welding (GTAW) is a welding technique that uses a non-consumable tungsten electrode to create a weld with or without filler material. The equipment needed differs significantly from MIG equipment, while just marginally from stick welding equipment. TIG welding may be performed on any welding machine with the necessary accessories.
Fundamental TIG Welding Equipment Supplies
As electrical equipment, TIG welder torches have a duty-cycle rating. The maximum current that the torch can sustain in 10 minutes is referred to as the duty cycle.
Torches are made up of various parts:
- Electrical leads that run from the welding machine to the torch.
- A collet that contains the tungsten electrode.
- An electrode cover.
- Shielding gas nozzle used to regulate the flow of gas. The bead width and gas volume determine the nozzle size. The nozzle form is intended to reduce turbulence.
- A hose to transport the shielding gas.
- A water coolant hose (unless using an air-cooled torch) for TIG equipment cooled by water; this usually comes with three hoses that extend to the torch.
Other classifications of TIG torches, like those for a lighter-duty, small TIG welder, are usually cooled by air and have only one hose, a mix of the electrode lead, and shielding gas. The electrode lead can either be a flexible cable or a woven tube. The shielding gas functions to cool down the lead as it travels through the torch.
The power supply for TIG welding tools and equipment can either be a direct or alternating current. The final electrical output is referred to as a constant current or drooping current characteristic. The welding current connection supplies a constant current for a specific power setting.
Direct Current Power Source
Direct current (DC) supply results in a stable arc which is why it is most commonly used. Before beginning your welding job, make sure the work surface is clean and that you have a good gas shield in place.
TIG welding power sources such as transistors and inverters are becoming more popular. Power sources are vital for providing a constant power supply for a specific welding setting. The benefits of using transistors and inverters are as follows:
- Because of their reduced size, they are more readily transportable, and arc ignition is simpler.
- Unique operational characteristics (like current pulsing) are easily included.
- Because of the increased stability of these power sources, low currents may be employed especially for micro-TIG welding—these have essentially supplanted the plasma method for micro-welding activities.
Alternating Current Power Source
AC power is required for materials with a persistent oxide deposit on the surface, such as aluminum.
The following are the disadvantages of traditional sine wave AC as compared to DC:
- More diffused arc.
- At each current reversal, HF is required to rekindle the arc.
Square wave alternating current (AC) or switched direct current (DC) power sources are particularly appealing for welding aluminum. Switching between polarities facilitates arc reignition, allowing the HF to be decreased or eliminated. By measuring the proportional amount of heat created in the workpiece and the electrode, the capacity to unbalance the waveform to shift the proportion of positive to negative polarity is significant.
To avoid heating the electrode, utilize a higher proportion of negative polarity in filler runs. It is feasible to keep a pointed electrode by applying 90% negative polarity. A balanced position (50% electrode positive and negative polarities) is ideal for welding heavily oxidized aluminum.
Regardless of electrode diameter, the electrode tip is usually honed to an angle of 60 to 90 degrees for manual welding. Because the tip angle dictates the form of the arc and affects the penetration profile of the weld pool in mechanized applications, consistency in grinding the tip and verifying its condition between welds is essential.
For alternating current, the electrode is frequently pure tungsten. Because of the heat created in the electrode during the positive half cycle, the tip generally has a spherical contour.
To guarantee laminar gas flow, a gas lens should be installed within the torch nozzle. This increases gas protection for delicate welding applications, including vertical, corner, and edge connections, and any welding jobs on curved surfaces. There is also a diverse assortment of nozzles available to provide varying gas coverage. The nozzle is mainly selected depending on the electrode diameter and the accessibility defined by the to-be-welded assembly.
Shielding gas is used to protect the underside of the weld pool and weld bead from oxidation while welding high integrity components. A localized gas shroud for sheets, dams, or plugs for tubular components is used to limit the quantity of gas consumed. In materials like stainless steel, as little as 5% air might result in a poor weld bead profile and decreased corrosion resistance. In pipe welding using gas backing systems, the pre-weld purge time is determined by the diameter and length of the pipe. Before welding, the flow rate and purge time are controlled to ensure at least five volume changes.
To protect and maintain the weld bead, stick-on tapes and ceramic backer bars are also employed. A flux-cored wire can be utilized in hand stainless steel welding instead of a solid wire in the root run. This prevents oxidation of the under bead without the need for gas backing.
To optimize the regularity of root penetration, a pre-placed insert might be employed. Its primary application is to avoid suck-back in an autogenous weld, particularly in the above position. The inclusion of an insert does not make welding any easier; competence is still necessary to avoid issues such as incomplete root fusion and unequal root penetration.
A TIG welding machine is utilized for a variety of welding jobs and is suitable for stainless steel and aluminum. The thickness of the metal is the most critical factor in determining which sort of welding is required. TIG is extremely hot, but you’ll want to focus on thinner metals.
When the metal becomes thicker, you should switch to MIG welding. MIG does not produce as much heat as TIG. MIG melts quicker, fusing the metals in a larger weld pool. As a result, it is a more powerful weld that is utilized for heavier-duty tasks. However, its appearance is not as clean. Before beginning any endeavor, always take precautions to be safe and protect yourself.