Gas Tungsten Arc Welding (GTAW) is also known as Tungsten Inert Gas or TIG welding. It is basically an arc welding technique that generates the weld using a non-consumable tungsten electrode. It is among the highly used welding processes in the United States. Therefore, GTAW is among the top services that we offer to our esteemed clients. Our company basically serves clients in Ventura, San Bernardino, Riverside, Los Angeles, and Orange County.
TIG became an overnight success welding technique way back in the 1940’s. It is mainly used to join aluminum and magnesium and this tells you why we heavily rely on it as an aluminum welding company. You protect the weld pool with the inert has shield, and not a slag. This welding process was an excellent replacement for manual metal arc or gas welding. It is one of the welding processes that we rely on heavily as a company.
If your welding calls for the use of GTAW, don’t hesitate to come to us. Our company has the best welding experts in the entire region of the United States. Also, we use modern TIG welding results to guarantee you the best quality welds. TIG plays a crucial role in accepting aluminum for the best quality welds and other structural applications.
Characteristics of the GTAW Process
For the TIG welding, you will need a drooping, constant supply of power, either AC or DC. It is essential to have a constant source of power to block the drawing of excessively high current whenever the electrodes are short-circuited on the surface of the workpiece. This can either happen deliberately during the arc starting process or inadvertently when welding.
Like the case with MIG welding, TIG also utilizes a flat characteristic of power source. Any contact with the surfaces of the workpiece can fuse the electrode to the workpiece surfaces or damage the electrode tip. In direct current, arc heat is distributed close to one third at the negative (cathode) and two thirds at the positive (anode). The anode is negative polarity all the time to block melting or overheating.
However, the alternative source of power connection of direct current electrode positive polarity is advantageous because once the cathode is on the workpiece, it cleans the surface from any oxide contamination. Because of this, you use AC to weld materials with tenacious surface oxide film like aluminum. It tells you why we heavily rely on this process as an aluminum welding company.
You can start the welding arc by scratching the surface to form a short circuit. The main welding current will only flow after breaking the short circuit. However, there is a risk of the electrode sticking to the surface and coursing a tungsten inclusion in your weld.
To minimize this risk, you should use the ‘lift arc’ technique which forms the short circuit at very low levels of the current. The use of High Frequency (HF) is the most common to start the TIG arc. HF comprises of high voltage sparks with several thousand volts that lasts for only a few microseconds. HF sparks make the electrode-workpiece gap to ionize or break down. After forming the ion/electron, current can easily flow from the source of power.
Because HF produces unusually high EM (Electromagnetic emission), welders should know that using it can interfere with the electronic equipment. EM emissions can either be airborne such as radio waves or they can be transmitted along power cables. You have to take a lot of care to avoid interfering with the instruments and control systems in the welding vicinity.
HF will also help to stabilize the AC arc. In the AC, the electrode polarity is reversed of an approximate polarity of 50 times per second making the arc to get extinguished at every change of polarity. To make sure that the arc is reignited at every polarity reversal, HF sparks are produces across the workpiece/electrode gap in order to coincide with the start of every half-cycle.
Electrodes thar are normally used for DC welding are usually pure tungsten with 1 to 4 percent thoria to enhance the ignition of the arc. The alternative additives are cerium oxide and lanthanum oxide that are known to have a superior performance (lower electrode consumption and arc starting). Selecting the correct tip angle and electrode diameter is crucial for the level of the welding current.
The thumb rule is that the smaller the tip angle and the electrode diameter, the smaller the electrode. The electrode in AC welding operates at a temperature that is much higher. A tungsten that has a zirconia is used in reducing the electrode erosion. Note that due to a large heat generation at the electrode, maintaining a pointed tip is hard and the electrode end assumes a ‘ball’ or spherical profile.
In GTAW welding, you choose a shielding gas depending on the material that you are welding. Here are some of the guidelines that will help you;
Argon: Argon is a shielding gas that is most commonly used in the welding industry. You can use this gas to weld a broad range of materials such as aluminum, stainless steel, and even steel materials. It tells you why we use this material so much in our aluminum welding works.
Argon + 2 to 5 percent H2: Adding hydrogen to argon will turn this gas into slightly reducing hence helping to produce clean-looking welds with no surface oxidation. As the arc is more constricted and hotter, it allows for higher welding speeds. The main disadvantages are the risk cracking hydrogen in the carbon steels. The other one is welding metal porosity in the aluminum alloys.
Helium & Helium/Argon Mixtures: When you add helium to argon, it will raise the temperature of the arc. It is an excellent way of supporting deeper welding penetration and promote high welding speeds. The disadvantage of using helium or a mixture of helium and argon is the high cost of the gas and the difficult process to start the arc.
You can apply GTAW in all industrial sectors but it is more idea for high quality welding. Relatively small arcs are ideal for thin sheet materials in manual welding or controlled penetration in the root running of pipe welds. Because the rate of deposition can be very low (when you use a different filler rod), MIG could be more preferable for thick materials and during fill passes in the thick-wall pipe welding.
TIG welding is also widely applicable in the mechanized systems either with filler wire or autogenously. However, there are so many ‘off the shelf’ systems for the orbital welding of pipes that are used to manufacture boilers or chemical plants. The systems do not require any manipulative skills but the operators should have the right training. This is not an issue when you are using Aluminum Welding experts for your GTAW project.
The welder has less control over the weld pool behavior and arc. Thus, you need to pay careful attention to edge preparation (not hand-prepared but mechanized, controlling welding parameters, and the joint fit-up. If you need GTAW in Ventura, San Bernardino, Los Angeles, Riverside, and Orange Count, all you need to do is to come to Aluminum Welding.
From our offices in California, Aluminum Welding serves households and businesses in Ventura, Riverside, San Bernardino, Los Angeles and Orange County. We offer a broad range of metal fabrication services to our esteemed customers. Contact us today to learn the kind of services that you can get from us.