Tungsten Inert Gas (TIG) Welding, also known as gas tungsten arc welding (GTAW), is a popular welding technique that uses electricity to join two pieces of metal together. It’s often used in our fabrication process for bespoke solutions – but how does TIG welding work and differ from MIG welding? In this post we’ll explore the intricacies of TIG welding, where it came from, the TIG welding process, its benefits and drawbacks, and how it measures up against other welding techniques.
TIG welding was first introduced back in the 1940s, with its roots traced back to the Californian aerospace industry. Developed as a solution to weld aluminium and magnesium, the process has since gained widespread recognition due to its versatility, cleanliness, and minimal finishing requirement. Even President Roosevelt praised it in a letter!
The Linde Division of Union Carbide bought the patent, then others started making torches and parts when the patents expired in the 1960s and 1970s. CK Worldwide (based in Seattle) became a big player, especially with Boeing. They fixed issues with their products, making them popular for making planes. Weldcraft, also in Southern California, fixed broken torches and made them better. They improved the insulation, making them more reliable.
Over time, TIG welding machines shrunk in size. In the 1970s, the Miller Corporation added a feature for better control. Printed circuit boards were then developed to make the TIG welding process even more precise.
In basic terms, TIG welding is a subtype of gas metal arc welding (GMAW). Although the details and techniques of the equipment have evolved over time, the fundamental principles of TIG welding remain unchanged.
Essentially TIG welding process uses electricity to create an “arc” (a short circuit) between a non-consumable tungsten electrode (a positive anode) and the metal being welded (known as a negative cathode). This arc is shielded by a flow of inert gas, like argon.
During TIG welding, the welder must ensure that the room is well ventilated and that the workshop has proper ductwork and extraction systems. The welder holds a metal torch in one hand and adds filler metal to the arc with the other. This method is commonly used for precise welding in materials like aluminium and stainless steel. To prevent the metals from getting too hot, the amperage going to the torch can be adjusted using a foot or fingertip controller.
Unlike the consumable electrode wire in MIG welding, the high melting point of TIG welding tungsten electrodes means they won’t melt during welding – making TIG advantageous at certain applications and uses. Instead, the arc between the electrode and the work melts the parent metal. At the same time (unless it’s an autogenous weld) like a temporary tack weld, the arc also melts a separate welding rod of filler metal to create a weld bead.
At the same time, the molten weld pool is protected by an inert shielding gas. This is typically argon or an argon mixture, although experienced TIG welders may use helium for projects under tight deadlines.
The gas that protects the welding process travels through a pipeline from the welding machine to the TIG torch with the tungsten electrode. When the heat is turned off, the melted metal cools and solidifies, creating a new welded piece.
If you’re a TIG welder, you must coordinate handling the TIG torch and filler rod while adjusting the electric current. This includes maintaining the right distance between the electrode and the weld, positioning the filler rod correctly, ensuring both are in the shielding gas and adjusting the current.
TIG welding needs good coordination skills in order to use a hand-held TIG torch with a filler rod, as well as varying the electrical current. Keeping the electrode the correct distance from the weld, holding the filler rod tip in position, as well as keeping both in the shielding gas and adjusting the current all add to TIG welding’s complexity.
Although TIG welding is complex, it’s far more suited to a wider range of applications, as well as different types of metals. These include mild steel, stainless steel, aluminium, magnesium, copper alloys, titanium, and even gold. Other metals can also be TIG welded – and all with minimal mess. Plus, TIG welding has proven particularly adept at handling tricky welds such as ‘S’ shapes, curves, corners, or any visible welds where accuracy and finish are important.
Years of experience have shown that, among all arc welding techniques, TIG welding consistently delivers the best combination of quality and finish. However, TIG welding does require a significant investment in time and effort to master.
A well-done weld looks neat and matches the colour of the original metal, both inside and out. The width of the melted area should be even and have a smooth surface. The edges of the melted area should blend seamlessly into the original metal without leaving a groove.
For a groove weld, the visible part should be flat or slightly rounded. For a fillet weld, the visible part can be indented, flat, or slightly rounded. If no extra material is used, a fillet weld will have an indented surface. It’s important to note that even if a weld doesn’t look perfect, it might still be acceptable – depending on the specifications and standards laid out.
As with any welding process, TIG welding comes with its own set of advantages and disadvantages.
Whilst TIG and MIG welding operate under similar principles, they each have their unique advantages and best use cases. MIG welding, for instance, is faster, results in shorter lead times and lower production costs, and is easier to learn. TIG welding, on the other hand, offers greater control, producing strong, precise, and aesthetically pleasing welds.
No matter which welding method you use – workplace safety must be prioritised – particularly as both TIG and MIG welding can expose welders to harmful gases and debris. Here at Airmatic, we produce the highest-quality ductwork, fabrication and extraction solutions to promote safety and productivity in your business. Get in touch today to discover more about our ventilation solutions.