TIG Welding

February 6, 2021

Want the best looking welds on the planet? Then TIG is the process you need!

TIG is known by many different names – Tungsten Inert Gas, Gas Tungsten Arc Welding (GTAW), or Heliarc when Helium is used as the shielding gas. Is is actually a form of ARC Welding, but the electrode isn’t consumable. Instead, the welder has a separate filler rod that they can dip into the weld puddle at a rate controlled manually by the operator – which is a very similar process to oxy-acetylene or gas welding. There is a lot of control over the arc via machine and torch settings so TIG is also used when delicate or thin material needs to be welded. Because of this, it can make beautiful but strong and high quality welds and a skilled welder could probably weld a razor blade to a boat anchor if they wanted. But of course everything has a trade off and because you have more control as a welder, the process happens a lot slower than other techniques.

How it Works – TIG Components

TIG Torch breakdown
A breakdown of the various parts of a TIG torch
  • The Torch – The business end of the process, and what the welder holds in their hand, is called the torch and it connects to the welding machine via a cable which feeds gas and electricity. The torch can be air cooled (cheaper, lower amperage) or water cooled (more expensive, higher amperage and can weld for longer). The torch can be broken down into a number of smaller components which include:
    • The tungsten – where the electric arc originates. Different tungsten can be used for different applications. Check out our guide to selecting the best TIG tungsten for your application.
    • The cup – This is made of a ceramic material and can withstand intense heat. It’s purpose is to direct the flow of gas onto the material being welded. A larger cup can direct more gas, but if you direct too much gas you’re just wasting money!
    • Gasket – Separates the cup from the head
    • The collet – This piece clamps the tungsten so it doesn’t move in the torch
    • The collet body – This is what allows the gas to flow down the torch. A more expensive version called a gas lens can also be used which will allow a better flow of gas, but requires a different shaped cup
    • The back cap – The cap will clamp the collet and are available in various lengths, depending on user preference and available space
  • Gas Bottle/Cylinder – Gas is a requirement for TIG and is most commonly pure Argon although Argon/Hydrogen and Argon/Helium can also be used, depending on what material you are welding. Argoshield or a mix of Argon, CO2 and Oxygen is unsuitable.
  • Flow Meter and Regulator – The regulator connects to the gas bottle and the flow meter sits between the regulator and the welding machine (or power supply). A flow meter is a critical piece of equipment if you value your wallet! You need enough gas to provide proper shielding, but too much gas is just wasting money
  • Welding Machine / Power Supply – The actual welding machine. There are a number of machines on the market (see our Best TIG machine buying guide), but the selection of machine will depend on the type and thickness of material you intend to weld.
    • Size – The size of the machine will be determined by the thickest material you want to weld. A 200 amp machine will be more than enough for most hobbyists, and is about the biggest you can go on a 220/240V circuit. If you need to weld thick material (more than around 6mm/or 1/4 inch) or if you want to weld all day every day without a break you may need a bigger machine and 3 phase power to drive it.
    • AC/DC – A “DC Only” machine is cheaper but can only weld mild and stainless steel. An AC/DC machine can also weld aluminum and magnesium. If you ever think you will need to weld aluminum, you should spring for an AC capable machine as they can’t be easily upgraded.
    • Foot control – most machines now come with foot control that can adjust the amperage ‘on the fly’ as the welder is in use. This can be useful at the start of a weld, where a higher amperage is required to heat the material then the operator can back off when the piece gets too hot.
    • High Frequency Start – In my option, an essential feature is a machine with with ‘High Frequency Start’. This is where the machine can start an arc without the tungsten touching the material. Machines that don’t have this feature mean the operator much touch the tungsten to the workpiece to start the arc which can cause the tungsten to become contaminated. A copper ‘strike plate’ can also be used but it makes the whole process more difficult for beginners.
  • Safety Gear – Required for all welding processes. Full length clothing, gauntlets and a welding helmet are a must. TIG welding gauntlets tend to be thinner to give the operator more dexterity but also have less heat resistance.

How it Works – The Process

For an in-depth look at how the process works, check out our detailed guides:

TIG Welding Mild Steel

TIG Welding Aluminium (coming soon!)

TIG Welding Magnesium (coming soon!)

TIG Welding Tips

Clean the base metal as if you were going to eat off it. You cannot get the metal too clean for TIG as there is no flux to float off impurities, if you don’t clean the base metal you will get inclusions.

Chose the correct tungsten and cup size for your base metal. Tungsten diameter should be about half base metal thickness. The cup size should be as large as possible without restricting movement.

Make sure you use clean filler rods

Limit air movement in the welding area. Cool air will crack the TIG weld as the heat affected area is smaller and more sensitive to rapid cooling. A breeze can also blow away the shielding gas.

Never touch the tungsten to the weld puddle. Capillary action will cause the molten metal to flow up the tungsten and contaminate the weld… which leads us to:

Sharpen your tungsten! The non-consumable tungsten electrode in the torch starts the arc to the workpiece. non-consumable because the tungsten is not consumed through the welding process, but the tungsten will become contaminated. You will touch the puddle with the tungsten or splatter will coat the tungsten. As soon as this occurs you should stop and sharpen your tungsten.

How sharp or blunt will depend on what sort of material you’re welding. A sharper point produces a finer puddle. Aluminium should use a fairly blunt tip – like a crayon. You should always sharpen your tungsten lengthways (towards the tip). Don’t grind it in a circular motion with an electric drill as it creates an uneven arc.

Use a gas lens if you have room. The gas flow will be more uniform and your welds should look better.

Adjust the post gas and keep the torch above the weld until the gas stops. This helps the steel from cracking and crystalising. If welding titanium, post gas is mandatory.

Sit down if possible. Get comfortable. TIG welding creates almost no sparks so take advantage of this to get into a comfortable position.

Dip the filler rod into the molten puddle, don’t try to melt the rod with the arc. Melting the rod with the arc will create a cold weld.

Common TIG Problems and their solutions

Electrode overheating quickly – Do you have your machine configured for a negative electrode? TIG uses a negative electrode process

ARC blows quickly through the material – Is the gas turned on? Do you have the correct flow rate? Are you using the correct gas? Pure Argon is the most commonly used gas for TIG (although Argon/Hydrogen and Argon/Helium are also used). Argoshield or a mix of Argon, CO2 and Oxygen is unsuitable.

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