TIG welding – how to choose the right equipment

TIG welding, also known as WIG, is slower than MIG but gives a neater and more precise weld. It is the only sensible way to weld thin stainless steel or aluminium when the weld will remain visible.

Machine: do you need AC/DC?

This is the first and most important choice. A DC-only machine is enough for steel, stainless steel and copper. Aluminium requires alternating current, i.e. an AC function, because the oxide layer on the surface of aluminium only melts at a much higher temperature than the aluminium itself – AC breaks up the oxide layer.

If you plan to weld aluminium at some point, buy an AC/DC machine straight away. Switching later works out more expensive.

Electrode

Gold WL15 and blue WL20 are lanthanated general-purpose electrodes and work on both DC and AC. They are the standard choice today. The old red WT20 contains thorium, which is radioactive – the grinding dust is a health risk, and it is no longer recommended.

Choosing the diameter: 1.6 mm up to about 150 amps, 2.4 mm up to about 250 amps.

Gas cup and gas lens

A standard ceramic cup is enough for steel. For stainless steel and aluminium, consider a gas lens: it straightens the gas flow and widens the shielded area so that the area around the weld does not oxidise. You can see the difference in the colour straight away.

Glass cups such as Furick give the same benefit, and you can also see the gas coverage while you weld.

Shielding gas

TIG welding uses pure argon. The flow rate is 6–12 litres per minute depending on the cup size. Too much flow does not improve shielding; it causes turbulence that draws air into the weld pool.

Filler metal

ER70S-6 for structural steel, 308L for stainless steel, and 309L for joining stainless to mild steel. For aluminium, 4043 for a smoother finish or 5356 for structures that need strength.

Gloves

A thick welding glove is not suitable for TIG welding. Feeding the filler rod requires fingertip feel, so choose a thin goatskin glove.