Impax IM-MULT160-K Instruction Manual page 47

TIG OPERATION
Tungsten Electrodes
Tungsten is a rare metallic element used for
manufacturing TIG welding electrodes. The TIG
process relies on tungsten's hardness and high-
temperature resistance to carry the welding
current to the arc. Tungsten has the highest
melting point of any metal, 3,410 degrees
Celsius.
Tungsten electrodes are nonconsumable and
come in a variety of sizes, they are made from
pure tungsten or an alloy of tungsten and other
rare earth elements. Choosing the correct
tungsten depends on the material being welded,
the amount of amps required and whether you
are using AC or DC welding current.
Tungsten electrodes are colour-coded at the end
for easy identification.
Thoriated (Red)
Thoriated tungsten electrodes contain a
minimum of 97.30 percent tungsten and 1.70 to
2.20 percent thorium and are called 2 percent
thoriated. They are the most commonly used
electrodes today and are preferred for their
longevity and ease of use. Thorium increases the
electron emission qualities of the electrode,
which improves arc starts and allows for a
higher current-carrying capacity. This electrode
operates far below its melting temperature,
which results in a considerably lower rate of
consumption and eliminates arc wandering for
greater stability. Compared with other
electrodes, thoriated electrodes deposit less
tungsten into the weld puddle, so they cause
less weld contamination.
Thorium however is a low-level radioactive
hazard and many users have switched to other
alternatives. Regarding the radioactivity, thorium
is an alpha emitter but when it is enclosed in a
tungsten matrix the risks are negligible. Thus
holding a stick of Thoriated tungsten in your
hand should not pose a great threat unless a
welder has open cuts on their skin. Thoriated
tungsten should not get in contact with open
cuts or wounds. The more significant danger to
welders can occur when thorium oxide gets into
the lungs. This can happen from the exposure to
vapours during welding or from ingestion of
material/dust in the grinding of the tungsten.
Follow the manufacturer's warnings,
instructions, and the Material Safety Data Sheet
(MSDS) for its use.
Ceriated (Grey)
Ceriated tungsten electrodes contain a minimum
of 97.30 percent tungsten and 1.80 to 2.20
percent cerium and are referred to as 2 percent
ceriated. Ceriated tungstens perform best in DC
welding at low current settings. They have
excellent arc starts at low amperages and
become popular in such applications as orbital
tube welding, thin sheet metal work. They are
best used to weld carbon steel, stainless steel,
nickel alloys, and titanium, and in some cases it
can replace 2 percent thoriated electrodes.
Ceriated tungsten is best suited for lower
amperages it should last longer than Thoriated
tungsten higher amperage applications are best
left to Thoriated tungsten.
Zirconiated (White)
Zirconiated tungsten electrodes contain a
minimum of 99.10 percent tungsten and 0.15 to
0.40 percent zirconium. Most commonly used
for AC welding Zirconiated tungsten produces a
very stable arc and is resistant to tungsten
spitting. It is ideal for AC welding because it
retains a balled tip and has a high resistance to
contamination. Its current-carrying capacity is
equal to or greater than that of thoriated
tungsten. Zirconiated tungsten is not
recommended for DC welding.
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