DC TIG Welding
The DC power source uses what is known as DC (direct current) in which the main elec-
trical component known as electrons ow in only one direction from the negative pole
(terminal) to the positive pole (terminal). In the DC electrical circuit there is an electrical
principle at work which should always be taken into account when using any DC circuit.
With a DC circuit 70% of the energy (heat) is always on the positive side. This needs to
be understood because it determines what terminal the TIG torch will be connected to
(this rule applies to all the other forms of DC welding as well ).
DC TIG welding is a process in which an arc is struck between a Tung-
sten electrode and the metal work piece. The weld area is shielded
by an inert gas ow to prevent contamination of the tungsten, molten
pool and weld area.
When the TIG arc is struck the inert gas is ionized and superheat-
ed changing it’s molecular structure which converts it into a plasma
stream. This plasma stream owing between the tungsten and the
work piece is the TIG arc and can be as hot as 19,000°C. It is a very
pure and concentrated arc which provides the controlled melting of
most metals into a weld pool. TIG welding oers the user the greatest
amount of exibility to weld the widest range of material and thickness
and types. DC TIG welding is also the cleanest weld with no sparks
HF ARC IGNITION for TIG (tungsten inert gas) Welding
HF (high frequency) ignition allows the arc to be started in Tig welding without touching the tungsten to the
work piece. By pressing the torch switch the machine will activate the gas ow and introduce the HF (high
frequency) (high voltage) spark, this “ionizes” the air gap making it conductive allowing an arc to be created
without touching the tungsten to the work piece. The gas molecules are superheated by the arc creating
a stream of super heated gas that changes the molecular structure into producing a plasma stream. This
plasma stream provides heat and energy that allows us to melt and fuse metals in an inert gas shielded
environment know as TIG (tungsten inert gas) welding.
gas ow HF plasma
The intensity of the arc is proportional to the current that ows from the
tungsten. The welder regulates the welding current to adjust the power
of the arc. Typically thin material requires a less powerful arc with less
heat to melt the material so less current (amps) is required, thicker
material requires a more powerful arc with more heat so more current
(amps) are necessary to melt the material.