3.3.3 DC TIG Welding
The DC power source uses what is known as DC (direct current) in
which the main electrical component known as electrons flowin 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 TUNGSTEN electrode and the metal work piece.
The weld area is shielded by an inert gas flow to prevent
contamination of the tungsten, molten pool and weld area.
When the TIG arc is struck the inert gas is ionized and
superheated changing it’s molecular structure which converts
it into a plasma stream. This plasma stream flowing 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 offers the user the greatest
amount of flexibility to weld the widest range of material and thickness and types. DC TIG
welding is also the cleanest weld with no sparks or spatter.
The intensity of the arc is proportional to the
current that flows 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
49
www.strata.co.nz
ADVANCEMIG 255C
