4.1 DC TIG Welding
The DC power source uses what is known as DC
(direct current) in which the main electrical
component known as electrons flowing 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 ).
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
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 required, thicker
material requires a more powerful arc with more
heat so more current (amps) are necessary to
melt the material.
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
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