6 - BASIC WELDING TECHNIQUE
The DC power source uses what is known as DC (direct current) in
which the main electrical component known as electrons flow 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
6-1 TIG welding technique
30
%
70
%
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 weldarea.
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.
Fig. 6-1-1: Heat input
Fig. 6-1-2: TIG arc
This plasma stream flowing between the tungsten and the work piece is the TIG arc and can
be as hot as 9000K+. 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
required, thicker
material requires a more powerful arc with more heat so more current (amps) are necessary to
melt the material.
Fig. 6-1-3: High current
Fig. 6-1-4: Low current
LIFT ARC IGNITION for TIG (tungsten inert gas) Welding
Lift Arc is a form of arc ignition where the machines has low voltage on the electrode to only a
few volts, with a current limit of one or two amps (well below the limit that causes metal to
transfer and contamination of the weld or electrode). When the machine detects that the
tungsten has left the surface and a spark is present, it immediately (within microseconds)
increases power, converting the spark to a full arc. It is a simple, safe lower cost alternative
arc ignition process to HF (high frequency) and a superior arc start process to scratch start.
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what terminal the TIG x 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).
Power Source
Nozzle
Argon gas
High Current
Low Current
Note!
This section being general welding technique guide is for reference only.
Specific functions of your machine please refer to previous chapters.
Summary of Contents for Dura ARC160
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