Unimig RAZOR 320 AC/DC, Operating Manual

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Power Source
Low Current High Current
DC TIG Welding
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 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
workpiece. 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 its
molecular structure which converts it into a plasma stream. This plasma stream flowing between the tungsten
and the workpiece 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 highest
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.
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 flow 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.
TIG WELDING GUIDE
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