Unimig RAZOR 320 AC/DC, Operating Manual

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30% 30%
current
AC TIG Welding - AC Wave Balance Control
AC (alternating current) enables us to TIG weld non ferrous alloys like Aluminium, Magnesium and Aluminium
Alloys. These materials have an insulating surface oxide layer that melts at a higher temperature than the base
metal making it difficult to weld the base metal if the oxides are not removed. AC welding current is ideal be-
cause the nature of the AC wave form assists in breaking the surface oxide layer.
AC (alternating current) has a current cycle that flows from + (direct) polarity to - (reverse) polarity.
The reversing of the polarity breaks the surface oxide while the direct polarity melts the base material.
reverse polarity
straight polarity
current
There are inherent problems that come with AC TIG arc rectification, arc stutter, arc wandering and arc stop-
page. These problems typically occur during the transition b and - cycles.
The current is lesser (30%) during the half of the cycle when the electrode is positive and there is a resistance
of the electron flow during this half cycle (rectification). The lack of current flow during this half cycle makes the
AC arc unstable.
To overcome this lack of flow during one half of the cycle, a high-frequency (HF) voltage is generated and fed
into the welding circuit. The HF maintains the arc stability during the half cycle when the electrode is positive.
High-frequency voltage flows continually in the welding circuit and keeps the shielding arc in the welding area
in an ionized state. When the arc is ionized the arc is maintained during the half of the cycle when the electrode
is positive. However while the arc is maintained less current flows during this half of the AC cycle, producing an
unbalanced wave.
UNBALANCED WAVE FORM
+
_
HF
30% 30%
current
Razor
32OAC/DC TIG-MMA
TIG WELDING GUIDE
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