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Idiomas disponibles
WELDING CURRENT
If current intensity is too high, the electrode
will burn too fast and the welding will be irre-
gular and difficult to control. If the current is
too low, you will lose power and the welding
will be narrow, irregular, with easy attach-
ments between the electrode and the piece.
ARC LENGTH
If the arc is too long, it will result in dripping
and in a small fusion of the piece being wor-
ked. If the arc is too short, the heat will not be
sufficient and the electrode will attach to the
piece being worked.
WELDING SPEED
Using a suitable welding speed, according
to the parameters employed, will allow for a
welding seam of the right size and with the
proper penetration.
WELDING WITH INFUSIBLE
ELECTRODE (AC/DC TIG)
TIG welding with direct current (DC) is speci-
fically used to weld steel and stainless steel.
For these types of welding, it is advisable to
use no pure tungsten electrodes (not green).
The tip of the infusible electrode is tapered so
that the arc is stable and the energy is con-
centrated on the contact point/area which is
to be welded. The length of the tapering will
depend on the diameter of the electrode: with
low current, tapered tip with tapering length
l = 3 x d; with high current, rounded tip with
tapering length l = 1 x d.
Fig. 15
TIG welding with alternating current (AC) is
specifically used to weld aluminum and its
alloys by using pure tungsten infusible elec-
trodes (green color).
During welding in alternating current (AC) the
ratio between the positive and negative half-
cycle of the current is called "balance." By
varying the value of the wave balance (see
Pos.18 AC button functions) varies thermal
effort between the infusible tungsten electro-
de and the workpiece:
• if the balance of the wave is posiive, it
means that the time of the positive half-
wave is greater than the time of the ne-
gative half-wave; in this case the heat is
more concentrated on the electrode than
on the piece to be welded; The result is
a pickling action (cleaning) on the bath
(bead) in welding;
• on the contrary, if the balance of the
wave is negative (negative half-wave time
greater than the positive half-wave time)
the heat is more concentrated on the pie-
ce than on the electrode;
• the operator has to calibrate the balance
of the wave in function of the diameter of
the infusible electrode in use, of the value
of the welding current, of the thickness
and material of the workpiece to be wel-
ded, and of alloy type and related oxida-
tion;
The triggering of the arc in TIG may be per-
formed with peaks of high voltage at high fre-
quency; this solution (HF system) does not
require contact between the electrode and
the piece in order to trigger the welding arc.
To trigger the arc without HF the electrode
must come into contact with the piece (Lift
Arc system).
The operational phases of the Lift Arc system
are:
• Lightly press the electrode on to the piece
which is to be welded (1).
• Press the torch button. The gas will flow
and the current will pass through the electro-
de.
• Move the electrode away from the piece,
rotating it so that the nozzle of the torch re-
mains in contact with the piece (2-3).
• The arc has now been established and the
current will reach the level of welding set be-
fore (4).
WARNING: To trigger the electric arc
with the Lift TIG system, follow the in-
structions below prior to supplying po-
wer to the current generator:
• Press the torch button. While keeping it
pressed, switch the inverter on.
• Release the torch button only after the in-
verter has performed the preliminary checks.
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