Arc Length; Welding With Infusible Electrode (Tig); Completing The Tig System With An Air Cooled Torch - Helvi COMPACT 400 Manual De Instrucciones

If current intensity is too high, the electrode
will burn too fast and the welding will be ir-
regular and diffi cult to control. If the current
is too low, you will lose power and the wel-
ding will be narrow, irregular, with easy at-
tachments 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
suffi cient 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 (TIG)
TIG welding with direct current is specifi cal-
ly used to weld steel and stainless steel. For
these types of welding, it is advisable to use
non 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.
The triggering of the arc in TIG may be per-
formed with peaks of high voltage at high
frequency; 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 elec-
trode must come into contact with the piece
(Lift Arc system). The arc trigger mode in TIG
available on the COMPACT range is subject
to the type of generator (read the IMPOR-
TANT notes below).
The operational phases of the Lift Arc system
are:
Fig. 15
• Lightly press the electrode on to the piece
which is to be welded (1).
• Press the torch button. The gas will fl ow
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).
IMPORTANT
• 415HF-420HF/C generators come with HF;
triggering the electric arc therefore requires
no contact between the electrode and the
piece.
• 400-400C generators come with the Lift
Arc system; triggering the electric arc there-
fore requires contact between electrode and
the piece.
WARNING: To trigger the electric arc
with the Lift TIG system also with 415HF-
420HF/C generators, follow the instruc-
tions below prior to supplying power to
the current generator:
• Press the torch button. While keeping it
pressed, switch on the inverter.
• Release the torch button only after the in-
verter has performed the preliminary checks.
COMPLETING THE TIG SYSTEM
WITH AN AIR COOLED TORCH
• Connect the ground lead to the positive (+)
Dinse socket of the generator (pos. 5) and
the ground pincer to the piece which is to be
welded.
• Connect the power cable of the torch to
the negative (-) Dinse socket of the generator
(pos. 4) and connect the torch button cable to
the three-pole socket on the generator (pos.
7) (PIN 1 & 2).
• Connect the gas tube to the "gas connec-
tion" located on the rear panel of the genera-
tor (pos. E) and to the pressure reducer as-
sembled on the suitably fi xed cylinder.
(Note: The gas which must be used is pure
argon; for further information on "PROTEC-
TION GAS CONNECTION", please read the
Fig. 16
31