Hf And Lift Strike; Tig Dc Welding; Tig Ac Welding (If Installed); Procedure - TIG DC Manuel D'instructions

stainless steel.
The electrode usually protrudes from the ceramic nozzle by 2-3mm, but this may reach
8mm for corner welding.
Welding is achieved by fusion of the edges of the joint. For properly prepared thin
pieces (up to about 1mm) weld material is not needed (FIG. H).
For thicker pieces it is necessary to use filler rods of the same composition as the base
material and with an appropriate diameter, preparing the edges correctly (FIG. I). To
achieve a good weld the pieces should be carefully cleaned and free of oxidation, oil,
grease, solvents etc.
6.1.1 HF and LIFT strike
HF strike:
The electric arc is struck without contact between the tungsten electrode and the piece
being welded, by means of a spark generated by a high frequency device. This strike
mode does not entail either tungsten inclusions in the weld pool or electrode wear and
gives an easy start in all welding positions.

Procedure:

Press the torch button, bringing the tip of the electrode close to the piece (2 -3mm),
wait for the arc strike transferred by the HF pulses and, when the arch has struck, form
the weld pool on the piece and proceed along the joint.
If there are difficulties in striking the arc even though the presence of gas is confirmed
and the HF discharges are visible, do not insist for long in subjecting the electrode to
HF action, but check the integrity of the surface and the shape of the tip, dressing it
on the grinding wheel if necessary. At the end of the cycle the current will fall at the
slope down setting.
LIFT strike:
The electric arc is struck by moving the tungsten electrode away from the piece to
be welded. This strike mode causes less electrical-radiation disturbance and reduces
tungsten inclusions and electrode wear to a minimum.
Procedure:
Place the tip of the electrode on the piece, using gentle pressure. Press the torch
button right down and lift the electrode 2-3mm with a few moments' delay, thus striking
the arc. Initially the welding machine supplies a current I
welding current setting will be supplied. At the end of the cycle the current will fall to
zero at the slope down setting.
6.1.2 TIG DC welding
TIG DC welding is suitable for all low- and high-carbon steels and the heavy metals,
copper, nickel, titanium and their alloys.
For TIG DC welding with the electrode to the (-) terminal the electrode with 2% thorium
(red band) is usually used or else the electrode with 2% cerium (grey band).
It is necessary to sharpen the tungsten electrode axially on the grinding wheel,
as shown in FIG. L, making sure that the tip is perfectly concentric to prevent arc
deviation. It is important to carry out the grinding along the length of the electrode. This
operation should be repeated periodically, depending on the amount of use and wear
of the electrode, or when the electrode has been accidentally contaminated, oxidised
or used incorrectly.
6.1.3 TIG AC welding (if installed)
This type of welding can be used to weld metals such as aluminium and magnesium,
which form a protective, insulating oxide on their surface. By reversing the welding
current polarity it is possible to "break" the surface layer of oxide by means of a
mechanism called "ionic sandblasting". The voltage on the tungsten electrode
alternates between positive (EP) and negative (EN). During the EP period the oxide
is removed from the surface ("cleaning"or "pickling") allowing formation of the pool.
During the EN period there is maximum heat transfer to the piece, allowing welding.
The possibility of varying the balance parameter in AC means that it is possible to
reduce the EP current period to a minimum, allowing quicker welding.
Higher balance values give quicker welding, greater penetration, a more concentrated
arc, a narrower weld pool and limited heating of the electrode. Lower values give a
cleaner piece. If the balance value is too low this will widen the arc and the de-oxidised
part, overheat the electrode with consequent formation of a sphere on the tip making it
more difficult to strike the arc and control its direction. If the balance value is too high
this will create a "dirty" weld pool with dark inclusions.
The table (TAB. 4) summarises the effects of parameter changes in AC welding.
The instructions for this welding procedure are also valid.
The table (TAB. 3) shows suggested values for welding on aluminium; the most
suitable electrode is a pure tungsten electrode (green band).
6.1.4 Procedure
- Use the knob to adjust the welding current to the desired value; if necessary adjust
during welding to the actual required heat transfer.
- Press the torch button and make sure the gas flow from the torch is correct; if
necessary, adjust pre-gas and postgas times; these times should be adjusted
according to operating conditions, the postgas delay in particular should be long
enough to allow the electrode and weld pool to cool at the end of welding without
coming into contact with the atmosphere (oxidation and contamination).
TIG mode with 2T sequence:
- Press the torch button (P.T.) right down to strike the arc with a current of I
current will increase according to the START SLOPE UP setting to the welding
current value.
- To interrupt welding, release the torch button so that either the current gradually
decreases (if the FINAL SLOPE DOWN parameter has been enabled) or the arc is
extinguished immediately, followed by postgas.
TIG mode with 4T sequence:
- The first time the button is pressed it will strike the arc with a current equal to I
When the button is released the current will increase according to the START
SLOPE UP setting to the welding current value; this value is maintained even with
the button is released. When the button is pressed again the current will decrease
according to the FINAL SLOPE DOWN setting, until it reaches I
will be maintained until the button is released to terminate the welding cycle and
start the postgas phase. If, on the other hand, the button is released while the FINAL
SLOPE DOWN function is proceeding, the welding cycle will terminate immediately
and the postgas phase will start.
TIG mode with 4T and BI-LEVEL sequence:
- The first time the button is pressed it will strike the arc with a current equal to I
When the button is released the current will increase according to the START
SLOPE UP setting to the welding current value; this value is maintained even when
the button is released. Now, every time the button is pressed (the time between
pressure and release should be short) the current will change between the setting
for the BI-LEVEL I parameter and the main current value I
1
- When the button is kept pressed down for a longer space of time the current will
decrease according to the FINAL SLOPE DOWN setting, until it reaches I
I current will be maintained until the button is released to terminate the welding
end
cycle and start the postgas phase. If, on the other hand, the button is released while
the FINAL SLOPE DOWN function is proceeding, the welding cycle will terminate
immediately and the postgas phase will start (FIG. M).
TIG SPOT and TIG THIN SPOT mode:
- Welding is carried out by keeping the torch push-button pressed until the pre-set
6.2 MMA WELDING
- It is most important that the user refers to the maker's instructions indicated on the
- The welding current must be regulated according to the diameter of the electrode in
- The user must consider that, according to the electrode diameter, higher current
- As well as being determined by the chosen current intensity, the mechanical
, after a few moments the
- The properties of the weld also depend on the ARC-FORCE value (dynamic
LIFT
- It should be noted that high ARC-FORCE values achieve better penetration and
6.2.1 Procedure
- Holding the mask IN FRONT OF THE FACE, strike the electrode tip on the workpiece
- As soon as arc is ignited, try to maintain a distance from the workpiece equal to the
- At the end of the weld bead, bring the end of the electrode backward, in order to

7. MAINTENANCE

MAKE SURE THE WELDING MACHINE IS SWITCHED OFF AND DISCONNECTED
FROM THE MAIN POWER SUPPLY.
7.1 ROUTINE MAINTENANCE
ROUTINE MAINTENANCE OPERATIONS CAN BE CARRIED OUT BY THE
OPERATOR.

7.1.1 Torch

- Do not put the torch or its cable on hot pieces; this would cause the insulating
- Make regular checks on the gas pipe and connector seals.
- Accurately match collet and collet body with the selected electrode diameter in order
- At least once a day check the terminal parts of the torch for wear and make sure they
7.2 EXTRAORDINARY MAINTENANCE
EXTRAORDINARY MAINTENANCE MUST ONLY BE CARRIED OUT BY
TECHNICIANS WHO ARE EXPERT OR QUALIFIED IN THE ELECTRIC-
MECHANICAL FIELD, AND IN FULL RESPECT OF THE IEC/EN 60974-4
. The
TECHNICAL DIRECTIVE.
s
AND WORKING INSIDE THE MACHINE MAKE SURE THE WELDING MACHINE
IS SWITCHED OFF AND DISCONNECTED FROM THE MAIN POWER SUPPLY
OUTLET.
.
If checks are made inside the welding machine while it is live, this may cause
s
serious electric shock due to direct contact with live parts and/or injury due to
direct contact with moving parts.
. The I current
- Periodically, and in any case with a frequency in keeping with the utilisation and with
end end
- At the same time make sure the electrical connections are tight and check the wiring
.
- At the end of these operations re-assemble the panels of the welding machine and
s
- Never, ever carry out welding operations while the welding machine is open.
- After having carried out maintenance or repairs, restore the connections and wiring
.
2
. The
end

8. TROUBLESHOOTING

IN CASE OF UNSATISFACTORY FUNCTIONING, BEFORE SERVICING MACHINE
OR REQUESTING ASSISTANCE, CARRY OUT THE FOLLOWING CHECK:
- Check that the welding current is correct for the diamter and electrode type in use.
- 8 -
time has been reached (spot time).
stick electrode packaging. This will indicate the correct polarity of the stick electrode
and the most suitable current.
use and the type of the joint to be carried out: see below the currents corresponding
to various electrode diameters:
Ø Electrode (mm)
1.6
2
2.5
3.2
4
5
6
values must be used for flat welding, whereas for vertical or overhead welds lower
current values are necessary.
characteristics of the welded join are also determined by the other welding
parameters i.e. arc length, working rate and position, electrode diameter and
quality (to store the electrodes correctly, keep them in a dry place protected by their
packaging or containers).
behaviour) of the welding machine. The setting for this parameter can be made
either on the panel or using the remote control with 2 potentiometers.
allow welding in any position typically with basic electrodes, low ARC-FORCE
values give a softer, spray-free arc typically with rutile electrodes.
The welding machine is also equipped with HOT START and ANTI STICK devices to
guarantee easy starts and to prevent the electrode from sticking to the piece.
as if you were striking a match. This is the correct strike-up method.
WARNING: do not hit the electrode on the workpiece, this could damage the
electrode and make strike-up difficult.
diameter of the electrode in use. Keep this distance as much constant as possible
for the duration of the weld. Remember that the angle of the electrode as it advances
should be of 20-30 grades.
fill the weld crater, quickly lift the electrode from the weld pool to extinguish the arc
(CHARACTERISTICS OF THE WELD BEAD - FIG. N).
WARNING! BEFORE CARRYING OUT MAINTENANCE OPERATIONS
materials to melt, making the torch unusable after a very short time.
to avoid overheating, bad gas diffusion and poor performance.
are assembled correctly: nozzle, electrode, electrode-holder clamp, gas diffuser.
WARNING! BEFORE REMOVING THE WELDING MACHINE PANELS
the environment's dust conditions, inspect the inside of the welding machine and
remove the dust deposited on the electronic boards with a very soft brush or with
appropriate solvents.
for damage to the insulation.
screw the fastening screws right down.
as they were before, making sure they do not come into contact with moving parts or
parts that can reach high temperatures. Tie all the wires as they were before, being
careful to keep the high voltage connections of the primary transformer separate
from the low voltage ones of the secondary transformer.
Use all the original washers and screws when closing the casing.
Welding current (A)
Min. Max.
25 50
40 80
60 110
80 160
120 200
150 280
200 350