of the pressure reducer. to the workpiece (2-3 mm). Wait for the striking of the arc
Check seal of all tubing and connections. transferred by HF impulses and when this occurs, form the
molten pool on the workpiece and proceed along the joint.
When it is difficult to strike the arc despite the presence of
TIG WELDING WITH DIRECT CURRENT
gas and the visible HF disharges, do not leave for long the
General rules
electrode under HF. Check the integrity of the electrode
TIG welding procedure uses the heat produced by the
surface and the shape of its tip and grind it if necessary.ù
electrical arc established and maintained between a
consumable electrode (Tungsten) and the workpiece. The
LIFT MODEL:
Tungsten electrode is held by a torch which transmits the
Ligthy touch the workpiece with the electrode tip. Push the
welding current. The torch is adapted to protect the
torch button fully and lift the electrode 2-3mm with a delayed
electrode and the weld pool from oxidation by a stream of
action, thereby obtaining strike-up of the arc with the same
inert gas (usually Argon: Ar 99,5) from the ceramic nozzle.
current value as that previously set.
Fig. E
To interrupt the welding release the torch pushbutton thus
On prepared thin thicknesses (up to 1mm ca.) welding may
causing the gradual turning off of the current (if "down-
be done without the filler rod, by the fusion of the edges of
slope" potentiometer is inserted) or the instantaneous arc
the joint.
turning off with following postgas.
Welding with turned edges Fig. F
The "down-slope" function is particularly useful to avoid the
formation of a crater at the end of the joint and allows filling
For greater thicknesses it is necessary to use filler rods of
with the filler rod during the down-slope phase of the current.
the same composition as the basic material. These must be
Moreover, by pushing the torch pushbutton in position ON-
of a suitable diameter, with the edges properly prepared.
OFF in rapid sequence, the thermic value and penetration in
Welding with turned edges with or without filler rod
difficult welds may be more easily controlled.
Fig. G
If difficult welds are to be performed and their welding
parameters are unknown, it is advisable to carry out several
trial runs on test pieces in order to determine the right
For a good weld it is important for the workpieces to be
welding current value and the best gas quantity.
accurately cleaned, with no oxides, oil, grease, solvents, etc.
remaining on the surface.
It is necessary to sharpen the tungsten electrode axially on
WARNING! Always turn off the gas cylinder valve at the
the grinder wheel as indicated below. Make sure that the tip
end of the work.
is perfectly concentric in order to avoid arc deviations. This
operation should be repeated periodically according to the
WELDING PARAMETERS FOR WELDING ON
usage and wear, or if the electrode is accidentally
STAINLESS STEEL (DC)
contaminated, oxidated or incorrectly used.
Check of the electrode tip Fig. H
Thickness Current Electrode Nozzle Argon ø Filler rod
øø
(mm) (A) (mm) (mm) (I/min) (mm)
The diameter of the electrode is to be chosen according to
0,5-0,8 15-30 1 6,5 3 ---
the following tables taking into account that for the DC
1 30-60 1 6,5 3-4 1
welding (electrode negative), 2% thoriated electrode (red
1,5 70-100 1,6 9,5 3-4 1,5
2 90-110 1,6 9,5 4 1,5-2,0
colour code) is generally used.
2,5 110-130 1,6 9,5 5 1,5-2,0
In order to produce a good weld it is most important that the
3 120-150 1,6-2,4 9,5 5-6 2-3
proper electrode diameter is used with the corresponding
4 140-180 2,4 9,5-11 5-6 3
current. The normal stick-out of the electrode from the
5 190-220 2,4-3,2 11-12,5 6-7 3-4
ceramic nozzle is 2-3 mm and can reach up to 8mm for
corner welding.
WELDING PARAMETERS FOR DEOXIDATED COPPER
Thickness Current ø Electrode ø Nozzle Argonø Filler rod
PROCEDURE
(mm) (A) (mm) (mm) (I/min) (mm)
Check that the machine is correctly connected and installed
0,5 - 0,8 20-30 1 6,5 4 ---
according to the instructions indicated in the paragraph
1 80-100 1,6 9,5 6 1,5
1,5 110-140 1,6 9,5 8 1,5
"Installation".
3 170-210 2,4 11 10 2
Check the the comands are set in the correct position
4 210-220 3,2 11-12,5 10-12 2,4-3,2
according to General Rules.
Set the welding current to the required value using the
potentiometer. If necessary, adjust during welding to the
COATED ELECTRODE WELDING
correct thermic value.
- Most stick electrodes are connected to the positive pole,
Push the torch trigger, checking the gas flow from the
although certain types must be connected to the
nozzle. If necessary, set postgas time; this time is to be set
negative pole, connect according to either type to the
according to welding conditions; in particular, gas delay
(+) or (-) quick plugs.
must allow for the cooling of the electrode and weld pool
- It is most important that the user refers to the maker's
avoiding their contact with the atmpshpere (oxidations and
instructions indicated on the stick electrode packaging.
contamination).
This will indicate the correct polarity of the stick
N.B.: The quantity of protection gas (litres/minute) can
electrode and the most suitable current.
only be adjusted by the pressure regulator of the
- The welding current must be regulated according to the
cylinder.
diameter of the electrode in use and the type of the joint
to be carried out: see below the currents
HF MODEL :
corresponding to various electrode diameters:
Press the torch pushbutton bringing the electrode tip close
13
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