Air Liquide Saf-Fro PRESTO 300MV Instructions D'utilisation page 9

5.2 - MANUAL GAS TUNGSTEN ARC WELDING (TIG)
1. Connect the welding accessories carefully in order to avoid power
losses. Carefully comply with safety rules.
2. Connect the welding cables to the output terminals of the unit for the
selected polarity.
3. Attention: insert the male connector with the key lining up with
the keyway and rotate approximately ¼ turn clockwise. Do not
over tighten.
4. Connect the work cable to positive output terminal (Ref.4-Fig.2) and the
clamp near the welding zone.
5. Connect the torch cable to negative output terminal (Ref.5-Fig.2) and
fit the required electrode and gas-guide nozzle on the torch (check the
condition of the infusible electrode).
6. Connect the gas hose of the torch to the flow-meter outlet mounted on
the protection gas bottle.
7. Turn on the bottle and torch taps to adjust the gas flow rate in relation
to the welding application; after close the gas cock on the torch handle.
8. Turn ON the machine (Ref.A-Fig.3). The unit will start up with the
same setting of the previous parameters.
9. Select TIG LIFT welding mode (Ref.19-Fig.8).
10. VRD: in TIG LIFT welding process the Voltage Reduction Device is
set ON by the factory (not possible to turn it OFF), this means that at
the end of welding the unit is OFF (stand-by), to automatically restart
when the electrode gets in touch with the work piece (ignition phase
in LIF TIG mode).
11. Pre-set the welding current on a range from min. to max. available (its
value depends on the supply voltage available in the area and by the
welding process) using the Encoder Control knob (Ref.3-Fig.8)
12. To use remote control: connect the remote control connector to the
10 pins receptacle on the front panel (Ref.6 – Fig.2) and enable it with
the key (Ref.13-Fig.8). In this condition the current can be adjusted
independently of the setting made on the unit, with the exception of
the maximum welding current which will be that set with the Encoder
Control Knob (Ref.3-Fig.8).
13. The welding current should be chosen following the instruction given
by the infusible electrodes manufacturer on the packaging, but the
following indications may be useful as general information:
Thickness Welding Electrode
sheet current diameter
mm A
1.0 30 - 60
1.5 70 - 100
2.0 90 - 110
3.0 120 - 150 1.6 – 2.4
5.0 190 - 250 2.4 – 3.2
NOTE: ADJUST THE WELDING CURRENT ACCORDING TO THE
DIAMETER OF THE INFUSIBLE ELECTRODE TO BE USED AND THE
PROCEDURE IN COURSE.
CONNECTION AND PREPARATION FOR WELDING
Fig.5
Argon Filler rod
consumption
mm l/min
1.0 3 - 4
1.6 3 - 4
1.6 4 1.5 – 2.0
4 - 5 2.0 – 3.0
4 – 6 3.0 – 4.0
Tab.2
5.2.1 - TIG LIFT ARC STRIKING
Open the gas valve on the torch handle (turn the knob).
■
The gas flow through the torch.
■
Put the tungsten electrode in contact with the piece; a low current
■
passes through the electrode.
As the torch is raised the electric arc is set up and the welding
■
current rises to the pre-set value.
5.2.2 - PREPARING TUNGSTEN ELECTRODE FOR DIRECT
CURRENT ELECTRODE NEGATIVE (DCEN)
approved respirator. Consider using tungsten containing cerium,
lanthanum, rare earths instead of thorium. Grinding dust from
thorium electrodes contains low-level radioactive material. Properly
dispose of grinder dust in a environmentally safe way. Wear proper
face, hands and body protection.
The tip of the electrode is sharpened into a cone so that the arc will be
stable and the energy concentrated on the area to be welded.
The length of the sharpened section depends on the electrode diameter:
1 Grinding wheel: grind end of tungsten on fine grit. Do not use wheel
for other jobs or tungsten can become contaminated causing lower
weld quality.
mm
2 Tungsten electrode: 2% lanthanum electrode is recommended for
better: striking, arc stability, life duration and no radioactivity at all.
1.0
3 Flat: diameter of this flat determines amperage capacity.
1,5
4 Straight ground: grind lengthwise, not radial (causes wondering arc)
EN-9
Fig.6
CAUTION: Grinding the tungsten electrode produces
dust and flying sparks which can cause injury and start
fires. Use local exhaust at the grinder or wear an
2-1/2 Times
Electrode Diameter
2
4
Ideal Tungsten Preparation - Stable Arc
Fig.7
EN
3
1