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towing-motor.
- Let the wire run for the whole length of the torch, turn the
main switch to position "l" and press the button of the torch.
To prevent the wire from implanting itself into the end of the
torch, in the position where the contact tip is located, the
tip should be removed.
WARNING! During the above described operations
the wire is live and under mechanic force. Therefore if
proper precautions are not taken into consideration,
electric shocks, injury and striking of unnecessary
electrical arcs may occur.
- Always wear protective and insulating clothes and
gloves
- Do not direct torch towards parts of the body
- Do not bring the torch near the gas cylinder
WELDING
Once the machine has been prepared for welding by
carrying out the operations described above, simply place
the earth clamp in contact with the workpiece and press the
torch button, keeping the torch at a safe distance from the
workpiece.
Before carrying out difficult sections of welding, tests should
be carried out on scrap pieces. These tests should be
carried out using the adjustment knob in order to obtain the
best welding possible. If the arc melts in drops and tends to
go out, the speed of the wire should be increased or the
welding current decreased. If, however, the wire hits the
piece violently and causes material to be projected, the wire
speed should be reduced.
It should be remembered that in order to obtain the best
results, each type of wire is suited to a specific current and
wire feed speed. Therefore, for difficult sections of welding
and welding which requires a great deal of time, wires with
different diameters should be tried so that the most suitable
may be chosen.
STEEL WELDING
(Basic information)
Method of metal transfer
A SHORT ARC TRANSFER
The melting of the electrode wire and the detachment of
the drop is produced by repeated short circuits (up to
200 times per second) from the tip of the wire to the
molten pool
- suitable wire diameter
- welding current range
- arc voltage range
- suitable gases
- wire stick out
- choice of choke tap
increases with increase in wire diameter
Application: minimum heat input with weld pool kept
under control; suitable for welding in any position, on
thin thicknesses and on first runs only on vanish
threads. Contact tip level with nozzle or protruding
when finer wires and lower arc tension are used.
B SPRAY ARC TRANSFER
Higher voltages and currents than for "short arc" are
used here to achieve the melting of the wire. The wire
tip does not come into contact with the molten pool; an
arc forms from the tip and through it flows a stream of
metallic droplets.
continuous melting of the electrode wire without short-
circuits involved.
- (suitable) wire diameter
- welding current range
- arc voltage range
- suitable gases
:
0.6-1.2 (1.6)
:
40-210a
:
13-23v
:
CO + argon/
2
CO 8-12 l/min
2
:
5-12 mm
: low for thin wires;
These are produced by the
:
0.8-1.6
:
:
24-40v
:
argon/CO 12-16
l/mim; 20 l/
- wire sti ck out
- ch oice of c hoke tap
Application : high heat input, high metal weld deposits,
molten pool very fluid. Only for positional welding on
thicknesses greater than 4mm.
Contact tube inside nozzle (5-10mm depending on
strength of voltage)
C GLOBULAR TRANSFER
This is an intermediate method between "short arc" and
"spray arc". Irregular shaped drops fall to the molten
pool mainly under the action of gravity rather than "arc
forces" as with "spray" transfer.
achieved using CO gas at voltages and currents higher
than those of "short arc", but because of the nature of
CO
the operating threshold of the "spray arc"
2
technique is not reached.
- suitable wire diameters
- welding current range
- arc voltage range
- suitable gases
- wire stick out
- choice of choke tap
reduce current transients (spatter)
Application: metal weld deposits higher than for "short
arc", lower heat input than for "spray arc", high level of
spatter.
Regulations
Welding current: is determined for a given wire diameter
by its own advanc ement spee d. Current can be a djusted
by regula tion pot entiomet er (on wi re feeder) . Remember
that for a given current the wire advanceme nt speed is
inversely proportional to the diameter used.
Current range suitable for manual welding of various steel
wires:
ø mm
min (A)
max (A)
Arc voltage: can be adjusted at short intervals (steps) by
switches on the power source. Voltage must comply with
the chosen speed of wire advancement (current), and
with the wire diameter and protective gas used. This may
be set out in the following equation giving the medium
value : U = 14 + 0,05 l
2
Where : U
2
l
2
Remember that in comparison with the no-load voltage
supplied for each step, the arc voltage will be less 2-4V for
every 100A delivered.
The argon/CO mixtures require arc voltages of 1-2V less
than that required with CO .
Welding
The quality of the weld seam is higher when less spatter is
produced. This is determined principally by a correct
balance of the welding parameters: current (wire speed),
wire diameter, arc voltage etc., as well as a correct choice
of choke taps.
In the same way the torch position must comply with the
data table in order to avoid excessive spatter and faults on
the weld seam.
The weld speed (i.e. the advancement speed along the
joint) is also a determining factor for the correct execution
of the sean.
>200a
penetration and correct shape of the sean.
2
- 10 -
:
:
pr eferred (no current
transist or present )
2
:
:
:
:
:
:
0,8
1
40
50
180
250
2
= arc voltage in volts;
= welding current in amperes.
2
2
This is particularly important for good
min >350a
10-20 mm
minimum or a s
This transfer is
0.8-1.6
200-280a
20-26v
CO (12-16 l/mim)
2
10-15 mm
high values to
1,2
1,6
60
100
350
450
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