- 8 -
8-
Reassemble the contact tip and nozzle.
6.2.3 Arc voltage
Can be adjusted at short intervals (steps) by switches on the power source. Voltage
5.7.2 Synthetic hose for aluminium wires
must comply with the chosen speed of wire advancement (current), and with the wire
diameter and shielding gas used. This may be set out in the following equation giving the
Carry out operations
1, 2, 3
as given for the steel hose (ignore operations
4, 5, 6, 7, 8
).
medium value:
9-
Re-tighten the contact tip for aluminium, making sure it comes into contact with the
U = (14 + 0,05 x l )
hose.
2
2
where :U = arc voltage in volts;
10-
At the other end of the hose (torch connector end) insert the brass nipple and the OR
2
l = welding current in amperes.
ring and, keeping slight pressure on the hose, tighten the hose locking nut.
2
Extract the capillary pipe for steel hoses from the wire feeder torch connector.
Remember that in comparison with the no-load voltage supplied for each step, the arc
11-
THE CAPILLARY PIPE IS NOT REQUIRED for aluminium hoses of diameter 1.6-
voltage will be less 2-4V for every 100A delivered. The argon/CO mixtures require arc
2
2.4mm (coloured yellow); the hose is therefore inserted into the torch connector
voltage of 1-2V less than that required with CO .
2
without it.
Cut the capillary pipe for aluminium hoses of diameter 1.2-1.6mm (coloured red) to
6.2.4 Weld quality
approx. 2mm shorter than the steel pipe, and insert it into the free end of the hose.
The quality of the weld seam is higher when less spatter is produced. this is determined
12-
Insert and lock the torch into the wire feeder connector, mark the hose at 1-2mm
principally by a correct balance of the welding parameters: current (wire speed), wire
from the rollers, take the torch out again.
diameter, arc voltage etc., as well as a correct choice of choke intakes.
13-
Cut the hose to the required size, without distorting the inlet hole.
In the same way the torch position must comply with the data in figure
(FIG. M)
in order
Reassemble the torch in the wire feeder connector and assemble the gas nozzle.
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 seam. This is particularly important for good penetration and correct
6. WELDING: DESCRIPTION OF THE PROCEDURE
shape of the seam.
6.1 METHODS OF METAL TRANSFER
The most common welding flaws are summarized in
TAB.5.
6.1.1 Short arc
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
7. MAINTENANCE
_____________________________________________________________________________________________________________________
pool.
Carbon and mild steels
WARNING! BEFORE CARRYING OUT MAINTENANCE OPERATIONS MAKE
- Suitable wire diameter:
0.6-1.2mm
- Welding current range:
40-210A
SURE THE WELDING MACHINE IS SWITCHED OFF AND DISCONNECTED FROM
- Arc voltage range:
13-23V
THE MAIN POWER SUPPLY.
_____________________________________________________________________________________________________________________
- Suitable gases:
CO , mix Ar/CO , Ar/CO /O
2
2
2
2
Stainless steels
7.1 ROUTINE MAINTENANCE
- Suitable wire diameter:
0.8-1mm
ROUTINE MAINTENANCE OPERATIONS CAN BE CARRIED OUT BY THE
- Welding current range:
40-160A
OPERATOR.
-
Arc voltage range:
14-20V
- Suitable gases:
mix Ar/O , Ar/CO (1-2%)
2
2
7.1.1.Torch
Aluminium and alloys
-
Do not put the torch or its cable on hot pieces; this would cause the insulating
- Suitable wire diameter:
0.8-1.6mm
materials to melt, making the torch unusable after a very short time.
- Welding current range:
75-160A
-
Make regular checks on the gas pipe and connector seals.
-
Arc voltage range:
16-22V
-
Every time the wire reel is changed, blow out the wire-guide hose using dry
- Suitable gases:
Ar 99.9%
compressed air (max. 5bar) to make sure it is not damaged.
- Wire stick out:
5-12mm
-
To control, before every I use, check the wear and correct assembly of the parts at
the end of the torch: nozzle, contact tip, gas diffuser.
Generally, the
contact tip
should be flush with the nozzle or protrude slightly when
using the thinnest wires and lowest arc voltages; the length of free wire (stick-out) will
7.1.2 Wire feeder
- Make frequent checks on the state of wear of the wire feeder rollers, regularly
normally be between 5 and 12mm. Select the
minimum reactance outlet
for carbon or
remove the metal dust deposited in the feeder area (rollers and wire-guide infeed
mild steels with C0 gas (wire diameters 0.8-1.2mm) and
average
for the same material
2
and outfeed).
with Ar/CO gas,
high
for stainless steel and aluminium.
2
7.2 EXTRAORDINARY MAINTENANCE
Application:
Welding in all positions, on thin material or for the first passage in bevelled
EXTRAORDINARY MAINTENANCE MUST ONLY BE CARRIED OUT BY
edges, with the advantage of limited heat transfer and highly controllable pool.
TECHNICIANS WHO ARE EXPERT OR QUALIFIED IN THE ELECTRIC-
MECHANICAL FIELD, AND IN FULL RESPECT OF THE IEC/EN 60974-4
Note:
SHORT ARC transfer for welding aluminium and alloys should be used with great
TECHNICAL DIRECTIVE.
care (especially with wires of diameter >1mm) because the risk of melting defects may
arise.
_____________________________________________________________________________________________________________________
6.1.2 Spray arc
WARNING! BEFORE REMOVING THE WELDING MACHINE PANELS AND
Higher voltages and currents than for "short arc" are used here to achieve the melting of
WORKING INSIDE THE MACHINE MAKE SURE THE WELDING MACHINE IS
the wire. The wire tip does not come into contact with the molten pool; an arc forms from
SWITCHED OFF AND DISCONNECTED FROM THE MAIN POWER SUPPLY
the tip and through it flows a stream of metallic droplets. These are produeced by the
OUTLET.
continuous melting of the electrode wire without short-circuits involved.
_____________________________________________________________________________________________________________________
Carbon and mild steels
If checks are made inside the welding machine while it is live, this may cause
- Suitable wire diameter:
0.8-1.6mm
-
Welding current range:
180-450A
serious electric shock due to direct contact with live parts and/or injury due to
- Arc voltage range :
24-40V
direct contact with moving parts.
- Inspect the welding machine regularly, with a frequency depending on use and the
-
Suitable gases :
mix Ar/CO , Ar/CO /O
2
2
2
dustiness of the environment, and remove the dust deposited on the transformer,
Stainless steels
reactance and rectifier using a jet of dry compressed air (max. 10bar).
- Suitable wire diameter:
1-1.6mm
- Do not direct the jet of compressed air on the electronic boards; these can be
-
Welding current range:
140-390A
cleaned with a very soft brush or suitable solvents.
-
Welding voltage range :
22-32V
- At the same time make sure the electrical connections are tight and check the wiring
-
Suitable gases :
mix Ar/O , Ar/CO (1-2%)
2
2
for damage to the insulation.
Aluminium and alloys
- At the end of these operations re-assemble the panels of the welding machine and
- Suitable wire diameter:
0.8-1.6mm
screw the fastening screws right down.
-
Welding current range:
120-360A
- Never, ever carry out welding operations while the welding machine is open.
-
welding voltage range :
24-30V
- After having carried out maintenance or repairs, restore the connections and wiring
-
suitable gases :
Ar 99.9%
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
The
contact tip
should generally be 5-10mm inside the nozzle, the higher the arc
careful to keep the high voltage connections of the primary transformer separate
voltage the further inside; the length of free wire (stick-out) should normally be between
from the low voltage ones of the secondary transformer.
10 and 12mm. Use the
minimum reactance outlet.
Use all the original washers and screws when closing the casing.
Application:
Horizontal welding with thicknesses of at least 3-4mm (very fluid pool);
8. TROUBLESHOOTING
(TAB.6)
execution rate and deposit rate are very high (high heat transfer).
_____________________________________________________________________________________________________________________
6.2 ADJUSTING THE WELDING PARAMETERS
WARNING! CARRYING OUT CERTAIN CHECKS IMPLIES THE RISK OF
6.2.1 Shielding gas
CONTACT WITH LIVE AND/OR MOVING PARTS.
shielding gas flow rate should be:
_____________________________________________________________________________________________________________________
short arc:
8-14 l/min
spray arc:
12-20 l/min
Before carrying out any operation on the wire feeder or inside the welding machine it is
depending on welding current intensity and nozzle diameter.
absolutely necessary to refer to section 7
“ MAINTENANCE”.
6.2.2 Welding current (FIG. L)
Is determined for a given wire diameter by its own advancement speed. Remember that
for a given current the wire advancement speed is inversely proportional to the diameter
used.
Approximate values for the current in manual welding mode for the most commonly
used wires are given in the table (
TAB. 4
).
