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spool gun button and wait for the end of the wire to pass completely
through the wire guide hose and for 10-15 cm to come out of the
front of the torch, release the torch button.
REPLACING THE LINER IN THE TORCH (FIG. I)
Before proceeding to replace the hose, lay out the torch cable straight
without any bends.
Coiled hose for steel wires
1- Unscrew the nozzle and contact tip on the torch head.
2- Unscrew the hose locking nut on the central connector and remove
the old hose.
3- Insert the new hose into the cable-torch duct and push it gently
until it comes out of the torch head.
4- Tighten up the hose locking nut by hand.
5- Trim off all the excess protruding hose pressing it slightly; remove it
from the torch cable again.
6- Smooth the part where the hose was cut and reinsert it into the
cable-torch duct.
7- Tighten up the nut again using a spanner.
8- Reassemble the contact tip and nozzle.
Synthetic hose for aluminium wires
Carry out operations 1, 2, 3 as given for the steel hose (ignore
operations 4, 5, 6, 7, 8).
9- Re-tighten the contact tip for aluminium, making sure it comes into
contact with the hose.
10-At the other end of the hose (torch connector end) insert the brass
nipple and the OR ring and, keeping slight pressure on the hose,
tighten the hose locking nut.
The excess part of the hose will be removed to size later on (see
(13)).
Extract the capillary pipe for steel hoses from the wire feeder torch
connector.
11-THE CAPILLARY PIPE IS NOT REQUIRED for aluminium hoses of
diameter 1.6-2.4mm (coloured yellow); the hose is therefore
inserted into the torch connector without it.
Cut the capillary pipe for aluminium hoses of diameter 1-1.2mm
(coloured red) to approx. 2mm shorter than the steel pipe, and
insert it into the free end of the hose.
12-Insert and lock the torch into the wire feeder connector, mark the
hose at 1-2mm from the rollers, take the torch out again.
13-Cut the hose to the required size, without distorting the inlet hole.
Reassemble the torch in the wire feeder connector and assemble
the gas nozzle
6. WIRE WELDING
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 pool.
Carbon and mild steels
- Suitable wire diameter:
- Welding current range:
- Arc voltage range:
- Suitable gases:
Stainless steels
- Suitable wire diameter:
- Welding current range:
- Arc voltage range:
- Suitable gases:
Aluminium and alloys
- Suitable wire diameter:
- Welding current range:
- Arc voltage range:
- Suitable gases:
- Wire stick out: 5-12mm
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 normally be between 5 and 12mm.
Application: Welding in all positions, on thin material or for the first
passage in bevelled edges, with the advantage of limited heat transfer
and highly controllable pool.
Note: SHORT ARC transfer for welding aluminium and alloys should
be used with great care (especially with wires of diameter >1mm)
because the risk of melting defects may arise.
WIRE WELDING
SPRAY ARC TRANSFER MODE
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. These are produeced by the continuous
melting of the electrode wire without short-circuits involved.
Carbon and mild steels
- Suitable wire diameter:
- Welding current range:
- Arc voltage range :
- Suitable gases :
Stainless steels
- Suitable wire diameter:
- Welding current range:
- Welding voltage range :
- Suitable gases :
Aluminium and alloys
- Suitable wire diameter:
- Welding current range:
0.6-1.2mm
40-210A
13-23V
CO , mix Ar/CO , Ar/CO /O
2
2
2
0.8-1mm
40-160A
14-20V
mix Ar/O , Ar/CO (1-2%)
2
2
0.8-1.6mm
75-160A
16-22V
Ar 99.9%
0.8-1.6mm
180-450A
24-40V
mix Ar/CO , Ar/CO /O
2
2
1-1.6mm
140-390A
22-32V
mix Ar/O , Ar/CO (1-2%)
2
2
0.8-1.6mm
120-360A
- welding voltage range :
- suitable gases :
The contact tip should generally be 5-10mm inside the nozzle, the
higher the arc voltage the further inside; the length of free wire (stick-
out) should normally be between 10 and 12mm.
In MANUAL MODE ("PRG 0"), once the wire feed rate and arc voltage
parameters have been selected correctly (i.e. with compatible values),
the selected value of the reactance is immaterial.
Application: Horizontal welding with thicknesses of at least 3-4mm
(very fluid pool); execution rate and deposit rate are very high (high
heat transfer).
WIRE WELDING
PULSE ARC TRANSFER MODE (WHERE PROVIDED)
This is a "controlled" transfer situated in the "spray arc" transfer area
(modified spray arc) and therefore has the advantages of speedy
melting and lack of projections, extending to significantly low current
values so as to satisfy many typical "short arc" applications as well.
Every current impulse corresponds to the separation of a single drop
from the wire electrode; the phenomenon occurs with a frequency that
is proportional to the wire feed rate with the variation rule related to the
type and diameter of the wire itself (typical frequency values: 30-
300Hz).
Carbon and mild steels
- Suitable wire diameter:
- Welding current range:
- Arc voltage range :
- Suitable gases :
Stainless steels
- Suitable wire diameter:
- Welding current range:
- Welding voltage range :
- Suitable gases :
Aluminium and alloys
- Suitable wire diameter:
- Welding current range:
- welding voltage range :
- suitable gases :
Normally the contact pipe should be 5-10mm inside the nozzle, the
higher the arc voltage, the further inside; the length of free wire (stick-
out) will normally be between 10 and 12mm.
Application: "horizontal" welding on medium-low thicknesses and on
heat-sensitive materials, particularly suitable for welding light
alloys (aluminium and its alloys) also on thicknesses below 3mm.
ADJUSTING THE WELDING PARAMETERS
Shielding gas
shielding gas flow rate should be:
short arc: 8-14 l/min
depending on welding current intensity and nozzle diameter.
Welding current
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.
2
Approximate values for the current in manual welding mode for the
most commonly used wires are given in the table (TAB. 5).
Arc voltage
Arc voltage can be adjusted by the operator by turning the encoder
knob (FIG.C (5)); it adjusts itself to the chosen wire feed rate (current)
according to the diameter of the wire being used and the type of
protective gas, progressively according to the following relationship,
which gives an average value:
U = (14 + 0,05 x l )
2
2
where :U = arc voltage in volts;
2
l = welding current in amperes.
2
Weld quality
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 intakes.
In the same way the torch position must comply with the data in figure
(FIG. L) 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 seam. This is
particularly important for good penetration and correct shape of the
seam.
The most common welding flaws are summarized in TAB.8.
TIG WELDING
TIG welding is a welding procedure that exploits the heat produced by
the electric arc that is struck, and maintained, between a non-
consumable electrode (tungsten) and the piece to be welded. The
tungsten electrode is supported by a torch suitable for transmitting the
welding current to it and protecting the electrode itself and the weld
pool from atmospheric oxidation, by the flow of an inert gas (usually
argon: Ar 99.5) which flows out of the ceramic nozzle (FIG. M).
To achieve a good weld it is absolutely necessary to use the exact
2
electrode diameter with the exact current, see the table (TAB.6).
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. N).
For thicker pieces it is necessary to use filler rods of the same
composition as the base material and with an appropriate diameter,
- 8 -
0.8-1.6mm
mix Ar/CO , Ar/CO /O (Co max 20%)
2
2
2
2
0.8-1.2mm
mix Ar/O , Ar/CO (1-2%)
2
0.8-1.6mm
24-30V
Ar 99.9%
60-360A
18-32V
50-230A
17-26V
2
40-320A
17-28V
Ar 99.9%
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