Telwin ADVANCE 227 XT MV/PFC VRD Manual De Instrucciones página 8

Ø Electrode (mm)
1.6
2
2.5
3.2
4
- Remember that for the same diameter electrode, high levels of current
will be used for flat welding, whilst lower current levels will be used for
vertical or overhead welding.
- The mechanical characteristics of the welded joint are determined by
the intensity of the selected current and also other welding parameters
such as the length of the arc, the operating speed and position, the
diameter and quality of the electrodes (to ensure correct conservation,
use special packaging or containers to store and protect the electrodes
against humidity).
Procedure:
- Keeping the mask IN FRONT OF YOUR FACE, rub the tip of the electrode
on the piece to be welded, moving as if striking a match; this is the most
correct method for igniting the arc.
ATTENTION: DO NOT TAP the electrode against the workpiece, which
could damage the coating and make arc striking difficult.
- As soon as the arc has struck, try to keep the electrode at a distance
from the workpiece that is equivalent to the diameter of the electrode
being used, and keep this distance as constant as possible while
welding; remember that the electrode angle while moving forward
must be approx. 20-30 degrees (Fig. G).
- At the end of the welding seam, take the electrode end slightly back as
to the forward direction, above the crater to fill it, then quickly lift the
electrode from the weld pool to switch off the arc.
ASPECTS OF THE WELDING SEAM
TIG WELDING: PROCESS DESCRIPTION
TIG welding is a welding procedure that takes advantage of the heat
produced by the electric arc which is struck, and maintained, between
an infusible electrode (Tungsten) and the piece to weld. The Tungsten
electrode is supported by a torch suitable for transmission of the welding
current and protecting the electrode itself and the welding bath from
atmospheric oxidation through an inert gas flow (normally Argon: Ar
99.5%) which exits the ceramic nozzle (FIG. L).
TIG DC welding is suitable for all types of low-alloy and high carbon steel,
and heavy metals such as copper, nickel, titanium and their alloys.
An electrode with 2% Cerium (grey band) is normally used for TIG DC
welding with electrode at the (-) pole.
The tungsten electrode must be axially sharpened using a grinding
wheel, see FIG. M; make sure the tip is perfectly concentric to prevent
arc deviation. The electrode must be ground along its length. This
operation must be repeated periodically according to the use and wear
state of the electrode, or when the electrode itself has been accidentally
contaminated, oxidised or used incorrectly.
For the welding to be good, the exact diameter of the electrode must be
used with the exact current, see table (TAB. 3).
The electrode normally projects from the ceramic nozzle by 2-3 mm, but
can reach 8 mm for welding edges.
The weld is created by the edges that melt. Filler metal is not needed
when welding suitably prepared thin material (up to about 1 mm) (FIG.
N).
A greater thickness requires rods made from the same material as the
basic material and with a suitable diameter, with edges that have been
suitably prepared (FIG. O). For welding to be successful, the pieces must
be carefully cleaned and free from oxide, grease, oil, solvent, etc.
Procedure (LIFT strike)
- Use the knob to adjust the welding current to the required rate; adjust
this value during welding to adapt to the actual heat transfer required.
- Make sure the gas is flowing correctly.
The arc ignites through contact, distancing the tungsten electrode
from the workpiece. This strike mode causes less electric-irradiated
disturbances and reduces tungsten inclusions and electrode wear to a
minimum, rest the tip of the electrode on the piece, with light pressure
and lift the electrode by 2-3mm with a few seconds delay, thereby
obtaining arc strike. Initially, the welding machine supplies current I
and after a few seconds, the welding current set will be supplied.
Welding current (A)
min. max.
25 50
40 80
60 110
80 160
120 200
Fig. H
- Quickly lift the electrode from the workpiece to interrupt welding.
7. MAINTENANCE
WARNING!
OPERATIONS MAKE SURE THE WELDING MACHINE IS SWITCHED OFF
AND DISCONNECTED FROM THE MAIN POWER SUPPLY.
EXTRAORDINARY MAINTENANCE
EXTRAORDINARY MAINTENANCE MUST ONLY BE CARRIED OUT BY
TECHNICIANS WHO ARE EXPERT OR QUALIFIED IN THE ELECTRIC-
MECHANICAL FIELD, AND IN FULL RESPECT OF THE IEC/EN 60974-4
TECHNICAL DIRECTIVE.
WARNING! BEFORE REMOVING THE WELDING MACHINE
PANELS AND WORKING INSIDE THE MACHINE MAKE SURE THE
WELDING MACHINE IS SWITCHED OFF AND DISCONNECTED FROM
THE MAIN POWER SUPPLY OUTLET.
If checks are made inside the welding machine while it is live, this
may cause serious electric shock due to direct contact with live parts
and/or injury due to direct contact with moving parts.
- Inspect the welding machine regularly, with a frequency depending
on use and the dustiness of the environment, and remove the dust
deposited on the transformer, reactance and rectifier using a jet of dry
compressed air (max. 10bar).
- Do not direct the jet of compressed air on the electronic boards; these
can be cleaned with a very soft brush or suitable solvents.
- At the same time make sure the electrical connections are tight and
check the wiring for damage to the insulation.
- At the end of these operations re-assemble the panels of the welding
machine and screw the fastening screws right down.
- Never, ever carry out welding operations while the welding machine is
open.
- After having carried out maintenance or repairs, restore the connections
and wiring 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 careful to keep the high
voltage connections of the primary transformer separate from the low
voltage ones of the secondary transformer.
Use all the original washers and screws when closing the casing.
8. TROUBLESHOOTING
IN CASE OF UNSATISFACTORY FUNCTIONING, BEFORE SERVICING
MACHINE OR REQUESTING
FOLLOWING CHECK:
- Check that the welding current, which is regulated by the
potentiometer with a graduated amp scale, is correct for the diamter
and electrode type in use.
- Check that when general switch is ON the relative lamp is ON. If this is
not the case then the problem is located on the mains (cables, plugs,
outlets, fuses, etc.)
- Check that the yellow led (ie. thermal protection interruption- either
over or undervoltage or short circuit) is not lit.
- Check that the nominal intermittance ratio is correct. In case there is
a thermal protection interruption, wait for the machine to cool down,
check that the fan is working properly.
- Check the mains voltage: if the value is too high or too low the welding
machine will be stopped.
- Check that there is no short-circuit at the output of the machine: if this
is the case eliminate the incovenience.
- Check that all connections of the welding circuit are correct,
particularly that the work clamp is well attached to the workpiece, with
no interferring material or surface-coverings (ie. Paint).
- Protective gas must be of appropriate type (Argon 99.5%) and quantity.
BASE
- 8 -
BEFORE CARRYING OUT
ASSISTANCE, CARRY
MAINTENANCE
OUT THE