Telwin Technomig 200, Instruction Manual

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l
2
= welding current in amperes.
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 DC 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
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,
preparing the edges correctly
(FIG.O)
. To achieve a good weld the
pieces should be carefully cleaned and free of oxidation, oil, grease,
solvents etc.
LIFT strike:
The electric arc is struck by moving the tungsten electrode away
from the piece to be welded. This strike mode causes less electrical-
radiation disturbance and reduces tungsten inclusions and electrode
wear to a minimum.
Procedure:
Place the tip of the electrode on the piece, using gentle pressure.
Lift the electrode 2-3mm with a few moments’ delay, thus striking the
arc. Initially the welding machine supplies a current I
BASE
, after a few
moments the welding current setting will be supplied.
TIG DC welding
TIG DC welding is suitable for all low- and high-carbon steels and the
heavy metals, copper, nickel, titanium and their alloys.
For TIG DC welding with the electrode to the (-) terminal the electrode
with 2% cerium (grey band).
It is necessary to sharpen the tungsten electrode axially on the
grinding wheel, as shown in FIG. P , making sure that the tip is
perfectly concentric to prevent arc deviation. It is important to carry
out the grinding along the length of the electrode. This operation
should be repeated periodically, depending on the amount of use and
wear of the electrode, or when the electrode has been accidentally
contaminated, oxidised or used incorrectly.
MMA WELDING WITH COATED ELECTRODES
- It is most important that the user refers to the maker’s instructions
indicated on the stick electrode packaging. This will indicate the
correct polarity of the stick electrode and the most suitable current.
- The welding current must be regulated according to the diameter
of the electrode in use and the type of the joint to be carried out
(TAB.7)
.
- The user must consider that, according to the electrode diameter,
higher current values must be used for flat welding, whereas for
vertical or overhead welds lower current values are necessary.
- In addition to being determined by the selected current intensity,
the mechanical characteristics of the welded join are determined
by the other welding parameters i.e. arc length, working rate and
position, electrode diameter and quality (to store the electrodes
correctly keep them dry and protected by suitable packaging or
containers).
The properties of the weld also depend on the ARC-FORCE value
(dynamic behaviour) of the machine.
- It should be noted that high ARC-FORCE values achieve better
penetration and allow welding in any position typically with basic
and cellulose electrodes, low ARC-FORCE values give a softer,
spray-free arc typically with rutile electrodes.
The welding machine is also equipped with HOT START and ANTI
STICK devices to guarantee easy starting and to prevent the
electrode from sticking to the piece.
Procedure
- Keeping the mask IN FRONT OF THE FACE, rub the tip of the
electrode on the piece to be welded with a movement like striking a
match; this is the best way to strike the arc.
WARNING: DO NOT TAP the electrode on the piece; this risks
damaging the coating and making arc strike difficult.
- As soon as the arc has struck, try to keep at a distance from the
piece equivalent to the diameter of the electrode being used and
keep this distance as constant as possible while carrying out the
weld; bear in mind that electrode inclination in the direction of
progress should be about 20-30 degrees (FIG.Q) .
- At the end of the welded seam, take the end of the electrode
backwards slightly with respect to the direction of progress, above
the crater so as to fill it, then lift the electrode quickly from the weld
pool so that the arc is extinguished. (Appearance of the weld
seam FIG. R).
7. MAINTENANCE
WARNING! BEFORE CARRYING OUT MAINTENANCE
OPERATIONS MAKE SURE THE WELDING MACHINE IS
SWITCHED OFF AND DISCONNECTED FROM THE MAIN
POWER SUPPLY.
ROUTINE MAINTENANCE:
ROUTINE MAINTENANCE OPERATIONS CAN BE CARRIED OUT
BY THE OPERATOR.
Torch
- Do not put the torch or its cable on hot pieces; this would cause the
insulating materials to melt, making the torch unusable after a very
short time;
- Make regular checks on the gas pipe and connector seals;
- Every time the wire reel is changed, blow out the wire-guide
hose using dry compressed air (max. 5 bar) to make sure it is not
damaged;
- Before every use, check the wear and correct assembly of the
parts at the end of the torch: nozzle, contact tip, gas diffuser.
Wire feeder
- Make frequent checks on the state of wear of the wire feeder
rollers, regularly remove the metal dust deposited in the feeder
area (rollers and wire-guide infeed and outfeed).
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. 10 bar).
- 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