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TECHNOLOGY TIG 172 AC/DC HF/LIFT
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Telwin TECHNOLOGY TIG 172 AC/DC HF/LIFT — основные характеристики сварки и параметры процесса [7/108]

Telwin TECHNOLOGY TIG 172 AC/DC HF/LIFT [7/108] Troubleshooting

LIFT strike:

characteristics of the welded join are also determined by the other welding

parameters i.e. arc length, working rate and position, electrode diameter and quality

The electric arc is struck by moving the tungsten electrode away from the piece to be

(to store the electrodes correctly, keep them in a dry place protected by their

welded. This strike mode causes less electrical-radiation disturbance and reduces

packaging or containers).

tungsten inclusions and electrode wear to a minimum.

- The properties of the weld also depend on the ARC-FORCE value (dynamic

Procedure:

behaviour) of the welding machine. The setting for this parameter can be made either

Place the tip of the electrode on the piece, using gentle pressure. Press the torch button

on the panel or using the remote control with 2 potentiometers.

right down and lift the electrode 2-3mm with a few moments' delay, thus striking the arc.

- It should be noted that high ARC-FORCE values achieve better penetration and allow

Initially the welding machine supplies a current I , after a few moments the welding

BASE

welding in any position typically with basic electrodes, low ARC-FORCE values give a

current setting will be supplied. At the end of the cycle the current will fall to zero at the

softer, spray-free arc typically with rutile electrodes.

slope down setting.

The welding machine is also equipped with HOT START and ANTI STICK devices to

guarantee easy starts and to prevent the electrode from sticking to the piece.

6.1.2 TIG DC welding

TIG DC welding is suitable for all low- and high-carbon steels and the heavy metals,

6.2.1 Procedure

copper, nickel, titanium and their alloys.

- Holding the mask IN FRONT OF THE FACE, strike the electrode tip on the workpiece

For TIG DC welding with the electrode to the (-) terminal the electrode with 2% thorium

as if you were striking a match. This is the correct strike-up method.

(red band) is usually used or else the electrode with 2% cerium (grey band).

WARNING: do not hit the electrode on the workpiece, this could damage the

It is necessary to sharpen the tungsten electrode axially on the grinding wheel, as

electrode and make strike-up difficult.

shown in FIG. M, making sure that the tip is perfectly concentric to prevent arc deviation.

- As soon as arc is ignited, try to maintain a distance from the workpiece equal to the

It is important to carry out the grinding along the length of the electrode. This operation

diameter of the electrode in use. Keep this distance as much constant as possible for

should be repeated periodically, depending on the amount of use and wear of the

the duration of the weld. Remember that the angle of the electrode as it advances

electrode, or when the electrode has been accidentally contaminated, oxidised or used

should be of 20-30 grades.

incorrectly. In TIG DC mode 2-stroke (2T) and 4-stroke(4T) operation are possible.

- At the end of the weld bead, bring the end of the electrode backward, in order to fill the

weld crater, quickly lift the electrode from the weld pool to extinguish the arc

6.1.3 TIG AC welding

(CHARACTERISTICS OF THE WELD BEAD - FIG. N).

This type of welding can be used to weld metals such as aluminium and magnesium,

which form a protective, insulating oxide on their surface. By reversing the welding

current polarity it is possible to “break” the surface layer of oxide by means of a

7. MAINTENANCE

mechanism called “ionic sandblasting”. The voltage on the tungsten electrode

_____________________________________________________________________________________________________________________

alternates between positive (EP) and negative (EN). During the EP period the oxide is

WARNING! BEFORE CARRYING OUT MAINTENANCE OPERATIONS MAKE

removed from the surface (“cleaning”or “pickling”) allowing formation of the pool. During

the EN period there is maximum heat transfer to the piece, allowing welding. The

SURE THE WELDING MACHINE IS SWITCHED OFF AND DISCONNECTED FROM

possibility of varying the balance parameter in AC means that it is possible to reduce the

THE MAIN POWER SUPPLY.

_____________________________________________________________________________________________________________________

EP current period to a minimum, allowing quicker welding.

It is possible to vary the balance from 20% to 90% (EN as a percentage of total time).

7.1 ROUTINE MAINTENANCE

Higher balance values give quicker welding, greater penetration, a more concentrated

ROUTINE MAINTENANCE OPERATIONS CAN BE CARRIED OUT BY THE

arc, a narrower weld pool and limited heating of the electrode. Lower values give a

OPERATOR.

cleaner piece. If the balance value is too low this will widen the arc and the de-oxidised

part, overheat the electrode with consequent formation of a sphere on the tip making it

7.1.1 Torch

more difficult to strike the arc and control its direction. If the balance value is too high this

- Do not put the torch or its cable on hot pieces; this would cause the insulating

will create a “dirty” weld pool with dark inclusions.

materials to melt, making the torch unusable after a very short time.

The table (TAB. 4) summarises the effects of parameter changes in AC welding.

- Make regular checks on the gas pipe and connector seals.

In TIG AC mode 2-stroke (2T) and 4-stroke (4T) operation are possible.

- Accurately match collet and collet body with the selected electrode diameter in order

The instructions for this welding procedure are also valid.

to avoid overheating, bad gas diffusion and poor performance.

The table (TAB. 3) shows suggested values for welding on aluminium; the most suitable

- At least once a day check the terminal parts of the torch for wear and make sure they

electrode is a pure tungsten electrode (green band).

are assembled correctly: nozzle, electrode, electrode-holder clamp, gas diffuser.

6.1.4 Procedure

7.2 EXTRAORDINARY MAINTENANCE

- Adjust the welding current to the desired value using the knob; if necessary adjust it

EXTRAORDINARY MAINTENANCE OPERATIONS SHOULD BE CARRIED OUT

during welding to the actual heat transfer needed.

ONLY AND EXCLUSIVELY BY SKILLED OR AUTHORISED ELECTRICAL-

- Press the torch button, making sure the gas flows correctly from the torch; if

MECHANICAL TECHNICIANS.

necessary calibrate the post gas time; this time should be adjusted according to

_____________________________________________________________________________________________________________________

operating conditions, in particular the gas delay should be such as to allow the

electrode and pool to cool at the end of welding without coming into contact with the

WARNING! BEFORE REMOVING THE WELDING MACHINE PANELS AND

atmosphere (oxidation and contamination).

WORKING INSIDE THE MACHINE MAKE SURE THE WELDING MACHINE IS

TIG mode with 2T sequence:

SWITCHED OFF AND DISCONNECTED FROM THE MAIN POWER SUPPLY

- Press the torch button right down, strike the arc keeping at 2-3mm from the piece.

OUTLET.

- To interrupt welding release the torch button, causing the current to decrease to

_____________________________________________________________________________________________________________________

nothing gradually (if the SLOPE DOWN function is enabled) or immediate extinction

If checks are made inside the welding machine while it is live, this may cause

of the arc with subsequent post gas.

serious electric shock due to direct contact with live parts and/or injury due to

TIG mode with 4T sequence:

direct contact with moving parts.

- The first time the button is pressed it will strike the arc with a current of I . When the

BASE

- Inspect the welding machine regularly, with a frequency depending on use and the

button is released the current will increase to the welding current value; this value is

dustiness of the environment, and remove the dust deposited on the transformer,

also maintained when the button is released. When the button is pressed again the

reactance and rectifier using a jet of dry compressed air (max. 10 bar).

current decreases according to the SLOPE DOWN function to I . This is

BASE

- Do not direct the jet of compressed air on the electronic boards; these can be cleaned

maintained until the button is released to end the welding cycle and start the post gas

with a very soft brush or suitable solvents.

period.

- At the same time make sure the electrical connections are tight and check the wiring

TIG mode with 4T sequence and BI-LEVEL:

for damage to the insulation.

- The first time the button is pressed (P.T.) it will strike the arc with a current of I .

BASE

- At the end of these operations re-assemble the panels of the welding machine and

When the button is released the current increases to the welding current value; this

screw the fastening screws right down.

value will also be maintained as long as the button is released. Every time the button

- Never, ever carry out welding operations while the welding machine is open.

is pressed after that (the time between pressure and release should be short) the

current will vary between the BI-LEVEL parameter setting I and the main current

8. TROUBLESHOOTING

value I .

IN CASE OF UNSATISFACTORY FUNCTIONING, BEFORE SERVICING MACHINE

If the button is kept pressed down for a longer period of time the current will decrease

OR REQUESTING ASSISTANCE, CARRY OUT THE FOLLOWING CHECK:

to I . This is maintained until the button is released to end the welding cycle and

BASE

- Check that the welding current is correct for the diamter and electrode type in use.

start the post gas period (FIG. M).

- 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.).

6.2 MMA WELDING

- Check that the yellow led (ie. thermal protection interruption- either over or

- It is most important that the user refers to the maker's instructions indicated on the

undervoltage or short circuit) is not lit.

stick electrode packaging. This will indicate the correct polarity of the stick

- Check that the nominal intermittance ratio is correct. In case there is a thermal

electrode and the most suitable current.

protection interruption, wait for the machine to cool down, check that the fan is

- The welding current must be regulated according to the diameter of the electrode in

working properly.

use and the type of the joint to be carried out: see below the currents corresponding

- Check the mains voltage: if the value is too high or too low the welding machine will be

to various electrode diameters:

stopped.

- Check that there is no short-circuit at the output of the machine: if this is the case

ø Electrode (mm) Welding current (A)

eliminate the incovenience.

min. max.

- Check that all connections of the welding circuit are correct, particularly that the work

1,6 25 - 50

clamp is well attached to the workpiece, with no interferring material or surface-

2 40 - 80

coverings (ie. Paint).

2,5 60 - 110

- Protective gas must be of appropriate type (Argon 99,5%) and quantity.

3,2 80 - 160

- 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.

- As well as being determined by the chosen current intensity, the mechanical

- 7 -

Telwin TECHNOLOGY TIG 172 AC/DC HF/LIFT — основные характеристики сварки и параметры процесса [7/108]

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