studder. Too much pressure will lead to poor results.
6. (SPOT) WELDING 4- The top piece should never be thicker than 1 mm.
6.1 PRELIMINARY OPERATIONS 5- The diameter of the electrode tip should be 2.5 mm.
Before carrying out any spot-welding operation it is necessary to make a series of 6- Make sure that the electrode locking nut is tightened up completely and that the
checks and adjustments, which should be carried out with the general switch in the “O” welding cable connectors are locked.
position and with the padlock closed. 7- When spot-welding, put the electrode on the sheet, exert slight pressure (3-4 kg).
- Ensure that the electrical connections are correct, in accordance with the above Press the button, weld for the preset time and only then take the studder away.
instructions. 8- Never weld more than 30 cm from where the earth bar is fastened.
- Check the compressed air hookup; connect the compressed air feed pipe to the
pneumatic network, use the reduction valve knob to adjust the pressure until the Simultaneous spot-welding and pulling on special grommets
gauge gives a reading between 4 and 8 bar (60 - 120 psi) depending on the thickness This is carried out by fitting and locking the chuck tightly (POS.4, FIG. H) onto the
of the sheet to be welded. body of the extractor (POS.1, FIG. H); lock the other terminal of the extractor tightly
- Between the electrodes, slide a shim equivalent to the thickness of the sheets; onto the studder (FIG. H). Insert the special grommet (POS.14, FIG. H) into the
ensure that the arms, brought together manually, are parallel and that the electrode chuck (POS.4, FIG. H), locking it with the special screw (FIG. H) Spot-weld it in the
holders are centred (tips coincide). required place, adjusting the studder as for spot-welding grommets and start pulling.
If necessary loosen the arm locking screws to adjust the arms by turning them or On completion, turn the extractor through 90° to detach the grommet, which can be
moving them in either direction along their axis; on completion secure the locking re-welded in a new position.
screws tightly.
- The working stroke is regulated by adjusting the electrodes. Always bear in mind that
the stroke should be 6-8 mm greater than the spot-welding position so as to exert the Heating and upsetting sheets 5
required force on the piece. In this operating mode the TIMER is off.
FIG. F shows a “standard” adjustment of the electrode position with the clamp at rest. The operating time is therefore determined manually by the time for which the
- When using the manual clamp, bear in mind that the force exerted by the electrodes studder button is pressed down.
during the welding phase is achieved by adjusting the knurled nut (FIG. G); turn it Current intensity is regulated automatically depending on the selected sheet
clockwise to increase the force in proportion to the increase in sheet thickness but thickness.
make the adjustment so that the clamp is able to close (triggering the corresponding Fit the carbon electrode (POS.12, FIG. H) into the studder chuck and lock it with the
microswitch) with very little effort. Position the arms and electrodes correctly as for ring nut. Touch the previously bared area with the carbon tip and press the studder
the pneumatic clamp. button. Work from the outside towards the inside with a circular movement so as to
heat the sheet, which will work harden and return to its original position.
6.2 ADJUSTING THE (spot-welding) PARAMETERS To prevent the sheet from over-hardening treat small areas and immediately
The parameters that affect the diameter (section) and mechanical strength of the spot afterwards wipe them with a damp cloth to cool the treated part.
weld are:
- Force exerted by the electrodes. Upsetting sheet metal 5
- Spot-welding current. In this position, working with the appropriate electrode, it is possible to flatten sheets
- Spot-welding time. that have undergone localised deformation.
When specific experience is lacking we recommend carrying out a number of test welds
using sheet of the same thickness and quality as that of the workpiece. Jogged spot-welding (Patching) 6
Regulate electrode force by adjusting the pressure regulator as instructed in section This function is suitable for spot-welding small rectangles of sheet to cover holes due
6.1, choosing medium-high values. to rust or other causes.
Spot-welding current and time are regulated automatically when the thickness of the Fit the appropriate electrode (POS.5, FIG. H) into the chuck, and tighten the ringnut
sheet to be welded is selected with key (2). If the spot-welding time is to be adjusted with to fasten it securely. Bare the area to be worked on and make sure the patch sheet to
respect to the standard (DEFAULT) value, this can be done within preset limits using key be welded is clean and free of grease and paint.
(1). For example, with a low power supply voltage ( LED ( -) on) it may be necessary Position the patch and put the electrode on it then press the studder button and keep
it pressed, advancing in rhythm with the work/rest intervals determined by the spot-
to increase the spot-welding time slightly and vice versa if LED ( / ) is on. In any case welder.
the operator can always take advantage of this opportunity to satisfy specific N.B.: The spot-welder regulates work and pause time automatically according to the
requirements. selected sheet thickness. When working exert slight pressure (3-4 kg) and follow an
Enable pulsed mode ( 9 ) when 0.8-1.2mm thick high yield point sheet is used. ideal line 2-3 mm from the edge of the new piece being welded.
The length of the pulse is automatic and requires no regulation. To achieve good results:
The spot-welding operation is deemed correct when a tensile test causes the spot- 1- Never weld more than 30 cm from where the earth is attached.
welding core to come out of one of the two sheets. 2- Use patch sheet no more than 0.8 mm thick, preferably stainless steel.
3- Move forwards in rhythm with the spot-welder. Advance during the pause and
6.3 PROCEDURE stop during welding.
PNEUMATIC CLAMP
- SQUEEZE TIME is automatic. The value depends on the selected sheet thickness. Using the supplied extractor (POS.1, FIG. H)
- Place an electrode on the surface of one of the two sheets to be spot-welded. Locking on and pulling grommets
- Press the button on the handgrip of the clamp so that: This is carried out by fitting and locking the chuck tightly (POS.3, FIG. H) on the body
a) The sheets close between the electrodes with the preset force (cylinder- of the electrode (POS.1, FIG. H) Lock onto the grommet (POS.13, FIG. H), which was
operated). been spot-welded as described previously, and start pulling On completion turn the
b) The welding current passes for a preset period indicated by the green LED ( * ) extractor through 90° to detach the grommet.
going on and off.
- Release the button shortly after the LED has gone off (end of welding); this delay Locking on and pulling pins
(holding) improves the mechanical properties of the spot-weld. This is carried out by fitting and locking the chuck tightly (POS.2, FIG. H) on the body
of the electrode (POS.1, FIG. H) Insert the pin (POS.15-16, FIG. H), which was spot-
MANUAL CLAMPS 7 & welded as described previously, into the chuck (POS.1, FIG. H) keeping the end
- Place the bottom electrode on the sheets to be spot-welded. pulled towards the extractor (POS.2, FIG. H) After insertion release the chuck and
- Pull the top lever on the clamp to the end of its stroke, so that: start pulling. On completion pull the chuck towards the hammer to extract the pin.
a) The sheets close between the electrodes with the preset force.
b) The preset welding current passes for the preset time, indicated by the green LED 7. MAINTENANCE
_____________________________________________________________________________________________________________________
( * ) going on and off.
- Release the clamp lever shortly after the LED has gone off (end of welding); this WARINING! BEFORE CARRYING OUT ANY MAINTENANCE OPERATION
delay (holding) improves the mechanical properties of the weld. MAKE SURE THE SPOT-WELDER HAS BEEN SWITCHED OFF AND
DISCONNECTED FROM THE MAIN POWER SUPPLY.
STUDDER GUN 0The main switch must be locked in the “O” position using the supplied padlock.
WARNING! _____________________________________________________________________________________________________________________
- To fit or release the accessories on the studder chuck use the two fixed hexagon 7.1 ROUTINE MAINTENANCE
wrenches to stop the chuck turning. ROUTINE MAINTENANCE CAN BE CARRIED OUT BY THE OPERATOR
- When operating on doors and bonnets the earth bar MUST be connected to the - adjustment/reset of electrode tip diameter and profile;
same part to prevent current passing through the hinges, and the bar must always - electrode alignment checks;
be set near the welding area (if the current has to travel over long distances this - cable and clamp cooling checks;
will reduce the efficiency of the weld). - discharge of condensation from the compressed air inlet filter.
- Spot-welding time is automatic and depends on which studder procedure has
been selected. 7.2 EXTRAORDINARY MAINTENANCE
EXTRAORDINARY MAINTENANCE OPERATIONS SHOULD BE CARRIED OUT
Connecting the earth cable: ONLY AND EXCLUSIVELY BY EXPERT OR SKILLED ELECTRICAL-MECHANICAL
a) Bare the sheet as close as possible to the point where you intend to work, cleaning PERSONNEL.
an area corresponding to the contact surface of the earth bar. _____________________________________________________________________________________________________________________
b1) Fasten the copper bar to the sheet surface using an ARTICULATED CLAMP
(welding model). WARNING! BEFORE REMOVING THE SPOT-WELDER PANELS AND
Alternatively to method b1 (when practical difficulties arise) proceed as follows: WORKING INSIDE IT MAKE SURE IT IS SWITCHED OFF AND DISCONNECTED
b2) Spot-weld a grommet to the prepared sheet surface; pass the grommet through FROM THE MAIN POWER SUPPLY OUTLET.
_____________________________________________________________________________________________________________________
the slit in the copper bar and lock it with the supplied terminal.
If checks are made inside the spot-welder while it is live, this may cause serious
Spot-welding the grommet for anchoring the earth terminal !electric shock due to direct contact with live parts and/or injury due to direct
Fit the appropriate electrode to the studder chuck (POS.9, FIG. H) and insert the contact with moving parts.
grommet (POS.13, FIG. H). Depending on how often the spot-welder is run and on the environmental conditions,
Place the grommet in the chosen area. Place the earth terminal in contact in the make regular checks inside the machine and remove the dust and the metallic particles
same area; press the torch button to weld the grommet to be used for anchorage as deposited on the transformer, the thyristor module, the terminal box, etc., using dry
described above. compressed air (max. 5 bar).
Do not direct the compressed air jet on the electronic boards; clean them using a
Spot-welding screws, washers, studs, rivets very soft brush or with the appropriate solvents.
Fit the appropriate electrode to the studder, insert the item to be welded and place it Take the opportunity to:
on the sheet at the desired point; press the button on the studder: release the button - Ensure that the wiring insulation is not damaged and the connections are tight and
only after the preset time (green LED goes off). free of oxidation.
*- Ensure that the transformer secondary screws connecting the output bars are tightly
Spot-welding sheets from one side only 4secured and that there are no signs of oxidation or overheating.
Fit the appropriate electrode to the studder chuck (POS.6, FIG. H) pressing on the IF SPOT-WELDER OPERATION IS UNSATISFACTORY, BEFORE PERFORMING
surface to be welded. Press the button on the studder and only release it after the MORE SYSTEMATIC CHECKS OR CONTACTING YOUR SERVICE CENTRE CHECK
WHETHER:
preset time (LED * goes off). - With the spot-welder main switch closed (pos. ” | ”) the green LED is on; if not the fault
WARNING! is in the power line (cables, outlet and plug, fuses, excessive voltage drop etc.);
The maximum sheet thickness that can be welded from only one side is: 1+1 mm. - The yellow LED is on (thermal safeguard triggered); wait until the LED goes off before
This type of welding must not be used on bodywork supporting structures. re-starting the spot-welder; if necessary, reduce the duty cycle.
To obtain correct results when spot-welding sheets with the studder the following - The parts making up the secondary circuit (arm-holder castings arms electrode
basic precautions should be taken: holders cables ) are inefficient due to loose screws or oxidation.
1- A perfect earth connection. - The welding parameters are actually appropriate for the job to be done.
2- The two parts to be spot-welded should be bared of any paint, grease or oil.
3- The parts to be welded should be in contact with one another, without an
intervening shim; if necessary press them together with a tool and not with the
