Inhaltsverzeichnis
Werbung
Verfügbare Sprachen
Verfügbare Sprachen
11. MMA WELDING: PROCESS DESCRIPTION
11.1 GENERAL PRINCIPLES
- It is essential to follow the recommendations provided by the manufacturer on the
electrode packaging which indicates the correct electrode polarity and relative rated
current.
- Welding current is regulated to suit the diameter of the electrode being used and the
type of soldering to be performed; an example of the currents used for the various
electrode diameters can be seen below:
Ø Electrode (mm)
1.6
2.0
2.5
3.2
- One can see 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).
WARNING:
Instability of the arc due to the composition of the electrode can occur, depending on
the brand, type and thickness of the electrode coatings.
11.2 Procedure
- Hold the mask IN FRONT OF THE FACE, then lightly scratch the electrode tip on the
piece to be welded as if you were trying to strike a match; this is the correct way of
striking the arc.
WARNING: DO NOT TAP the electrode against the piece; this can damage the
coating and make it difficult to strike the arc.
- A soon as the arc is struck, try to maintain a distance from the piece which is
equivalent to the diameter of the electrode being used, and try to maintain this
distance as constant as possible during the welding operations; remember that the
angle of the electrode as it moves forwards should be about 20-30 degrees.
- At the end of the welding seam, move the electrode tip backwards slightly, above the
crater, and fill it in; now quickly lift the electrode from the weld pool to extinguish the
arc (Examples of welding seams - FIG. Q).
11.3 LCD DISPLAY IN MMA MODE (Fig. C)
-
MMA operation mode;
- Welding values;
welding voltage;
welding current;
-
recommended electrode diameter.
12. RESET FACTORY SETTINGS
The welding machine can be taken back to the factory settings by keeping the two
knobs (Fig.C-1) and (Fig.C-2) pressed during starting operation.
13. ALARM SIGNALS
Reset is automatic when the reason for alarm activation stops.
Alarm messages that can appear on the display:
-
Welding machine thermostatic safeguard intervention. Operation is stopped
until the machine has cooled sufficiently.
- ALL 001: intervention for protection from over/undervoltage. Check the power supply
voltage
- ALL 002: intervention for protection from short-circuit between torch and earth. Make
sure the welding circuit has not short-circuited.
- ALL 003: intervention for protection from overcurrent in the welding circuit. Make
sure the feeder speed and/or welding voltage are not too high.
When the welding machine is switched off, the signal ALL 001 may appear for
a few seconds.
14. MAINTENANCE
WARNING! BEFORE CARRYING OUT MAINTENANCE OPERATIONS
MAKE SURE THE WELDING MACHINE IS SWITCHED OFF AND DISCONNECTED
FROM THE MAIN POWER SUPPLY.
14.1 ROUTINE MAINTENANCE:
ROUTINE MAINTENANCE OPERATIONS CAN BE CARRIED OUT BY THE
OPERATOR.
14.1.1 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.
- Accurately match collet and collet body with the selected electrode diameter in order
to avoid overheating, bad gas diffusion and poor performance.
- At least once a day check the terminal parts of the torch for wear and make sure they
are assembled correctly: nozzle, electrode, electrode-holder clamp, gas diffuser.
- Before using the welding machine, always check the terminal parts of the torch for
wear and make sure they are assembled correctly: nozzle, electrode, electrode-
holder clamp, gas diffuser.
14.1.2 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).
Welding current (A)
Min.
Max.
25
50
40
80
60
110
80
170
14.2 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 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.
15. TROUBLESHOOTING
IN CASE OF UNSATISFACTORY FUNCTIONING, BEFORE SERVICING MACHINE
OR REQUESTING ASSISTANCE, CARRY OUT THE FOLLOWING CHECK:
- 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.)
- There is no alarm signalling intervention of the thermostat safeguard, over or
undervoltage or short-circuit.
- 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 and quantity.
- 9 -
Werbung
Inhaltsverzeichnis
