Würth MIG 180-5S Mode D'emploi Original page 34

(see fig. L (c) on page 9)
6.6 Spot welding instructions
1. Select the wire diameter and heat setting recom-
mended above for the method of spot welding
you intend to use.
2. Tune in the wire speed as if you were going to
make a continuous weld.
3. Hold the torch nozzle completely perpendicular to
and about 6 mm off the work piece.
4. Pull the trigger on the torch and release it when
it appears that the desired penetration has been
achieved.
5. Make practice spot welds on scrap metal, varying
the length of time you holding the trigger, until a
desired spot weld is achieved.
6. Make spot welds on the actual work piece at
desired locations.
7. Electrode
The welding electrode is a rod coated with a layer of
flux. When welding, electrical current flows between
the electrode (rod) and the grounded metal workpiece.
The intense heat of the arc between the rod and the
grounded metal melts the electrode and the flux.
8. Selecting the proper electrode
There is no golden rule to determine the exact elec-
trode or heat setting required for every particular sit-
uation. The type and thickness of metal and the posi-
tion of the workpiece rule the electrode type and
the amount of heat needed during welding process.
Heavier and thicker metals require more amperage.
It is best to practice your welds on scrap metal which
matches the metal you intend to work with, in order
to define correct heat setting as well as make appro-
priate electrode choice. Please observe some follow-
ing helpful troubleshooting tips to determine if you
are using a correct electrode.
a. When electrode of proper size is used
- The bead will lay smoothly over the workpiece with-
out ragged edges.
- The base metal puddle will be as deep as the bead
that rises above it.
- The welding operation will make a crackling sound
similar to the sound of eggs frying.
b. When too thin electrode is used
- The weld bead will be too high and irregular
- The arc will be difficult to maintain
c. When too thick electrode is used
- The arc will burn through thin metals
- Occurrence of the weld bead undercutting
- The bead will be flat and porous
34
- Rod might get freezed or sticked to the workpiece
NOTE: Rate of travel over the workpiece also affects
the weld. To ensure proper penetration and enough
rod deposit, the arc must be moved slowly and
evenly along the weld seam.
(see fig. M on page 10)
Operation
1. Setting the adequate amperage
Your welder is capable of welding with 2.5mm,
3.2mm and 4mm electrodes. There is no golden rule
that determines the exact amperage required for every
particular situation. It is best to practice your welds
on scrap metal which matches the metals you intend
to work with in order to determine correct settings for
your job. The electrode type and the thickness of the
metal workpiece define the amount of heat needed
in the welding process. Heavier and thicker metals
require more current (amperage), whereas lighter and
thinner metals require less current (amperage).
2. Welding techniques
The best way to teach yourself how to weld is with
short periods of practice at regular intervals. All
practice welds should be done on scrap metal that
can be discarded. Do not attempt to make any
repairs on valuable equipment until you are satisfied
with yourself and your practice welds are of good
appearance and free of slag or gas inclusions.
2.1 Holding the electrode
The best way to grip the electrode holder is the way
that feels most comfortable to you. To position the
electrode on a workpiece when striking the initial
arc, it is necessary to hold the electrode perpendic-
ular to the workpiece. Once the arc is started the
angle of the electrode in relation to the workpiece
should be between 10 and 30 degrees. This will
allow good weld penetration, with minimal spatter.
2.2 Striking the arc
WARNING!
EXPOSURE TO A WELDING ARC IS EXTREMELY
HARMFUL TO THE EYES AND SKIN.
- Never strike an arc or begin welding until you have
adequate protection.
- Wear flameproof welding gloves, heavy long-
sleeved shirt, cuffless trousers, high-topped shoes
and a welding helmet or shield.
Scratch the work piece with the end of electrode to
start arc and then raise it quickly to about 3 mm