Operation - Helvi MONOMIG 186 Manuel D'instructions

for NO GAS welding the torch must be connected to the negative terminal (-), while the
ground cable must be connected to the positive terminal (+).
In GAS welding, to avoid the oxidation of the weld puddle, we need a shielding gas. In
NO GAS welding the protection is given by the flux cored wire.
• Connect the ground cable to the proper
female outlet on the bottom right-hand
corner of the welder (on some models the
ground cable is already connected).
• Attach the ground clamp to the bare metal
to be welded, making sure of good con-
tact;
• Make sure that the wire-roller groove in the
roller corresponds to the diameter of the
wire being used. Refer to paragraph 5.
• Plug the machine to a suitable outlet.
• Open the gas valve on the gas cylinder re-
gulator, (turn knob counter-clockwise) and
adjust the flow rate using the regulator
knob (turn it counter-clock wise to decrea-
se the gas flow; turn it clockwise to increa-
se the gas flow). Note: The gas flow may need adjustments in order to obtain a better welding,
this depends on the type and thickness of the metal and on the welding current.
11.0
A certain experience is required to adjust and use a Mig power source. In Mig welding two parameters are
fundamental: the welding voltage and the wire speed. The resulting welding current is a result of these two
settings.
• Set the voltage and wire feed controls to positions suitable for the thicknesses of the material to be welded.
• Welding current varies in relationship to wire speed. For low welding current output, the wire speed
control knob should be set at the low end of the wire feed speed scale.
• Turning the wire speed control knob clockwise, will result in increased wire feed speed and welding
current. Welding voltage must be adjusted to match the wire feed speed (welding current).
• Progressively select higher voltage positions, while increasing the wire speed.
Increase of the welding voltage, at the same wire speed, leads to a longer arc (without substantially affecting
the current). Conversely, a decreased welding voltage results in a
shorter arc (the current again is not substancially changed).
A change in wire diameter results in changed parameters. A smaller diameter wire requires an increase in
wire feed speed to reach the same current. But be careful: If certain limits are exceeded, a satisfactory weld
cannot be obtained:
• A) A too high wire feed speed (too high with regard to the welding voltage) results in pulsing within
the torch. This is because the wire dips into the puddle and cannot be melted off fast enough. This
will cause excessive spatter,
• B) A too high welding voltage (too high with regard to the wire feed speed), will result in excessive
and unstable arc. By increasing still further the voltage, the contact tip will burn.
• C) In any case, an excessive wire speed can be corrected through the arc voltage increase. The li-
mit of this operation depends on the thickness of the material to weld (a certain limit exceeded will
result in the perforation).Place the torch over the seam to be welded holding it at approximately
a 45° angle, with the nozzle at 5 mm distance from the piece to be welded. Lower the shielding
helmet and press the welding torch trigger to initiate an arc. As the arc has struck, move the torch
from a left to right direction, slowly along the seam at a constant speed.
• Using the wire speed control knob, adjust for a "crisp" sounding arc: experience will help to reco-
gnize the right "sound" of the arc.
-ENGLISH-
GAS
NO GAS

operation

FIG. 13
29