19
WIRE SIZE SPECIFICATION CHART
TUNING THE WELDER
The tuning of a Mig welding machine requires some practice, due to the fact that -
contrary to the arc welding procedure - two parameters must be accommodated to
achieve a perfect weld. These are:
(A) Wire Feed Speed, and (B) Welding Voltage.
It is important to arrive at the correct combination to suit the type and thickness of
material to be welded.
The current necessary for welding is directly dependent
upon the wire feed speed.
If the wire feed speed is increased, the current is also increased, but the arc length
is decreased. Conversely, if the wire feed speed is decreased, and current is therefore
decreased, the length of arc is increased.
Increase of the welding voltage 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 substantially 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. If certain limits
are exceeded, a satisfactory weld cannot be obtained. These are:
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 electrode dips into the puddle
and cannot be melted off fast enough.
B) If the welding voltage is set too high, large drops can be seen at the end of the
wire electrode. These drops are often deposited beside the welding seam.
The correct rate of wire feed speed (current) and welding voltage, results in very little
spatter and a continuous, intensive hissing can be heard from the arc.
1
2
3
4
5
6
SWITCH
STEEL WIRE
DIAMETER
(mm)
WIRE SPEED
ADJUSTMENT
SWITCH
POSITIONS
1
2
3
4
5
6
7
0.6
0.6
0.6 - 0.8
0.6 - 0.8
0.8
0.8
1.0
LOW
LOW
MEDIUM
MEDIUM
MEDIUM - HIGH
HIGH
HIGH
9 Reposition the pressure roller and plastic knob and tighten slightly.
IMPORTANT: Too tight will crush the wire and damage the wire feed motor,
too loose will not allow the wire to be pulled by the roller.
10 Pull off the torch shroud by twisting it clockwise, and unscrew the contact tip.
Close the side panel of the machine, plug into a 230V, 50HZ outlet (or switch on
isolator), switch on the machine and press the trigger. The wire will feed through
the hose and when it appears at the torch end, release the trigger, switch off the
machine and replace the contact tip and the torch shroud.
IMPORTANT: Ensure the hose is kept straight during this operation, to assist
the wire as it is feed through to the nozzle.
PREPARATION FOR WELDING
1 Attach the earth clamp to the bare metal to be welded, making sure of good
contact.
2 Make sure that the wire-roller groove in the roller corresponds to the diameter of
the welding wire being used. Refer to “Loading wire” above.
3 Plug the machine into a 230V AC 50Hz outlet.
4 Open the gas valve on the gas cylinder regulator, (turn knob clockwise)and adjust
the gas regulator to the proper setting position.
NOTE: this varies with different
metals, thicknesses and currents. Refer to a MIG welding manual for
instructions.
OPERATION
1 These machines have 7 welding positions (see the table below) in which to
regulate current for various conditions.
2 The selection of a welding position is determined by the thicknessof the metal
to be welded. The thicker it is, the higher the current must be.
3 According to the thickness to be welded, the amount of gas regulated to the
work also varies and must be adjusted accordingly.
4 For welding adjustments, refer to the table below.
WARNING
(i) Make sure all flammable materials are removed from the work area.
(ii) Never look directly at the welding arc, it can seriously damage your eyes.
Always use an approved welding mask or helmet.
(iii) Wear protective clothing so that all skin areas are covered.
(iv) Keep a fire extinguisher handy.
