CARBONE PowerMaster205, Operator'S Manual

Page: 26 / 48

B-12 OPERATION B-12
"Maximum" refers to a fully depressed Foot
Ampcontrol,or a fully extended Hand Ampcontrol.
When the welder is in TIG modes activating the
Ampcontrol energizes the electrode terminal and
varies the output welding current from its minimum
value of 5 Amp (DC) or 20 Amp (AC), to the
maximum value set by the Current Control on the
control panel. This helps eliminate accidental high
current damage to the work piece and/or tungsten,
and provides a fine control of the current. When the
welder is in the stick mode a remote control has no
effect and is not used.
It is important to note that, in some cases, the
tungsten will not start an arc at the minimum current
because the tungsten may be too large or cold. To
start an arc reliably, it is important to depress the
Ampcontrol far enough so that the machine output
current is near the tungsten operating range. For
example, a 3/32" tungsten may be used on DC- to
weld over the full range of the machine.
To start the arc, the operator may have to turn the
cur-rent control up and depress the Ampcontrol
approximately 1/4 of the way down. Depressing the
Ampcontrol to its minimum position may not start
the arc. Also if the current control is set too low, the
arc may not start. In most cases, a large or cold
tungsten will not readily establish an arc at low
currents. This is normal. In Direct Current mode the
PRECISION TIG will start a 3/32", 2% thoriated
tungsten electrode at 20 amperes provided the
electrode tip is properly grounded and not
contaminated.
BENEFITS OF THE PRECISION TIG DESIGN
In AC TIG welding of aluminum, the positive portion
of the AC wave provides cleaning (removal of
aluminum oxide) of the work piece. This is desirable
on materials with a heavy oxide coating. However
the positive portion may also cause the electrode to
overheat at high currents causing "tungsten spitting".
The negative portion of the AC wave offers no
cleaning action but concentrates more heat on the
work.
The AC waveform of the PRECISION TIG
optimizes cleaning and heating of the work. The
result is the capability to weld through the complete
range in AC TIG or DC- TIG requiring only one
electrode, a 3/32" 2% thoriated tungsten.