Lincoln Electric PRECISION TIG 185 - Manual (Page 20)

B-5 OPERATION B-5
REMOTE CONTROL OPERATION
A Foot Amptrol ™is included with the PRECISION
TIG 185 Ready-Pak models and availiable for other
models (See Accessories Section) for remote current
control while TIG welding. An optional Hand Amptrol
may also be used. An optional Arc Start Switch may
be used to start and stop the welding if no remote
control of the current is desired. Refer to the
Accessories Section of this manual.
Both the Hand and Foot Amptrol work in a similar
manner. For simplicity, the following explanation will
refer only to “Amptrols”, meaning both Foot and Hand
models. The term “minimum” refers to a foot pedal in
the “up” position, as it would be with no foot pressure,
or a Hand Amptrol in the relaxed position, with no
thumb pressure.
“Maximum” refers to a fully depressed Foot Amptrol,or
a fully extended Hand Amptrol.
When the welder is in TIG modes activating the
Amptrol energizes the electrode terminal and varies
the output welding current from its minimum value of 5
Amp (DC) or 7 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 tung-
sten 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
Amptrol 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 Amptrol approximately
1/4 of the way down. Depressing the Amptrol 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 185 will
start a 3/32”, 2% thoriated tungsten electrode at 15
amperes provided the electrode tip is properly ground-
ed and not contaminated.
BENEFITS OF THE PRECISION TIG 185 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 por-
tion may also cause the electrode to overheat at high
currents causing “tungsten spitting”. The negative por-
tion of the AC wave offers no cleaning action but con-
centrates more heat on the work.
The AC waveform of the PRECISION TIG 185 opti-
mizes 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.
PRECISION TIG 185