OPERATION | ||
|
|
|
REMOTE CONTROL OPERATION
A Foot Amptrol ™is included with the PRECISION TIG 225
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 (AC), to the maximum value set by the Current Control on the control panel. This helps elimi- nate accidental high current damage to the work piece and/or tungsten, and provides a fine control of the cur- rent. 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 225 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 225 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 225 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.
