The TIGACDC200GD welder has a very adjustable Pulse feature which can be adjusted multiple ways to offer an almost infinite
range of variables.
Pulse is just as it implies, a pulsing of amperage power while welding.
Pulse Frequency is the number of times per second amperage pulses will occur. The range is 0.5 to 200 HZ, or times per
second. Peak time on allows the user to set the time within that second that the amperage will be at the dialed in peak setting
(highest amperage). Base amps is the measure of what the lesser amperage will be during the pulse, and is represented in a
percentage of whatever the user has chosen for the peak amps.
AC Welding
When welding carbon steel using the TIG function, the welder’s polarity is set to DC current, Straight Polarity Electrode
Negative. The current flows in one direction only. Doing so directs the heat / current, from the tungsten into the metal to be
welded. This polarity helps keep the TIG tungsten cool, and heats the work.
Welding Aluminum presents an entirely different set of problems that welding with DC Straight Polarity does not do well with.
Aluminum forms a very thin layer / skin over itself called aluminum oxide. Interestingly, aluminum oxide melts at about 3500
degrees F. while the actual aluminum itself we want to weld, melts at a much lower 1500 degrees F. So attempting to weld with
DC current flowing from the tungsten to the work metal, the aluminum melts UNDER the oxide coating layer without actually
melting the aluminum oxide. This results in an what looks like trying to weld through a glob of mud, or even a mercury like
consistency covering. This does not make for a good weld.
The solution, while a bit complicated, provides excellent results. Choosing DC Reverse Polarity will create a current flow from
the metal work back up into the TIG Torch tungsten, bursting through the aluminum oxide layer very well, but … we cannot
choose to weld with DC Reverse Polarity where the current flows from the metal work into the Tungsten, because we would
quickly melt our TIG Torch, tungsten, and collets. The solution is to weld using AC or Alternating Current. Current that
switches back and forth between DC Electrode Negative and DC Electrode Positive, back and forth many times per second.
While it is the DC Electrode Positive cycle that cleans up the aluminum oxide, it is also the cycle that can melt away our
tungsten, so we have to carefully meter the amount of time our welding current spends in the DC Electrode Positive phase.
AC Balance feature allows for the adjustment of time during the alternating current cycle that the current spends in electrode
positive. The least amount of time in this cycle will provide the best cooling of our TIG tungsten. This is why cleaning the
aluminum to be welded prior to welding is so important. It allows us to keep our current in the straight polarity electrode
negative cycle longer. An initial setting of 30 % to 35% is recommended to help keep the tungsten cool.
AC Frequency setting is a setting that allows for the adjustment of how many times per second your chosen AC balance setting
cycles. It is adjustable from 0.5 to 200 HZ (times per second).
The lower horizontal line of controls is first your choice of 2T or 4T.
(Always select 2T when using the foot pedal)
Second, the
main control knob. It has the ability to vary by 1 increment or, if pushed in, 10 increments at a time. Next is the toggle between
pulse, and normal ( no pulse) and lastly is the toggle between AC and DC current.
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