A Better Way to MIG Weld Sheet Metal
Power Mode, a Lincoln Electric GMAW technology, has been around since 2001. It is on all the PowerWave series machines. For instance, it is on the Invertec V350 (with advanced pulse panel) and the more affordable PowerMIG 350 MP. You may not have heard of this technology because it got lost among a plethora of other impressive pulsing technologies. These technologies were introduced around the same time and on the same machines where Power Mode GMAW is found.
Power Mode, a modified short circuit transfer, works exceptionally well on 24 to 12g mild steel/stainless steel sheet fabrication when compared, side by side, to standard constant voltage (CV) short circuit MIG.
How Power Mode Works
Power Mode, derived from Lincoln’s Waveform Control Technology (ie. software), regulates arc power (watts), not arc voltage. At lower amperages (</= 225A), Power Mode exhibits characteristics of both a Constant Voltage and Constant Current power source. That is, both amperage and voltage remain relatively stable (or constant) even with fluctuations in contact-tip-to-work distance. The image to the right (vertical axis is amps, horizontal axis is volts) clearly show that, during CTWD changes, CV amperage and voltage is all over the place while power mode amperage and voltage stay in a much tighter range.
Joint penetration primarily correlates with amperage, so a reduction in amp fluctuation means a more consistent penetration profile and less heat input, distortion and blow through. Amperage and voltage stability also means a less violent short circuit dance between the two parameters, the result being significantly less spatter generation. In addition to sheet metal fabrication, the Power Mode arc is so calm, cool and controlled that it has been implemented, successfully, on mild steel and stainless open root pipe applications.
(Note: Power Mode is also applicable to aluminum, but only in a spray transfer)
Author: Bob Page