When we join Kevin, he’s welding some aluminum using AC, learning more about its advanced AC pulse function. It uses positive AC on the high side of the pulse, dropping to a negative DC on the low side of the pulse. This creates a quick freezing puddle and more definition on the puddle ripple. It also helps control the cleaning width similar to what you get with AC balance. It really helps when welding thin metal.
Kevin’ll cover this in another video, but today he is going to try out the machine in DC, welding some thicker metal – 1/4″ steel plate, in this case – so he can crank up the amps, then welding some 16 gauge steel at as low an amperage as possible. He shows the 1/4″ steel plate he cleaned up and butted together and clamped to the bench. Kevin’s running a water-cooled torch with an 1/8″ E3 tungsten sharpened almost to a point with a little flat spot on the end. The machine is set to 135 amps, normal set up, DC welding, 4T (so the trigger on the torch works), and pulse is off.
Back at the bench, he welds a bit with at 125 amps and sees he is not getting enough penetration, so he increases the amperage to 140. The puddle starts, but he’s still not happy, so he turns up the welder to 170 amps. That’s better! The puddle started nice and quick, and he can see that he’s getting about 1/8″ penetration. Kevin is impressed with the machine at the higher amperage.
Now it’s time to try the welder at the low end of the welder’s range, so he changes to the air-cooled torch, which also comes with the machine. He’s using a 1/16″ E3 tungsten sharpened to a point for the 16 gauge metal. The starts the welder at 4 amps, but he couldn’t even get his helmet lens to stay dark, so he bumps the amperage up to 5. Kevin had never used an arc that small before. His helmet kept flashing – a fixed-lens helmet would probably work better than his auto-darkening helmet to weld at that low of an amperage. He also didn’t really get good penetration at 5 amps. The 1/16″ filler rod was actually bigger than the arc, so a little smaller filler rod would help, as would more experience on his part. The machine, he says, was certainly capable of making, holding and keeping an arc that small, but he just isn’t used to it.
At the other end of the scale, Kevin has run the TIG welder at 250 amps, but he needs a bigger tungsten, as it was starting to melt the 1/8″ one.