Migatronic Sigma2 500 Pulse is an inverter multiprocess power source: MIG/MAG with pulse, MMA and air carbon arc gouging. You set the current from 40 to 500 A, at 420 A the machine runs at a 100% duty cycle. The housing has class IP23, the supply is 3 x 400 V.
What this machine is for
This is a power source for heavy fabrication, series production and robot stations. Besides basic MIG/MAG you have pulsed welding, an MMA mode with a covered electrode and air carbon arc gouging, with which you remove faulty welds, prepare edges and take off excess material. So one machine handles several jobs in a department.
The duty cycle at 40°C is 100% at 420 A and 60% at 500 A. At 420 A you run long welds without breaks to cool, and you hold the full 500 A for six minutes in ten. The setting range covers from 40 to 500 A, some sources give a lower limit from 15 A, so you check the real bottom on the panel of the unit.
Pulse keeps the heat in check on stainless steel, aluminium and thin sheet, where a plain spray arc overheats the material. DUO Plus works with slower pulsing and lays a face close in look to a TIG weld, which helps on root runs and where the weld stays visible. PowerArc guides the arc for deeper penetration in thick material and on joints that carry responsibility.
Pulse works by the current jumping between a base and a peak value. At the peak a droplet of metal detaches, at the base the pool cools, so the material gets less heat than with a continuous spray arc. On thin sheet that is less distortion, on stainless steel a smaller heat affected zone and less discolouration, on aluminium a calmer metal transfer. This is the main reason why a power source with pulse is bought instead of a plain wire welder.
The synergic control shortens the setting up. You point to the material, the gas and the wire diameter, and the machine gives a full set of parameters, which you then correct with one knob. You save your own settings in memory, so you start a repeat part from the same point and not from scratch. In series production and in shift work that is a difference in changeover time and in the repeatability of the weld.
Air carbon arc gouging is a separate process. A carbon electrode melts the metal and a stream of compressed air blows it out of the groove, so you remove a faulty weld or prepare a bevel without a grinder. It needs an air supply, a separate gouging torch and extraction, because the process is loud and throws out a lot of spatter.
Features and equipment
- MIG/MAG in constant voltage mode and with pulse, for steel, stainless steel and aluminium.
- DUO Plus, slower pulsing that improves the look of the face, useful on root runs.
- PowerArc, arc guidance for deep and sure penetration in thick material.
- MMA mode for assembly work, repairs and welding in places with hard access.
- Air carbon arc gouging for removing faulty welds and preparing edges.
- Digital synergic control with a Pulse panel and memory for your own settings.
- IGC, intelligent gas control, which the manufacturer describes as cutting gas use by up to 50%.
- Software update by SD card.
- Prepared for work with a robot after an RCI interface is added, the power source then takes the settings from the station controller.
- Works with external MWF 41 and RWF Multi feeders or runs in the version with a built in feeder.
- Prepared for liquid cooling, needed with torches working at the upper current settings.
The MMA mode comes in useful in assembly and repairs, where you cannot pull in a feeder or a cylinder. A covered electrode works in wind and on material that cannot be cleaned properly, so on a building site and in a refit it is sometimes the only sensible choice. At this power of the source you will also strike thicker electrodes, and a change between modes is a matter of switching on the panel and plugging in the electrode holder.
Technical data
| Brand | Migatronic |
|---|---|
| Model | Sigma2 500 Pulse |
| Type | inverter power source, multiprocess |
| Welding processes | MIG/MAG in constant voltage mode, pulse, DUO Plus, PowerArc, MMA, air carbon arc gouging |
| Supply voltage | 3 x 400 V with a tolerance of 15%, from 50 to 60 Hz |
| Recommended slow blow fuse | 32 A |
| Welding current range | from 40 to 500 A, some sources give from 15 A |
| Duty cycle at 40°C | 100% at 420 A, 60% at 500 A |
| Power factor | 0.90 |
| Efficiency | 0.85, that is 85% |
| Control | digital, synergic, Pulse panel |
| Software update | by SD card |
| Intelligent gas control IGC | option, present in this unit |
| Work with a robot | after an RCI interface is added |
| Housing protection class | IP23 |
| Cooling | liquid, cooling unit as a separate module |
| Wire feeder | external, for example MWF 41 or RWF Multi, or built in the C version |
| Weight | about 128 kg, depending on the version |
What to watch out for
The supply is 3 x 400 V with a tolerance of 15% at 50 to 60 Hz, with a slow blow 32 A fuse, that is a separate power circuit. The weight needs attention: the description gives about 128 kg with the note that the value depends on the compact version or the one with a separate feeder, while the power source alone in the S version may weigh around 36 kg. You settle the weight and the configuration before transport.
This power source works with a wire feeder, in the version with a separate feeder that was for example MWF 41 or RWF Multi. The record gives liquid cooling, the cooling unit is a separate module, so you check that it is there and check the coolant level. The Pulse panel is needed for the full set of functions, work with a robot needs the RCI interface. The model is out of production, so access to software updates and parts can be limited.
At such a current the rest of the station counts. A torch for 500 A works with a liquid circuit, the interconnection cable and the earth cable must have a section matched to the current, and a shielding gas cylinder goes down faster than on smaller machines, so IGC has a real effect on cost here. Gouging needs a separate torch and compressed air. Before you start, check the coolant level in the cooling unit, the flow in the circuit and the state of the rollers in the feeder, because these are the parts that wear at the upper settings. Pay attention to the wire guide and the contact tip in the torch, with pulse they wear faster than with a plain spray arc, and you will know a worn tip by an unstable arc and the wire sticking.
This unit is sold
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