Keep two figures apart. Quality cutting leaves an edge ready for further work, maximum cutting is a forced cut, with dross and a bevel. A 40 A machine cuts 10 to 12 mm to quality, 60 A about 16 to 20 mm, 100 A about 25 to 30 mm, 120 A reaches 40 mm.
The second condition is air: dry, free of oil, at a steady flow. For 40 A count on 150 to 180 litres per minute at 5 bar, for 60 A about 200 to 250, for 100 A as much as 400. A filter with a dryer costs less than a replacement set of nozzles and electrodes. Water in the line is the most common cause of arc loss and of the double arcing that burns out the nozzle.
HF ignition is fast, but it interferes with electronics and copes less well with mesh and gratings. Contactless pilot arc ignition lets you cut interrupted material and is safer for CNC controls.
The duty cycle means something different in cutting than in welding, because you usually cut in short runs. For continuous work on a CNC table, though, look for 60 percent and more at your working current.
Count the cost of consumables. The nozzle and the electrode are a pair, replace them together. Cutting with a standoff guide makes nozzles last longer than dragging the torch along the material. In the product listing we give the torch type, the set included and the prices of consumables.