Plasma cutting relies on an ionized gas to carry the electrical arc that melts and ejects material. Oxygen is one of several gas options, and it has a specific niche: it works best on carbon steel, where the oxygen actively participates in an exothermic reaction with the molten iron, adding extra heat to the cut and helping produce a cleaner edge than an inert gas would on the same material.
Why Oxygen Isn't a Universal Choice
That same reactivity is a liability on stainless steel and aluminum, where it causes oxidation and discoloration at the cut edge rather than helping the cut. For those materials, plasma systems typically switch to nitrogen, argon-hydrogen mixes, or compressed air depending on thickness and the finish required. Choosing the wrong gas for the material doesn't just affect edge appearance -- it can leave a harder, more brittle oxidized layer that causes problems in downstream welding.
Practical Takeaway
If a shop processes primarily carbon steel plate and structural sections, an oxygen-capable plasma system is usually the right default -- our P1325 and P1530 tables are both configured for this. Shops with a mixed material stream -- carbon steel one day, stainless or aluminum the next -- need a system that can switch gas types rather than one locked into a single consumable setup, which is a spec question worth raising before buying rather than after.