The cutting of plasma metals is a procedure that includes the combined action of a gas - very high-speed blown with a nozzle - combined with electrons and ions, then to an electric arc.
The reaction that the gas has in contact with this electric arc does that turn into plasma.
The plasma transfers heat to the metallic material until it takes it to the melting temperature and thus break the continuity of the metal.
The gases affect the quality of the cut and must be chosen according to the material you want to work.
In this regard, it is essential to consider the physical properties of the gases, such as the energy of ionization and dissociation, thermal conductivity, atomic weight and chemical reactivity.
Usually two types of gases are used in this process:
- Plasma gas, highly ionizing, allows you to generate plasma
- Assistance gas, has the function of helping metal takeaway and protect the flaps of the material cut during oxidation.
Some features of the gases used in the plasma cut:
Compressed air
Net reduction in the life of the widespread parts of the torches.
Nitriding in cutting ferrous steels.
Oxidation in stainless steels
The percentage rate of hydrogen increasing the thickness allows high cutting speeds.
The argon contained is ideal for triggers thanks to its low ionization potential.
Nitrogen
Used for fast and non-oxidation cuts for medium and thin thicknesses.
Increase in the life of the worn parts up to 3 times higher than the use of compressed air.
Possible metal nitriding on the cut surface.
Oxygen
In cutting carbon steels, it allows to obtain regular cuts, without slag or bave thanks to the exothermic reaction with iron.
High cut speed.
Reduced thermally altered area.
Methane
It has a high calorific value and improves the quality of cutting aluminum alloys.
Increase of cutting speed.
Hydrogen mixtures
They allow to take advantage of hydrogen properties by greatly improving the quality cutting parameters for stainless steels, light and nickel alloys.