When explaining the plasma cutting process, the names of gas types are often mentioned. In order to offer a clear definition we have explained the individual gas types in the following.
Definition of Gas Types
1. Plasma gas (PG):
Plasma gas means all gases or gaseous mixtures which can be used to generate the plasma beam and carry out the cutting process. It can be assumed that there are two main phases of the plasma arc: the ignition phase and the cutting phase. Accordingly, plasma gases are divided into ignition and cutting gases. These may differ in terms of gas type as well as volume flow rate.
Ignition gas (ZG):
This gas is used to ignite the plasma arc. Its function is to facilitate the ignition process and it can have a positive influence on the lifetime of the cathode.
Cutting gas (SG):
By ionization the cutting gas is electrically conductive and generates the main arc between cathode and work-piece. First, the energy of the arc makes the material melt and then the melted material is blown out by the flow speed of the cutting gas. In order to achieve optimum cutting results the cutting gases differ depending on material type and thickness. (Example: ignition gas air with cutting gas oxygen or ignition gas argon with cutting gas Ar/H2, Ar/H2/N2, Ar/N2)
Marking gas (MG):
The gas used for plasma marking is referred to as marking gas.
2. Swirl gas (WG):
This gas covers the plasma beam. It helps to further increase the cutting quality because it focuses and cools the arc additionally and protects the consumables during piercing and underwater cutting. For this purpose, too, different gases can be used.
Sealing gas (SpG):
Sealing gas is a swirl gas with reduced volume flow rate during cutting breaks when using underwater plasma cutting. It prevents the water from entering the torch head while the torch is underwater.
3. Control gas (KG):
This gas is led to the torch head and controls the presence of the protection cap which is situated there. It means that the machine can only be started when the torch is properly installed.
Identification gas (IG):
This gas is the control gas which is returned from the torch. It is used to identify the different torch heads.
