A plasma cutting table is used in industrial processes to cut metal and other sheet materials of varying thickness. Generally, plasma cutting uses a high pressure stream of inert gas to which an electrical arc is applied. The electrified gas becomes plasma that is hot enough to cut the material while also having enough force to blow molten material away from the site of the cut. There are three different types of plasma cutting processes: the high frequency (HF) contact process, the pilot arc process, and the computer numerical controlled (CNC) process. Older plasma cutting tables use the HF contact process to cut sheet metal, while pilot arc and CNC process machines are newer and can cut thicker non-conductive materials like glass.
The HF contact process of plasma cutting is named for its use of a high frequency spark to initiate the electrical arc. In this process, the electrical arc must be in contact with material being cut. The user of a HF contact plasma cutting table must therefore keep the nozzle that produces the plasma in contact with the material. A plasma cutting table that uses the HF contact process can only be used to cut conductive materials like sheet steel or other metals.
The pilot arc type of plasma cutting table creates the electrical arc necessary to make plasma in a two-stage process. Similar to a pilot light on a stove, a pilot arc plasma cutting table creates a pilot arc, or a small pocket of plasma, that is maintained within the nozzle until it comes in contact with the material being cut. This pilot arc then becomes a full plasma arc, which gets hot enough to cut the material. The fact that the plasma arc is contained within the nozzle allows pilot arc plasma cutting machines to cut non-conductive materials such as heavy plastic or glass. Like HF contact process machines, the plasma torch on most pilot arc plasma cutting tables is hand-controlled.
One of the newest forms of plasma cutting is the computer numerical controlled, or CNC, process. A plasma cutting table that uses the CNC process has a fixed plasma torch that is controlled by a computer, which moves the plasma torch over the material in a pre-programmed pattern. There are many different types of CNC industrial machines and cutters, like lasers, that use other methods of cutting besides plasma.