CNC plasma cutting refers to the cutting of metals using a plasma torch controlled from a computer. Plasma cutters operate by forcing a gas or compressed air at high speeds through a nozzle. Once an electric arc is introduced to the gas, ionized gas or plasma is created, the fourth state of matter. It, in turn, cuts through the metal. These machines are highly accurate and fast cutting through, slicing metals at speeds of up to 500 inches per minute. Plasma cutters require a plasma gas and an assist gas to function, and they vary according to the material being cut.