Plasma Arc Cutting (PAC) Principles:
The main difference among PAC and Plasma Arc Welding (PAW) is the velocity of the orifice gas. PLASMA ARC CUTTING utilized the principle of passing an electric arc through a quantity of gas travelling by a limited outlet. The electric arc heats the gas as it travels by the arc. The gas is heated up to such a high temperature that it turns into what is called PLASMA. Plasma is the fourth state of matter - not a liquid, gas or a solid. A great deal of heat energy is needed to change the gas to plasma. The heat needed is furnished by the electric arc. It is this heat in the plasma that heats the base metal. The heat of the plasma is released on the metal like the plasma turns back to a gas. By using the plasma procedure, temperatures as high as 25,200oF (14,000oC) have been attained.
Cutting torches utilized has several ports. Only the center port contains the arc plasma, while the surrounding ports provide a shielding gas defence. Gas flow might be as high as 250 cu. Ft./hr. Nitrogen is frequently used as the plasma gas. The shielding gas for mild steel is CO2 or air. An helium and argon mixture is utilized as the shielding gas for aluminium.