conductive gas to transfer energy from an electrical power source trough a plasma-cutting torch to the material being cut.
Inside the plasma torch the arc is struck between the cathode (electrode — polarity) and an anode (tip + polarity) As compressed air is introduced in the arc, plasma is produced and forced out trough the tip with high kinetic velocity, forming what is referred to as the pilot arc. Upon impact with the positive pole of the work piece the arc is transferred from electrode / tip to electrode work piece following the plasma gas. Due to the design of the torch tip this arc and the high velocity of flow of free electrons and ionized particles called the plasma jet is constricted to a very small cross section with high-energy concentration. In the impact zone the high inherent energy of the jet, consisting of heat, ionization energy and dissociation energy is released, creating temperatures up to 28000°C (50000°F). The high velocity air plasma jet will efficiently melt and blow away practically any electrically conductive material, and provide a narrow smooth cut.
The basic plasma cutting equipment consists of a constant current DC
power supply, an arc starting circuit (High frequency or air type) and a torch.
The output current (Amperage) of the power supply determines the speed and cut thickness capacity of the system. Most of these hand held systems are rated at under 100 Amps, for cutting materials under 16 mm (5/8") thick. The main function of the power supply is to provide the correct energy to maintain the plasma arc after ionization.
The arc starting circuit uses compressed air to force back the electrode from the tip, creating an electric arc. This in turn, positively charges the air stream, creating a plasma arc. This method is referred to as " blowback " technology.
The Unitor UPC-838 uses NO HIGH
FREQUENCY to initiate the plasma arc. This is of great importance for shipboard use.
The torch serves as the holder for the consumable tip and electrode, and provides cooling to these parts. The tip and electrode constrict and maintain the plasma jet.
The process generally uses a single gas (usually air or nitrogen) Air is the most widely used plasma gas, due to the fact that compressed air is readily available at most location and that it is cheap compared to single gases. Consumable parts life is acceptable (usually between 100 to 200 starts). The consumable part life depends largely on air quality that must be oil and water free.