Ion is the fourth state in which the substance exists. If the ice changes from solid to liquid (water) as the temperature rises, then the heating turns to gas and continues to heat to a certain temperature, it turns to plasma (i. E. Plasma). The electron with a negative charge in the plasma is in a state of equilibrium with the ion with a positive charge, which allows it to use large currents and thus has high energy density and very high temperatures. Controlling the energy density, temperature and velocity of plasma arcs can cut, weld and spray metals. Plasma arc cutting is the use of a plasma arc to heat the cut metal to melting state and then to blow the melted metal away with a supporting gas, a plasma arc temperature generally ranging from 10,000 to 15,000°c for the purpose of cutting, and a water-recompressed temperature of up to 50,000°c, so that the arc energy density is quite high, and when cutting a thin plate with a thickness of less than 20 mm, it has the advantage of speed, deformation, high accuracy and high dissectority。
When the plasma arc stream is released from the nozzle, the air energy density, current speed and temperature are rapidly reduced. For example, when the working current is 200a, the plasma arc rate at 10 mm from the nozzle is 1040 mm/s, while at 20 mm it is rapidly reduced to 760 mm/min. This results in uneven distribution of temperature in the direction of the plate at the time of cutting, and can easily cause defects in the lower laminates, upper and lower widths above the cut, which are exacerbated by the increase in cutting thickness, and a sharp decline in the pace and quality of cutting. So plasma arc cutting is more appropriate for plate cutting, but the material that can be cut is quite extensive and includes almost all the metal materials that conduct electricity, such as high alloy steel, copper, aluminium, etc。
