CNC plasma cutting machines usually have a high no-load voltage and operating voltage. When using gases with high ionization potential, such as nitrogen, hydrogen or air, the voltage required for the plasma arc is higher. When the current is constant, the voltage increase means that the progress of the arc enthalpy and cutting ability. When cutting with oxygen, the cutting mode and the CNC flame cutting machine imagine that the high-temperature and high-energy plasma arc can make the cutting speed faster. However, it is necessary to use the spiral duct machine with high temperature oxidation resistant electrodes and prevent the electrode from arcing Impact protection to extend electrode life. Because plasma arc cutting generally uses a constant current or steep drop out of the power characteristics of the nozzle height increases, the current change is small, but will increase the arc length and lead to an increase in arc voltage, so that the arc power improvement; but it will also make The arc length exposed to the environment increases and the energy lost by the arc column increases.
Even with a mixture of argon and other gas cutting will have a tendency to sticky.
1, the air contains about 78% of the volume fraction of nitrogen, so the use of air cutting the formation of the dross conditions and cutting with nitrogen imagine very much; the air also contains about 21% of the volume fraction of oxygen, due to the presence of oxygen, with air The cutting speed of low carbon steel is also high; the same time the air is the most economical working gas. And the use of the nozzle and electrode have a higher life. At present, the use of steel in China's machinery industry has reached more than 300 million tons, and the amount of steel cut is very large. Along with the development of modern machinery industry, the work efficiency and product quality requirements of sheet metal cutting also improve simultaneously.
2, oxygen can improve the cutting speed of low carbon steel. However, when using air cutting alone, there will be dross and cut oxidation, nitrogen and other topics, and the lower electrode and nozzle life will also affect the efficiency and cutting costs. Because hydrogen can significantly improve the arc voltage, hydrogen plasma jet has a high enthalpy, when mixed with argon, the plasma jet cutting ability greatly improved.
3, Argon at almost no reaction with any metal, argon plasma cutting machine is not chaos. Therefore, it is rare to use pure argon for plasma cutting
CNC plasma cutting machine in the use of gas and the choice of the length of the very important, the use of gas will severely affect the cutting accuracy, dross and other phenomena. Nitrogen can be used alone or in combination with other gases using plasma cutting machines. For example, nitrogen or air is often used as the working gas for automated cutting, and these two gases have become the standard gas for high speed cutting of carbon steel. Therefore, the market potential of CNC cutting machine is still very large, the market prospect is more optimistic. Nitrogen is also sometimes used as the starting gas for oxygen plasma arc cutting.
Hydrogen is usually used as an auxiliary gas to mix with other gases. For example, the well-known gas H35 (35% by volume of hydrogen and the balance of argon) is one of the most powerful gases for plasma arc cutting, which is mainly beneficial to hydrogen . However, the plasma arc argon plasma voltage is low, the enthalpy is not high, limited cutting capacity, compared with the cutting of air cutting the thickness of about 25% reduction.In addition, argon gas in the environment, the larger the surface tension of molten metal, Than in the nitrogen environment is about 30% higher, so there will be more hanging slag problem. If, at the same time as the enthalpy increases, the jet diameter is reduced and the gas flow rate is increased, faster cutting speeds and better cutting quality are often achieved.
5, nitrogen is a commonly used working gas, under the premise of a higher supply voltage, nitrogen plasma arc has better turbulence and higher jet energy than argon, even cutting liquid metal viscosity of the material Such as stainless steel and nickel-based alloy, cut the lower edge of the amount of dross is also very small.