Plasma cutting machines generally have higher no-load voltage and working voltage, and the increase of voltage means the increase of arc enthalpy. While increasing the enthalpy, reducing the jet diameter and increasing the gas flow rate can improve the cutting speed and cutting quality. Higher voltages are required when using gases with high ionization energies, such as nitrogen, hydrogen or air. What are the different gas selection tips and points? Let’s take a look at the detailed analysis of gas by professional plasma cutting machine manufacturers.
Hydrogen is generally used as an auxiliary gas mixed with other gases, and gas H35 is one of the gases with the strongest plasma arc cutting ability. When hydrogen is mixed with argon, the volume fraction of hydrogen is generally 35%. Since the hydrogen can significantly increase the arc voltage, the hydrogen plasma jet has a high enthalpy, and the cutting ability of the plasma jet is greatly improved.
Oxygen can increase the speed of cutting mild steel materials. When cutting with oxygen, the cutting mode is very similar to that of a CNC flame cutting machine. The high-temperature and high-energy plasma arc makes the cutting speed faster, but it must be used in conjunction with high-temperature oxidation-resistant electrodes. Extend the life of the electrodes.
The slag formed by air cutting and nitrogen cutting is similar, because the volume content of nitrogen in the air is about 78%, and there is about 21% oxygen in the air, so the speed of cutting low carbon steel with air is also very high, and Air is the most economical working gas, but cutting with air alone will cause problems such as slag hanging, kerf oxidation, and nitrogen increase. The lower life of electrodes and nozzles will also affect work efficiency and cutting costs.
Under the condition of high power supply voltage, the nitrogen plasma arc has better stability and higher jet energy than argon. For example, when cutting stainless steel and nickel-based alloys, there is very little slag on the lower edge, and nitrogen can be used alone. It can also be mixed with other gases. Nitrogen or air is often used as the working gas in automatic cutting, and these two gases have become the standard gas for high-speed cutting of carbon steel.
The performance of argon is stable, and it does not react with any metal even at high temperature, and the nozzle and electrode used have a long service life. However, the voltage of the argon plasma arc is low, the enthalpy is not high, and the cutting capacity is limited. Compared with air cutting, the cutting thickness will be reduced by about 25%. In addition, the surface tension of molten metal is relatively high, which is about 30% higher than that in nitrogen environment, so there will be more slag hanging problems. Even cutting with mixed gas of other gases will tend to stick to slag. Therefore, pure argon is rarely used alone for plasma cutting.
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Post time: May-09-2023