In the case of plasma cutting systems, you can choose systems that have a dual-gas or a multi-gas system. For different applications, you can make use of varied plasma gases and different shield gases. If you are engaged in cutting different types of materials, then using multi-gas torches can give you plenty of flexibility. Depending on the type and thickness of the material being cut, to achieve the best quality cut, productivity, cost efficiency and prolonged consumable life, different kinds of gases are used.
Choosing the correct gas for your plasma cutting system can be quite confusing and in this article, we will be looking at the pros and cons of the various gases.
Shop air or simply air is the most adaptable plasma gas. You can achieve good cutting speed and good quality cuts on stainless steel, mild steel and aluminium. There is no need to buy gases when using air and this helps to reduce the cost of operation.
However, you must remember that air is not all free of cost. Before use, the shop air has to be cleaned to remove any contamination like particles, moisture and traces of oil. A compressor, a set of filters and a refrigerated dryer are needed to remove any contaminants.
Another issue with air plasma is cut edge weldability. In the case of air plasma, the cut surface gets some oxidation and nitriding which may cause the welds to become porous. You can correct this problem by using weld wire of very good quality with deoxidizers and denitriders. Air is a very good alternative for several shops that require good speed, versatility, prolonged part life and low levels of dross. When making use of air plasma, it is best to use air as the shield gas.
Today, when it comes to mild steel cutting, typically oxygen is used as the plasma gas as it delivers fast cutting speed and the best quality of cut. However, in the case of aluminium and stainless steel cutting, it is not recommended to use oxygen as the plasma gas.
A fine molten spray of metal is produced when the carbon steel reacts with the oxygen gas. This spray can be easily removed from the kerf that is produced. The main drawback of oxygen is its cost and the life of the consumables. However, today high-tech oxygen plasma cutting systems make use of inert gases like nitrogen as the starting gas along with oxygen as the plasma gas. Usually, air shields are best used with oxygen as the plasma gas.
We have looked at the use of air and oxygen in plasma cutting in Part 1 of the series. In Part 2, we will take a look at the rest of the gases that can be used as plasma gases and their advantages and disadvantages.