Gas Cutting: Principle of Operation of Gas Cutting

Gas Cutting

Oxy fuel gas cutting is a process by which metal (ferrous) to be cut is heated up by means of flame and then oxygen gas is impinged on this red heat metal so as to form the metal oxide and then remove the metal from there. Metal upto thickness as high as 2 m can be cut by this method.

Principle of Operation of Gas Cutting

Iron and steel when heated to a temperature between 800 to 1000°C get oxidised (burn). When a high pressure (300 kPa) oxygen jet is directed against a metal, it burns the metal and blows it away causing the cut (kerf).

Oxy-Acetylene torch tips
Oxy-Acetylene torch tips

The oxy-acetylene gas cutting outfit is similar to that of oxy-acetylene welding except for the torch tip. Here, the torch tip has provision for preheating the plate as well as providing the oxygen jet. Thus the tip has a central hole for oxygen jet with surrounding holes for preheating flames as shown in Fig. The cutting tip should be properly chosen for intended application. The size normally depends on the thickness of the plate as it determines the amount of preheating as well as the oxygen jet flow required for cutting.

Gas cutting would be useful only for those materials which readily get oxidised and the oxides have lower melting points than the metals. Thus it is most widely used for ferrous materials. But it cannot be used for materials such as aluminium, bronze, stainless steel and like metals since they resist oxidation.

Oxy-Acetylene cutting
Oxy-Acetylene cutting

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