Oxygen - and plasma cutting

While cutting with a highly concentrated plasma-arc between a non-consumable electrode and a material, the base material is melted and removed from a crack. 

Non-consumable electrodes are made of copper with a zirconium or hafnium plate pressed in them. They are intensively cooled with water or air. Air is commonly used to produce plasma. In high-power equipment, instead of air, the following gases are used: argon, nitrogen, helium, carbon dioxide and mixtures of argon and helium or argon and hydrogen.

Thyristor rectifiers and inverters are used as power sources because of their parameters: setting welding current, high efficiency, light weight and small dimensions. The following metals can be cut with plasma-arc: cast iron, steel, high-alloy steel, aluminium, copper, etc. different power sources are used depending on thickness or a cut material. Thick materials are usually cut automatically. Because of harmful oxides and nitride of metals, which are emitted at high temperatures, every working place should be equipped in ventilation regardless of clamp's power. Materials can be also cut with oxygen. Metals with iron matrix are heated up to the temperature of ignition above which exothermic processes of oxygen and iron take place. Continuity of a process is ensured by movements of a clamp along a cutting line. This method can be used only for metals containing up to 1.6% of carbon. Torch is basic equipment for oxygen cutting. Its head consists of a cutting nozzle, through which flows oxygen, and a heating nozzle, through which flows a mixture of a gas and oxygen necessary for heating the material. Not only acetylene, but also propane-butane, hydrogen and natural gas can be used. Cutting can be manual, semi-automatic or automatic (CNC) dependently on required quality of surfaces and repeatability of dimensions.

It is important to consider the following before choosing an appropriate power source: technical compatibility of a source, efficiency of a process, amount and reliability of joints.