Plasma cutting: operating principle and features

Plasma jet cutting is a special type of material processing that uses a plasma jet.

To produce a plasma jet, an electric arc is ignited between the electrode and the nozzle of the device. A gas mixture is then fed into the nozzle at high pressure (several atmospheres) and, passing through the electric arc, creates a plasma jet with a very high temperature of 5000⁰From up to 30,000⁰C. The speed reaches from 500 to 1500 m/s, capable of cutting metal up to 200 mm.

A high-voltage pulse is used to initially ignite the arc or to create a short circuit between the nozzle and the material being cut.

To produce a plasma jet, various gases are used, which are further divided into active and inactive. Active gases include oxygen and air and are used for cutting ferrous metals. Inactive gases include hydrogen, argon, nitrogen, and water vapor and are used for cutting non-ferrous metals and their alloys.

Plasma jet cutting has many advantages:

• It is possible to cut almost all metals - ferrous, refractory, non-ferrous and others;
• a small heating area of the cutting part eliminates its thermal deformation;
• high cutting speed of metal of different thicknesses;
• excellent cut purity, good surface quality;
• the work process is safe;
• the ability to cut out various geometries specified by the program.

Plasma jet cutting Cutting can be simple, gas-shielded, or water-shielded. The simple method uses electric current, air, or nitrogen for cutting, with a limited arc length. This method is used for cutting low-alloy steel. Oxygen is used as the cutting tool, resulting in a clean cut edge with reduced nitrogen content. Gas-shielded cutting uses a plasma-forming gas, which protects the cut from environmental influences, improving metal cutting quality. When water is used, it protects the cut from environmental influences during the cutting process, prevents the plasma torch from overheating, and absorbs harmful fumes.

Cutting process, principle and main points

Plasma jet cutting Cutting can be either separating or surface cutting, but the separating method is most commonly used. During jet cutting, the metal being cut is not part of the electrical circuit, as the arc occurs between the electrodes and a jet is formed when gas is supplied. Plasma jet cutting technology This process involves the formation of plasma and its precise, accelerated direction toward the cutting metal. Plasma is a gas saturated with ions, containing charged particles that conduct electricity. The ionization process occurs during heating and increases with increasing gas temperature.

The cutting process occurs with direct current and involves localized melting of the metal and subsequent blowing away of the metal, leaving a clean cut. To generate the working arc, an auxiliary arc (pilot arc) must be ignited between the electrode and the nozzle. This pilot arc is blown out of the nozzle by starting air, forming a 20-40 mm flame. Then, when the pilot arc flame contacts the metal, the cutting arc, which is the cutting jet, is generated. The metal is then continuously cut.

A little about the equipment

Equipment used for plasma jet cutting, Equipped with everything necessary for precise and clean work, our CNC machines, equipped with Tesla and Welding Dragon plasma cutters, are successfully used by small and medium-sized businesses. They cut metal up to 25 mm thick, ferrous metal, stainless steel, and aluminum, and accurately replicate metal cutting.