What Are the Different Types of Plasma Cutting Systems?

Plasma arc cutting is a processing method that uses the heat of a high-temperature plasma arc to locally melt (and evaporate) the metal at the cut of the workpiece, and uses the momentum of high-speed plasma to remove the molten metal to form the cut.

Plasma cutting with different working gases can cut a variety of oxygen cutting difficult-to-cut metals, especially for non-ferrous metals (stainless steel, aluminum, copper, titanium, nickel); its main advantage is that cutting of metal with small thickness At that time, the plasma cutting speed is fast, especially when cutting ordinary carbon steel sheets, the speed can reach 5-6 times that of the oxygen cutting method, the cutting surface is smooth, the thermal deformation is small, and there is less heat affected zone.

1950s traditional plasma cutting

Since the plasma arc process in the mid 1950s, considerable research has focused on increasing arc compression without generating double arcs. Plasma arc cutting applied during that period is now called "conventional plasma cutting." If the user is cutting multiple types and different plate thicknesses, traditional plasma cutting can be cumbersome. For example, cutting stainless steel and aluminum using traditional plasma processes requires different gases and gas flows to achieve the best cutting quality on both metals. Although traditional plasma cutting was dominant from the 1950s to the 1990s, this process often required a very expensive argon-hydrogen mixture ^[1]

The plasma cutting system is mainly composed of a water supply device, a power supply and a cutting torch. The water-cooled gun also needs a device for cooling circulating water.

(1) Gas supply device The main equipment of air plasma arc cutting gas supply device is an air compressor larger than 1.5kw. The gas pressure required during cutting is 0.3-0. 6MPa. If other gases are selected, bottled gas can be used for cutting after decompression.
(2) Power supply Plasma cutting uses a DC power supply with steep drop or constant current characteristics. In order to obtain satisfactory arc starting and stabilizing effects, the no-load voltage of the power supply is generally twice the arc voltage. The no-load voltage of common cutting power supply is 350-400V.

(3) The specific form of the cutting torch depends on the current level of the cutting torch. Generally, cutting torches below 60A mostly adopt air-cooled structure; while cutting torches above 60A mostly adopt water-cooled structure. The electrodes in the torch can be pure tungsten, thorium tungsten, bell tungsten rods, or inlay electrodes. The electrode material is preferably cast tungsten.
Plasma cutting has the advantages of large cutting thickness, flexible cutting, simple clamping of workpieces, and cutting curve. It can be widely used for cutting all metal materials and non-gold materials.

In addition to the general plasma cutting method, the derived forms include water compression plasma cutting. The most commonly used methods are general plasma cutting and air plasma cutting.

General cutting

General plasma cutting does not require a protective gas. The working gas and the cutting gas are ejected from the same nozzle. When starting the arc, a small gas stream of ionic gas is ejected as the ionizing medium; when cutting, a large gas stream of gas is simultaneously ejected to exclude molten metal.

Air cutting

Air plasma cutting generally uses compressed air as the ion gas. This method has low cutting cost and convenient air source. Compressed air is heated, decomposed, and ionized in the arc. The generated oxygen cuts the metal to produce a chemical exothermic reaction, which accelerates the cutting speed. The enthalpy of the fully ionized air plasma is high, so the energy of the arc is large and the cutting speed is fast.

The development of plasma cutting to the present, the working gas can be used (working gas is the conductive medium of the plasma arc, and

Various

1. A water tank should be set in the lower part of the plasma cutting, and the cutting part should be placed under water during cutting to avoid the toxicity of smoke to the human body.

2. Avoid direct visual observation of the plasma arc during plasma arc cutting. Wear professional protective glasses and face shields to avoid burns to the eyes and skin caused by arc light.

3 During the plasma arc cutting process, a large amount of poisonous gas will be generated, and it is necessary to ventilate and wear a multi-layer filtered dust mask.

4 During the plasma arc cutting process, you need to wear towels, gloves, foot coverings and other protective equipment to prevent the skin from being burned by the sparks.

5. During the plasma arc cutting process, the high-frequency and electromagnetic radiation generated by the high-frequency oscillator will cause damage to the body, and some long-term practitioners may even have infertility symptoms. Although the medical profession and the industry are inconclusive, protection is still needed. jobs.