Recently, the use of plasma flow for cutting materials is gaining popularity. The appearance of handheld devices on the market further expands the scope of this technology, by means of which plasma cutting of metal is carried out.
Plasma cutting of metal of considerable thickness
The essence of plasma cutting
Plasma cutting involves local heating of the metal in the separation zone and its subsequent melting. Such significant heating is provided through the use of a plasma jet, which is formed using special equipment. The technology of obtaining a high-temperature plasma jet is as follows.
- First, an electric arc is formed, which ignites between the electrode of the device and its nozzle or between the electrode and the metal, that is cut. The temperature of such an arc is 5000 degrees.
- After that, gas is fed into the nozzle of the equipment, which raises the temperature of the arc already to 20000 degrees.
- When interacting with an electric arc, the gas is ionized, which leads to its transformation into a plasma jet, whose temperature is already 30000 degrees.
The resulting plasma jet is characterized by a bright glow, high electrical conductivity and speed of exit from the nozzle of the equipment (500-1500 m / s). This jet locally heats and melts the metal in the treatment area, then it is cut, which is clearly visible even in the video of such a process.
Different gases can be used in special installations to produce a plasma jet. These include:
- ordinary air;
- technical oxygen;
- nitrogen;
- hydrogen;
- argon;
- steam, obtained by boiling water.
Plasma metal cutting technology involves cooling the equipment nozzle and removing molten material particles from the treatment area. These requirements are met by the flow of gas or liquid, supplied to the zone, where cutting is carried out. Plasma jet characteristics, molded on special equipment, allow to make with its help cutting of details from metal, the thickness of which reaches 200 mm.
Device and principle of operation of plasma cutting
Plasma cutting devices are successfully used in enterprises of various industries. With their help, not only metal parts are successfully cut, but also products made of plastic and natural stone. Thanks to such unique opportunities and its versatility, this equipment is widely used in machine-building and shipbuilding plants, in advertising and repair companies, in the communal sphere. Another great advantage of using such installations is that, that they allow you to get very even, thin and precise cut, which is an important requirement in many situations.
Plasma cutting equipment
Devices are offered in the modern market, by means of which cutting of metal with use of plasma is carried out, two main types:
- devices of indirect action - cutting is carried out in a non-contact way;
- devices of direct action - sharp contact method.
Equipment of the first type, in which the arc is ignited between the electrode and the nozzle of the cutter, used for processing non-metallic products. Such installations are mainly used at various enterprises, you will not meet them in the workshop of a craftsman or in the garage of a repairman.
The device for plasma cutting of Resanta IPR-25
In devices of the second type the electric arc is ignited between an electrode and directly a detail, which, naturally, can only be made of metal. Thanks to that, that the working gas in such devices is heated and ionized on the entire gap between the electrode and the part), the plasma jet in them has a higher power. Such equipment can be used to perform manual plasma cutting.
Any plasma cutting machine, working on the contact principle, consists of a standard set of components:
- power supplies;
- plasmatron;
- cables and hoses, by means of which the plasmatron is connected to the power supply and the working gas supply source;
- gas cylinder or compressor to obtain an air stream of the required speed and pressure.
The main element of all such devices is the plasmatron, it is he who distinguishes such equipment from conventional welding. Plasmatrons or plasma cutters consist of the following elements:
- working nozzle;
- electrode;
- insulating element, which is characterized by high heat resistance.
Cutter for manual plasma cutting
The main purpose of the plasmatron is, to convert the energy of the electric arc into the thermal energy of the plasma. Gas or air-gas mixture, coming out of the nozzle of the plasmatron through a hole of small diameter, passing through a cylindrical chamber, in which the electrode is fixed. The nozzle of the plasma cutter provides the required speed and shape of the working gas flow, and, in accordance, the plasma itself. All manipulations with this cutter are performed manually by the equipment operator.
Given that fact, that the operator has to keep the plasma cutter on the weight, it is very difficult to ensure high quality metal cutting. Often details, for which manual plasma cutting was used, have edges with irregularities, traces of influx and jerks. In order to avoid such shortcomings, use various devices: stands and stops, allowing to provide equal movement of a plasmatron on a cutting line, as well as the constancy of the gap between the nozzle and the surface of the workpiece.
Air or nitrogen can be used as working and cooling gas when using manual equipment. Such an air-gas jet, in addition, It is also used for blowing molten metal from the cutting zone. When using air is supplied from the compressor, and nitrogen comes from a gas cylinder.
Power supplies required
Though, that all power supplies for plasma cutters are powered by AC mains, some of them can turn it into a permanent one, and others to strengthen it. But those devices have higher efficiency, operating on direct current. Installations, operating on alternating current, are used for cutting metals with relatively low melting point, example, aluminum and alloys based on it.
In those cases, when you do not need too much plasma power, conventional inverters can be used as power sources. Such devices, differing in high efficiency and providing high stability of burning of an electric arc, used to equip small factories and home workshops. Of course, cut a piece of metal of considerable thickness with a plasmatron, powered by an inverter, not work, but it is optimal for many tasks. The big advantage of inverters is their compact dimensions, so they can be easily carried with you and used to perform work in hard-to-reach places.
Transformer-type power supplies have higher power, using which can be done as a manual, and mechanized cutting of metal using a jet of plasma. Such equipment is not only high power, but also higher reliability. They are not afraid of voltage drops, from which other devices may fail.
Cutting pattern
Any power supply has such an important characteristic, as the duration of inclusion (PV). In transformer power supplies PV is 100%, this means, that they can be used all day, without a break for cooling and rest. But, Of course, such power supplies have disadvantages, the most significant of which is their high energy consumption.
How to perform manual plasma cutting?
First, what needs to be done in order to start using the device for plasma cutting of metal, - is to bring together all its constituent elements. The inverter or transformer is then connected to a metal workpiece and to an AC mains.
Next, the cutting technology involves bringing the nozzle of the device to the workpiece at a distance of close 40 mm and ignition of the so-called next arc, due to which the ionization of the working gas will be carried out. After the arc lit up, an air-gas flow is fed into the nozzle, which should form a plasma jet.
When a plasma jet is formed from the working gas, having high electrical conductivity, a working arc is created between the electrode and the part, and the next one automatically shuts off. The task of such an arc is, to maintain the required level of ionization of the plasma jet. It happens, that the working arc goes out, in this case, shut off the gas supply to the nozzle and repeat all the above steps again. Best of all, if there is no experience of such a process, watch the training video, which shows in detail the manual cutting of metal.