The concept of processing solid-state materials under the influence of an air-plasma arc has existed for several decades. But in recent years, technologists have been able to achieve unprecedented high quality cutting. The modern design of the plasma torch allows it to be used in domestic work operations. The functionality of the devices focuses on ensuring user safety and improving processing accuracy.
Technology purpose
The plasma arc cutting method is used universally. If in the same household, with the help of this processing principle, it can qualitatively repair a car body or repair a roof from a metal profile, then in industry this technology is used for in-line molding of workpieces. Due to the high precision of cutting, plasma torches are widely used in artistic creation. Masters of this direction, in particular, carry out original designer fences, gates, elements for landscape design, etc. The main condition is a metal material with characteristics suitable for processing.
As standard, a small handheld plasma cutter can handle aluminum, copper, cast iron and brass. High-alloy steels are also available for productive devices. If we talk about specific tasks, then the plasma torch is able to make holes, prepare edges, cut neat strips of sheet metal, make stamped blanks, etc.
The principle of operation of the plasma torch
As a direct cutter, an artificially created electric arc is used, which the tool ignites between the workpiece and the electrodes. The plasma jet is formed due to gas, which is sent to the working area under a certain pressure. Depending on the processing conditions and cutting requirements, the temperature of the arc can vary from 5000 to 30,000 ° C, which determines the effective melt. The speed of the jet can reach 1500 m / s.
The type of gas affects the nature of the treatment. The active and inactive mixtures are fundamentally separated. For example, a plasma cutter for ferrous metals works in an oxygen-air environment, and models for colormetric use hydrogen, nitrogen or argon. The devices are also divided by the type of cooling system. In domestic conditions, plasmatrons are often used with lowering the temperature of the nozzle due to the same gases - the air system. However, in production, a more effective cooling effect is required, for which liquid channels with the direction of water flows are used.
Equipment specifications
The current strength is the main operating parameter of the plasma torches. The correct calculation for this indicator will allow you to ultimately get high-quality cutting with a minimum percentage of slag, sag and scale. The calculation should be made on the basis of the standard value of the current strength required to melt 1 mm of the workpiece. For example, to work with steel and cast iron, 4 A per 1 mm will be required, and for non-ferrous metal - 6 A. If the task is to process a 20 mm steel sheet, then 80 A will have the minimum current strength that the torch must support. For plasma cutting of an aluminum billet with the same parameters, a 120 A device will be needed.
As for the processing speed, it will depend on the power of the equipment. Household models are provided with a potential of 2.8 kW, which allows, for example, to cope with a thin-sheet profile at speeds up to 1 m / min. Of course, powerful three-phase units for industrial use at 7.5 kW in a shorter period will also process thick sheets for building structures.
Arc ignition methods
A button is provided on the torch that excites the pilot arc, during the short-term burning of which a working stream is formed. But the ignition itself can occur by contact and non-contact methods. In the first case, a short circuit is required to form a working arc. It occurs at the time of the cessation of air supply during the combustion of the arc on duty. The air flow is directed parallel to the exit of the spark from the nozzle of the plasma torch, which provokes the ignition of the torch.
With the non-contact method, the pilot arc will have a high current frequency. Its occurrence occurs between the nozzle of the cutter and the electrode under high voltage conditions. The working jet is formed without direct contact during the approach of the nozzle to the surface of the metal workpiece.
The first attempt to ignite does not always work, so it’s worthwhile to complete several cycles. However, an unsuccessful series of ignitions may mean that the system is operating at insufficient air pressure. There may also be problems in the electrical equipment of the equipment.
Device "CEDAR CUT-40B"
An inexpensive model by the standards of productive devices, which plugs into a 220 V household outlet and maintains power at a professional level of 7.5 kW. With this tool, you can safely process workpieces with a thickness of 12 mm made of stainless steel, copper, aluminum, galvanized alloys, etc. What distinguishes this model from other representatives of the middle class is its thoughtful configuration with an effective air supply system.
An air compressor is included in the basic kit, which allows the use of CUT-40B plasma torches in stand-alone mode (in terms of supporting the cooling function). But in order to save electricity, you can connect the equipment to a centralized air supply system. The device also does not disappoint in the quality of the result. The seam is smooth and reliable. If we talk about the shortcomings, then the main one will be the small thickness of the cut, which does not allow us to consider the device as a universal metalworking tool.
Tomahawk 1538 by Lincoln Electric
Professional inverter equipment for industrial enterprises or the construction industry. The three-phase plasmatron operates at a voltage of 380 V and provides the ability to cut structures and parts up to 35 mm thick. Using the integrated carbon electrode, the operator can also use the air-arc gouging method. But even in standard operating modes, the Tomahawk 1538 inverter plasma cutter shows its best. It is especially worth emphasizing the advantages of an innovative burner, which creates narrowly directed turbulence of the jet at high power. In this case, the heating of the workpiece will be minimal, which eliminates the deformation of surfaces outside the working area. The only drawback of the device is the cost, which is about 140 thousand rubles.
Apparatus "Resanta IPR 40K"
A balanced offer from a Latvian company, whose products are very popular in Russia. Also an inverter cutter, characterized by precision machining, a rich set of functions and the possibility of smooth adjustment through a potentiometer. The small size of the structure and a weight of 11 kg make it easy to transport the Resant plasma torch within the work platform or transport it to the cottage. Users note the fast cutting of thin-sheet materials, accuracy of cutting and cleanliness. However, you should not count on a high productivity potential. The model is designed to solve for the most part simple domestic tasks.
Aurora PRO AIRFORCE 80
Highly specialized model oriented to work with non-ferrous metals. The target area is the installation of electrical engineering, in which it is necessary to service copper, aluminum and steel alloys with galvanization. At the same time, the technical data for the model is quite high. It’s enough to note a power of 7.8 kW, a cut thickness of up to 20 mm and a supply voltage of 380 V. However, such attractive operating data are limited by a very modest current strength of 80 A. In other words, the Aurora plasma torch shows an example of a device that is flexible in adjustment, which covers a limited segment of tasks. The advantages of processing with this tool include the absence of a deforming effect, the wide range of available temperature conditions, the use of IGBT technology and the increased insulation class of the case.
What to consider in the choice?
Practice shows that in the process of operation, power does not come to the forefront in terms of importance. With skillful handling, an experienced craftsman and a budget machine with a potential of 2.8 kW will be able to perform quality cuts. Much more important is structural ergonomics and a suitable set of functions. As for the first, a convenient plasma cutter for metal with an inverter installation is provided with carrying handles, holders, a running gear with wheels and connectors for connecting auxiliary equipment. Of the functions, it is recommended that you first pay attention to protective systems. These are blockers, emergency and automatic mode switches, voltage stabilizers, etc.
Conclusion
It has already been noted that the user experience is greatly influenced by the user experience. There are many subtleties and nuances of organizing the cutting process, the knowledge of which will ensure a good result. For example, skilled craftsmen recommend placing the plasma cutter so that it has direct access to air flows. This solution minimizes the risk of overheating even with a stably operating own cooling system. Another tip related to the use of auxiliary units. So, a properly organized pneumatic network with a compressor and the installation of a water-oil separator minimize the ingress of foreign particles with liquid into the treatment zone. Also, do not forget about additional accessories in the form of clamps for holding workpieces, electrodes and mandatory personal protective equipment.