The concept of air plasma arc machining of solid materials has been around for decades. But in recent years, technologists have managed to achieve an unprecedented high quality of cutting. The modern design of the plasma cutter allows it to be used in domestic work operations. The functionality of the devices is focused on ensuring the safety of the user and improving the accuracy of processing.
Purpose of technology
The plasma arc cutting method is used everywhere. If in the same household, with the help of this processing principle, it is possible to repair a car body or repair a roof from a metal profile with high quality, then in industry this technology is used for in-line molding of blanks. Due to the high cutting accuracy, plasma torches are widely used in art. Masters of this direction, in particular, perform original designer fences,gates, landscaping elements, etc. The main condition is a metal material with suitable characteristics for processing.
The standard low power handheld plasma cutter cuts 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 capable of making holes, preparing edges, cutting neat strips of sheet metal, making 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 the gas, which is directed to the working area under a certain pressure. Depending on the processing conditions and cutting requirements, the arc temperature can vary from 5,000 to 30,000 °C, which leads to an effective melt. The jet speed can reach 1500 m/s.
The nature of processing is influenced by the type of gas. Active and inactive mixtures are fundamentally separated. For example, a plasma cutter for ferrous metals works in an oxygen-air environment, and models for non-ferrous metals use hydrogen, nitrogen or argon. The devices are also divided according to the type of cooling system. In domestic conditions, plasmatrons are more often used with a decrease in the temperature of the nozzle due to the same gases - an air system. However, in production, a more efficient cooling effect is required, forwhat liquid channels are used with the direction of water flows.
Hardware Specifications
Current is the main operating parameter of plasma torches. The correct calculation for this indicator will eventually allow you to get a high-quality cutting with a minimum percentage of slag, sagging and scale. The calculation should be made based on the standard value of the current required for the melt of 1 mm of the workpiece. For example, working with steel and cast iron will require 4 A per 1 mm, and for non-ferrous metal - 6 A. If the task is to process a 20 mm steel sheet, then 80 A will be the minimum current that the cutter must support. For plasma cutting of an aluminum billet with the same parameters, you will need a 120 A device.
As for the processing speed, it will depend on the capacity 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 a speed of up to 1 m / min. Of course, powerful three-phase units for industrial use at 7.5 kW will also process thick sheets for building structures in a shorter period.
Arc ignition methods
The torch is provided with a button that initiates a pilot arc, during the short-term burning of which a working jet 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 when the air supply is cut off during the combustion process.duty arc. The air flow is directed parallel to the exit of the spark from the nozzle of the plasma cutter, 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 cutter nozzle and the electrode under high voltage conditions. The working jet is formed without direct contact as the nozzle approaches the surface of the metal workpiece.
The first attempt to ignite is not always successful, so it is worth doing several cycles. However, an unsuccessful firing sequence may mean that the system is operating with insufficient air pressure. There may also be problems in the electrical stuffing of the equipment.
Apparatus "KEDR CUT-40B"
Inexpensive by performance standards, plugs into a 220V household outlet and maintains a pro-level power of 7.5kW. This tool 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 a well-thought-out package with an efficient air supply system.
The basic kit includes an air compressor, which allows you to use CUT-40B plasma cutters in stand-alone mode (in terms of supporting the cooling function). But in order to save energy, you can connect the equipment to a centralized air supply system. In terms of the quality of the result, the device is also notdisappointing. 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 tool for metalworking.
Lincoln Electric Tomahawk 1538
Professional inverter equipment for industrial enterprises or the construction industry. The three-phase plasma torch operates at a voltage of 380 V and provides the ability to cut structures and parts up to 35 mm thick. Using the built-in 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 side. It is especially worth emphasizing the merits of the innovative burner, which creates narrowly directed swirls of the jet under 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 well-balanced offer from a Latvian company whose products are very popular in Russia. It is also an inverter cutter, characterized by processing accuracy, a rich set of functions and the possibility of smooth adjustment through a potentiometer. The small dimensions of the structure and the weight of 11 kg make it easy to transport the Resanta plasma cutter within the working site or transportto the cottage Users note the fast cutting of thin-sheet materials, the accuracy of cutting and cleanliness. However, you should not count on high performance potential. The model is designed to solve mostly simple everyday tasks.
Aurora PRO AIRFORCE 80
A highly specialized model focused on working with non-ferrous metals. The target area is the installation of electrical engineering, in which copper, aluminum and steel alloys with galvanization have to be serviced. At the same time, the technical data of the model is quite high. It is enough to note the power of 7.8 kW, the thickness of the cut up to 20 mm and the supply voltage of 380 V. However, such attractive performance data is limited to a very modest current strength of 80 A. In other words, the Aurora plasma cutter 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, a wide range of available temperature conditions, the use of IGBT technology and an increased class of body insulation.
What to consider when choosing?
Practice shows that in the process of operation, it is far from power and performance that come to the fore in terms of importance. With skillful handling, an experienced craftsman and a budget device with a potential of 2.8 kW will be able to perform a cut with high quality. Structural ergonomics and a suitable set of functions are much more important. As for the first, a convenient plasma cutter for metal with an inverter installationprovided with carrying handles, holders, undercarriage with wheels and connectors for connecting auxiliary equipment. From functions it is recommended to pay attention to protective systems first of all. These are blockers, emergency and automatic mode switches, voltage stabilizers, etc.
Conclusion
It has already been noted that user experience has a significant impact on the quality of work. There are many subtleties and nuances of organizing the cutting process, the knowledge of which will ensure a good result. For example, qualified craftsmen recommend positioning a plasma cutter so that it has direct access to air currents. This solution minimizes the risk of overheating even with a stable internal cooling system. Another tip is related to the use of auxiliary units. Thus, a properly organized pneumatic network with a compressor and the installation of a moisture-oil separator minimize the ingress of foreign particles with liquid into the treatment area. Also, do not forget about additional accessories in the form of clamps for holding workpieces, electrodes and mandatory personal protective equipment.
