Plasma cutters are widely used in enterprises working with non-ferrous metals. Unlike ordinary steel, which can be cut with a propane-oxygen flame, stainless steel or aluminum cannot be processed in this way, due to the greater thermal conductivity of the material. When attempting to cut with a conventional flame, a wide part of the surface is exposed to heat, which leads to deformation in this area. A plasma cutter is capable of point heating of metal, producing cutting with a minimum cutting width. When using filler wire, the machine can, on the contrary, weld non-ferrous types of steel. But this equipment is quite expensive. How to assemble a plasma cutter yourself from a welding inverter? On what principle does the device work? What is the equipment layout? Is it possible to make a cutter gun yourself, or is it better to buy this item? The following discusses the answers to these questions, including a topical video.
You can make a plasma cutter from an inverter with your own hands if you have a good understanding of the operating principle of the device and the elements involved in the process. The essence of the functioning of a plasma cutter is as follows:
- The current source generates the necessary voltage, which is supplied through cables to the torch torch (plasma torch).
- The plasma torch contains two electrodes (cathode and anode), between which an arc is excited.
- The air flow, supplied under pressure and special twisted channels, directs the electric arc outward, while simultaneously increasing its temperature. Other models use a liquid that evaporates and creates release pressure. The resulting high-temperature ionized flame (as it looks externally) is plasma.
- A ground cable, pre-connected to the product, helps close the arc on the surface being cut, which makes it possible for the plasma cutter to operate.
- When welding is performed, the supplied gas can be argon or other inert mixtures that protect the weld pool from the external environment.
The temperature of the arc, due to acceleration by air flow, can reach 8000 degrees, which allows you to instantly and precisely heat the required section of the metal, performing cutting, and without overheating the rest of the product.
Plasma cutters differ in power and configuration. Small models are capable of cutting metal about 10 mm thick. Industrial machines work with steels up to 100 mm thick. Often these are large machines on brackets, onto which steel sheets are fed by hoists. A plasma cutter made at home will be able to cut stainless steel and other metals up to 12 mm. They can make shaped cuts in sheet iron (circles, spirals, wave-like shapes), as well as welding alloy steel with filler wire.
The simplest homemade plasma cutter should have four component parts:
- power supply;
- plasmatron;
- compressor;
- mass.
Current source
Assembling the product must begin by finding a suitable power source. Industrial models use powerful transformers that produce high current and are capable of cutting thicknesses over 80 mm. But at home you don’t have to work with such values, and such a transformer will make a lot of noise.
As a current source, you can take a regular inverter, which costs four times less than the simplest plasma cutting machine. It will outperform the transformer by producing a stable voltage at a high frequency. Thanks to this, the stability of the arc and the required cut quality will be ensured. The inverter will also be convenient due to its small size, in case of on-site work with a plasma cutter. Light weight will make it easier to transport the device to the desired location.
The plasma cutter from the inverter, in finished form, must meet a number of key requirements:
- powered by 220V network;
- operate at a power of 4 kW;
- have a current adjustment range from 20 to 40 A;
- idle 220V;
- nominal operating mode 60% (with a cycle of about 10 minutes).
To achieve these parameters, the product must be equipped with additional equipment, strictly according to the scheme.
Plasma cutter circuit and its operation
How to make a plasma cutter is well shown in some videos on the network. There you can also find important diagrams according to which the device is assembled. To read symbols, basic electrical engineering skills and the ability to understand symbols are required.
The plasma cutter circuit ensures that the device can actually perform the work. This happens as follows:
- The plasma torch has a process start button. Pressing the button turns on the relay (P1), which supplies current to the control unit.
- The second relay (P2) supplies current to the inverter, and at the same time connects the solenoid valve that purges the burner. The air flow dries the burner chamber and frees it from possible scale and debris.
- After 3 seconds, the third relay (P3) is activated, powering the electrodes.
- Simultaneously with the third relay, an oscillator is started, ionizing the air between the cathode and anode. An arc called a pilot arc is excited.
- When the flame is brought to a product connected to ground, an arc is ignited between the plasma torch and the surface, called the working one.
- The reed switch relay cuts off the supply of current that operates for ignition.
- The material is being cut or welded. If contact with the surface is lost (the arc hits an already cut place), then the reed switch relay is activated again to ignite the pilot arc.
- After turning off the button on the plasma torch, any type of arc goes out, and the fourth relay (P4) starts a short-term supply of purge air to remove burnt elements from the nozzle.
Plasma torch assembly
Plasma cutting and welding is performed with a torch (plasma torch). It can have various modifications and sizes. It is quite difficult to build a model that runs on water at home, so it is worth purchasing such a “gun” in a store.
It is much easier to make a plasmatron with an air system. Homemade versions of the plasma cutter are most often just like this. To assemble it yourself you will need:
- handle with holes for cables (can be used from an old soldering iron or toys);
- start button;
- special electrode;
- insulator;
- flow swirler;
- nozzles for different metal diameters;
- splash-proof tip;
- distance spring to maintain the gap between the nozzle and the surface;
- nozzles for removing chamfers and carbon deposits.
Welding and cutting with the same device can be carried out on different thicknesses of metal thanks to the replaceable elements of the plasma torch head. For this purpose, a variety of nozzles are provided, differing in the diameter of the outlet opening and the height of the cone. It is they who direct the formed plasma jet to the metal. Nozzles are purchased separately in the store. It is worth buying several pieces of each type, because they will melt, which will require replacement over time.
The nozzles are secured with a special clamping nut, the diameter of which allows the nozzle cone to pass through and clamp its wide part. Immediately behind the nozzle there is an electrode and an insulating sleeve that prevents the arc from igniting in an unintended place. Afterwards, there is a mechanism for twisting the air flow, which enhances the effect of the arc. All this is placed in a fluoroplastic case and covered with a metal casing. Some of these items can be made yourself, while others are better purchased at the store.
A store-bought plasma torch may also have an air cooling system, which will allow the device to operate longer without overheating. But if cutting will be carried out for a short time, then this is not necessary.
Electrodes used
Electrodes are playing important role in ensuring the arc burning process and cutting with a plasma torch. Beryllium, hafnium, thorium and zirconium are used in their manufacture. Due to the formation of a refractory surface film, the electrode rod is not subject to overheating and premature destruction when working at high temperatures.
When buying electrodes for a homemade plasma cutter, you should find out what material they are made of. Beryllium and thorium produce hazardous fumes and are suitable for use in special environments that provide adequate protection to the welder. Therefore, for home use it is better to purchase hafnium electrodes.
Compressor and cable hoses
Most homemade plasma cutters include a compressor and air supply paths to the burner in their design. This is an important part of the device, allowing the temperature of the electric arc to develop up to 8000 degrees, and ensuring the cutting process. Additionally, the compressor blows through the channels of the equipment and the plasma torch, draining the system of condensate and removing debris. The possibility of compressed air passing through the burner helps to cool the working parts.
You can install a simple compressor in your plasma torch, which is used when painting with a spray gun. Connection to the device is made with a thin hose and an appropriate connector. An electric valve is installed at the inlet to regulate the air supply to the system.
The channel from the plasma cutter to the torch already contains an electrical component (a cable for powering the electrode), so a thicker hose is used, for example from an old washing machine, inside which the electrical wire is placed. The supplied air will simultaneously cool the cable. The mass is made from wire with a cross-section of more than 5 mm square, with a clamp at the end. If the ground contact is poor, the pilot arc will not be able to switch to the working arc. Therefore, it is important to buy a clamp that is strong and reliable.
It is quite possible to assemble a plasma cutter at home using a video and purchased components. A working inverter and circuit will serve as the basis for realizing the goal. And the above tips will help you better understand the process and purpose of each element in the assembly.
Plasma cutters are widely used in workshops and enterprises related to non-ferrous metals. Most small businesses use a homemade plasma cutter.
It performs well when cutting non-ferrous metals, since it allows local heating of products and not deforming them. Self-production of cutters is due to the high cost of professional equipment.
In the manufacturing process of such a tool, components from other electrical appliances are used.
The inverter is used to perform work in both domestic and industrial environments. There are several types of plasma cutters for working with different types of metals.
There are:
- Plasma cutters operating in an environment of inert gases, such as argon, helium or nitrogen.
- Instruments operating in oxidizing agents, such as oxygen.
- Equipment designed to work with mixed atmospheres.
- Cutters operating in gas-liquid stabilizers.
- Devices operating with water or magnetic stabilization. This is the rarest type of cutter, which is almost impossible to find on the open market.
Or a plasmatron is the main part of plasma cutting, responsible for direct cutting of metal.
Disassembled plasma cutter.
Most inverter plasma cutters consist of:
- nozzles;
- electrode;
- protective cap;
- nozzles;
- hose;
- cutter heads;
- pens;
- roller stop.
The operating principle of a simple semi-automatic plasma cutter is as follows: the working gas around the plasma torch is heated to very high temperatures, at which plasma appears that conducts electricity.
Then, a current passing through the ionized gas cuts the metal by local melting. After this, the plasma jet removes the remaining molten metal and a neat cut is obtained.
Based on the type of impact on metal, the following types of plasmatrons are distinguished:
- Indirect action devices.
This type of plasmatron does not pass current through itself and is suitable only in one case - for cutting non-metallic products. - Direct plasma cutting.
Used for cutting metals by generating a plasma jet.
Making a plasma cutter with your own hands
DIY plasma cutting can be done at home. The prohibitive cost of professional equipment and the limited number of models on the market force craftsmen to assemble a plasma cutter from a welding inverter with their own hands.
A homemade plasma cutter can be made provided you have all the necessary components.
Before making a plasma cutting installation, you need to prepare the following components:
- Compressor.
The part is necessary to supply air flow under pressure. - Plasmatron.
The product is used for direct cutting of metal. - Electrodes.
Used to ignite an arc and create plasma. - Insulator.
Protects electrodes from overheating when performing plasma cutting of metal. - Nozzle.
A part whose size determines the capabilities of the entire plasma cutter, assembled with your own hands from an inverter. - Welding inverter.
Source direct current for installation. Can be replaced with a welding transformer.
The power source of the device can be either transformer or inverter.
Scheme of operation of a plasma cutter.
Transformer DC sources are characterized by the following disadvantages:
- high electrical energy consumption;
- large dimensions;
- inaccessibility.
The advantages of such a power source include:
- low sensitivity to voltage changes;
- more power;
- high reliability.
Inverters can be used as a power supply for a plasma cutter if necessary:
- construct a small apparatus;
- assemble a high-quality plasma cutter with a high coefficient useful action and a stable arc.
Due to the availability and lightness of the inverter power supply, plasma cutters based on it can be constructed at home. The disadvantages of the inverter include only the relatively low power of the jet. Because of this, the thickness of the metal workpiece cut by an inverter plasma cutter is seriously limited.
One of the most important parts of a plasma cutter is the manual cutter.
This element of metal cutting equipment is assembled from the following components:
- handle with cuts for laying wires;
- gas plasma burner start button;
- electrodes;
- flow swirl system;
- a tip that protects the operator from splashes of molten metal;
- a spring to ensure the required distance between the nozzle and the metal;
- nozzles for removing scale and carbon deposits.
Cutting metal of various thicknesses is carried out by changing the nozzles in the plasma torch. In most plasmatron designs, the nozzles are secured with a special nut, with a diameter that allows you to pass the conical tip and clamp the wide part of the element.
After the nozzle, electrodes and insulation are located. To be able to strengthen the arc, if necessary, an air flow swirler is included in the design of the plasmatron.
Do-it-yourself plasma cutters based on an inverter power source are quite mobile. Thanks to its small dimensions, such equipment can be used even in the most inaccessible places.
Blueprints
There are many different plasma cutter drawings available on the Internet. The easiest way to make a plasma cutter at home is to use a DC inverter source.
Electrical circuit of a plasma cutter.
The most common technical drawing of a plasma arc cutter includes the following components:
- Electrode.
This element is supplied with voltage from a power source to ionize the surrounding gas. As a rule, refractory metals are used as an electrode, forming a strong oxide. In most cases, welding machine designers use hafnium, zirconium or titanium. Best choice The electrode material for home use is hafnium. - Nozzle.
A component of an automatic plasma welding machine generates a jet of ionized gas and passes air to cool the electrode. - Cooler.
The element is used to remove heat from the nozzle, since during operation the plasma temperature can reach 30,000 degrees Celsius.
Most plasma cutting machine circuits imply the following operating algorithm for the cutter based on a jet of ionized gas:
- The first press of the start button turns on the relay that supplies power to the device control unit.
- The second relay supplies current to the inverter and connects the electric burner purge valve.
- A powerful air stream enters the burner chamber and cleans it.
- After a certain period of time, set by resistors, the third relay is activated and supplies power to the electrodes of the installation.
- The oscillator is started, thanks to which the working gas located between the cathode and anode is ionized. At this stage, a pilot arc occurs.
- When an arc is brought to a metal part, an arc is ignited between the plasma torch and the surface, called the working arc.
- Turning off the current supply to ignite the arc using a special reed switch.
- Carrying out cutting or welding work. In the event of an arc loss, the reed switch relay turns on the current again and ignites the standby plasma jet.
- When work is completed after the arc is turned off, the fourth relay starts the compressor, the air of which cools the nozzle and removes the remains of burnt metal.
The most successful plasma cutter schemes are the APR-91 model.
What do we need?
Plasma cutter drawing.
To create a plasma welding machine you need to acquire:
- DC source;
- plasmatron.
The latter includes:
- nozzle;
- electrodes;
- insulator;
- compressor with a capacity of 2-2.5 atmospheres.
Most modern craftsmen make plasma welding connected to an inverter power supply. A plasmatron designed using these components for manual air cutting works as follows: pressing the control button ignites an electric arc between the nozzle and the electrode.
After completion of work, after pressing the shutdown button, the compressor supplies a stream of air and knocks off the remaining metal from the electrodes.
Inverter assembly
If a factory inverter is not available, you can assemble a homemade one.
Inverters for cutters based on gas plasma, as a rule, have the following components:
- power unit;
- power switch drivers;
- power block.
Plasma torch in section.
For plasma cutters or welding equipment can not do without necessary tools as:
- set of screwdrivers;
- soldering iron;
- knife;
- hacksaws for metal;
- threaded type fasteners;
- copper wires;
- PCB;
- mica.
The power supply for plasma cutting is assembled on the basis of a ferrite core and must have four windings:
- primary, consisting of 100 turns of wire, 0.3 millimeters thick;
- the first secondary of 15 turns of cable with a thickness of 1 millimeter;
- second secondary of 15 turns of 0.2 mm wire;
- the third is secondary from 20 turns of 0.3 mm wire.
Note! To minimize the negative consequences of voltage surges in the electrical network, winding should be carried out across the entire width of the wooden base.
The power unit of a homemade inverter must consist of a special transformer. To create this element, you need to select two cores and wind copper wire 0.25 millimeters thick on them.
Special mention should be made of the cooling system, without which the inverter power supply of the plasma torch can quickly fail.
Plasma cutting technology drawing.
When working with the device, to achieve the best results, you must follow the recommendations:
- regularly check the correct direction of the gas plasma jet;
- check the correct choice of equipment in accordance with the thickness of the metal product;
- monitor the condition of plasma torch consumables;
- ensure that the distance between the plasma jet and the workpiece is maintained;
- always check the cutting speed used to avoid dross;
- from time to time diagnose the condition of the working gas supply system;
- eliminate vibration of the electric plasmatron;
- Maintain a clean and tidy work area.
Conclusion
Plasma cutting equipment is an indispensable tool for accurately cutting metal products. Thanks to their thoughtful design, plasma torches provide fast, even and high-quality cuts of metal sheets without the need for subsequent surface treatment.
Most crafters from small workshops prefer to assemble mini cutters with their own hands for working with thin metal. As a rule, a self-made plasma cutter does not differ in characteristics and quality of work from factory models.
- 1 Design features
- 2 Design of a plasma cutter, tips for making the device
- 3 How does a plasma cutter work?
- 4 Ventilation during plasma cutting
- 5 Homemade plasma cutter schemes
Making a plasma cutter with your own hands from an inverter is not as difficult as it seems at first. Before you start making the device yourself, you need to prepare everything you need:
- plasma cutter (plasma torch);
- an inverter device or a transformer that acts as a source of electric current;
- a compressor, with the help of which an air jet will be formed, forming and cooling the plasma flow;
- cables, hoses designed to connect all parts of the device.
When choosing a power source, you need to take into account the current generated by the device. An inverter inverter is often used, which makes the cutting process stable and saves electrical energy. An inverter, unlike a transformer, weighs little and is small in size, so it is convenient to use. The main disadvantage of an inverter-based plasma cutter is that it is difficult for them to cut very thick workpieces.
To make a plasma cutter with your own hands, you can use the diagrams below. Below you will also find a video that explains the process of assembling the equipment. It is necessary to strictly follow the diagram, select the components so that the parts of the device fit together.
Design features
The first thing you need to find to create a plasma cutter is a power source. From it, an electric current with the required parameters will flow into the plasma cutter for metal processing. Usually a plasma cutter is made from a welding inverter. The use of a transformer can result in high electrical energy consumption. It must be remembered that any transformer welding device is large and weighs a lot.
An important component of the device is the plasma cutter. The quality of the cut and the efficiency of its implementation depend on it.
A compressor is used to create a stream of air that turns into a plasma jet. Electric current from the inverter/transformer and air flow from the compressor are supplied to the cutter through a cable and hose complex.
The plasma torch contains the following parts:
- nozzle hole;
- a channel for passing air flow;
- electrode;
- cooling insulator.
How to make a plasma cutter from an inverter? To make a plasma cutting device with your own hands, you need to choose the optimal electrode. Beryllium, thorium, zirconium, and hafnium electrodes are usually used. When heated, refractory oxide films are formed on the surface of these materials, preventing destructive processes.
Certain materials, when heated, release toxic substances. This must be taken into account when selecting an electrode. Beryllium releases radioactive oxides. Thorium vapors combine with oxygen to produce highly toxic elements. It is safest to use a hafnium electrode.
Do-it-yourself plasma cutter for metal creates a flow through a nozzle hole. This part of the device determines the efficiency of the work flow.
The optimal nozzle diameter is 15 millimeters. The nozzle is responsible for how accurately and efficiently the metal will be cut. Remember that a long nozzle is prone to wear out quickly.
A do-it-yourself plasma cutter for metal from an inverter must have a compressor. It creates and delivers an oxygen stream to the hole. The use of pressurized air as a working and cooling medium, together with an inverter device that supplies an electric current of 200 A, makes it possible to effectively cut steel parts with a thickness of up to 50 millimeters.
To prepare the plasma cutter for the work process, you need to connect the plasma torch, inverter device and compressor. Cables and hoses are used for this.
How does a plasma cutter work?
How to make a plasma cutter for metal with your own hands? To understand this, you need to understand how this device functions. When the inverter device is turned on, electricity flows to the electrode. Because of this, an arc is ignited. The temperature of the electric arc that lights up between the working electrode and the metal end of the nozzle hole is approximately 6000-8000 degrees. After the arc is ignited, pressurized air enters the nozzle chamber. It passes through an electrical discharge. An electric arc provides heating and ionization of the air flow passing through it. Due to this, the volume of air is increased by 100 or more times. The air becomes able to pass electric current.
Using a nozzle, a plasma jet is formed from an air flow. Its temperature increases rapidly and can reach 25,000-35,000 degrees. The speed of the plasma jet, through which metal workpieces are cut, at the exit from the nozzle hole is approximately 2-3 meters per second. When the plasma jet touches the surface of a steel workpiece, electric current from the electrode element begins to flow through it, and the burning arc goes out. A new arc that lights up between the electrode element and the workpiece being cut is called cutting.
A distinctive feature of plasma cutting is that the material being cut melts only in the area in which the plasma jet acts on it. In view of this, it is necessary to ensure that the plasma exposure area is located in the central part of the electrode. If you ignore this requirement, you may encounter a disruption in the plasma-air flow. Consequently, the cutting efficiency will decrease. To ensure compliance, air is supplied tangentially to the nozzle.
Do not allow the formation of 2 plasma streams instead of one. If you do not follow the modes and rules of the technological process, you can damage the inverter apparatus.
A very significant characteristic of plasma cutting is the speed of the air stream. It shouldn't be very high. The best ratio of cutting quality and speed of execution is ensured at an air flow speed of 800 meters per second. The current coming from the inverter should not exceed 250 amperes. When cutting metal in this mode, it is necessary to take into account that the air flow used to form the plasma flow will be quite large.
It is not difficult to make a plasma cutting device with your own hands. You need to familiarize yourself with the theory, watch videos and choose the correct components of the device. The advantage of an inverter plasma cutter is that it can be used not only for cutting, but also for welding.
If you don't have an inverter, you can make a plasma cutter from a welding machine, i.e. transformer. However, in this case the device will have rather large dimensions. Also, the disadvantage of a plasma cutter for metal, which is made from a transformer, is that it is not very mobile. Due to this, it is difficult to move it from one place to another. This is not too critical if you rarely work with the device. However, if you often need to cut metal workpieces, be sure to start creating a plasma cutter from an inverter with your own hands.
Ventilation for plasma cutting
Ventilation is necessary for plasma cutting. When metal is cut with a device, smoke and dust particles are generated. They must be removed from the room in which the work is being carried out. For this purpose, ventilation systems are used, which make it possible to solve this problem.
If plasma cutting is performed manually, inclined lifts are used. They provide suction of dust particles. It is worth remembering that the lower part of such a device should not be higher than thirty-five centimeters above the cutting area.
If large metal sheets are cut, special suction devices are used. Tables with a box are also often used for ventilation. The box serves as a kind of receiver for various particles formed during the working process. The main requirement for such a table is to cover its surface by eighty percent with the sheets being processed. This makes it possible to provide the desired air flow speed, suck in dust particles and smoky elements.
Ventilation for plasma cutting is considered effective if the air flow speed is 1.3 m/s (carbon steel, titanium alloys) or 1.8 m/s (aluminum alloys, high-alloy steel).
If you decide to make your own plasma cutter, carefully study the above recommendations. This way you can make a device that will function correctly and have a long service life. If you have an inverter machine, be sure to use it as a source of electricity, and not a welding transformer. The small overall dimensions of the device are a significant advantage.
Homemade plasma cutter diagrams
Plasma cutting is a fairly popular operation, especially when it comes to cutting thick metal parts or workpieces. The process happens quickly, the edges of the metal remain smooth. But such a device is not cheap. Therefore, many craftsmen make their own plasma cutter from different types equipment, combining them into one structure. Their connection diagram is simple, the main thing is to choose the right devices according to the required technical characteristics.
Plasma cutting is based on ionized gas, which flies out of the torch nozzle at high speed. This gas is that same plasma. What is she doing.
- Essentially, this ionized medium is an excellent conductor of electric current, which flows from the electrode to the metal workpiece.
- The plasma heats the metal to the required temperature.
- It blows away the molten metal and frees up the cutting space.
This means that to create plasma, you need gas and a source of electricity. And these two components must come together in one place. Therefore, plasma cutting equipment consists of a gas cylinder, a high-power source of electricity and a cutter in which the electrode is installed.
The design of the cutter is made in such a way that gas passes around the electrode and, when heated from the electrode, escapes out through a small hole. The small diameter of the hole and gas pressure create the necessary speed for the plasma. When making homemade plasma cutting, you just need to purchase a ready-made cutter and not think about creating it. Because everything is already thought out in it, plus the factory version is a guarantee of safety.
As for gas, all options have long been abandoned, leaving compressed air. You can get it today very simply - purchase and install a compressor.
There are certain conditions that guarantee the quality of plasma cutting.
- The current strength at the electrode should not be less than 250 A.
- Compressed air must be supplied to the cutter at a speed within 800 m/sec.
How to make a plasma cutter with your own hands
The basics of plasma cutting are clear, the design of the plasma cutter is also clear, and you can begin assembling it. By the way, you don’t need special drawings for this.
So what will be needed.
- We need to find a source of electricity. The simplest option is a welding transformer or inverter. For many reasons, an inverter is better. For example, it has a stable current value, without drops. It is more economical in terms of energy consumption. You will have to pay attention to the current that the welding machine produces. Its value should not be less than 250 amperes.
- Source of compressed air. The compressor remains unchanged here. But which one? The main parameter is air pressure. You will need to pay attention to him. 2.0-2.5 atm. - it will be fine.
- The cutter can be purchased at the store. And this will be the ideal solution. If you have a cutter for argon welding, then it can be converted for plasma cutting. To do this, you will have to make an attachment from copper in the form of a nozzle, which is inserted into the argon welding cutter.
- A set of hoses and cables for connecting all parts of a homemade plasma cutter. Again, the kit can be purchased in the store as a single connecting element.
Here are the four elements with which a homemade plasma cutter is assembled.
Auxiliary elements and materials
What else should you pay attention to when assembling a plasma cutting machine with your own hands? As mentioned above, the main characteristic of a plasma cutter is the diameter of its hole. What size should it be to ensure maximum cutting quality? Experts believe that a diameter of 30 mm is the optimal size. Therefore, when buying a cutter in a store, you need to pay attention to whether it comes with a nozzle with such a hole.
In addition, it is necessary to select a nozzle with a significant length. It is this size that allows the jet of compressed air to gain the required speed. This results in a neat metal cut, and the cutting process itself is quick and easy. But you shouldn’t buy a very long nozzle. Such a device quickly collapses under the influence of high temperatures.
As for choosing an electrode for a plasma cutter, you need to pay attention to the alloy from which it is made. For example, if the alloy contains beryllium, then it is a radioactive substance. It is not recommended to work with such electrodes for a long time. If the alloy contains thorium, then when high temperatures it releases toxic substances. An ideal electrode for plasma cutting, the alloy of which includes hafnium.
Checking the plasma cutter
So, the hoses connect the cutter and the compressor, the cable cutter and the inverter. Now you need to check whether the assembled structure works. All units are turned on, the button on the cutter to supply electricity to the electrode is pressed. In this case, an arc is formed with a temperature of 6000-8000C. It slips between the metal of the electrode and the nozzle.
After this, compressed air begins to flow into the cutter. Passing through the nozzle and heated by an electric arc, it sharply expands tenfold and at the same time acquires conductive properties. That is, it turns out to be an ionized gas.
It passes through a narrowed nozzle, while acquiring a speed of 2-3 m/sec. But the plasma temperature rises to 25000-30000C. The most important thing is that the arc, with the help of which the compressed air was heated and turned into plasma, goes out as soon as the plasma begins to act on the metal workpiece prepared for cutting. But immediately the second, so-called working arc is turned on, which acts locally on the metal. Exactly in the cutting area. Therefore, metal is cut only in this zone.
If, when checking the operation of the plasma cutter, you were able to cut metal with a thickness of at least 20 mm, then all the elements of the new design, assembled with your own hands, were selected correctly. It is necessary to note that the plasma cutter cannot cut workpieces with a thickness of more than 20 mm from the inverter. It just doesn't have enough power. To cut thicker metal, you will have to use a transformer.
Attention! Any work related to the use of plasma cutting must be carried out wearing protective clothing and gloves.
There are many points that necessarily affect the operation of the unit.
- There is no need to purchase, for example, a large compressor. But 2-2.5 atmospheres may not be enough for a large amount of work. The way out is to install a receiver on the compressor. It works like an accumulator that accumulates pressure in compressed air. For this purpose, you can use, for example, bolts from the brake systems of heavy vehicles. The option is actually simple. The volume of the cylinder is large, and it should be enough for a long period of time.
- In order for the air pressure to be stable and uniform, a reducer must be installed at the receiver outlet.
- Of course, the optimal solution is to purchase a compressor complete with a receiver. It costs more than usual, but if this unit is used for other things, for example, for painting, then you can increase its functionality and thereby cover the costs.
- To make a mobile version of the machine, you can make a small trolley. After all, all the elements of a plasma cutter are small devices. Of course, you will have to forget about mobility if the machine is made on the basis of a welding transformer. It's too big and heavy.
- If you can’t buy a ready-made hose-cable kit, you can make it yourself. You need to combine the welding cable and high-pressure hose into one sleeve and place them in a single sheath. For example, into a regular hose of larger diameter. A set made in this way simply will not get in the way, which is very important when cutting metals.
Making your own plasma cutter is not difficult at all. Of course, you will need to obtain the necessary information and study it; it is definitely recommended to watch the training video. And after that, correctly select all the elements exactly to the required parameters. By the way, the assembled plasma cutter based on a serial inverter makes it possible not only to carry out plasma cutting of metals, but also plasma welding, which increases the functionality of the unit.
Assembling a plasma cutter with your own hands from an inverter is a relatively simple matter.
A plasma cutter can be used not only for cutting various parts, but also for welding.
Before assembling a homemade plasma cutter with your own hands, you should prepare in advance some of the components included in the design of the plasma cutter. The plasma cutter design includes the following elements:
- plasma cutter;
- power source, which can be an inverter or transformer;
- a compressor device for supplying an air flow and forming a plasma flow;
- cable hoses for assembling all components into a single complex.
A homemade plasma cutter can be used to carry out a variety of technical operations not only in production, but also in the home.
At home, these devices can be used for processing metal products if thin and precise cutting is required.
The industry offers consumers devices that can be used to weld metals in a protective gas environment. The inert gas argon is used as protection during welding.
During assembly homemade device special attention should be paid to the current strength. The value of this parameter depends on the power source used.
It is best to use an inverter as a source of electric current. This device ensures stable operation of the plasma cutting machine. In addition, the use of an inverter allows for more economical energy consumption than when using a transformer as a power source.
The disadvantage of using an inverter power source in the design of a plasma cutter is the small thickness of the workpieces that can be processed using such a device.
The advantages of a plasma cutter based on the use of an inverter are the relatively small weight of the device and low electrical energy consumption. In addition, the efficiency of a device based on an inverter power supply is 10% higher than that of a device with transformer block, which affects the quality of operations.
When assembling a device, attention should be paid to the accuracy and quality of the assembly in accordance with the design, as well as the integration of elements in the system.
When assembling the device in a structure, you need to use a nozzle of sufficient length, which should not be too long, otherwise it will have to be replaced frequently.
Selection of structural elements for assembling the fixture
When making a device with your own hands, you need to choose the right components.
Power supply for equipment. An inverter is used as this element - this is a device that supplies voltage with predetermined characteristics for the operation of the equipment. In addition to the inverter, a transformer can be used. If a transformer is used as a power supply, then when designing the equipment, the large weight of the welding transformer must be taken into account. In addition, it should be remembered that when using a transformer, the device consumes a large amount of electrical energy.
To assemble the tool, you need to prepare a plasma cutter, which is the main element of the device that ensures the execution of work operations. You will also need to purchase an air flow injection device - a compressor and a cable-hose package.
Using an inverter power supply is more profitable, since this device is more economical and its cost is much lower. A device whose operation is based on the use of an inverter power supply is easier to use. This device can be used when carrying out work at home and in small factories. When using this type of power supply, voltage stability is achieved, which allows for high-quality work in hard-to-reach places where the use of transformer devices is impossible.
The plasma torch is the main element of the cutter. The design of this device consists of a nozzle, an air flow channel that ensures cutting of metal workpieces, an electrode and an insulator, which simultaneously plays the role of a cooler.
Plasma cutter assembly
To assemble the plasma torch, you need to select the appropriate electrode. The most commonly used electrodes are made using thorium, beryllium, zirconium or hafnium. Such materials are considered optimal for cutting metal with an air-flame flow. During the operation of the installation, refractory oxides are formed on the surface of the electrode material, which prevent destruction of the electrode material. When choosing the type of electrode, it should be remembered that some of the materials used to make the electrode body are hazardous to the worker. For example, beryllium in the electrode during operation causes the formation of radioactive oxides, and the use of thorium causes the formation of toxic compounds with oxygen. The best material is hafnium, which is absolutely safe for the worker carrying out the work.
During the assembly process, special attention should be paid to the nozzle, which generates the jet for cutting. From technical characteristics The quality of the working jet depends on this element. It is optimal to use a device with a diameter of 3 cm. The length should be sufficient so that the cut has a neat and high-quality appearance. If the nozzle is too long, it may quickly be destroyed during operation.
To supply air flow, a compressor is used in the design of the plasma cutter. A special feature of the cutter’s operation is the use of gases for protection and plasma formation during the operation of the equipment. The work of cutting metal is carried out at a current of 200 A. When operating the device, compressed air is used, which is required to cool the operating equipment and form a plasma jet. The use of this design during operation allows cutting metal workpieces with a metal thickness of up to 50 mm.
A cable-hose package is used to connect all elements of the installation. When assembling the installation, a certain order of work must be followed. First, the inverter is connected to the electrode using a cable to supply voltage to it. The hose supplies compressed air from compressor unit to the plasma torch, where a plasma jet is formed.
Operating principle of the cutter
After the installation for cutting metal has been assembled, it is necessary to check its functionality. When started, the inverter supplies high-frequency electric current to the plasmatron. After applying voltage to the electrode, an electric arc is formed; its temperature at the moment of occurrence varies in the range from 6 to 8 thousand degrees Celsius. Arc formation occurs between the electrode and the nozzle tip. Next, a stream of compressed air is supplied, which, when passing through the electric arc, heats up and increases in volume a hundred times, while the flow is ionized, and it acquires conductive properties.
Using a nozzle, a narrow plasma stream is formed. The speed of the plasma flow is 2-3 meters per second. At the moment of expiration of the plasma jet, its temperature increases significantly and reaches 25-30 thousand degrees. At the exit from the nozzle, a stream of high-temperature plasma is formed, which is used to carry out the cutting process. At the moment of contact of the plasma jet with the metal of the workpiece, the initial arc is extinguished and the cutting arc is ignited, with the help of which the workpiece is processed. Melting of the metal occurs locally, at the point of exposure to the plasma flow.