Design

Plasma machine with your own hands. Homemade plasma cutter

Increasingly, in small private workshops and small enterprises, plasma cutting machines are used instead of grinders and other devices. Air-plasma cutting allows you to perform high-quality straight and figured cuts, align the edges of sheet metal, make openings and holes, including figured ones, in metal blanks and other more complex work. The quality of the resulting cut is simply excellent, it turns out to be even, clean, practically free of scale and burrs, and also neat. Air plasma cutting technology can process almost all metals, as well as non-conductive materials such as concrete, ceramic tiles, plastics and wood. All work is carried out quickly, the workpiece is heated locally, only in the cut area, so the workpiece metal does not change its geometry due to overheating. Even a beginner without welding experience can handle a plasma cutting machine, or as it is also called, a plasma cutter. But so that the result does not disappoint, it still does not hurt to study the plasma cutter device, understand its principle of operation, and also study the technology of how to work with an air-plasma cutting machine.

The device of the air-plasma cutting machine

Knowledge of the plasma cutter device will allow not only to work more consciously, but also to create a home-made analogue, which requires not only deeper knowledge, but also engineering experience is desirable.

The air plasma cutting machine consists of several elements, including:

Power supply;
Plasmatron;
Cable-hose package;
Air compressor.

Power supply for a plasma cutter, it is used to convert voltage and supply a certain current to the cutter / plasma torch, due to which an electric arc ignites. The power source can be a transformer or an inverter.

Plasmatron- the main element of the air-plasma cutting machine, it is in it that the processes occur, due to which the plasma appears. The plasma torch consists of a nozzle, an electrode, a housing, an insulator between the nozzle and the electrode, and air channels. Items such as the electrode and nozzle are consumables and require frequent replacement.

Electrode in the plasma torch it is the cathode and serves to excite the electric arc. The most common metal from which electrodes for plasma torches are made is hafnium.

Nozzle has a conical shape, compresses the plasma and forms a plasma jet. Escaping from the outlet channel of the nozzle, the plasma jet touches the workpiece and cuts it. The dimensions of the nozzle affect the characteristics of the plasma cutter, its capabilities and the technology of working with it. The most common nozzle diameter is 3 - 5 mm. The larger the diameter of the nozzle, the greater the volume of air per unit time it can pass through itself. The width of the cut, as well as the speed of the plasma cutter and the cooling rate of the plasma torch, depend on the amount of air. The most common nozzle length is 9 - 12 mm. The longer the nozzle, the more accurate the cut. But a nozzle that is too long is more prone to destruction, so the length is optimally increased by a size equal to 1.3 - 1.5 of the nozzle diameter. It should be taken into account that each current value corresponds to the optimal nozzle size, which ensures stable arcing and maximum cutting parameters. It is not advisable to reduce the nozzle diameter and make it less than 3 mm, since the resource of the entire plasma torch is significantly reduced.

Compressor supplies compressed air to the plasma torch for the formation of plasma. In air-plasma cutting machines, air acts as both a plasma-forming gas and a protective gas. There are devices with a built-in compressor, as a rule, they are low-power, as well as devices with an external air compressor.

Cable-hose package consists of an electric cable connecting the power source and the plasma torch, as well as a hose for supplying air from the compressor to the plasma torch. What exactly happens inside the plasma torch, we will consider below.

The principle of operation of the air-plasma cutting machine

The air plasma cutting machine operates according to the principle described below. After pressing the ignition button, which is located on the handle of the plasma torch, a high-frequency current is supplied from the power source to the plasma torch. As a result, a standby electric arc lights up. Due to the fact that the formation of an electric arc between the electrode and the workpiece is directly difficult, the nozzle tip acts as the anode. The temperature of the pilot arc is 6000 - 8000 °C, and the arc column fills the entire nozzle channel.

A couple of seconds after the ignition of the pilot arc, compressed air begins to flow into the plasma torch chamber. It passes through the standby electric arc, ionizes, heats up and increases in volume by 50 - 100 times. The shape of the plasma torch nozzle is narrowed down, due to which the air is compressed, a stream is formed from it, which breaks out of the nozzle at a speed close to sonic - 2 - 3 m / s. The temperature of the ionized heated air escaping from the outlet of the nozzle can reach 20,000 - 30,000 °C. The electrical conductivity of the air at this moment is approximately equal to the electrical conductivity of the metal being processed.

Plasma just called the heated ionized air escaping from the nozzle of the plasma torch. As soon as the plasma reaches the surface of the metal being processed, the working cutting arc is ignited, at this moment the pilot arc goes out. The cutting arc heats the workpiece at the point of contact, locally, the metal begins to melt, a cut appears. The molten metal flows to the surface of the workpiece and solidifies in the form of drops and small particles, which are immediately blown away by the plasma flow. This method of air-plasma cutting is called a sharp plasma arc (direct arc), since the metal being processed is included in the electrical circuit and is the anode of the cutting arc.

In the case described above, the workpiece is cut using the energy of one of the near-electrode spots of the arc, as well as the plasma of the column and the torch flowing from it. Plasma arc cutting uses a direct current arc of direct polarity.

Plasma-arc cutting of metal is used in such cases: if it is necessary to produce parts with curly contours from sheet metal, or to produce parts with straight contours, but so that it is not necessary to process the contours additionally, for cutting pipes, strips and rods, for cutting holes and openings in details and more.

But there is also another way of plasma cutting - plasma jet cutting. In this case, the cutting arc ignites between the electrode (cathode) and the nozzle tip (anode), and the workpiece is not included in the electrical circuit.. Part of the plasma is taken out of the plasma torch in the form of a jet (indirect arc). Typically, this cutting method is used to work with non-metallic non-conductive materials - concrete, ceramic tiles, plastic.

The air supply to the plasma torch of direct action and indirect action is performed in different ways. Plasma arc cutting requires axial air supply (direct). And for plasma jet cutting, tangential air supply.

Tangential or vortex (axial) air supply to the plasma torch is necessary to ensure that the cathode spot is located strictly in the center. If the tangential air supply is disturbed, the displacement of the cathode spot is inevitable, and with it the plasma arc. As a result, the plasma arc does not burn stably, sometimes two arcs ignite simultaneously, and the entire plasma torch fails. Homemade air plasma cutting is not able to provide tangential air supply. Since to eliminate turbulences inside the plasma torch, nozzles of a special shape, as well as liners, are used.

Compressed air is used for air-plasma cutting of such metals:

Copper and copper alloys - no more than 60 mm thick;
Aluminum and aluminum alloys - up to 70 mm thick;
Steel up to 60 mm thick.

But it is absolutely impossible to use air for cutting titanium. We will consider in more detail the subtleties of working with a manual air-plasma cutting machine below.

How to choose an air plasma cutting machine

To make the right choice of a plasma cutter for private household needs or a small workshop, you need to know exactly for what purposes it will be used. What blanks will you have to work with, what material, what thickness, what is the intensity of loading the device and much more.

For a private workshop, an inverter may well fit, since such devices have a more stable arc and a 30% higher efficiency. Transformers are suitable for working with workpieces of greater thickness and are not afraid of voltage drops, but at the same time they weigh more and are less economical.

The next gradation is plasma cutters of direct and indirect action. If you plan to cut only metal blanks, then you need a direct-acting device.

For a private workshop or home needs, it is necessary to purchase a manual plasma cutter with a built-in or external compressor, designed for a certain current strength.

Plasma cutter current and metal thickness

The current strength and the maximum thickness of the workpiece are the main parameters for choosing an air-plasma cutting machine. They are interconnected. The more current the plasma cutter power supply can supply, the thicker the workpiece can be processed with this machine.

When choosing a device for personal needs, you need to know exactly what thickness of the workpiece will be processed and from what metal. The characteristics of plasma cutters indicate both the maximum current strength and the maximum thickness of the metal. But pay attention to the fact that the thickness of the metal is indicated based on the fact that ferrous metal will be processed, and not non-ferrous and not stainless steel. And the current strength is indicated not nominal, but maximum, at these parameters the device can work for a very short time.

Cutting different metals requires different amperages. The exact parameters can be seen in the table below.

Table 1. Current required for cutting various metals.

For example, if you plan to cut a steel workpiece 2.5 mm thick, then a current of 10 A is required. And if the workpiece is made of non-ferrous metal, for example, copper 2.5 mm thick, then the current should be 15 A. To make a high quality cut , it is necessary to take into account a certain power reserve, so it is better to purchase a plasma cutter designed for a current of 20 A.

The price of an air-plasma cutting machine directly depends on its power - the output current. The greater the current, the more expensive the device.

Operating mode - duty cycle (PV)

The operating mode of the apparatus is determined by the intensity of its loading. On all devices, such a parameter as the duration of inclusion or duty cycle is indicated. What does she mean? For example, if PV = 35% is indicated, then this means that the plasma cutter can be operated for 3.5 minutes, and then it must be allowed to cool for 6.5 minutes. The duty cycle is designed for 10 minutes. There are devices with PV 40%, 45%, 50%, 60%, 80%, 100%. For household needs, where the device will not be used constantly, devices with PV from 35% to 50% are sufficient. For CNC machine cutting, plasma cutters with duty cycle = 100% are used, as they provide continuous operation throughout the entire shift.

Please note that in the process of working with manual air plasma cutting, there is a need to move the plasma torch or move to the other end of the workpiece. All these intervals are counted towards the cooling time. Also, the duration of the inclusion depends on the load of the device. For example, from the beginning of the shift, even a plasma cutter with PV = 35% can work without interruption for 15 - 20 minutes, but the more often it is used, the shorter the time of continuous operation will be.

Do-it-yourself air-plasma cutting - work technology

We chose a plasma cutter, familiarized ourselves with the principle of operation and the device, it's time to get to work. In order not to make mistakes, for starters, it does not hurt to get acquainted with the technology of working with an air-plasma cutting machine. How to comply with all safety measures, how to prepare the device for operation and choose the right current strength, and then how to ignite the arc and maintain the necessary distance between the nozzle and the surface of the workpiece.

Take care of safety

Air plasma cutting involves a number of hazards: electric current, high plasma temperature, hot metal and ultraviolet radiation.

It is necessary to work in special equipment: dark glasses or a welder's shield (4-5 class of glass darkening), thick gloves on hands, trousers made of thick fabric on the legs and closed shoes. When working with a torch, gases can be generated that pose a threat to the normal functioning of the lungs, so a mask or respirator must be worn on the face.
The plasma cutter is connected to the network through the RCD.
Sockets, work stand or table, surrounding objects must be well grounded.
The power cables must be in perfect condition, the windings must not be damaged.

The fact that the network must be designed for the voltage indicated on the device (220 V or 380 V) is a matter of course. Otherwise, compliance with safety precautions will help to avoid injuries and occupational diseases.

Preparing the air plasma cutting machine for operation

How to connect all the elements of the air-plasma cutting machine is described in detail in the instructions for the machine, so let's immediately move on to further nuances:

The device must be installed so that it has access to air. Cooling the body of the plasma cutter will allow you to work longer without interruption and less often turn off the device for cooling. The location must be such that drops of molten metal do not fall on the apparatus.
The air compressor is connected to the plasma cutter through a moisture and oil separator. This is very important, since water or oil drops that have entered the plasma torch chamber can lead to the failure of the entire plasma torch or even its explosion. The pressure of the air supplied to the plasma torch must correspond to the parameters of the apparatus. If the pressure is insufficient, the plasma arc will be unstable and will often go out. If the pressure is excessive, then some elements of the plasma torch may become unusable.
If there is rust, scale or oil stains on the workpiece that you are going to process, it is better to clean and remove them. Although air-plasma cutting allows you to cut rusty parts, it is still better to play it safe, since toxic fumes are released when rust is heated. If you plan to cut the containers in which combustible materials were stored, then they must be thoroughly cleaned.

In order for the cut to turn out to be even, parallel, without scale and sagging, it is necessary to correctly select the current strength and cutting speed. The tables below show the optimal cutting parameters for various metals of various thicknesses.

Table 2. The force and speed of cutting with the help of an air-plasma cutting machine for workpieces from various metals.

At first, it will be difficult to select the cutting speed, experience is required. Therefore, at first, you can focus on the following rule: it is necessary to guide the plasma torch in such a way that sparks are visible on the reverse side of the workpiece. If sparks are not visible, then the workpiece is not cut through. Also note that too slow a torch lead will negatively affect the quality of the cut, dross and sagging will appear on it, and the arc may burn unstable and even go out.

Now you can start the cutting process itself.

Before starting the electric arc, the plasma torch should be purged with air to remove stray condensation and foreign particles. To do this, press and then release the arc ignition button. Thus, the device enters the purge mode. After about 30 seconds, you can press and hold the ignition button. As already described in the principle of operation of the plasma cutter, a standby (auxiliary, pilot) arc will light up between the electrode and the nozzle tip. As a rule, it burns no longer than 2 seconds. Therefore, during this time it is necessary to ignite the working (cutting) arc. The method depends on the type of plasma torch.

If the plasma torch is direct, then it is necessary to make a short circuit: after the formation of the pilot arc, it is necessary to press the ignition button - the air supply stops and the contact closes. Then the air valve opens automatically, the air flow breaks out of the valve, ionizes, increases in size and removes the spark from the plasma torch nozzle. As a result, the working arc between the electrode and the workpiece metal lights up.

Important! Contact ignition of the arc does not mean that the plasma torch must be applied or leaned against the workpiece.

As soon as the cutting arc lights up, the pilot arc goes out. If it was not possible to ignite the working arc the first time, it is necessary to release the ignition button and press it again - a new cycle will begin. There are several reasons why the working arc may not ignite: insufficient air pressure, incorrect assembly of the plasma torch, or other malfunctions.

In the process of work, there are also cases when the cutting arc goes out. The reason, most likely, is the wear of the electrode or the non-observance of the distance between the plasma torch and the surface of the workpiece.

Distance between plasma torch and metal

Handheld air plasma cutting is fraught with the difficulty that the distance between the torch/nozzle and the metal surface must be maintained. When working with your hand, this is quite difficult, since even breathing knocks your hand, and the cut is uneven. The optimal distance between the nozzle and the workpiece is 1.6 - 3 mm; special distance stops are used to maintain it, because the plasma torch itself cannot be pressed against the surface of the workpiece. The stops are put on top of the nozzle, then the plasma torch rests on the workpiece with the stop and the cut is performed.

Please note that it is necessary to keep the plasma torch strictly perpendicular to the workpiece. Permissible deflection angle 10 - 50 °. If the workpiece is too thin, then the cutter can be held at a slight angle, this will avoid strong deformations of thin metal. Molten metal should not fall on the nozzle.

Do-it-yourself work with air-plasma cutting can be done on your own, it is only important to remember safety precautions, as well as the fact that the nozzle and electrode are consumables that require timely replacement.

Both specialists and beginners often use plasma cutting in their work. This is understandable: after all, it is an indispensable process in a variety of construction and production processes. There is only one drawback: devices produced by various companies cost a lot of money, not everyone can afford them. Therefore, a variety of working people, whether they are construction teams or individual craftsmen, are thinking about how to create a plasma cutter from an inverter, relying only on their own hands and on available equipment, thereby saving a significant amount.

Video: Homemade plasma cutter, plasma cutter made in a month

The main purpose of a manual plasma cutter is cutting different types of metals. Such actions are necessary during the construction of various structures. There is no need to use other tools. The use of all kinds of electrodes with which the welding process is carried out is also possible if a home-made plasma cutter is available.

In this unit, the fundamental principle by which the joining of metals occurs is soldering. It is thanks to the high temperature of the solder that a manual plasma cutter allows you to securely fasten a variety of metals - this is its main advantage, which is why this equipment is so necessary for many.

In addition to standard construction activities, this handy tool is also used in blacksmithing. After all, with his direct participation, it is possible to perform various manipulations, both with non-ferrous and ferrous metals. In addition to their welding: also thermal cleaning, and hardening, and annealing. For this reason, the presence of a manual plasma cutter for such work is mandatory, this ensures both product quality and significant time savings.

Its design features

Before you start to independently assemble a plasma cutter from an inverter, you need to accurately determine its configuration and how it will be arranged. It should be understood that it is better to purchase individual parts of the future device ready-made than to assemble it yourself, because. such an assembly will be fraught with certain difficulties.

Usually the assembled apparatus consists of the following main components, without which its operation is impossible: an air compressor, a hose-cable type package, a power source and a cutter, which is officially called a plasma torch.

A kind of "heart" of a manual plasma cutter is a power source. It is he who supplies the current of the required power. The technical characteristics of the unit are determined by this particular component.

If we compare the cutter (or “plasma torch”) used on this device, it can be seen that its design differs significantly from similar components used in welding units. However, it is no less important than the power source. It is the cutter (plasma cutter) that is the part, the independent creation of which from an inverter is associated with significant problems. It is better to buy a cutter ready-made, in a store. In the future, this will save you from many problems.

In powerful units for hot cutting of metal, internal cooling functions are necessary. There, various gas mixtures are used for this. Cooling is also necessary in a manual plasma cutter, but here only timely air supply is sufficient. For this purpose, a compressor is used, for the operation of which a current of power within 200 A is needed.

The connecting part, through which the current flows from the source to the torch, and air is also forced by the compressor, is a cable-hose package.

About using a transformer or inverter

Most often, when it is planned to assemble a plasma cutter, either an inverter or a special transformer is taken as a power source. Each of these options has its own advantages, but in order to understand which one is right, you need to know exactly what technical characteristics your plasma cutter should have, respectively, you need to know the features of the inverter and transformer.

The advantages of a plasma cutter made on the basis of an inverter are as follows: on average, its efficiency is one third higher than that of analogues in which a transformer is present, they are the most efficient and economical. Such a device ensures the stability of the arc. The disadvantages include the fact that the work is carried out exclusively with materials of insignificant thickness.

If a transformer is taken as the basis, then such an assembly will certainly be bulky and require an additional platform for use. But a significant plus is that it allows you to work with rather massive and thick parts. Such devices are placed either in specially equipped rooms or on mobile platforms.

Therefore, if it is not planned to cut especially large objects, then it is recommended to use a plasma cutter created from an inverter. The principle is simple: you need to connect the power source already at your disposal and other parts, following a certain sequence.

What equipment will be needed

Of course, before proceeding directly to the assembly of a device for plasma cutting of metal, you will need to purchase all the parts that will make up the final product. But if you want the intended functions to be performed at a high level, without breakdowns, then some of the components must be bought ready-made.

inverter

This is the "heart" of our future unit, and you can take it from any welding machine. In most cases, this is the main material investment in the described project. In order to choose a suitable inverter, you need to know exactly what work will be done by the plasma cutter, their volume, etc. Then it will not be difficult to choose the power of the inverter.

We have to hear that some craftsmen assemble the inverter on their own. To do this, carefully select the details, use the materials at their disposal. But in practice, it turns out that such home-made designs are less reliable than purchased options. In addition, at home it is difficult to ensure the same standards as in production. Therefore, it is still preferable to purchase the inverter option.

Cutter

When craftsmen or amateurs make a plasma cutter on their own, they often make the mistake of trying to fully assemble the cutter with the supply of electricity and air. The components of the cutter are: nozzle, supply elements and handle. Moreover, the handle, due to its intensive use, wears out in a short period of time and often has to be replaced. Therefore, the best choice would be to buy a factory nozzle, but the rest of the components can be assembled on your own. But the opinion that spending a large amount of money and effort on self-assembly of this component is not productive is also quite reasonable. It is better to buy a factory product.

Compressor

According to the instructions, the use of a compressor implies that oxygen or an inert gas will be used. In practice, more often it is connected to cylinders, in which there is a special mixture. It is this mixture that provides a strong plasma beam with decent cooling. If the plasma cutter is used in everyday life, then for economy and simplicity of business it is recommended to use a simple compressor. It is quite possible to assemble this component on your own, where the role of the receiver will be performed by an ordinary cylinder. The compressor is often taken from the refrigerator, or from the ZIL car. It is important not to make a mistake with the pressure regulation. This is done empirically, by masters, at the initial stage of work.

Cable-hose package

This component of the plasma cutter can be bought both separately and together with the main equipment. The main thing is to know some of the characteristics of the unit, namely: what pressure will be during operation, as well as what cross-section of the cable - the characteristics of the hoses also depend on this. The conductor is selected according to the power of the inverter. Otherwise, it will overheat and may catch fire and even electric shock.

Assembly process

This is a fairly simple build sequence. The plasma cutter nozzle is connected to the inverter and compressor. For such purposes, a cable-hose package is needed. You will need a set of clamps and clamps. With their help, you can quickly assemble and disassemble the plasma cutter. If everything is done correctly, then the output will be a device of very compact parameters. It is easy to transport it to the place where the next work will be carried out.

First of all, you should make sure that there are enough spare gaskets available. After all, plasma cutting occurs when using gas, and gaskets are needed to connect hoses. And if the unit is planned to be transported quite often, then this element cannot be dispensed with, moreover, the absence of gaskets can cause a stop to all work.
Particularly high temperatures affect the torch nozzle. Therefore, in the long term of using the device for a long time, it is this part that wears out faster than others. So there should be a spare nozzle available.
The range of prices for inverters is very large: from very cheap to really expensive. The main thing that affects the price is the power of the inverter. So before you buy, decide what power you need. And starting from your real needs, choose one or another model. So save money and create a plasma cutter that is right for your job.
Do not do without electrodes made of refractory metals. The choice on the market is quite large. For example, products made of zirconium, beryllium or thorium. But with significant heating from certain metals, hazardous components are released. The safest, and therefore preferred electrodes are those made of hafnium.
During the work, the plasma in such an apparatus heats up to 30 thousand degrees. This means that all security measures are required. Without this, fire is possible, or harm can be done to both the welder and others. For this reason, beginners who have not undergone any training should not work on such equipment. Ideally, a specialist with significant experience should work.
The reason why experts recommend using only factory-made cutters for work is that home-made variations can introduce disturbances in the vortex airflow. And this is unacceptable, because. it is possible to form 2 arcs that will cause the product to break. Therefore, it is better to spend money once than to invest additional funds and effort in repairing the unit later.
If using the inverter it is planned to perform only one type of work, then it is possible to make some modifications to it, designed to facilitate just this type of work. For example, some craftsmen introduce their own modifications to the nozzle or create a special casing to protect their hands. The main principle of any such addition is that they should not go against the safety rules.

conclusions

So, after reading this material, it becomes clear that in order to assemble a plasma cutter with an inverter, you will need to purchase ready-made components from different manufacturers. As for the manufacture of a plasma cutter, this is a simple assembly. But still, the selection of individual parts can save money, because. if you take a complete ready-made kit from one manufacturer, then it will come out much more expensive.

Video: How to turn a manual welding inverter into a semi-automatic

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 that make up the plasma cutter design. The design of the plasma cutter includes the following elements:

plasma cutter;
power supply, 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 home-made plasma cutter can be used to carry out a variety of technical operations not only in production, but also in the household.

At home, these devices can be used for processing metal products, if fine 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.

When assembling a homemade device, special attention should be paid to the current strength. The value of this parameter depends on the power supply 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 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 mass of the device and low consumption of electrical energy. In addition, the efficiency of a device based on an inverter power supply is 10% higher than that of a device with a transformer unit, which affects the quality of operations.

When assembling the fixture, attention should be paid to the accuracy and quality of the assembly in accordance with the system, as well as the combination of elements in the system.

When assembling the fixture in a structure, a nozzle of sufficient length must be used, which should not be too long, otherwise it will have to be replaced frequently.

The choice of structural elements for the assembly of fixtures

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 provides voltage supply with predetermined characteristics for the operation of the equipment. In addition to the inverter, you can use a transformer. If a transformer is used as a power supply, then when designing equipment, the heavy 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 performance 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 beneficial, as this device is more economical and its cost is much lower. A device based on the use of an inverter power supply is easier to use. Such a device can be used when working at home and in small production. When using this type of power supply, voltage stability is achieved, which allows 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 provides cutting of metal blanks, an electrode and an insulator, which simultaneously plays the role of a cooler.

Assembling the Plasma Cutter

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 do not allow the destruction of the electrode material. When choosing the type of electrode, it should be remembered that some of the materials used to make the body of the electrodes are hazardous to the worker. So, for example, beryllium in the composition of 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 forms the cutting jet. The quality of the working jet depends on the technical characteristics of 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, then it is possible to quickly destroy it during operation.

To supply the air flow in the design of the plasma cutter, a compressor is used. A feature of the cutter is the use of gases during the operation of the equipment for protection and plasma formation. Work on the implementation of metal cutting is performed at a current strength of 200 A. During the operation of the device, compressed air is used, which is required to cool the functioning equipment and form a plasma jet. The use of such a design in the process of work allows cutting metal blanks with a metal thickness of up to 50 mm.

A cable-hose package is used to connect all elements of the installation. When carrying out the assembly of the installation, it is required to follow a certain order of work. First, the inverter is connected to the electrode with a cable to supply voltage to it. By means of a hose, a compressed air flow is supplied from the compressor unit to the plasma torch, where a plasma jet is formed.

How the cutter works

After the installation for metal cutting is assembled, it is required to check its performance. When starting, the inverter supplies an electric current with a high frequency to the plasma torch. After applying voltage to the electrode, an electric arc is formed, its temperature at the time of occurrence varies in the range from 6 to 8 thousand degrees Celsius. The arc is formed 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 by a hundred times, while the stream is ionized, and it acquires conductive properties.

With the help of a nozzle, a narrow plasma stream is formed. The outflow velocity of the plasma flow is 2-3 meters per second. At the moment of the plasma jet outflow, its temperature increases significantly and reaches 25-30 thousand degrees. At the outlet of the nozzle, a high-temperature plasma flow 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 site of exposure to the plasma flow.

Metal cutting is carried out in several ways - mechanically, arc welding or high-temperature plasma exposure. In the latter case, an inverter can be used as a power source. To make an effective plasma cutter with your own hands, you will need to familiarize yourself with the scheme and principle of operation of the device.

Diagram of a plasma cutter

Processing of metal surfaces, their cutting and controlled deformation takes place with the help of a jet of air or an inert gas. The pressure and the presence of an ignitable component (electrode) ensure the formation of a plasma region. It exerts an effect of high temperature and pressure on the area of the workpiece, as a result of which it is cut.

Features of the manufacture of a plasma cutter based on an inverter welding machine:

Preliminary calculation of equipment power. The defining parameter is the thickness and properties of the material being cut.
Mobility of the structure and its dimensions.
Duration of continuous cutting.
Budget.

The latter indicator should not affect the quality, and most importantly, the safety of the homemade plasma cutter. It is recommended to use as many factory-made components as possible.

An inverter welding machine is an arc source for plasma ignition. It is also used for its intended purpose - the formation of connecting seams. To complete the plasma cutter, you need to purchase only factory models, since home-made ones will not be able to ensure stable operation.

To ensure mobility, you need to buy an inverter with the function of argon arc welding. Its design provides a place for connecting a hose from an air or inert gas source. The average cost is 19,500 rubles.

Additionally, the following components are required:

Cutting torch with the function of supplying electricity, wire (electrode) and air.
Compressor. It is needed for gas injection, an alternative is filled cylinders.
Cable-hose package. These are lines for electricity, an air hose and a wire feeder.

Of the entire list, you can only make a handle for the cutter with your own hands. It is she who most often fails due to constant temperature exposure. The dimensions and performance properties of the remaining components must meet quality standards.

Step by step assembly instructions

In fact, the plasma cutter is not manufactured, but assembled from the elements described above. The possibility of connecting individual components is preliminarily checked, the operating modes are specified - the magnitude of the supplied current from the inverter, the intensity of the air jet, and the temperature of the plasma.

Additionally, you need to use a pressure gauge to control the pressure in the air line. The best location option is on the case. On the holder, it will interfere with the precise formation of the cut.

Operating procedure:

Check inverter power.
Check the tightness of the air line.
Set the inert gas jet pressure to the desired level.
Connect the negative electrode of the inverter to the workpiece.
Arc test, air supply activation.
Plasma cutting.

The width of the cut should be small, without significant deformation of the metal along the edges. The maximum thickness of the processed material is up to 3 mm. With an increase in this parameter, the inverter is replaced by a more powerful transformer.

During the cutting process, problems arise - lack of components, unstable installation mode. Possible consequences - the inability to continue work, poor-quality cut. The way out is to carefully prepare for this event.

Spare gaskets for the air line. Frequent switching leads to their erasure and loss of tightness.
Nozzle quality. With prolonged exposure to temperature, it can become clogged, change the geometry.
Electrodes only from refractory materials.
The reason for the breakdown of homemade cutters is the occurrence of 2 air vortices, which leads to deformation of the nozzle.
Be sure to work only in protective clothing.

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 trying to cut with a conventional flame, a wide part of the surface is heated, which leads to deformation in this area. The plasma cutter is capable of spot heating the metal, producing cutting with a minimum cutting width. When using a 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 layout of the equipment? Is it possible to make a cutter gun by yourself, or is it better to buy this item? Below are the answers to these questions, including a thematic video.

It will be possible to make a plasma cutter from an inverter with your own hands if you have a good understanding of the principle of operation of the device and the elements involved in the process. The essence of the functioning of the plasma cutter is as follows:

The current source generates the required voltage, which is supplied through the cables to the cutter-torch (plasma torch).
The plasma torch contains two electrodes (cathode and anode), between which an arc is initiated.
The air flow, supplied under pressure and through special swirling channels, directs the electric arc outward, while increasing its temperature. Other models use a liquid that evaporates to create exhaust pressure. The resulting high-temperature ionized flame (as it looks externally) is plasma.
The mass cable, previously connected to the product, contributes to closing the arc on the surface being cut, which makes it possible for the plasma cutter to work.
In the case of welding, the role of 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 pointwise heat the required area of the metal, making cutting, and without overheating the rest of the product.

Plasma cutters differ in power and configuration. Small models are capable of cutting metal with a thickness of about 10 mm. Industrial machines work with steels up to 100 mm thick. Often these are large machines on brackets, on which sheets of steel 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 will be able to perform curly 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 nodes:

power supply;
plasma torch;
compressor;
mass.

Current source

The assembly of the product must begin with the search for a suitable current source. Industrial models use powerful transformers that allow you to get a lot of current and are able to cut a thickness of more than 80 mm. But at home, you don’t have to work with such values, and such a transformer will buzz a lot.

As a power source, you can take a conventional inverter, which costs four times cheaper than the simplest plasma cutting machine. It will outperform the transformer by delivering a steady voltage at a high frequency. This will ensure the stability of the arc and the required cut quality. The inverter will also be convenient due to its small size, in case of field work with a plasma cutter. Light weight will make it easier to transport the device to the right place.

A plasma cutter from an inverter, in finished form, must meet a number of key requirements:

powered by 220V;
work at a power of 4 kW;
have a current adjustment range from 20 to 40 A;
idling 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 scheme and its operation

How to make a plasma cutter is well shown in some videos on the net. There you can also find important schemes according to which the device is assembled. To read the symbols, you need elementary electrical engineering skills and the ability to understand the symbols.

The scheme of the plasma cutter provides in reality the possibility of performing work by the device. It happens like this:

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) energizes the inverter and at the same time activates 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, feeding the electrodes.
Simultaneously with the third relay, an oscillator is started, which ionizes the air between the cathode and anode. An arc is excited, called the duty one.
When the flame is brought to the product connected to the mass, 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 for ignition.
Material is being cut or welded. If contact with the surface was lost (the arc fell on an already cut place), then the reed switch relay is triggered again to ignite the duty arc.
After turning off the button on the plasma torch, any kind 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 by a torch (plasma torch). It can have various modifications and sizes. It is quite difficult to build a water-powered model at home, so you should buy such a “gun” in the store.

Making a plasma torch with an air system is much easier. Homemade versions of the plasma cutter are most often just that. For DIY assembly 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 diameters of metal;
tip with splash protection;
remote spring to maintain the gap between the nozzle and the surface;
nozzles for chamfering and carbon deposits.

Welding and cutting with the same device can be carried out at different thicknesses of metal due to the replaceable elements of the plasma torch head. For this, various nozzles are provided, differing in the diameter of the outlet 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 each type of several pieces, because they will be melted, which will require, over time, replacement.

The nozzles are fastened with a special clamping nut, whose diameter allows the nozzle cone to pass through itself and clamp its wide part. Immediately behind the nozzle is an electrode and an insulating sleeve that prevents the arc from igniting in an unintended place. After, there is a mechanism for swirling the air flow, which enhances the action of the arc. All this is placed in a fluoroplastic case and closed with a metal casing. Some of these items you can make yourself, while others are better to buy in the store.

A store plasma torch may also differ in an air cooling system, which will allow the device to work longer without overheating. But if the cutting will be carried out for a short time, then this is not necessary.

Used electrodes

Electrodes play an important role in ensuring the process of arc burning and cutting with a plasma torch. In their manufacture, beryllium, hafnium, thorium and zirconium are used. Due to the formation of a refractory surface film, the electrode rod is not subject to overheating and premature destruction when operating 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 harmful fumes and are suitable for working in a special environment that provides adequate protection for 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 torch in their circuit. This is an important part of the device, which allows to develop the temperature of the electric arc up to 8000 degrees, and ensures the cutting process. Additionally, the compressor purges the channels of the equipment and the plasma torch, draining the system from condensate and removing debris. The possibility of compressed air passing through the burner contributes to the cooling of 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 a corresponding connector. An electrovalve is installed at the inlet, which regulates the air supply to the system.

The channel from the plasma cutter to the burner already contains an electrical component (cable for powering the electrode), therefore, a thicker hose is used, for example, from an old washing machine, inside which a power wire is placed. The supplied air will simultaneously cool the cable. The mass is made of a wire with a cross section of more than 5 mm square, with a clamp at the end. If the ground contact is bad, then the standby arc will not be able to switch to the working one. Therefore, it is important to buy a clamp strong and reliable.

It is quite possible to assemble a plasma cutter at home using videos 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.