How to make a good plasma cutter from an inverter with your own hands. Do-it-yourself plasma cutter from an inverter: drawings, manufacturing instructions Plasma cutter installation

Plasma cutting of sheet metal is usually used in large industries for the production of complex parts. You can cut any metals on industrial machines - regular and stainless steel, aluminum, copper, brass, super-hard alloys. You can also make a plasma cutter with your own hands, and it’s a completely workable design, albeit with somewhat limited capabilities.

It will not be suitable for large-scale production, but cutting out several parts in a metalworking workshop, metalworking shop or at home, in a garage, for example, will always work. At the same time, there are practically no restrictions on the complexity of the configuration and hardness of the metal being processed. Limitations relate to metal thickness, sheet size and cutting speed.

The easiest way to build a plasma cutting machine is based on an inverter welding machine. A do-it-yourself plasma cutter made from an inverter is distinguished by its relatively simple design, operability, and accessibility of main components and parts. Those that cannot be purchased can be made independently in a workshop with average equipment.

A homemade plasma cutting machine is not equipped with a CNC - this is its disadvantage and advantage. The disadvantage is that it is difficult to produce two absolutely precise parts when operated manually. Even small series of blanks will differ in some way.

The advantage is that you don’t have to buy one of the most expensive units. Not every highly qualified engineer can make it, and assembling it from ready-made components is the same as buying a new device. A mobile cutter does not need a CNC due to the other tasks it performs.

The main components of a homemade plasma cutter are:

DC source;
plasmatron;
oscillator
compressor or compressed gas cylinder;
connection hoses;
power cable.

As you can see, the device does not include anything particularly complicated. But difficulties begin upon closer examination of the characteristics of a particular unit.

Current source

The characteristics of plasma cutting require that the current be at least at the level of a medium-power welding machine. This current is generated by a conventional welding transformer and an inverter machine. In the first case, the installation will be conditionally mobile - the large weight and dimensions of the transformer will make it difficult to move. In combination with a compressed gas cylinder or compressor, the system will turn out to be quite cumbersome.

In addition, transformers are characterized by low efficiency, which will lead to increased energy consumption when cutting metal. The circuit using an inverter is somewhat simpler and more convenient to use, as well as more energy efficient. A welding inverter will produce a fairly compact plasma cutter that can easily handle cutting metal up to 25-30 mm thick. It is for these thicknesses that industrial installations are used. the transformer will be able to process thicker workpieces, but this is required less often. All the advantages of plasma cutting are manifested precisely on thin and ultra-thin sheets. This:

line accuracy;
smooth edges;
no metal splashes;
there are no overheated zones near the interaction between the arc and metal.

A homemade plasma cutter is assembled on the basis of any inverter welding machine. The number of operating modes does not matter - only direct current with a power of more than 30A is needed.

Plasma torch

The second most important element of the plasma cutter. Let's briefly consider the principle of its operation. A plasma cutter consists of two electrodes, one of which, the main one, is made of refractory metal, the second is the nozzle. It is usually made from copper. The main electrode serves as the cathode, the nozzle as the anode, and during operation, the current-conducting part being processed.

In this case, we are considering a direct plasma torch for cutting metals. An arc occurs between the cutter and the workpiece. There are also indirect plasma torches that cut with a plasma jet, but they will be discussed below. The inverter plasma cutter is designed for direct action.

In addition to the electrode and nozzle, which are consumables and can be replaced as they wear out, the plasma torch body contains an insulator that separates the cathode and anode units and a small chamber in which the supplied gas swirls. A thin hole is made in the conical or hemispherical nozzle, through which gas heated to a temperature of 5000-3000 0 C escapes.

Gas is supplied to the chamber from a cylinder or from a compressor through a hose combined with power cables, which form a hose-cable package. They are connected in one insulating sleeve, or connected in the form of a bundle. Gas enters the chamber through a straight pipe located on top or side of the vortex chamber, which is needed so that the working medium moves only in one direction.

How does a plasma torch work?

Gas, entering under pressure into the space between the nozzle (anode) and the electrode (cathode), quietly passes into the working hole and escapes into the atmosphere. When the oscillator, a device that generates a pulsed high-frequency current, is turned on, an arc appears between the electrodes, which is called a preliminary arc and heats the gas located in the limited space of the combustion chamber. The heating temperature is so high that it turns into another type of physical state - plasma.

This type of material state is distinguished by the fact that almost all atoms are ionized, that is, electrically charged. In addition, the pressure in the chamber increases sharply and the gas rushes out in the form of a hot jet. When the plasma torch is brought to the part, a second arc appears, more powerful. If the current from the oscillator is 30-60 A, then the working arc occurs at 180-200 A.

This arc additionally heats the gas, which accelerates under the influence of electrical forces to an extremely high speed - up to 1500 m/s. The combined effect of the high temperature of the plasma and the speed of movement cuts the metal in a very fine line. The thickness of the cut depends on the properties of the nozzle.

An indirect plasma torch works differently, in which a nozzle acts as the main anode. It is not an arc that escapes from the cutter, but a stream of plasma - a jet that cuts non-conductive substances. Homemade equipment with such plasma torches very rarely works.

Due to the complexity and subtle settings, it is almost impossible to make it yourself, despite the simple drawings that are available on the Internet. It operates under high pressures and temperatures and becomes downright dangerous if done incorrectly. You can assemble a plasma cutter according to drawings with your own hands from ready-made parts that are sold in welding equipment stores. But, like most machines and mechanisms, assembly from components costs more than a complete cutter.

Oscillator

This is a kind of starter that serves to start the preliminary arc. For those versed in electronics, its circuit is simple. The functional diagram looks like this:

And the electric one is something like this (one of the options):

You can see how the homemade oscillator looks and works in the video. If you don’t have time to assemble electrical circuits and search for parts, use factory-made oscillators, for example VSD-02. Its characteristics are best suited to work with an inverter. The plasmatron power supply is connected in parallel or in series, depending on the requirements of the instructions for a particular device.

Working gas

Before making a plasma cutter, you should outline the preliminary scope of its application. If you are going to work only with ferrous metals, then you can only get by with a compressor. Copper, titanium and brass require nitrogen, and occurs in a mixture of nitrogen and hydrogen. High alloy steels are cut in an argon atmosphere. In this case, the device is also designed for compressed gas.

Assembling the device

Due to the rather complex and numerous components of a plasma cutting machine, it is difficult to place it in a portable case or box. It is best to use a warehouse cart to transport goods. On it you can compactly place an inverter, cylinders or compressor, cable and hose group. It is very easy to move them within a workshop or workshop. If you need to travel to another site, everything can be loaded into a car trailer.

Making a plasma cutter from an inverter with your own hands is a task that almost any good owner can do. One of the main advantages of this device is that after cutting with such a device there will be no need for additional processing of the edges of metal sheets.

Direct acting devices

Currently, there are many options for manual plasma cutters, as well as many different options for how they work. One such setup is the direct action cutter. The operation of this type of device is based on the use of an electric arc. This arc has the form of a cylinder to which a gas stream is supplied. It is due to this unusual design that this device can reach a colossal temperature of approximately 20,000 degrees. In addition, this device is capable of not only developing enormous temperatures, but also quickly cooling other working elements.

Indirect action device

Indirect installations are not used as often as direct ones. The thing is that they are characterized by a lower efficiency, that is, efficiency.

The design of these tools is also quite specific and consists in the fact that the active points of the circuit are placed either on a pipe or on a special tungsten electrode. These devices have become quite widely used when it is necessary to spray or heat metal parts. However, this type of equipment is not used as a plasma cutter. Most often they are used to repair automotive components without removing them from the body.

The peculiarities of the operation of such cutters also include the fact that they can only work if there is an air filter, as well as a cooler. The presence of air filters in this device ensures a longer service life of elements such as the cathode and anode, and also affects the acceleration of the process of starting the mechanism.

Hand tool design

In order to ensure that a plasma cutter from an inverter performs all the necessary functions with your own hands, you need to understand the basic principle of operation. The entire functionality of the device depends on the supply of highly heated air from the cutter to the sheet of metal. The temperature conditions that need to be created are several tens of thousands of degrees. When oxygen is heated to such limits, it is supplied under pressure from the cutter to the surface that needs to be cut. It is this work process that is fundamental. Metal sheets are cut using highly heated oxygen under high pressure.

In order to speed up this process, it is necessary to take into account ionization by electric current. It is also important to note that you can increase the service life of a plasma cutter made with your own hands from an inverter if the device contains some additional parts.

Additional items

There are a total of five main elements that must be included in the design of a plasma cutter.

The first and main part is the plasmatron. It is this element that is responsible for performing all the main functions of the cutter.
Next comes the plasma cutter. The design of this element can be done in two ways - direct or indirect. The difference between these designs is described above.
It is also important to have electrodes as consumables for a plasma cutter.
One of the most important parts was the nozzle. The configuration of this particular element allows the master to understand what kind of metal sheet this cutter is intended for cutting.
Compressor. The need for this detail is quite understandable. Since cutting requires oxygen to be supplied under high pressure, the presence of this device is vital for the functioning of the device as a whole.

Parts selection

In order to make a plasma cutter with your own hands from an inverter, you need to decide which elements to create it from.

The part that will create the necessary power for cutting can be an inverter or transformer. When choosing this element of the device, it is very important to understand exactly what thickness of metal will need to be cut. It is the thickness of the metal that will be the fundamental factor that will influence the choice of this part. Since a manual cutter is being assembled, it is, of course, better to purchase a welding inverter. Its power is slightly less than that of a transformer, but it is much lighter and will save a large amount of electricity.

The second important detail will be the choice between a plasma cutter or a plasma point. The main selection criterion here will be the same factor as when selecting a welding inverter, that is, the thickness of the metal. However, one more nuance needs to be taken into account. Direct impact equipment is designed to work with elements capable of conducting current. An indirect element is most often installed if it is necessary to do without things that use current in the work.

Another important element is the compressor. Its choice is already simpler, since the only important requirement is power, which must fit the previously selected parts.

The last piece is the cable-hose package. Designed to connect all the parts given above.

Operating principle

In order to create a good working tool of this type, it is very important to understand the operating principle and design of the plasma cutter. This device works as follows:

When the equipment starts up, it begins to generate the required voltage, which is transmitted through the cable to the torch-torch.
There are two main elements in a plasmatron (cutter-torch) - a cathode and an anode. An arc will be initiated between these two parts.
A powerful stream of air, which moves under high pressure, and also overcomes special twisted cables, brings the arc out. At the same time, the supplied air greatly increases the arc temperature.
Next, the ground cable comes into play, which is always connected to the device in advance. It creates an arc closure on the working surface, which ensures stable operation of the plasma cutter.
It is important to note that when converting an inverter into a plasma cutter, welding remains possible. That is, the cutter can also be used as a welding machine. In this case, it is best to use argon as the main gas or another inert mixture that can protect the weld pool from environmental influences.

Cutter device

Since the temperature of the arc is artificially increased by supplying hot air, its temperature in a homemade plasma cutter can reach 8,000 degrees. This is a very high temperature indicator, which allows for spot cutting of metal without heating other parts of the sheet. Like any other technical devices, plasma cutters made from an inverter with your own hands will differ from each other in their power, which will determine how thick a sheet of steel the device can cut. Hand cutters can most often cut sheets up to 10 mm thick. Industrial units are capable of handling metal 100 mm thick. A homemade plasma cutter made on your own will be able to cut sheets with a thickness of up to 12 mm.

Such products can be used for figure cutting, as well as welding alloy steels with filler wire. The simplest cutters include four main parts - a plasma torch, a compressor, and a mass.

How to make a plasma cutter?

Assembling this device should always start with the power source. In industrial units, a transformer is used to achieve more power and, therefore, cut thicker metal. For a manual home cutter, a regular inverter is perfect, as it can provide such indicators as stable voltage and high frequency. The advantage of using an inverter will be its light weight, which will make the device more convenient for transportation, and it is also quite capable of ensuring stable burning of the torch arc and the quality of the cutting itself.

In addition, the inverter must meet several more requirements:

Its power supply must be supplied from a 220V network.
The cutter should operate with a power of 4 kW.
The current adjustment range for a manual device should be from 20 to 40 A.
Idling is also 220V.
The nominal operating mode for a 10-minute cycle should not exceed 60%.

In order to achieve all these parameters, it is necessary to use certain additional equipment.

Plasma cutter diagram

In order to make a working device, it is necessary to consult the diagram of this device. You can easily find such a diagram on the Internet, but you still need to read it. To do this, you need to have the most minimal knowledge in electrical engineering. It is the correct assembly according to the diagram that ensures the actual operation of the unit.

Product circuit operation

Do-it-yourself assembly of a plasma cutter according to a drawing is the most important process that will ensure stable operation of the device in the future. The finished and correctly assembled circuit looks like this:

The plasma torch has a button that starts the entire workflow. Pressing this button will activate relay P1. The function of this element is to supply current to the control unit.
Next, relay P2 is switched on. It performs tasks such as starting current to the inverter and simultaneously turning on the solenoid valve, which purges the burner. This blowing is necessary in order to dry the burner chamber and clean it of possible debris or scale.
After a three second delay, relay P3 is turned on, which supplies current to the electrodes.
Together with the activation of this relay, an oscillator is started, which ionizes the air between the cathode and the anode, thereby exciting a pilot electric arc.
When the flame is brought to the product, an arc is ignited between the sheet and the plasma torch, which is called the working arc.
At this moment, the current supply that operates for ignition is cut off.
Next, work is carried out on cutting or welding the metal.
Upon completion of work and pressing the button on the plasma torch, relay P4 is activated, which turns off both arcs and also turns on the air supply to the burner chamber for a short period of time to remove burnt elements.

Plasma torch, electrodes, compressor

Cutting or welding of metal is carried out by an element such as a plasma torch. Making it water-based on your own is very problematic, and therefore it is better to buy it. Plasmatrons with an air system are most often made with their own hands.

For this, a compressor is required, which is responsible for blowing and heating the arc to the required 8,000 degrees. This element also performs a cleaning function in the cutter, drying it and clearing it of unwanted elements and debris. As a compressor, you can use a part used in a conventional spray gun.

An important part of a homemade cutter will be the electrodes used. When purchasing them, it is important to clarify what material they are made of. Beryllium and thorium emit harmful fumes when used. It is better to use them only in a special environment where human safety is guaranteed. The best choice for a home cutter would be hafnium electrodes.

Plasma cutting is widely used in various industries: mechanical engineering, shipbuilding, advertising, utilities, metal structures and other industries. In addition, a plasma cutter can also be useful in a private workshop. After all, with the help of it you can quickly and efficiently cut any conductive material, as well as some non-conductive materials - plastic, stone and wood. You can cut pipes, sheet metal, make a shaped cut or make a part simply, quickly and conveniently using plasma cutting technology. The cut is performed using a high-temperature plasma arc, which requires only a power source, a torch and air to create. To make working with a plasma cutter easy and the cut to be beautiful and smooth, it doesn’t hurt to learn the operating principle of a plasma cutter, which will give you a basic understanding of how you can control the cutting process.

A device called a “plasma cutter” consists of several elements: power supply, plasma cutter/plasma torch, air compressor And cable-hose package.

Power supply for plasma cutter supplies a certain current to the plasmatron. May be a transformer or inverter.

Transformers They are heavier, consume more energy, but are less sensitive to voltage changes, and they can be used to cut workpieces of greater thickness.

Inverters lighter, cheaper, more economical in terms of energy consumption, but at the same time they allow cutting workpieces of smaller thickness. Therefore, they are used in small industries and private workshops. Also, the efficiency of inverter plasma cutters is 30% greater than that of transformer ones, and their arc burns more stable. They are also useful for working in hard-to-reach places.

Plasma torch or whatever they call it "plasma cutter" is the main element of the plasma cutter. In some sources you can find a mention of a plasma torch in such a context that one might think that “plasma torch” and “plasma cutter” are identical concepts. In fact, this is not so: a plasma torch is directly a cutter with which the workpiece is cut.

The main elements of a plasma cutter/plasma torch are nozzle, electrode, cooler/insulator between them there is a channel for supplying compressed air.

The plasma cutter diagram clearly demonstrates the location of all plasma cutter elements.

Inside the plasma torch body there is electrode, which serves to excite an electric arc. It can be made of hafnium, zirconium, beryllium or thorium. These metals are suitable for air plasma cutting because during operation, refractory oxides are formed on their surface, which prevent the destruction of the electrode. However, not all of these metals are used because the oxides of some of them can be harmful to the operator's health. For example, thorium oxide is toxic, and beryllium oxide is radioactive. Therefore, the most common metal for the manufacture of plasmatron electrodes is hafnium. Less commonly, other metals.

Plasma torch nozzle compresses and forms a plasma jet, which escapes from the output channel and cuts the workpiece. The capabilities and characteristics of the plasma cutter, as well as the technology for working with it, depend on the size of the nozzle. The dependence is as follows: the diameter of the nozzle determines how much air volume can pass through it in a unit of time, and the width of the cut, the cooling rate and the operating speed of the plasma torch depend on the volume of air. Most often, the plasma torch nozzle has a diameter of 3 mm. The length of the nozzle is also an important parameter: the longer the nozzle, the more accurate and better the cut. But you need to be more careful with this. A nozzle that is too long will break down faster.

Compressor for a plasma cutter it is necessary for air supply. Plasma cutting technology involves the use of gases: plasma-forming and protective. Plasma cutting machines, designed for currents up to 200 A, use only compressed air, both to create plasma and for cooling. This machine is sufficient for cutting workpieces 50 mm thick. An industrial plasma cutting machine uses other gases - helium, argon, oxygen, hydrogen, nitrogen, as well as their mixtures.

Cable-hose package connects the power source, compressor and plasmatron. The electric cable supplies current from a transformer or inverter to initiate an electric arc, and the hose carries compressed air, which is necessary for the formation of plasma inside the plasma torch. We will describe in more detail what exactly happens in the plasmatron below.

As soon as the ignition button is pressed, the power source (transformer or inverter) begins to supply high-frequency currents to the plasmatron. As a result, a pilot electric arc appears inside the plasma torch, the temperature of which is 6000 - 8000 °C. The pilot arc lights up between the electrode and the nozzle tip for the reason that it is difficult to form an arc between the electrode and the workpiece being processed immediately. The pilot arc column fills the entire channel.

After the pilot arc occurs, compressed air begins to flow into the chamber. It breaks out of the pipe, passes through an electric arc, as a result of which it heats up and increases in volume by 50 - 100 times. In addition, the air is ionized and ceases to be a dielectric, acquiring conductive properties.

The plasmatron nozzle, narrowed to the bottom, compresses the air, forms a flow from it, which escapes from the nozzle at a speed of 2 - 3 m/s. The air temperature at this moment can reach 25,000 - 30,000 °C. It is this high-temperature ionized air that is in this case plasma. Its electrical conductivity is approximately equal to the electrical conductivity of the metal being processed.

At the moment when the plasma escapes from the nozzle and comes into contact with the surface of the metal being processed, the cutting arc is ignited, and the pilot arc goes out. The cutting/working arc heats up the workpiece being processed at the cutting site - locally. The metal melts, a cut appears. Particles of just molten metal appear on the surface of the metal being cut, which are blown away from it by a stream of air escaping from the nozzle. This is the simplest plasma metal cutting technology.

Cathode spot The plasma arc must be located strictly in the center of the electrode/cathode. To ensure this, the so-called vortex or tangential supply of compressed air is used. If the vortex feed is disrupted, then the cathode spot moves relative to the center of the electrode along with the plasma arc. This can lead to unpleasant consequences: the plasma arc will burn unstably, two arcs may form simultaneously, and in the worst case, the plasma torch may fail.

If you increase the air flow, the speed of the plasma flow will increase, and the cutting speed will also increase. If you increase the diameter of the nozzle, the speed will decrease and the width of the cut will increase. The speed of the plasma flow is approximately 800 m/s at a current of 250 A.

Cutting speed is also an important parameter. The larger it is, the thinner the cut. If the speed is low, the cutting width increases. If the current increases, the same thing happens - the width of the cut increases. All these subtleties relate directly to the technology of working with a plasma cutter.

Plasma cutter parameters

All plasma cutting machines can be divided into two categories: manual plasma cutters and machine cutting machines.

Manual plasma cutters are used in everyday life, in small industries and in private workshops for the manufacture and processing of parts. Their main feature is that the plasma torch is held in the hands of the operator, he guides the cutter along the line of the future cut, holding it in weight. As a result, the cut is even, but not perfect. And the productivity of such technology is low. To make the cut more even, without sagging and scale, a special stop is used to guide the plasma torch, which is placed on the nozzle. The stop is pressed against the surface of the workpiece and all that remains is to guide the cutter, without worrying about whether the required distance is maintained between the workpiece and the nozzle.

For a manual plasma cutter, the price depends on its characteristics: maximum current, thickness of the workpiece being processed, and versatility. For example, there are models that can be used not only for cutting metals, but also for welding. They can be distinguished by their markings:

CUT - cutting;
TIG - argon arc welding;
MMA - arc welding with a stick electrode.

For example, the FoxWeld Plasma 43 Multi plasma cutter combines all of the listed functions. Its cost is 530 - 550 USD. Characteristics related to plasma cutting: current strength - 60 A, workpiece thickness - up to 11 mm.

By the way, the current strength and the thickness of the workpiece are the main parameters by which a plasma cutter is selected. And they are interconnected.

The higher the current, the stronger the plasma arc, which melts the metal faster. When choosing a plasma cutter for specific needs, you need to know exactly what metal will have to be processed and what thickness. The table below shows how much current is needed to cut 1 mm of metal. Please note that processing non-ferrous metals requires high amperage. Keep this in mind when you look at the characteristics of a plasma cutter in a store; the thickness of the ferrous metal workpiece is indicated on the device. If you plan to cut copper or other non-ferrous metal, it is better to calculate the required amperage yourself.

For example, if you need to cut copper 2 mm thick, then you need to multiply 6 A by 2 mm, we get a plasma cutter with a current strength of 12 A. If you need to cut steel 2 mm thick, then multiply 4 A by 2 mm, you get a current strength of 8 A. Only Take a plasma cutting machine with a reserve, since the specified characteristics are maximum, not nominal. You can only work on them for a short time.

CNC plasma cutting machine used in manufacturing plants for the manufacture of parts or processing of workpieces. CNC stands for Computer Numerical Control. The machine operates according to a given program with minimal operator participation, which eliminates the human factor in production as much as possible and increases productivity significantly. The cutting quality of the machine is ideal; no additional edge processing is required. And most importantly - figured cuts and exceptional precision. It is enough to enter the cutting diagram into the program and the device can make any intricate shape with perfect accuracy. The price of a plasma cutting machine is significantly higher than that of a manual plasma cutter. First, a large transformer is used. Secondly, a special table, portal and guides. Depending on the complexity and size of the device, the price can be from 3000 USD. up to 20,000 USD

Machine plasma cutting machines use water for cooling, so they can work the entire shift without interruption. The so-called PV (on duration) is 100%. Although for manual devices it can be 40%, which means the following: the plasma cutter works for 4 minutes, and it needs 6 minutes to cool down.

It would be most reasonable to purchase a ready-made, factory-made plasma cutter. In such devices, everything is taken into account, adjusted and works as perfectly as possible. But some “Kulibina” craftsmen manage to make a plasma cutter with their own hands. The results are not very satisfactory, since the quality of the cut is poor. As an example, we will give a stripped-down version of how you can make a plasma cutter yourself. Let us immediately make a reservation that the diagram is far from ideal and only gives a general concept of the process.

So, a transformer for a plasma cutter must have a falling current-voltage characteristic.

Example in the photo: the primary winding is from below, the secondary winding is from above. Voltage - 260 V. Winding cross-section - 45 mm2, each bus 6 mm2. If you set the current to 40 A, the voltage drops to 100 V. The inductor also has a cross-section of 40 mm2, wound with the same bus, about 250 turns in total.

To operate, you need an air compressor, of course, a factory-made one. In this case, a unit with a capacity of 350 l/min was used.

Homemade plasma cutter - operation diagram.

It is better to purchase a factory-made plasma torch; it will cost about 150 - 200 USD. In this example, the plasma torch was made independently: a copper nozzle (5 cu.) and a hafnium electrode (3 cu.), the rest is “handicraft”. Due to this, the consumables quickly failed.

The circuit works like this: there is a start button on the cutter, when it is pressed, the relay (p1) supplies voltage to the control unit, the relay (p2) supplies voltage to the transformer, then releases air to purge the plasma torch. The air dries the plasma torch chamber from possible condensation and blows out all excess, it has 2 - 3 seconds for this. It is with this delay that the relay (p3) is activated, which supplies power to the electrode to ignite the arc. Then the oscillator is turned on, which ionizes the space between the electrode and the nozzle, as a result, the pilot arc lights up. Next, the plasma torch is brought to the workpiece and the cutting/working arc lights up between the electrode and the workpiece. The reed switch switches off the nozzle and ignition. According to this scheme, if the cutting arc suddenly goes out, for example, if the nozzle gets into a hole in the metal, then the reed switch relay will turn on the ignition again and after a few seconds (2 - 3) the pilot arc will light up, and then the cutting arc. All this is provided that the “start” button is not released. Relay (p4) releases air into the nozzle with a delay, after the “start” button is released and the cutting arc goes out. All these precautions are necessary in order to extend the life of the nozzle and electrode.

Making a plasma cutter yourself at home makes it possible to save a lot, but there is no need to talk about the quality of the cut. Although if an engineer takes on the work, the result may be even better than the factory version.

Not every enterprise can afford a CNC plasma cutting machine, because its cost can reach 15,000 - 20,000 USD. Quite often, such organizations order plasma cutting work to be performed at special enterprises, but this is also expensive, especially if the volume of work is large. But you really want your own new plasma cutting machine, but you don’t have enough money.

In addition to well-known specialized factories, there are enterprises that produce plasma cutting machines, purchasing only profile parts and assemblies, and producing everything else themselves. As an example, we will tell you how engineers make CNC plasma cutting machines on a production floor.

Components of a do-it-yourself plasma cutting machine:

Table 1270x2540 mm;
Belting;
Step parts;
Linear guides HIWIN;
System that controls the height of the THC flame;
Control block;
The terminal stand in which the CNC control unit is located is separate.

Machine characteristics:

The speed of movement on the table is 15 m/min;
The accuracy of setting the plasma torch position is 0.125 mm;
If you use a Powermax 65 machine, the cutting speed will be 40 m/min for a 6 mm workpiece or 5 m/min for a 19 mm thick workpiece.

For a similar metal plasma cutting machine, the price will be about 13,000 USD, not including the plasma source, which will have to be purchased separately - 900 USD.

To manufacture such a machine, components are ordered separately, and then everything is assembled independently according to the following scheme:

The base for welding the table is being prepared, it must be strictly horizontal, this is very important, it is better to check with a level.
The machine frame is welded in the form of a table. Square pipes can be used. The vertical “legs” must be reinforced with jibs.

The frame is coated with primer and paint to protect it from corrosion.

Supports for the machine are being manufactured. The material of the supports is duralumin, the bolts are 14 mm, it is better to weld the nuts to the bolts.

The water table is welded.

Fastenings for the slats are installed and the slats are installed. For slats, metal is used in the form of a 40 mm strip.
Linear guides are installed.
The table body is covered with sheet iron and painted.
The portal is installed on the guides.

A motor and end inductive sensors are installed on the portal.
The guide rails, rack and pinion and Y-axis motor are installed.

The guides and motor are installed on the Z axis.
A metal surface sensor is installed.

A tap is installed to drain water from the table, and limiters for the portal are installed so that it does not move off the table.
Cable channels Y, Z and X are installed.

All wires are hidden in corrugation.
A mechanized burner is installed.

Next, the CNC terminal is manufactured. First, the body is welded.
A monitor, keyboard, TNS module and buttons for it are installed in the CNC terminal housing.

That's it, the CNC plasma cutting machine is ready.

Despite the fact that the plasma cutter has a fairly simple device, you still shouldn’t start making it without serious knowledge of welding and extensive experience. It’s easier for a beginner to pay for a finished product. But engineers who want to implement their knowledge and skills at home, as they say “on the knee,” can try to create a plasma cutter with their own hands from start to finish.

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.

When assembling a 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 a transformer unit, 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. 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, 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. A hose is used to supply a compressed air flow from the 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.