A homemade plasma torch is a variant of gas welding. Do-it-yourself plasma cutter from an inverter - at a reasonable cost it is possible Do-it-yourself plasma cutting

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 plasma torch 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 carried out 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.

The technology of various metal products is used with equal success in everyday life and in large industrial production. Using special equipment, you can easily cut non-ferrous metals, as well as work efficiently with stainless steel, aluminum and other alloys. Cutting non-ferrous metals is carried out using special plasma cutters, which are at the same time easy to use, functional and reliable. Let's tell you more about this equipment and talk about how to make a plasma cutter with your own hands from an inverter.

Industrial plasma cutters are productive equipment that allows for the most accurate cutting of metals with different refractoriness indices. Such industrial plasma cutters are designed primarily for operation under conditions of increased loads and are equipped with CNC, which makes it possible to manufacture parts in a serial manner.

If you need a plasma cutter for domestic use, as well as for the use of such equipment in construction, then such a cutter you can make it yourself from a simple welding inverter. Subsequently, self-made equipment will be distinguished by its versatility in use and will allow you to effectively cut non-ferrous metals and thick sheet steel.

Making such a cutter with your own hands from an inverter will not be particularly difficult. You can easily find diagrams for the implementation of such devices on the Internet and, using the calculations obtained, make such an easy-to-use device. We can recommend that you make plasma cutters based on compact welding inverters, which will significantly simplify the design and guarantee the necessary efficiency of such devices.

Homemade plasma cutting machines are not equipped with CNC, so it will be impossible to use such equipment for work that is fully controlled by automation. You must understand that using such homemade plasma cutters it will be impossible to make two perfectly accurate parts.

A homemade plasma cutter will consist of the following elements:

Plasmatron.
DC source.
Compressor or gas cylinder.
Oscillator.
Power cables.
Connection hoses.

Principle of operation

The operating principle of such equipment is extremely simple:

The current source used, and in our case it is an inverter, generates voltage and supplies it through cables to the plasmatron.
The plasma torch contains two electrodes, between which a high-temperature arc is excited.
Through specially twisted channels under high pressure, a stream of air or gas is supplied to the working area with a ignited arc.
A work cable is pre-connected to the product being cut, which closes to the surface being cut and provides the ability to work with metal.

DC power supplies

Plasma cutting technology will invariably require high operating current power, the performance of which should be at the level of semi-professional and professional inverter welding machines. It is not recommended to use transformer welding machines as a power source, since such devices are bulky and inconvenient to use. But an inverter will be an excellent choice, since such devices combine compact dimensions and provide high-quality electric current.

Schemes and drawings of a plasma cutter with your own hands are simple, while the costs of manufacturing such equipment are significantly reduced. A hand-made compact plasma cutter made from a welding inverter will be able to cope with cutting metal whose sheet thickness will reach 30 mm. If we talk about the advantages of such home plasma cutters made using an inverter, then we note the following:

No metal sparks.
Smooth edges.
Line accuracy.
Overheating problems resolved.

Important: making a homemade plasma cutter based on an inverter is not difficult. It is only necessary that the device generate an electric current with a force of at least 30 Amps.

The current source used must meet the following requirements:

Power supply from a network with a voltage of 220 Volts.
Ability to operate with a power of 4 kW.
The idle speed should be 220 Volts.
The current adjustment range is in the range of 20−40 Amperes.

Plasma torch design

The plasma torch is the second most important element of a metal cutter. Let's take a closer look at the design of the plasma torch and the principle of its operation. It consists of a main and auxiliary electrode. The main electrode is made of refractory metals, and the auxiliary electrode, which has the shape of a nozzle, is usually made of copper.

In a plasma torch, the cathode is the main electrode made of a refractory metal, and a copper electrode-nozzle is used as an anode, which makes it possible to provide high-quality electric current and a high-temperature arc for cutting metal.

The completed plasma torch is responsible for creating and maintaining an arc that is located between the workpiece and the cutter. The thickness of the cut, as well as the temperature created by such a cutter, will depend on the shape and design of the nozzle. The nozzle used can be hemispherical or conical, providing an operating temperature of 30,000 degrees Celsius.

During operation of the plasma torch, the main electrode and nozzle may wear out, which leads to a deterioration in the quality of metal cutting. If these elements become so worn, they should be replaced with new ones, which will ensure excellent quality of work with metal.

The plasma torch is supplied with working gas from a cylinder, using special heavy-duty gas hoses that can withstand high pressure. In each specific case, depending on the material being worked with, the gas used, which is necessary for cutting the metal, may differ.

The working gas is supplied through special channels, and the presence of numerous turns in the supply tube makes it possible to provide the necessary air turbulence, which, in turn, guarantees a high-quality cutting plasma arc that will have the correct shape. This improves the quality of metal cutting and welding and minimizes the thickness of the seam.

Oscillator

A special feature of plasma cutters is the fact that To start work, preliminary ignition of the arc is required, only after this gas is supplied to the plasmatron, the arc is created at the required temperature and the metal is cut. An oscillator is used as such a kind of starter, which serves to pre-ignite the arc. The implementation scheme of the oscillator is not difficult.

On the Internet you can find functional and electrical diagrams of oscillators, which will not be difficult to complete. It is only necessary to use high-quality electrical circuits and capacitors, which will be suitable in their parameters to the electric current generated by the inverter. Depending on its type, such a torch can be connected to the plasma torch power circuit in series or in parallel.

Working gas

Even before choosing a specific design for manufacturing a plasma cutter, you should decide on the scope of use of such equipment. If you plan to use the device exclusively for working with ferrous metals, you can exclude gas cylinders from the circuit and use only a compressor with compressed air. If you plan to use such equipment for brass, titanium and copper, then you need to choose a plasma cutter with a nitrogen cylinder. Aluminum cutting is performed using a special gas mixture with hydrogen and nitrogen.

Let's figure out how plasma cutting of metal is done with our own hands. After turning on the inverter, the generated electric current enters the plasma cutter onto the electrode, and the oscillator ignites the electric arc. Its temperature can initially be 6-8 thousand degrees. Immediately after the arc is ignited, air or gas is supplied to the nozzle under high pressure, through which an electric charge passes. The air flow is heated and ionized by an electric arc, after which its volume can increase hundreds of times, and the gas and air itself begins to conduct electric current.

A plasma cutter produces a thin jet of plasma, the temperature of which can reach 30,000 degrees. Subsequently, such a high-temperature plasma jet is supplied to the metal being processed, which makes it possible to cut heavy-duty metal elements.

One of the features of using plasma cutting is the fact that the metal being processed is cut and melted exclusively at the point where it is exposed to the plasma flow. It is extremely important to correctly position the plasma impact spot, which should be located strictly in the center of the working electrode. If this requirement is neglected, the air-plasma flow is disrupted, which deteriorates the quality of metal cutting.

The quality of work with such a plasma cutter will also depend on the air flow rate. It is recommended that all work be carried out with a current of 250 Amperes, while the speed of the air stream will be 800 meters per second. This will allow you to easily work with metals with different refractoriness characteristics, ensuring high-quality cutting without thermal effects on the structure of the alloy.

A plasma cutter is a special device that allows you to quickly, efficiently and effectively cut metal of various structures. You can either purchase plasma cutters that have already been manufactured in a factory, or make them yourself. You can easily find suitable schemes for making plasma cutters from an inverter or transformer welding machine, which will allow you to make such equipment yourself, saving on buying it in a store.

Both experts and novice craftsmen often use plasma cutting in their work. This is understandable: after all, this is an indispensable process for a wide variety of construction and production processes. There is only one drawback: devices produced by various companies cost a lot of money, and not everyone can afford them. Therefore, a variety of working people, be it construction crews 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. After all, you don't need to use other tools. The use of all kinds of electrodes with which the welding process is carried out is also possible if you have a homemade plasma cutter.

In this unit, the fundamental principle by which metals are joined is soldering. It is thanks to the high temperature of the solder that a manual plasma cutter allows you to reliably bond 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 convenient tool is also used for blacksmithing. After all, with his direct participation, it is possible to perform various manipulations with both non-ferrous and ferrous metals. In addition to their welding: also thermal cleaning, 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.

Design features

Before you start assembling a plasma cutter from an inverter yourself, 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 rather than assemble it yourself, because such an assembly will be fraught with certain difficulties.

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

The peculiar “heart” of a manual plasma cutter is the power source. It is he who supplies the current of the required power. The technical characteristics of the unit are determined precisely by this component.

If we compare the cutter (or “plasma torch”) used on this device, we can see that its design is significantly different 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 whose independent creation from an inverter is associated with significant problems. It’s better to buy a cutter ready-made in a store. This will save you from many problems in the future.

In powerful units for hot metal cutting, internal cooling functions are required. 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, the operation of which requires a current of 200 A.

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

About using a transformer or inverter

Most often, when you plan to assemble a plasma cutter, either an inverter or a special transformer is used as the power source. Each of these options has its own advantages, but in order to understand which one is suitable, you need to know exactly what technical characteristics your plasma cutter should have; accordingly, 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 that contain a transformer; they are the most efficient and economical. This device ensures arc stability. The disadvantages include the fact that the work is carried out exclusively with materials of insignificant thickness.

If a transformer is used as a basis, then such a unit will certainly be bulky and require an additional platform for use. But a significant advantage is that it allows you to work with fairly massive and thick parts. Such devices are installed either in rooms specially equipped for them or on mobile platforms.

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

What equipment will you need?

Of course, before you begin directly assembling 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 purchased 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 project being described. In order to choose a suitable inverter, you need to know exactly what work will be performed by the plasma cutter, its volume, etc. Then it will no longer be difficult to select the power of the inverter.

We have heard that some craftsmen assemble the inverter on their own. To do this, they painstakingly select parts and 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, it is difficult to achieve the same standards at home as in production. Therefore, a purchased inverter option is still preferable.

Cutter

When craftsmen or amateurs make a plasma cutter on their own, they often make the mistake of trying to completely 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 has to be replaced frequently. Therefore, the best choice would be to buy a factory nozzle, but you can assemble the remaining components yourself. But the opinion that spending a large amount of money and effort on independently assembling this component is not productive is also quite reasonable. It is better to buy a factory product.

Compressor

According to the instructions, using a compressor implies that oxygen or inert gas will be used. In practice, more often it is connected to cylinders containing a special mixture. It is this mixture that provides a strong plasma beam with decent cooling. If the plasma cutter is used at home, then for economy and simplicity of the matter it is recommended to use a simple compressor. This component can be assembled on your own, where the role of a receiver will be played by a regular cylinder. The compressor is often taken from a refrigerator or from a ZIL car. It is important not to make mistakes with pressure regulation. This is done experimentally, by craftsmen, at the initial stage of work.

Cable-hose package

This component of the plasma cutter can be purchased either individually or together with the main equipment. The main thing is to know some characteristics of the unit, namely: what pressure there 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 strength of the inverter. Otherwise, it will overheat and may catch fire and even cause electric shock.

Build process

This is a fairly simple assembly 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 terminals and clamps. With their help, you can quickly assemble and disassemble the plasma cutter. If everything is done correctly, the output will be a device with very compact parameters. It is easy to transport it to the place where the next work will be carried out.

First of all, you must ensure that you have sufficient spare gaskets on hand. After all, plasma cutting occurs when using gas, and gaskets are necessary to connect the hoses. And if the unit is planned to be transported quite often, then this element cannot be avoided; moreover, the lack of gaskets can cause the entire work to stop.
Particularly high temperatures affect the cutter nozzle. Therefore, in the long term of long-term use of the device, this particular part wears out more quickly than others. So there should be a spare nozzle available.
The price range for inverters is very wide: from very cheap to really expensive. The main thing that affects the price is the power of the inverter. So, before you buy, decide how much power you need. And based on your real needs, choose one model or another. This way, you’ll save money and create a plasma cutter that’s right for your job.
You cannot do without electrodes made of refractory metals. There is quite a wide choice on the market. For example, products made from zirconium, beryllium or thorium. But with significant heating, hazardous components are released from certain metals. Electrodes made of hafnium are considered the safest, and therefore preferable.
During work, the plasma in such a device heats up to 30 thousand degrees. This means that all safety measures must be observed. Without this, a fire may occur, or harm may be caused 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 when working is that homemade variations can disrupt the vortex air flow. And this is unacceptable, because... the formation of 2 arcs is possible, which will cause damage to the product. Therefore, it is better to spend money once than to invest additional money and effort into repairing the unit later.
If you plan to perform only one type of work with the help of an inverter, then it is possible to make some modifications designed to facilitate this particular 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: they should not contradict safety rules.

conclusions

So, having familiarized yourself with this material, it becomes clear that to assemble a plasma cutter with an inverter you will need to purchase ready-made components from different manufacturers. As for making a plasma cutter, it’s a simple assembly. But still, the selection of individual parts will allow you to save money, because... If you take a complete ready-made kit from one manufacturer, it will be much more expensive.

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

Plasma cutting is a method of processing metal empty parts with a plasma stream. This method allows you to cut metal because it is enough to be done in such a way that the material is electrically conductive. Compared to similar methods, plasma cutting of metals allows for a faster and higher-quality process without the use of massive rollers and special additives.

In this way, it is possible to process a variety of metal sheets, pipes of different diameters, shaped and sorted products. During processing, a high-quality cut is obtained, which requires minimal cleaning effort. Even with the help of this technology, various imperfections can be eliminated from the metal surface such as bulges, seams and irregularities and prepare for welding, drilling and other operations.

Plasma cutting of sheet metal is an extremely effective method.

Unlike other methods, it can be used to process ferrous and non-ferrous metals. For this reason, there is no need to prepare the surface and clean it of contaminants, which could make it difficult to ignite the arc. In the industry, the main competitor to this method is laser processing, which has even greater precision but also requires significantly more expensive equipment.

At home, there are no equivalent competitors to the plasma device.

Quality of plasma cutting of metals

Plasma cutting technology

Plasma cutting is carried out using a special device, which has dimensions similar to those of a conventional welding machine. At first these devices were large in size, but as they were improved they became smaller.

The device is connected to a 220V power supply for household appliances and 380V for industrial applications.
During the production process, cutting is carried out using CNC machines, which consist of one or more torches with mechanisms for moving them.

The machine can implement measures according to a specific program, which greatly facilitates the work of several sheets in the same cut.

To create a plasma jet, you need to connect the system to a compressor or air line.

The compressed air supplied to the device must be free of dirt, dust and moisture. For this purpose, air filters and dehumidifiers are installed in front of the device. Without such devices, wear of electrodes and other elements will accelerate faster. Liquid-cooled plasma torches also require plumbing.

Manual cutting of steel pipe

Circular cutting of steel pipe
self-propelled vehicle

Air plasma cutting technology achieves quality edges (no sucking or grating) and no warping (also on low-thickness sheets).

This allows subsequent welding of the cleaned metal without pre-treatment.

Manual cutting of metals on a sample

Essence of Plasma Sheet

Plasma cutting of steel in everyday life is carried out with devices along which the length of pipes reaches 12 m.

Manual devices have a cutting head equipped with a motorized handle. Such devices use air cooling because it is simpler in design and does not require additional refrigeration units. Water cooling is used in industrial installations where plasma cutting of steel sheets is more efficient, but the cost of the devices is higher.

Oxygen plasma technology

Oxygen plasma cutting requires a special electrode and nozzle, which has a significant temperature effect as a consumable. First, an auxiliary arc begins, which is excited by the discharge caused by the DC generator. Thanks to the arc, a plasma torch 20-40 mm long is created. When the torch touches the metal, a working arc appears and the auxiliary bow is turned off.

How to make a plasma welding machine with your own hands?

Thus, the plasma acts as a guide between the device and the workpiece. Arisen arc is self-sufficient, creating plasma due to the ionization of air molecules.

Plasma cutting using working fluid at temperatures up to 25000 ° C.

Plasma cutting of large diameter pipes and other tanks

Plasma cutting and welding can be done in workshops and workshops, as well as outdoors.

This method may not be as efficient as a gas power plant for renovation and construction work without a central system for electricity and compressed air. In this case, a sufficiently strong generator is required to provide power to the device and the compressor.

Similar to gas flame cutting, this method can be used to process empty pieces of different sizes and shapes.

Plasma cutting of large diameter pipes does not create any problems: it is performed manually or using self-propelled machines. The fixed burner rotates outside the tube. The use of self-propelled machines ensures precise and smooth cutting. Work with formed and sorted rolled products can also be automated in industrial settings.

Advantages of using SIBERIAN devices:

Versatility (can be applied to any metal, including non-ferrous and refractory metals);
Cutting speed;
High quality surface after cutting;
Economics (using compressed air);
Almost complete absence of thermal deformations on the product to be reduced;
Mobility rather than heavy weight of air-cooled units;
Easy to use.

Arc ignition devices

Devices for the initial ignition of the arc are divided into two classes: ignition of the arc from a short circuit and by breakdown of the electrode-product gap with high-voltage pulses.

Ignition by short circuit is carried out by short-term contact of the electrode and the product and their subsequent separation. The current through the microprotrusions of the electrode heats them to boiling temperature, and the field that arises when the electrodes are separated provides the emission of electrons sufficient to initiate the arc.

With this ignition, transfer of electrode material into the weld is possible. To eliminate this undesirable phenomenon, ignition should be carried out at a low current not exceeding 5-20A. The ignition device must provide a low short-circuit current, maintain the current at this level until the arc is formed, and only then smoothly increase to the operating level.

(UDG-201, ADG-201, ADG-301).

Basic requirements for gap ignition devices (arc exciters or oscillators):

1) must ensure reliable arc initiation;

2) must not endanger the safety of the welder and equipment.

Exciters can be designed to initiate a DC or AC arc. In the latter case, a number of specific requirements are imposed on the exciters related to the moment of ignition of the arc. The circuit diagram of the OSPZ-2M oscillator is shown in Fig.

Rice. 5.5. Schematic diagram of the OSPZ-2M oscillator. F1 – fuse; PZF – noise protection filter; TV1 – step-up transformer; FV – spark gap; Cg – capacitor of the oscillatory circuit; Cn – decoupling capacitor; TV2 – high voltage transformer; F2 – fuse.

Capacitor Cr is charged from the voltage of the secondary winding of step-up transformer TV1.

After charging it to the breakdown voltage of the spark gap FV, an oscillatory circuit is formed, consisting of a capacitor Cr and the primary winding of a high-voltage transformer TV2. The oscillation frequency of this circuit is approximately 500 - 1000 kHz. From the secondary winding, this voltage with a frequency of 500 - 1000 kHz and a value of about 10,000 V is supplied to the electrode-product gap through a separating capacitor Cn and fuse F2.

In this case, a spark appears in this gap, which ionizes the gap, as a result of which an electric arc is excited from the power source. After the arc is excited, the oscillator automatically turns off.

Please note that the oscillator has high voltage.

It is not dangerous for humans due to the low power of the source. However, if the source circuit contains semiconductors (diodes, thyristors, etc.), then their breakdown by the oscillator voltage is possible.

To avoid this, the oscillator must be connected to the source using protection systems (Fig. 5.6).

How to make a plasma cutter with your own hands from an inverter?

Connection diagram of the oscillator to the power source.

The choke is protected by DZ for the high frequency of the oscillator, has a very large inductive reactance and does not allow the oscillator voltage to pass to the source.

The protective capacitor SZ, on the contrary, has a very low resistance for high frequency, protecting the source from the high frequency and high voltage voltage of the oscillator. The decoupling capacitor Cp protects the oscillator from the power supply voltage.

Recommendations. Typical mistakes of the MTP operator during plasma cutting and ways to avoid them

Using consumables until they fail

If you look at a number of parts of the same type that were cut out using this approach, you can unmistakably identify those parts for which the nozzle or electrode was already “on the way.”

The use of heavily worn nozzles and electrodes can not only lead to defects when cutting the part, but also cause expensive repairs to the flame cutter and even the plasma cutting machine, during which the plasma cutting machine will be idle.

Failure of nozzles and electrodes can be easily prevented by several signs indicated by worn consumables. An experienced operator will always tell you when it is time to change the electrode by the sound of cutting and the color of the arc flame (when the zirconium insert burns out, it acquires a greenish tint), as well as the need to reduce the height of the plasma torch when punching.

Also, one of the best ways to assess the condition of cutter parts is the quality of the cut. If the quality of the cut suddenly begins to deteriorate, then this is a reason to check the condition of the nozzle and electrode. A reasonable approach is to keep a log of the average electrode or nozzle operating time from replacement to replacement. The nozzle and electrode can withstand different amounts of piercing depending on the cutting current, material type and thickness.

For example, when cutting stainless steel, consumables need to be replaced more frequently.

Once you have determined from such a log the average lifetime of the electrode for each specific type of cut-out part, you can perform a planned replacement of nozzles and electrodes without leading to defects in the cut-out parts or breakdown of the flame cutter.

Replacing nozzles and electrodes too frequently

Among the used nozzles and electrodes, you can often find those that can still be used for cutting.

Excessively frequent replacement of consumables is also very common among operators of CNC metal cutting machines, and especially plasma cutting machines.

When replacing a nozzle or electrode, the operator must clearly know what to look for. The nozzle requires replacement in the following situations:

1. If the nozzle is deformed from the outside or inside.

This often happens when the punching height is too low and the metal is not cut through. Molten metal hits the outer surface of the nozzle or protective cap and deforms it.

2. If the nozzle outlet is shaped differently from a circle. With a high piercing height, if the movement begins before the metal is cut, then the arc deviates from perpendicular to the sheet and passes through the edge of the nozzle hole.

To determine whether the electrode is worn out, you need to look at the silver-colored metal insert at the end of the copper electrode (usually an alloy of zirconium, hafnium or tungsten). In general, an electrode is considered operational if this metal exists at all and the depth of the hole in its place does not exceed 2 mm for air plasma or oxygen plasma cutting. For plasma cutting in a protective gas environment (nitrogen or argon), the hole depth can reach 2.2 mm. The swirler needs to be replaced only if a careful inspection reveals clogged holes, cracks, arc marks, or severe wear.

Swirlers are especially likely to be replaced prematurely. The same applies to protective caps, which only need to be replaced in case of physical damage. Very often the protective caps can be cleaned with sandpaper and reused.

Using incorrect plasma settings and consumables

The choice of consumables for plasma cutting depends on the type of metal being cut (steel, copper, brass, stainless steel, etc.), its thickness, the set arc current on the plasma cutting machine, plasma-forming and protective gases, etc.

The Plasma Cutting Machine Operator's Reference Guide describes which consumables to use for different cutting process conditions. The modes and recommendations regarding plasma cutting settings specified in the operator's manual should be followed.

The use of consumables (nozzles, electrodes) that do not correspond to the current plasma cutting mode usually leads to accelerated failure of the consumables and to a significant deterioration in the quality of the flame cut.

It is very important to perform plasma cutting of metal with exactly the arc current for which the consumables used are designed. For example, you should not cut metal with a 100-amp plasma if the plasma cutter has a 40-amp nozzle, etc.

The highest cut quality is achieved when the current on the plasma cutting machine is set to 95% of the rated cutting current for which the nozzle is designed. If the plasma cutting mode is set to a low arc current, the cut will be slagged, and there will be a significant amount of burr on the reverse side of the cut parts; the flame cut will be of unsatisfactory quality.

If the current set on the plasma cutting machine is too high, the life of the nozzle will be significantly reduced.

Incorrect plasma cutter assembly

The flame cutter must be assembled in such a way that all its parts fit tightly together, and there is no impression of “looseness”.

The tight fit of the plasma torch parts ensures good electrical contact and normal circulation of air and coolant through the plasma cutter. When replacing consumables, you should try to disassemble the plasma cutter on a clean surface so that dirt and metal dust generated during plasma cutting do not contaminate the plasma torch.

Cleanliness when assembling/disassembling a plasma cutter is very important and yet this requirement is often not met.

Failure to perform regular scheduled maintenance of the plasma torch

A plasma cutter can run for many months, even years, without proper maintenance.

However, the gas and coolant passages inside the plasma cutter must be kept clean, and the nozzle and electrode seats must be checked for contamination or damage. Dirt and metal dust must be removed from the plasma cutter. To clean the plasma torch, use a clean cotton cloth and electrical contact cleaner or hydrogen peroxide.

Cutting metal without checking the pressure of the plasma gas or the supply of coolant to the plasma cutter

The flow and pressure of plasma gas and coolant should be checked daily.

If the flow rate is insufficient, the torch parts will not be cooled properly and their life will be reduced. Insufficient coolant flow due to a worn pump, clogged filters, or insufficient coolant is a common cause of plasma cutter failures.

Constant pressure of the plasma gas is very important for maintaining the cutting arc and for a quality cut. Excessive pressure of the plasma-forming gas is a common cause of difficult ignition of the plasma arc, despite the fact that all other requirements for settings, parameters and the plasma cutting process are fully satisfied. Too high pressure of the plasma-forming gas causes rapid failure of the electrodes.

The plasma-forming gas must be cleared of impurities, because its cleanliness has a strong influence on the service life of consumables and the plasma torch as a whole. Compressors supplying air to plasma cutting machines tend to contaminate the air with oils, moisture and fine dust particles.

Punching at a low plasma torch height above the metal

The distance between the workpiece and the plasma torch nozzle cut has a huge impact on both the quality of the cut and the service life of consumables.

Even small changes in the height of the plasma cutter above the metal can significantly affect the bevels on the edges of the parts being cut. The height of the plasma cutter above the metal during piercing is especially important.

A common mistake is punching when the height of the plasma torch above the metal is insufficient. This causes molten metal to splash out of the piercing hole and onto the nozzles and protective caps, destroying these parts.

This significantly degrades the quality of the cut. If piercing occurs when the plasma cutter touches the metal, arc retraction may occur.

If the arc is “pulled” into the plasma torch, then the electrode, nozzle, swirler, and sometimes the entire cutter are destroyed.

The recommended piercing height is 1.5-2 times the thickness of the metal being cut by the plasma. It should be noted that when punching a sufficiently thick metal, the recommended height is too high, the pilot arc does not reach the surface of the metal sheet, therefore, it is impossible to start the cutting process at the recommended height. However, if the punching is carried out at a height at which the plasma cutter can ignite an arc, then splashes of molten metal may fall on the plasma torch.

A solution to this problem may be the use of a technological technique called “jumping”. When processing the command to turn on the cutting, the plasma cutting is turned on at a low height, then the cutter rises up to a given jump height, at which the metal splashes do not reach the cutter.

After punching has been completed, the cutter is lowered to the piercing height and begins to move along the contour.

Plasma cutting of metal at too high or too low speed

The discrepancy between the plasma cutting speed and the selected mode significantly affects the quality of the cut. If the set cutting speed is too low, the cut parts will have a large amount of flash and various metal deposits along the entire length of the cut on the lower part of the edge of the parts.

Slow cutting speeds can cause larger kerf widths and large amounts of metal spatter on the top surface of parts. If the cutting speed is set too high, the arc will bend back, causing distortion of the cut edges, a narrow cut, and small beads of burr and flash at the bottom of the cut edge.

The burr formed at high cutting speeds is difficult to remove. With the correct cutting speed, the amount of burr, flash and metal sagging will be minimal. The surface of the flame cut edge at the correct speed should be clean and machining should be minimal. At the beginning and end of the cut, the arc may “deviate” from the perpendicular.

Homemade plasma cutter from an inverter welding machine: diagram and assembly procedure

This occurs because the arc cannot keep up with the torch. Deflection of the arc leads to the fact that it cuts into the side surface of the nozzle, thereby violating its geometry. If you are cutting from an edge, the center of the nozzle hole must be exactly in line with the edge of the part. This is especially important in combined machines that use both a punching head and a plasma cutter.

Arc deflection can also occur when the plasma torch, when cutting is turned on, passes through the edge of the sheet, or if the lead out line intersects the old cut. Fine adjustment of timing parameters is necessary to reduce this effect.

Mechanical damage or breakdown of the plasma cutter

Collisions between the cutter and the sheet metal, cut parts, or edges of the cutting table can completely damage the cutter. Collisions between the cutter and the cut parts can be avoided if the control program specifies idle passes around, rather than over, the cut parts.

For example, the ProNest optimal cutting program produced by MTC-Software has such a feature, which allows you to minimize the risk of plasma torch failure and save significant money. Torch height stabilizers also provide some protection against metal collisions. However, if only a torch height sensor based on arc voltage is used, then “pecks” may occur at the end of the cut, because The arc voltage changes as a result of its “deflection” and the cutter moves down to compensate.

CNC systems use a multi-level system of protection against collisions with metal. Used as a touch sensor that measures the resistance between the antenna around the torch and the sheet, a capacitive sensor and an arc voltage sensor. This allows you to take full advantage of each sensor type. Also, to protect the cutter, you can use “brittle” brackets, which will break faster in a collision than a plasma cutter.

Thus, a competent plasma cutting machine operator can save his business a huge amount of money, time and overhead costs on plasma cutting.

The result of the work of a good equipment operator will be increased profitability of plasma cutting and increased profit for the enterprise as a whole.

At the present stage of development of construction equipment, diamond cutting and concrete drilling are most often used.

However, other technologies for cutting high-strength materials, for example, plasma cutting technology for concrete, are not excluded.

This technology was developed and patented at the end of the 20th century.

Do-it-yourself plasma cutter from an inverter for plasma cutting of metal (7 photos + 2 videos)

But equipment that works on this principle has only now begun to be used.

What is the principle of plasma cutting based on? Very simple. Due to the effect of heat generated by a compressed plasma arc, even dense material, including concrete and reinforced concrete, melts. Then a jet of hot plasma very quickly removes the molten mass.

It is thanks to the acquisition of electrically conductive properties by inert gases, as well as their transformation into plasma, that plasma cutting of concrete is carried out.

After all, plasma is nothing more than an ionized gas heated to ultra-high temperatures, formed when an instrument is connected to a specific source of electricity.

A plasma torch is a special technical device that generates plasma, compresses an electric arc and blows plasma-generating gas into it.

It should be noted that this technology is becoming increasingly popular among specialists in industrial materials processing.

The difference between plasma cutting of concrete and oxygen lance cutting is that during the cutting process the material melts very intensively and is rapidly removed from the cut furrow.

During processing, the temperature reaches 6000°C.

The powder lance used in plasma cutting increases the heat to 10,000 - 25,000°.

Specialists use two different concrete cutting technologies to operate the equipment: plasma jet cutting and plasma-arc cutting technology.

How are they different?

The fact that the cutting arc lights up when cutting with a plasma jet between the electrode and the generating tip of the installation, but the object of influence is located outside the electrical circuit.

A high-speed plasma jet comes from the plasma torch, and it is its powerful thermal energy that cuts reinforced concrete, as well as other high-strength materials.

With the plasma arc cutting method, a plasma arc ignites between a non-consumable electrode and the plane of the material being cut. The cutting process occurs due to the action of several components: the energy of the near-electrode arc spot, as well as the plasma column and the torch escaping from it.

Plasma arc cutting is considered the most effective by practitioners and is often used in metal processing.

Plasma jet cutting technology is mainly used to process non-conductive materials.

Do-it-yourself plasma cutting - working technology

Safety precautions when working with a plasma lamp

Plasma cutting involves a number of hazards: electrical current, high plasma temperatures, hot metals and ultraviolet radiation.

Safety precautions when working with plasma cutting:

Preparing the air and plasma cutting machine for operation

How to connect all the elements of the air and plasma cutting device is described in detail in the instructions for the device, so immediately start adding additional shades:

The device must be installed in such a way that air is accessible.
Cooling the plasma cutter body allows you to work longer without interruption and have fewer coolant shutdowns. The location should be such that there are no drops of molten metal on the device.
The air compressor is connected to the plasma torch through a moisture-oil separator. This is very important because water entering the plasmatron chamber or oil droplets can lead to the destruction of the entire plasma or even its explosion. The air pressure transmitted to the plasmatron must correspond to the parameters of the device.
If the pressure is insufficient, the plasma arc will be unstable and will often go out. If the pressure is excessive, some parts of the plasma lamp may become useless.
If rust, mask or oil is applied to the workpiece, it should be better cleaned and removed. Although air cutting is plasma and can cut out brown parts, it is best to forget that toxic fumes are released when the rust is heated.
If you plan to cut into tanks that store flammable materials, they should be thoroughly cleaned.
If you want a smooth, parallel cut without dross or pitting, you must select the correct flow rate and cutting speed.
The following tables show the optimal cutting parameters for different metals of different thicknesses.

Table 2. Plasma cutting power and cutting speed for blank parts of various metals.

Air plasma cutting parameters

The first time you select the burner speed it will be difficult, you need experience.

Thus, this principle can be initially controlled: the plasma torch must be controlled so that the sparks are visible from the back of the workpiece. If no sparks are visible, the workpiece will not cut. Also note that operating the knife too slowly will negatively affect the quality of the cut, there are dimensions and bark on it, and the armpit can also be unstable to burn and even come out.

Plasma cutting

You can now continue the cutting process.

Before ignition of the electric arc, the plasmatron must be bubbled with air to remove accidental condensation and foreign particles.

To do this, press and release the ignition button. Thus, the device enters the cleaning method. After about 30 seconds, you can press and hold the ignition button.

As already described in the principle of operation of a plasma lamp, an auxiliary (pilot, pilot) arc lights up between the electrode and the tip of the nozzle. Typically it will not light for more than 2 seconds. Therefore, during this time it is necessary to illuminate the working (cutting) arc. The method depends on the type of plasma lamp.

If the plasma flash works directly, it is necessary to make a short circuit: after forming the length of the turn, you must press the ignition button - the air supply will stop and the contact will close.

The air valve then automatically opens, a stream of air flows out of the valve, ionizes, increases in size and drains the spark from the plasma lamp nozzle. Therefore, a working arc lights up between the electrode and the metal of the part.

Important! Contact arc ignition does not mean that the plasma torch should be applied or applied to the workpiece.

Plasma flame ignition

Once the indicator lights up, the light will go off.

If the working arc cannot be turned on for the first time, you must release the ignition button and press it again - a new cycle begins.

Features of producing a plasma lamp with your own hands from a converter: circuit, working stages, equipment

There are several reasons why the working arc may not be lit: insufficient air pressure, insufficient assembly of the plasma lamp, or other damage.

There are also cases where the cutting blade is turned off.

The reason will most likely be wearing the electrode or ignoring the distance between the plasma fuel and the workpiece surface.

Distance between lamp and metal

To learn more:

Plasma metal cutting with remote shutdown

Manual pneumatic plasma cutting involves the problem of observing the distance between the torch/nozzle and the metal surface.

When working with the hand, this is quite difficult, as breathing gets out of control and the cutting turns out to be uneven. The optimal distance between the nozzle and the workpiece is 1.6-3 mm; special spacers are used for observation, since the plasma itself cannot be pressed against the surface of the workpiece.

The ladders are located at the top of the nozzle, then the plasmatron mounted on the workpiece and cutting.

Keep in mind that the plasma lamp must be firmly perpendicular to the workpiece. Permissible deviations from 10 to 50 °. If the workpiece is too thin, the cutter can be held in a small corner, which will prevent severe deformation of the thin metal.

Melted metal should not fall into the nozzle.

You can master working with plasma cutting yourself, but it is important to remember safety measures, but also that the nozzle and electrode are consumables that require timely replacement.

Operating principle of a plasma cutter

When the power source is turned on, current begins to flow into the working area into the internal chamber of the plasma cutter, where the electric pilot arc between the nozzle tip and the electrode is activated. The forming arc fills the nozzle channel, where an air mixture begins to flow under high pressure, which, due to the high temperature of 6000-8000 °C, heats up greatly and increases in volume from 50 to 100 times. Due to the internal shape of the tapering nozzle, which has the shape of a cone, the air flow is compressed, heating up to an outlet temperature of 25,000 - 30,000 °C, forming a plasma jet that cuts the processed blank. Moreover, the initially activated pilot arc goes out and the working arc between the electrode and the metal product is activated. The resulting products from the effects of plasma combustion and metal melting are removed due to the force of the jet.

Fig. 1 Carrying out metal cutting operations where cutting or welding of a product is necessary, using a hand-made homemade one or a professional plasma cutter.

The optimal indicators for the workflow are:

gas supply at speeds up to 800 m/sec;
The current indicator can be up to 250 - 400 A.

Scheme 1. Drawing of the plasma cutting process of the workpiece.

A manual plasma cutter assembled using an inverter is mainly used for processing workpieces and is characterized by its low weight and economical power consumption.

Selection of plasma cutter components

To assemble a plasma cutter using drawings (based on an inverter), you need the following units with your own hands:

pressure gas supply device – compressor;
plasma cutter;
electrical device - an inverter that provides current to form an electric arc;
high pressure working hoses for air supply and protected electrical cable.

To supply air, we select a compressor taking into account the output volume for 1 minute. Manufacturing companies produce 2 types of compressors:

piston apparatus;
screw device (which has lower power consumption, is lighter, but 40-50% more expensive).

Rice. 2 Plasma cutter (device) with a cable set for the cutter and connection to the workpiece (as an anode).

Piston compressors are divided into oil and non-oil based, based on the drive principle - with a belt or direct connection of elements.
When operating compressors, a number of rules must be observed:

at negative ambient temperatures, it is necessary to preheat the oil contained in the crankcase;
It is necessary to regularly change the air (inlet) filter;
strictly control the oil level in the crankcase;
At least once every six months it is necessary to completely clean the units from foreign impurities;
Upon completion of work, it is necessary to relieve pressure (using a regulator) in the system.

During repair work, products from ORLIK KOMRESSOR (Czech Republic) are often used. The ORL 11 device allows cutting workpieces using a current of 200-440 A and an air-gas flow coming under pressure.

The equipment set includes:

compressor;
block of main filters for the air-gas mixture;
gas dryers;
receiver.

At the outlet of the unit, purified air free of oil, dust and moisture arrives. An example of screw compressors is the CA series product from Atlas Copco (Sweden). The device is equipped with an automatic condensate removal system for air purification.

A plasmatron is a special device in which, using an electric current, an electric arc is formed that heats air supplied under pressure in a chamber to form a cutting plasma stream.

The cutter consists of elements:

special holder with electrode;
an insulating gasket separating the nozzle and the electrode assembly;
plasma generation chambers;
output nozzles for the formation of a plasma jet (see drawings);
supply systems;
tangential plasma supply elements (on some models) to stabilize the arc discharge.

According to the method of performing work (welding or cutting), cutters are divided into:

Double-flow, used in reducing, oxidizing and inert environments.
Gas inert (using helium, argon), reducing (hydrogen, nitrogen).
Gas oxidizing (the air-gas mixture includes oxygen).
Gas using a stabilizing (gas-liquid) arc.

The plasmatron cathode is made in the form of a rod or inserts made of tungsten, hafnium, and zirconium. Plasmatrons with a sleeve cathode, used for cutting using an air-gas flow under pressure, have become widespread.

To cut products in an oxidizing environment, a hollow cathode made of copper with a forced cooling system using water is used.

Rice. 3 Portable device (inverter) for plasma cutting.

Double-flow plasma cutters (inverter) are equipped with 2 coaxial nozzles, external and internal. The gas entering the internal nozzle is considered primary, and the external one is considered additional, and the gases can have different compositions and volumes.

A plasma cutter with arc stabilization due to the supply of a gas-liquid flow has a difference, which is the supply of water to the torch chamber to stabilize the state of the arc discharge.

To activate the working arc, a workpiece is used as an anode, which is connected to the inverter using clamps and a cable.

As a power plant for carrying out the plasma cutting process, a device (inverter) is used that provides the necessary current strength, which has a higher efficiency than a transformer, but the transformer’s metal processing capabilities are much higher.

Scheme 2. Drawing of the plasmatron power supply with your own hands.

Inverter advantages:

the ability to uniformly change parameters;
light weight;
stable state of the working arc;
high quality cutting or welding.

The equipment set also includes a set of high pressure hoses for connecting a stationary compressor and an electrical connecting cable.

To assemble a plasma cutter with your own hands, a device diagram is developed indicating the necessary units that meet the required characteristics, which should include all additions and changes used during assembly with the necessary calculations of the most important indicators. You can assemble a homemade plasma cutter with your own hands using ready-made blocks and assemblies produced by specialized companies; in this case, it is necessary to make accurate calculations and coordinate the output parameters of the ongoing processes.

Features of marking plasma cutters

Plasma cutters produced by industrial enterprises can be divided into 2 categories:

machine cutting units;
manual.

Hand cutters are more affordable if you need to do it yourself. Manufactured models have special markings:

MMA - the device is designed for arc welding using an individual electrode;
CUT - a device (plasma cutter) used for cutting metal;
TIQ - the device is used for work where argon welding is necessary.

Manufacturing enterprises produce equipment for metal cutting:

Profi CUT 40 (RT-31 burner, permissible cut thickness – 16 mm, air-gas mixture flow rate – 140 l/min, receiver volume 50 l);
Profi CUT 60 (P-80 burner, permissible workpiece cutting thickness - 20 mm, air-gas mixture flow rate - 170 l/min.);
Profi CUT 80 (burner R. – 80, permissible cutting thickness of the workpiece – 30 mm, air-gas mixture flow rate – 190 l/min.);
Pro CUT 100 (burner A-101, permissible cutting thickness of the workpiece - 40 mm, air-gas mixture flow rate - 200 l/min.), receiver with a volume of 100 l.

Making a CNC plasma cutter with your own hands

A CNC-equipped plasma cutter must have a unified assembly using drawings made on the basis of the prepared technical specifications for the product, which include:

work table;
belt transmission;
function control unit;
step elements;
linear guides;
cutting height adjustment system;
CNC control unit;

Scheme 3. Drawing of an inverter device for plasma cutting.

Drawings of all plasma cutter blocks can be purchased taking into account the required power and installation characteristics and financial capabilities, or you can do it yourself if you have experience and knowledge.

To complete and assemble a CNC machine, it is necessary to manufacture a number of elements using drawings:

table base for welding;
a durable frame is assembled and then painted;
support posts are attached;
the water table is assembled;
fastenings and the slats themselves are installed;
linear guides are mounted;
the table cover is installed;
guides are installed together with the portal;
the portal is equipped with a motor and signal sensors;
the guides, the Y guide motor and the positioning control rack are mounted;
a guide equipped with a motor is mounted;
a metal surface signal sensor is mounted;
a tap is installed to remove water from the table;
connecting cables-channels X.Z.Y are laid;
the wires are insulated and covered with cladding;
the working cutter is mounted;
The CNC device is assembled and installed.

Carrying out operations for the manufacture and assembly of a CNC plasma torch should only be carried out in the presence of qualified specialists. The device diagram (drawings) must include all the necessary elements to ensure high quality of work and safety of metal cutting. Equipping enterprises with CNC equipment can increase labor productivity and the complexity of operations. Make production processes performed using CNC equipment more economical by increasing labor productivity and reducing the processing speed of products.

You may also be interested in the following articles:

How to make a wood planer with your own hands How to make a guillotine for cutting metal with your own hands?