Do-it-yourself plasma cutter from an inverter. Making a plasma cutter with your own hands from an inverter. Features of the production of a plasma lamp with your own hands from the converter: scheme, working steps, equipment

Do-it-yourself plasma cutter from an inverter. Making a plasma cutter with your own hands from an inverter. Features of the production of a plasma lamp with your own hands from the converter: scheme, working steps, equipment

21.02.2022 Insulin

Plasma cutting is very widely used in various sectors of construction and manufacturing. The convenience of work and the quality of the final result of this processing method have gained immense popularity among specialists. That is why many novice craftsmen and even individual teams often ask how to make a plasma cutter from an inverter with their own hands, since the original device is quite expensive and everyone wants to save money using the available equipment.

Purpose

First of all, this device allows you to quickly cut various metals. This is very convenient when creating all kinds of designs without using another tool. Also, a manual plasma cutter can use different electrodes with which welding is performed.

The process of joining metals using a unit involves the use of the soldering method. Therefore, the main advantage of such equipment is that thanks to it, completely different metals can be joined using high-temperature solder.

The use of such a tool in blacksmithing deserves special attention. The fact is that with its help it is possible to harden, anneal, thermally clean and weld ferrous and non-ferrous metals together. Therefore, its presence in such production is a necessity, which greatly saves time.

Design features

When assembling a plasma cutter from an inverter with your own hands, you need to know its device and equipment. However, it is immediately worth noting the fact that some parts are much easier to purchase ready-made than to create it yourself.

A typical apparatus consists of a plasma torch, which is also very often called a “torch”, an air compressor and a hose and cable package.

A power source is needed in order to supply the device with a current of a certain strength. In fact, it is the heart of the device, and its technical characteristics depend on it.
No less important is the cutter or plasma torch itself. It has a certain design, which is significantly different from similar products on It is immediately worth noting that when creating a plasma cutter from an inverter with your own hands, it is better to purchase this part in a store. This will greatly facilitate operation and solve a lot of problems with the replacement of some elements.
The compressor in the device, operating with a current of no more than 200 A, is necessary to supply air, which performs the functions of cooling and allows you to create a dense plasma beam. For more powerful installations, argon, helium, hydrogen, nitrogen, oxygen, and mixtures thereof are used.
The cable-hose package performs the functions of a connecting element through which electric current flows from the power source and air from the compressor to the plasma torch.

Transformer or Inverter

Typically, a plasma cutting machine uses an inverter or a power source. Both of these options are great for self-production, but before making a choice, you need to know what are the differences between them and how this affects the technical characteristics of the final product.

A typical plasma cutter from a welding inverter is the most efficient and economical. It is 30% more efficient than units using a transformer and produces a stable arc. However, such a device can only perform strictly defined tasks, working with materials of a certain thickness.
When using a transformer, you need to remember that this product is rather bulky and requires space for placement. At the same time, its power makes it possible to work with large parts of a rather large thickness. That is why it is installed in stationary premises or on special mobile platforms.

Given these features of both units, it is best to create a plasma cutter from an inverter, connecting a ready-made power source and other parts in a certain sequence with your own hands.

Necessary equipment

First of all, you need to purchase all the necessary items. However, it is immediately worth noting the fact that in order for the installation to turn out to be of high quality and practical, many of them will have to be purchased ready-made.

inverter

This unit can be taken from the finished welding machine. Its cost is relatively low, although it can be considered the most expensive investment in this project. Usually, when choosing this device, specialists are guided by a certain power. It is determined, focusing on the scope of work and its specifics.

Some experts prefer to create an inverter on their own, selecting parts for specific needs or using existing materials. However, as practice shows, it is much easier to use a ready-made unit, since it is more reliable, and certain standards were used in its manufacture.

Cutter

When creating a homemade plasma cutter, craftsmen often make a mistake when trying to completely create the cutter itself, which will be supplied with current and air. The fact is that this product consists of a handle, supply elements and a nozzle. At the same time, with intensive use, the latter wears out very quickly and needs to be replaced periodically. That is why it is recommended to purchase a factory nozzle, and the remaining elements can be made independently. However, professionals believe that it is not worth spending a lot of effort and money on the independent creation of this element, since it is much easier to purchase it ready-made.

Compressor

Usually, a plasma cutter, the instructions for which require the use of an inert gas or oxygen, is preferred to be connected to cylinders with special mixtures. The fact is that it is they that make it possible to obtain the densest plasma beam and create the best cooling. However, for domestic use, it is easier and more economical to use a conventional compressor.

It is immediately worth noting the fact that this unit can be created independently, using a conventional cylinder as a receiver. The compressor itself can be taken from a ZIL car or from a refrigerator. However, it is very important to correctly adjust the pressure. Usually, specialists do this empirically directly at work.

Cable-hose package

This equipment can be purchased as a set for a specific unit, or separately from each other. The fact is that it consists of hoses that are designed for the pressure necessary for work, and a cable of a certain section. It is worth remembering that the conductor is selected for the power of the inverter itself, because otherwise it will overheat and there may be a risk of fire and even electric shock.

Assembly

The whole manufacturing process consists in connecting the plasma cutter nozzle to the compressor and inverter. For this, a cable-hose package is used. It is best to use special clamps and clips here, which allow both assembly and disassembly to be carried out very quickly. This approach makes it possible to obtain a compact device that can be conveniently transported to the place of work, which is highly appreciated by specialists.

Considering that the principle of operation of the plasma cutter is based on the use of gas, it is worth taking care of the availability of spare gaskets in advance, which are used when connecting hoses. This is especially important if the unit is constantly disassembled and transported. An elementary lack of this element can stop all work.
It is also very important to have a spare nozzle for the cutter. This part fails most often during prolonged use, because it is affected by high temperatures and rapid cooling.
It is important to remember that inverters from can be quite expensive, and the price of the issue depends on its power. Therefore, before purchasing it, it is worth deciding on the output characteristics and needs for which the device is being created. This will help to save a lot and get a unit that is ideal for specific jobs.
To work with such a tool, you will need to purchase special electrodes made of refractory metals. Materials of thorium, hafnium, zirconium or beryllium are best suited for these purposes. However, it is worth remembering that some metals emit harmful substances when heated and can harm the welder. For example, thorium is highly toxic, while beryllium forms radioactive oxides. That is why it is easier and safer to use hafnium.
It is important to remember that the operating temperature of the plasma in such units reaches 30,000 degrees. Therefore, when working, it is necessary to strictly observe safety rules so as not to harm yourself or others or cause a fire. That is why only qualified specialists are allowed to work with such a tool.
During operation, the vortex air flow must not be disturbed. Otherwise, two arcs may form, which will completely disable the device. Given this, experts prefer to use factory cutters, believing that it is better to spend money once than to constantly repair the inverter itself.
When performing the same type of work, certain modifications can be made to the device. For example, some craftsmen make a special protective cover for the hand or modify the nozzle. However, it is worth remembering that all these additions should not affect the operation of the equipment itself and should not violate safety rules.

Output

Having considered the question of how to make a plasma cutter using an inverter, you can understand that almost all the necessary equipment will have to be purchased from various manufacturers. In fact, the manufacture itself is an elementary assembly. However, even with this approach, you can save a lot, since a complete set of a new unit will cost several times more.

Plasma cutting is a method of processing metal empty parts with a plasma stream. This method makes it possible to cut the metal, since it is enough to be carried out in such a way that the material has an electrical conductivity. Compared to similar methods, plasma cutting of metals allows for a faster and better process without the use of massive rollers and special additives.

In this way, various metal metal sheets, pipes of different diameters, shaped and sorted products can be processed. During processing, a high-quality cut is obtained, which requires minimal cleaning effort. Even with this technology, it is possible to eliminate various imperfections 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 efficient method.

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

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

The quality of plasma cutting of metals

Plasma cutting technology

Plasma cutting is carried out using a special device that has dimensions similar to those of a conventional welding machine. At the beginning, these devices were large, but during the improvement they became smaller.

The device is connected to a 220 V power supply for household appliances and 380 V for industrial use.
In the production process, cutting is carried out using CNC machines, which are one or more burners with mechanisms for moving them.

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

To create a plasma jet, it is necessary to connect the system to a compressor or an air line.

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

Manual cutting of steel pipe

Circular cutting of steel pipe
self-propelled machine

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

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

Manual cutting of metals on a sample

Plasma Leaf Essence

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

Manual devices have a cutting head equipped with an electrically operated 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 sheet is more efficient, but the cost of 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, a pilot arc starts, which is initiated by a discharge caused by a DC generator. Thanks to the arc, a plasma torch 20-40 mm long is created. When the torch touches 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 a 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.

It may not be as efficient as a gas-fired power plant for renovation and construction work, in the absence of a central system for electricity and compressed air. In this case, a sufficiently strong generator is needed to provide power to the device and the compressor.

Similar to gas flame cutting, this technique can be used to process empty parts of various sizes and shapes.

Plasma cutting of large diameter pipes does not pose any problems: it is done manually or with self-propelled machines. The fixed burner rotates outside the tube. The use of self-propelled machines ensures accurate and even cutting. The handling of shaped and sorted rolled products can also be automated in an industrial setting.

Benefits of using SIBERIAN devices:

Versatility (the ability to apply to any metal, including non-ferrous and refractory metals);
Cutting speed;
High surface quality after cutting;
Economy (using compressed air);
Almost complete absence of thermal deformations on the product to be reduced;
Mobility, not the heavy weight of air-cooled units;
Easy to use.

Arc ignition devices

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

Ignition by a short circuit is carried out by short-term contact of the electrode and the product and their subsequent dilution. The current, through the microprotrusions of the electrode, heats them up to the boiling point, and the field that occurs when the electrodes are separated ensures the emission of electrons sufficient to initiate the arc.

With this ignition, the transfer of the 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, maintaining the current at this level until the arc is formed, and only then a smooth increase to the working one.

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

Basic requirements for devices for ignition through the gap (arc starters or oscillators):

1) must ensure reliable arc excitation;

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

Exciters can be designed to excite an arc of direct or alternating current. In the latter case, the exciters are subject to a number of specific requirements relating to the moment of ignition of the arc. The scheme of the oscillator OSPZ - 2M is shown in fig.

Rice. 5.5. Schematic diagram of the OSPZ-2M oscillator. F1 - fuse; PZF - anti-interference filter; TV1 - step-up transformer; FV – arrester; Cg - capacitor of the oscillatory circuit; Cn - isolating capacitor; TV2 - high voltage transformer; F2 - fuse.

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

After charging it to the breakdown voltage of the arrester 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 equal to 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 through the separating capacitor Cn and the fuse F2 to the gap between the electrode and the product.

In this case, a spark arises 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 initiated, the oscillator automatically turns off.

It should be noted that the oscillator has a high voltage.

For humans, it is not dangerous due to the low power of the source. However, if there are semiconductors in the source circuit (diodes, thyristors, etc.), then their breakdown by the oscillator voltage is possible.

To exclude 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?

Scheme of connecting the oscillator to the power source.

The DZ protection inductor for the high frequency of the oscillator has a very large inductive resistance and does not pass the oscillator voltage to the source.

The protective capacitor C3, on the contrary, has a very low resistance for high frequency, protecting the source from the high frequency and high voltage of the oscillator. The isolation capacitor Cp protects the oscillator from the power supply voltage.

Recommendations. Typical MTP Operator Mistakes in Plasma Cutting and How to Avoid Them

Using consumables until they fail

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

The use of badly worn nozzles and electrodes can not only lead to defective cutting of the part, but also cause costly repairs to the flame torch and even the plasma cutter, during which the plasma cutter will be idle.

The failure of nozzles and electrodes can be easily prevented by several signs that are given out by worn consumables. An experienced operator 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, if necessary, to reduce the height of the plasma torch during punching, will always tell you when it is time to change the electrode.

Also, one of the best ways to assess the condition of the torch parts is the quality of the cut. If the cut quality suddenly begins to deteriorate, then this is an occasion to check the condition of the nozzle and electrode. A reasonable approach is to keep a log of the average electrode or nozzle run 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, cutting stainless steel requires more frequent replacement of consumables.

Once having determined the average life time of the electrode for each specific type of cut parts from such a log, it is possible to carry out a scheduled replacement of nozzles and electrodes without leading to the appearance of defects in the cut parts or to the breakdown of the flame cutter.

Excessive replacement of nozzles and electrodes

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

Excessive replacement of consumables is also very common among CNC machine tool operators, and in particular plasma cutting machines.

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

1. If the nozzle has deformations on the outside or inside.

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

2. If the nozzle outlet is not circular in shape. With a high piercing height, if the movement begins before the metal is cut, then the arc deviates from the perpendicular to the sheet and passes through the edge of the nozzle hole.

To determine if the electrode is worn, you need to look at the silver-colored metal insert on the end of the copper electrode (usually an alloy of zirconium, hafnium or tungsten is used). In the general case, the electrode is considered to be operational if this metal is present 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 be up to 2.2 mm. The vane only needs to be replaced if a thorough inspection reveals clogged holes, cracks, arc marks, or heavy wear.

Swirlers are especially often replaced prematurely. The same goes for protective caps, which only need to be replaced in case of physical damage. Very often 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.), on its thickness, the arc current set on the plasma cutting machine, plasma-forming and shielding gases, etc.

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

The use of consumables (nozzles, electrodes) that do not correspond to the current plasma cutting mode usually leads to an accelerated failure of consumables and 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 best cut quality is achieved when the current on the plasma cutter is set to 95% of the rated cutting current for which the nozzle is rated. If the plasma cutting mode is set with a low arc current, then the cut will be slagged, and there will be a significant amount of burrs on the reverse side of the cut parts, the flame cut will be of unsatisfactory quality.

If the current setting on the plasma cutter is too high, the nozzle life will be greatly reduced.

Incorrect assembly of the plasma cutter

The flame cutter must be assembled in such a way that all its parts fit snugly together, and there would be no “loose” impression.

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 the dirt and metal dust generated during plasma cutting does not contaminate the plasma torch.

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

Failure to perform regular scheduled maintenance of the plasma torch

A plasma cutter can operate for many months and even years without proper maintenance.

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

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

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

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

The constant pressure of the plasma gas is very important for maintaining the cutting arc and for a quality cut. Plasma gas overpressure is a common cause of difficult plasma arc ignition when all other requirements for settings, parameters and plasma cutting process are fully satisfied. Too high plasma gas pressure causes rapid electrode failure.

Plasma-forming gas must be purified from impurities, because. its purity has a strong influence on the service life of consumables and the plasma torch as a whole. Compressors supplying air to plasma cutters tend to contaminate the air with oils, moisture and fine dust particles.

Punching at a low height of the plasma torch above the metal

The distance between the workpiece and the cut of the plasma torch nozzle 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 torch above the metal can significantly affect the bevels on the edges of the parts being cut. The height of the plasma torch above the metal during piercing is particularly important.

A common mistake is punching when the plasma torch is not high enough above the metal. This causes molten metal to spurt out of the hole formed during punching and hit the nozzles and protective caps, destroying these parts.

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

If the arc is "drawn" into the plasma torch, then the electrode, nozzle, swirler, and sometimes the entire cutter are destroyed.

The recommended punching 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 large, the pilot arc does not reach the surface of the metal sheet, therefore, the cutting process at the recommended height cannot be started. However, if the punching is carried out at a height at which the plasma cutter can ignite the arc, then splashes of molten metal can fall on the plasma torch.

The solution to this problem can be the use of a technological technique called "jumping". When the command to start cutting is processed, plasma cutting is turned on at a low height, then the cutter rises up to the specified jump height, at which the metal splashes do not reach the cutter.

After working off the punching, the cutter lowers to the height of the cut 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 cutting speed is set too low, the cut parts will have a large amount of flash and a variety of metal buildup along the entire length of the cut at the bottom of the edge of the parts.

Slow cutting speeds can cause wide cuts and a lot of spatter on the top surface of parts. If the cutting speed is set too high, the arc will bend back, causing deformation of the edges of the cut part, there will be a narrow cut, and small beads of flash and flash at the bottom of the cut edge.

Burr formed at high cutting speed is difficult to remove. With the right cutting speed, the amount of burr, flash and metal sagging will be minimal. The surface of the flame cut edge at the right speed should be clean and machining should be minimal. At the beginning and end of the cut, a "deviation" of the arc from the perpendicular may occur.

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

This is because the arc cannot keep up with the torch. The deflection of the arc leads to the fact that it cuts into the side surface of the nozzle, thereby violating its geometry. When cutting from an edge, the center of the nozzle hole must be exactly on the edge line 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 on, passes over the edge of the sheet, or if the lead out line crosses the old cut. Fine tuning of the timing parameters is necessary to reduce this effect.

Mechanical damage or breakage of the plasma torch

Collisions between the torch and the sheet, cut parts, or edges of the cutting table can completely destroy the torch. Collisions between the torch and the parts to be cut can be avoided by setting idle passes around rather than over the parts being cut out in the part program.

For example, MTC-Software's ProNest optimal nesting program has this feature, which allows you to minimize the risk of plasma torch breakdown and save significant money. The torch height stabilizers also provide some protection against metal collisions. However, if only the arc voltage torch height sensor is used, “pecking” may occur at the end of the cut, as the voltage of the arc changes as a result of its "deviation" and the torch moves down to compensate.

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

In this way, a skilled plasma cutting machine operator can save their business a huge amount of money, time and overhead on plasma cutting.

The result of a good MTP operator will be an increased profitability of plasma cutting and an increase in the profit of 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 are not excluded, for example, the technology of plasma cutting of concrete.

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 the equipment that works according to this principle has only just 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, it occurs during the melting of even dense material, including concrete and reinforced concrete. Then a jet of hot plasma very rapidly 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, which is formed when a tool 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 the industrial processing of materials.

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

During processing, the temperature reaches 6000°C.

Increases the heat of a powder lance used in plasma cutting to 10,000 - 25,000°.

Specialists in the operation of the equipment use two different technologies for cutting concrete: 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 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 flame escaping from it.

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

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

Do-it-yourself plasma cutting - work technology

Plasma Lamp Safety Precautions

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 device for cutting air and plasma is described in detail in the instructions for the device, so immediately proceed to additional shades:

The device must be installed in such a way that air is available.
Cooling the body of the plasma cutter allows you to work longer without interruption and less likely to turn off the cooling device. The place must 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 that gets into the plasma torch chamber or oil droplets can lead to the destruction of the entire plasma or even its explosion. The air pressure transmitted to the plasma torch must correspond to the parameters of the device.
If there is not enough pressure, the plasma arc will be unstable and often extinguished. 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 cutting and cuts out brown parts, it's best to forget that toxic fumes are released when rust is heated.
If you plan to cut tanks that store flammable materials, they must be thoroughly cleaned.
If you want a smooth, parallel cut without dross or pits, you must select the correct flow rate and cutting speed.
The following tables show the optimal cutting parameters for different metals with different thicknesses.

Table 2. Power and cutting speed with plasma cutting machine for blank parts of various metals.

Air plasma cutting parameters

The first time you choose a 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 sparks are not visible, the workpiece is not cut. Also note that too slow control of the knife negatively affects the quality of the cut, it has dimensions and bark, and the armpit can also be unstable to burn and even come out.

Plasma cutting

Now you can continue the cutting process.

Before ignition of the electric arc, the plasma torch must be sparged 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. As a rule, it does 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, a short circuit must be performed: after the turn length has been formed, the ignition button must be pressed - the air supply will stop and the contact will close.

Then the air valve automatically opens, the air flow flows out of the valve, ionizes, increases in size, and exhausts the spark from the plasma lamp nozzle. Therefore, the working arc lights up between the electrode and the metal of the part.

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

Plasma Flame Ignition

As soon as the indicator lights up, the light will turn off.

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

Features of the production of a plasma lamp with your own hands from the converter: scheme, working steps, equipment

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

There are also cases where the cutting disc is off.

The reason is likely to be wearing the electrode or ignoring the distance between the plasma fuel and the surface of the workpiece.

Distance between lamp and metal

To learn more:

Plasma cutting metal with remote shutdown

Hand held 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 cut is 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.

Ladders are located at the top of the nozzle, then a plasma torch mounted on the workpiece, and cutting.

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

The molten metal must not fall into the nozzle.

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

Some plans for the future

As practice has shown, this design also turned out to be experimental. Finally got stable work within 5 - 10 minutes. But it is still far from complete perfection.

Replaceable anodes gradually burn out, and it is difficult to make them from copper, and even with a thread, it would be better without a thread. The cooling system does not have direct liquid contact with a replaceable anode, and because of this, heat transfer leaves much to be desired. A direct cooling option would be more successful.

The details are machined from the semi-finished products at hand, the design as a whole is too complicated to repeat.

It is also necessary to find a powerful isolation transformer; without it, it is dangerous to use the plasma torch.

And at the end, more pictures of the plasma torch when cutting wire and steel plates. Sparks fly almost a meter :)

Unlike, the inverter is compact, lightweight and highly efficient, which explains its popularity in home workshops, small garages and workshops.

It allows you to cover most of the needs for welding, but for high-quality cutting, a laser or plasma cutter is required.

Laser equipment is very expensive, plasma cutter is also expensive. small thickness has excellent characteristics, unattainable when using electric welding. At the same time, the power unit of the plasma cutter and in many respects have the same characteristics.

There is a desire to save money, and with a little refinement, use it for plasma cutting. It turned out that this is possible, and you can find many ways to convert welding machines, including inverter ones, into plasma cutters.

The plasma cutting machine is the same welding inverter with an oscillator and a plasma torch, a mass cable with a clamp and an external or internal compressor. Often the compressor is used external and is not included in the package.

If the owner of the welding inverter also has a compressor, then you can get a home-made plasma cutter by purchasing a plasma torch and making an oscillator. The result is a versatile welding machine.

How the burner works

The operation of the plasma welding and cutting apparatus (plasma cutter) is based on the use of plasma, the fourth state of matter, as a cutting or welding tool.

It requires high temperature and high pressure gas to produce it. When an electric arc is created between the anode and cathode of the burner, a temperature of several thousand degrees is maintained in it.

Plasma formation

If a jet of gas is passed through the arc under such conditions, it will ionize, expand in volume by several hundred times and heat up to a temperature of 20-30 thousand ° C, turning into plasma. High temperature almost instantly melts any metal.

Unlike a cumulative projectile, the process of plasma formation in a plasma torch is adjustable.

The anode and cathode in the plasma cutter are at a distance of several millimeters from each other. The oscillator generates a pulsed current of large magnitude and frequency, passes it between the anode and cathode, which leads to the occurrence of an electric arc.

After that, a gas is passed through the arc, which is ionized. Since everything happens in a closed chamber with one outlet, the resulting plasma breaks out at great speed.

At the outlet of the plasma cutter torch, it reaches a temperature of 30,000 ° and melts any metal. Before starting work, a mass wire is connected to the workpiece using a powerful clamp.

When the plasma reaches the workpiece, an electric current begins to flow through the mass cable and the plasma reaches its maximum power. The current reaches 200-250 A. The anode-cathode circuit is broken using a relay.

cutting

When the main arc of the plasma cutter disappears, this circuit turns on again, preventing the plasma from disappearing. Plasma plays the role of an electrode in electric arc welding, it conducts current, and due to its properties creates a high temperature area in the area of contact with the metal.

The area of contact between the plasma jet and the metal is small, the temperature is high, and heating occurs very quickly, so there are practically no stresses and deformations of the workpiece.

The cut is even, thin and does not require further processing. Under the pressure of compressed air, which is used as the working fluid of the plasma, the liquid metal is blown out and a high-quality cut is obtained.

When using inert gases with a plasma cutter, high-quality welding can be carried out without the harmful effects of hydrogen.

Do-it-yourself plasma torch

When making a plasma cutter from a welding inverter with your own hands, the most difficult part of the work is the production of a high-quality cutting head (plasmatron).

Tools and materials

If you make a plasma cutter with your own hands, it is easier to use air as a working fluid. For manufacturing you will need:

Plasma cutter consumables in the form of nozzles, an electrode should be bought at a welding equipment store. They burn out during cutting and welding, so it makes sense to purchase several pieces for each nozzle diameter.

The thinner the metal to be cut, the smaller the opening of the plasma cutter torch nozzle should be. The thicker the metal, the larger the nozzle opening. The most commonly used nozzle with a diameter of 3 mm, it covers a wide range of thicknesses and types of metals.

Assembly

The plasma cutter torch nozzles are attached with a clamping nut. Directly behind it is an electrode and an insulating sleeve, which does not allow an arc to occur in an unnecessary place in the device.

Then a flow swirler is located, which directs it to the desired point. The whole structure is placed in a fluoroplastic and metal case. A pipe is welded to the outlet of the tube on the handle of the plasma cutter torch for connecting an air hose.

Electrodes and cable

The plasma torch requires a special electrode made of refractory material. They are usually made from thorium, beryllium, hafnium and zirconium. They are used because of the formation of refractory oxides on the electrode surface during heating, which increases the duration of its operation.

When used at home, the use of hafnium and zirconium electrodes is preferable. When cutting metal, they do not produce toxic substances, unlike thorium and beryllium.

The cable from the inverter and the hose from the compressor to the plasma cutter torch must be laid in one corrugated pipe or hose, which will ensure the cooling of the cable in case of heating and ease of use.

The cross section of the copper wire must be selected at least 5-6 mm2. The clamp at the end of the wire must ensure reliable contact with the metal part, otherwise the arc from the duty one will not spread to the main arc.

The compressor at the outlet must have a reducer to obtain a normalized pressure on the plasma torch.

Options for direct and indirect action

The design of the plasma cutter torch is quite complicated; it is difficult to perform at home, even with various machines and tools, without a highly qualified worker. That's why the manufacture of plasma torch parts should be entrusted to specialists, and even better to buy in the store. The direct-acting plasma torch torch was described above; it can only cut metals.

There are plasma cutters with indirect action heads. They can also cut non-metallic materials. In them, the role of the anode is performed by the nozzle, and the electric arc is inside the plasma cutter torch, only the plasma jet comes out under pressure.

With a simple design, the device requires very precise settings; it is practically not used in amateur production.

Refinement of the inverter

To use an inverter power source for a plasma cutter, it needs to be modified. An oscillator with a control unit must be connected to it, which will act as a starter that ignites the arc.

There are quite a few oscillator circuits, but the principle of operation is the same. When the oscillator is started, high-voltage pulses pass between the anode and cathode, which ionize the air between the contacts. This leads to a decrease in resistance and causes an electric arc to occur.

Then the gas solenoid valve is turned on and under pressure, air begins to pass between the anode and cathode through an electric arc. Turning into plasma and reaching the metal workpiece, the jet closes the circuit through it and the mass cable.

The main current of approximately 200 A begins to flow through the new electrical circuit. This causes the current sensor to trip, which turns off the oscillator. The functional diagram of the oscillator is shown in the figure.

Functional diagram of the oscillator

In the absence of experience with electrical circuits, you can use a factory-made oscillator of the VSD-02 type. Depending on the connection instructions, they are connected in series or in parallel to the plasma torch power circuit.

Before making a plasma cutter, you must first determine which metals and what thickness you want to work with. A compressor is enough to work with ferrous metal.

Nitrogen is required for cutting non-ferrous metals, high-alloy steels require argon. In this regard, a trolley for transporting gas cylinders and reduction gears may be required.

Like any equipment and tool, a plasma head welding machine requires some skill from the user. The movement of the cutter must be uniform, the speed depends on the thickness of the metal and its type.

Slow motion results in a wide cut with jagged edges. Fast movement will cause the metal not to be cut in all places. With proper skill, you can get a high-quality and even cut.

Plasma cutting is a fairly popular operation, especially when it comes to cutting thick metal parts or blanks. The process is fast, the edges of the metal remain smooth. But such a device is not cheap. Therefore, many craftsmen make a plasma cutter for themselves with their own hands from different types of equipment, combining them into one design. Their connection scheme is simple, the main thing is to choose the right devices according to the necessary technical characteristics.

Plasma cutting is based on ionized gas, which flies out of the torch nozzle at high speed. This gas is the same plasma. What is she doing.

In fact, this ionized medium is an excellent conductor of electric current, which flows from the electrode to the metal workpiece.
The plasma heats the metal to the required temperature.
It also blows off the molten metal, freeing up the cutting space.

This means that in order to create a plasma, a gas and a source of electricity are needed. And these two components must be connected in one place. Therefore, plasma cutting equipment consists of a gas cylinder, an increased power source and a torch in which an electrode is installed.

The design of the cutter is made in such a way that gas passes around the electrode and, in the form heated from the electrode, bursts out through a small hole. The small diameter of the hole and the gas pressure create the required plasma velocity. When making homemade plasma cutting, you just need to purchase a ready-made cutter and not think about creating it. Because everything is already thought out in it, plus the factory version is a guarantee of safety.

As for gas, all options have long been abandoned, leaving compressed air. You can get it today very simply - purchase and install a compressor.

There are certain conditions that guarantee the quality of plasma cutting.

The current on the electrode should not be less than 250 A.
Compressed air must be supplied to the torch at a speed within 800 m/s.

How to make a plasma cutter with your own hands

The basics of plasma cutting are clear, the design of the plasma cutter is also clear, you can start assembling it. By the way, this does not require special drawings.

So what will be needed.

We need to find a source of electricity. The simplest option is a welding transformer or inverter. For many reasons, an inverter is better. For example, it has a stable current value, without drops. It is more economical in terms of electricity consumption. You will have to pay attention to the current that the welding machine produces. Its value should not be less than 250 amperes.
Source of compressed air. Here, the compressor is unchanged. But what? The main parameter is air pressure. It will be necessary to pay attention to it. 2.0-2.5 atm. - will be fine.
The cutter can be purchased at the store. And that would be the perfect solution. If there is a cutter for argon welding, then it can also be converted to plasma cutting. To do this, you will have to make a nozzle in the form of a nozzle from copper, which is inserted into the argon welding cutter.
A set of hoses and cables for connecting all parts of a homemade plasma cutter. Again, the kit can be purchased at the store as a single connecting element.

Here are four elements with which a homemade plasma cutter is assembled.

Auxiliary elements and materials

What else you need to pay attention to when assembling a plasma cutting machine with your own hands. As mentioned above, the main characteristic of a plasma cutter is the diameter of its hole. What size should it be in order for the quality of the cut to be maximum. Experts believe that a diameter of 30 mm is the optimal size. Therefore, when buying a cutter in a store, you need to pay attention to whether there is a nozzle with such a hole in its kit.

In addition, it is necessary to select a nozzle with a significant length. It is this size that allows the jet of compressed air to gain the required speed. From what the metal cut turns out to be neat, and the cutting process itself is quick and easy. But you should not buy a nozzle that is too long. Such a device is quickly destroyed under the influence of high temperatures.

As for the choice of an electrode for a plasma cutter, then it is necessary to pay attention to the alloy from which it is made. For example, if beryllium is included in the alloy, then this is a radioactive substance. It is not recommended to work with such electrodes for a long time. If thorium is included in the alloy, then at high temperatures it releases toxic substances. The ideal electrode for plasma cutting, which alloy contains hafnium.

Checking the plasma cutter

So, the hoses connect the cutter and the compressor, the cable cutter and the inverter. Now you need to check if the assembled structure works. All units are turned on, the button for supplying electricity to the electrode is pressed on the cutter. In this case, an arc is formed with a temperature of 6000-8000C. It slips between the metal of the electrode and the nozzle.

After that, compressed air begins to flow into the cutter. Passing through the nozzle and heating up from the electric arc, it expands sharply tenfold and at the same time acquires conductive properties. That is, an ionized gas is obtained.

It passes through a narrowed nozzle, while acquiring a speed in the range of 2-3 m/s. But the plasma temperature rises to 25000-30000C. The most important thing is that the arc, with which the compressed air was heated and turned into plasma, goes out as soon as the plasma begins to act on the metal workpiece prepared for cutting. But then the second, so-called working arc, which acts locally on the metal, turns on. Right in the cut zone. Therefore, the metal is cut only in this zone.

If, when checking the operation of a plasma cutter, you managed to cut metal with a thickness of at least 20 mm, then all the elements of the new design, assembled by yourself, were selected correctly. It should be noted that the plasma cutter from the inverter does not cut workpieces with a thickness of more than 20 mm. It just doesn't have enough power. To cut thicker metal, you will have to use a transformer.

Attention! Any work related to the use of plasma cutting must be carried out in protective clothing and gloves.

There are many points that necessarily affect the operation of the unit.

There is no need to purchase, for example, a large compressor. But 2-2.5 atmospheres with a large amount of work may not be enough. The way out is to install a receiver on the compressor. It works like an accumulator that accumulates pressure in compressed air. For this case, you can adapt, for example, bolts from the brake system of heavy vehicles. The option is really simple. The volume of the balloon is large, and it should be enough for a long period of time.
In order for the air pressure to be stable and the same, a reducer must be installed at the outlet of the receiver.
Of course, the best solution is to purchase a compressor complete with a receiver. It costs more than usual, but if this unit is used for other things, for example, for painting, then you can increase its functionality and thereby cover the costs.
To make a mobile version of the machine, you can make a small trolley. After all, all the elements of the plasma cutter are small-sized devices. Of course, you will have to forget about mobility if the machine is made on the basis of a welding transformer. It's too big and heavy.
If it is not possible to buy a ready-made hose-cable kit, then you can make it yourself. It is necessary to combine the welding cable and the high pressure hose into one sleeve and place them in a single sheath. For example, in a regular hose of a larger diameter. A kit made in this way simply will not get in the way, which is very important when cutting metals.

Making your own plasma cutter is not difficult at all. Of course, you will need to get the necessary information, study it, it is definitely recommended to watch the training video. And after that, correctly select all the elements exactly for the required parameters. By the way, the assembled plasma cutter based on a serial inverter makes it possible not only to carry out plasma cutting of metals, but also plasma welding, which increases the functionality of the unit.