Technology of electrospark processing of metal. Small electric spark machine

Electroerosion is the destruction of metal surfaces under the influence of electric charges on them. This technology is based on the work of Soviet scientists N. I. Lazarenko and B. R. Lazarenko. Using this method, you can easily change the dimensions of metal products, get holes in them of various shapes and depths. Excellent results are obtained by electroerosive machining of profile grooves and grooves, shaped cavities in machine parts and mechanisms. Such equipment is especially in demand for the manufacture of hard alloy parts, where conventional machining is difficult.

Machine tools of the electroerosion type have universal capabilities in the processing of materials with a dense surface structure. This type of material processing compares favorably with other methods of changing the shape and size of parts, since the labor intensity of operations is sharply reduced due to electroerosive technology.

The principle of operation of the EDM machine is shown in the diagram below. Under the action of a pulsed electrical generator, sparks or other electrical interactions are formed in the gap between the electrode and the surface of the part. The space of the spark gap is continuously washed by the coolant flow, due to which the destroyed metal is removed from the treated surface. Under the control of the CNC unit, the process proceeds in a given direction and in the required quantity. Brass wire is most often used as an electrode, which, as it is consumed, is fed into the EDM zone. A more modern consumable for electroerosion is molybdenum wire, the consumption of which for processing one part is negligible. However, these machines also have significant limitations compared to machines for machining parts. After all, they are suitable for processing only conductive metals and their alloys.

It is possible to influence the metal in an electroerosive way in various ways: by applying both electric discharges and parametric pulses to the spark gap. Depending on the desired processing result, a more suitable way of its implementation is selected. A very important element of this effect on metal surfaces is that with it it is possible to process the workpiece in different directions at the same time.

Among the methods of electroerosive processing of products, there are:

electropulse;
electrospark;
electrocontact;
anodomechanical.

Technological operations that are performed by electroerosion include:

structural strengthening;
grinding;
marking;
cutting;
fine-tuning;
bulk copying;
fine-tuning.

With the help of electrical erosion on these machines, it is possible to make various blind openings, recesses and holes of non-geometric configuration. It is also possible to make threads of any profile on the surface of holes. Machine tools are able to sample metal from the inner surface of products to a given depth, thereby performing operations that replace milling and turning. The technology of electrical erosion is used in the processing of metals that are difficult to classical mechanical machine action. These include, in particular, titanium and its alloys.

To choose which EDM machine to buy, you need to accurately determine the tasks that will be set for this equipment at the enterprise and what operating parameters of the machine will be required to solve these problems. It is quite acceptable to buy a used machine to perform certain technological operations in the workshop, having previously checked its performance. Practice shows that even with a large number of operating hours, EDM equipment is almost not subject to wear.

EDM machines

The methods of electrical discharge machining implemented in production can vary greatly depending on the design of the machines, but the principle of operation of the equipment remains the same. Consider the main types of EDM machines used for processing metal blanks.

Wire cutting machine

This machine tool is used for contouring products with high precision and low surface roughness. The workpiece is exposed to an electrode in the form of a molybdenum wire with a diameter of 0.18 mm. The operating costs of this equipment are quite low, since the wire itself is used many times. The traditional EDM wire-cutting machine, which cannot reuse the wire, significantly loses in the cost of similar work operations.

The role of the electrolyte in the working area of the machine is played by the coolant, the flow of which flushes out the erosive products and protects the machined surface of the part from air oxidation. A water-soluble concentrate of a special composition is used as a coolant.

The price of an EDM copier is not very high compared to similar traditional type machines, but its maintenance is very convenient due to the use of a CNC unit. It will take no more than two days to train the operator in the basic methods of working on it.

With this machine you can make:

various molds;
stamps;
gear wheels;
slotted holes;
keyways;
recesses of a complex profile with a depth of up to 20 cm.

The figure above shows a high-speed CNC EDM cutter, which is a jet type and is used for contouring parts. Machines of this type can be used both in the workshops of a small enterprise with piece production of products, and in large enterprises in mass production. The DK 7720 wire EDM machine can currently be purchased for 850 thousand rubles.

piercing machine

The electroerosive copy-piercing machine in a modern version is equipped with a CNC unit, in which the functions of automatic positioning, the orbitality of the movement of parts and the possibility of burning side surfaces are built-in. Also, the machine is equipped with the functions of automatic edge search and search for the center point of the processing zone. Along with this, the programs of the CNC block include the determination of the depth of the cavity and the automatic exit of the tool head to the zero point.

The EDM piercing machine is designed to process both internal and external spherical elements, working along a 3-dimensional linear path. Along with the possible surface treatment along a 2-dimensional arc, it can perform electro-erosion piercing, using the original matrix of the product as an original for copying.

At present, the price of an electroerosive machine of this type fluctuates around 1 million 800 thousand rubles.

Electroerosive machine for cutting metals

EDM wire cutting is used when it is impossible to perform the required cut of a metal part or workpiece using classical traditional processing, when both the cutter and the cutter of the lathe are powerless before the strength of the workpiece. Mechanical cutting is not beneficial or even impossible when it is required to obtain sharp corners with ultra-small radii of curvature inside or outside the part. This situation occurs when machining parts that have undergone hardening or carbide metal joints. Sometimes they also resort to electroerosive cutting of metal if, due to the depth or complex structure of the cavity, it is impossible to perform a simple mechanical operation on a milling machine. Wire-cutting machines complement the set of operations in the manufacture of complex parts of modern engineering.

Electric discharge cutting is an intensive electroerosion of metal in the desired section of the part. The high-frequency pulses generated by the generator are fed to the electrode, which is a molybdenum wire. When the generator is running, the part itself moves in the right direction with the help of an electric drive of the guides of the machine plate. The metal is burned out by electric sparks, and then the destroyed layer is washed off with a coolant of a special composition, which is continuously supplied to the cutting zone. The movement of wire for EDM machines always occurs in the direction perpendicular to the axis of the winding drum.

It is possible to distinguish those technological operations where the operation of electroerosive cutting machines compares favorably with the mechanical processing of metals:

processing of superhard metals and alloys;
making cuts in workpieces with angular sharp edges having ultra-small rounding radii;
processing of cylindrical and shaped surfaces of great depth;
surface treatment with very high precision.

To program the processing of a part with an EDM machine, you need to have a technical task and a layout of the product itself. The format of the presented data can be any, its translation into commands of the CNC block is carried out by the machine operator or programmer.

In EDM cutting, there is no need to use tools that are harder than the material of the workpiece. For cutting carbide joints, non-ferrous alloy wire is used, which is obtained in the usual way. Equipment for cutting is also not very complex, as well as the technological methods of working with it. The speed of the working process does not depend on the hardness and strength of the material being processed. When cutting, no mechanical effort is required, so the processing quality is very high. The number of various operations and transitions to one processing is reduced to a minimum even with a very complex shape of the part. Cutting machines of different technical characteristics have different workflow performance, but they can all perform similar operations, only in different times.

Models of modern machines

A modern machine for electrical discharge machining of metals consists of the following units:

electric motors operating independently of each other;
wire feeder to the erosion zone;
working bath with coolant;
desktop for the location of the workpiece in the process of processing;
machine control unit.

Manufacturers of machines of this type are both Asian and European countries. Having the same purpose, machines from different manufacturers differ greatly in their functionality and price. If Chinese and South Korean equipment is much cheaper than European equipment, then the latter is performed by manufacturers at a higher level with a greater degree of automation of work processes.

ARTA

Russian manufacturers produce ARTA precision equipment for electroerosive machining of metals.

Scientific and industrial corporation "Delta-Test" today is the leader in Russia in the manufacture of equipment of this type. By manufacturing new machines, the company is also engaged in the modernization of equipment of earlier production periods.

Sodick

In the modern equipment market, Sodick is a well-known company that produces wire-cut EDM machines.

Possessing high technological parameters, the equipment of this company is used for processing refractory metals and single crystals. With the help of these machines, perforated plates and pipes, working elements of copying machines, stamps with three-dimensional measurement profiles, metal-ceramic stamps are produced. Specialists using such equipment can easily produce cams and their prototypes, electrodes-tools for machines of the copy-and-pierce group.

The Mitsubishi MV1200S wire-cutting machine at a cost of about 7 million rubles allows you to perform the most complex operations for electroerosive machining of parts of any shape made from a wide variety of conductive materials.

With intensive use of this machine tool in modern production, the cost of its purchase pays off in a short time.

Agie

Agie EDM equipment is made in Switzerland and competes with other models of this machine group.

With small overall dimensions, the Agie machine can automatically perform the most complex work on the processing of carbide products for a wide range of purposes.

As can be seen from the article, there are plenty of equipment for electrical discharge machining of parts on the modern market. It is produced by almost all the leading industrial countries of the world under various brands and at different prices. It is not easy to choose from this proposal exactly what our domestic manufacturer needs. However, having measured your financial capabilities and held substantive negotiations with the managers of the companies presented on the Internet sites of this subject, you can draw the right conclusions, and then make the purchase itself.

To change the shape of the dimensions of a metal workpiece, you can use the electroerosive processing method. It has been used for many years in various industries, it is characterized by high accuracy but low productivity. To apply this processing method, you should use a special electric spark machine, which can be purchased or made by yourself. Homemade version can be used in everyday life in small-scale production. Its cost of making it yourself will be lower than buying an industrial version. Therefore, let us consider in more detail how you can make the electric spark machine in question with your own hands, what is needed for this and in what cases it can be used.

Homemade electric spark machine

The principle of the considered processing method

A feature of processing with an electric spark installation can be called the fact that the evaporation of the metal occurs due to the effect of a certain charge on the surface of the workpiece. An example of such an impact can be called the closure of a capacitor on a metal plate - a hole of a certain size is formed. EDM creates a high temperature that simply vaporizes the metal from the surface. It is worth noting that a machine from this group has already been used over the past 50 years in various industries. The main condition for using such an electric spark machine is that the workpiece must be made of a certain metal. In this case, it is not the degree of machinability that is taken into account, but the electrically conductive properties.

Main structural element

The EDM has a spark generator that acts as a capacitor. For processing, a large capacity storage element should be used. The principle of processing is to accumulate energy for a long time, and then release it over a short period of time. The device of the laser installation also works according to this principle: a decrease in the time interval for the release of energy leads to an increase in the current density, which means that the temperature rises significantly.

Electrical diagram of the electrospark installation

The principle of operation of the generator, which is installed on the EDM machine, is as follows:

the diode bridge conducts rectification of industrial current with a voltage of 220 or 380 volts;
the installed lamp limits the short circuit current and protects the diode bridge;
the higher the load indicator, the faster the charging of the electric spark machine;
after charging is completed, the lamp will turn off;
having charged the installed accumulator, it is possible to bring the electrode to the workpiece being processed;
after the circuit is opened, the capacitor starts charging again;
The charging time of the installed storage element depends on its capacity. As a rule, the time interval is from 0.5 to 1 second;
at the moment of discharge, the current strength reaches several thousand amperes;
the wire from the capacitor to the electrode must have a large cross section, about 10 square millimeters. In this case, the wire must be made exclusively of copper.

The frequency of generation when the electrode of the electric spark machine is applied is 1 Hz.

The design of the electric spark machine

There are schemes that are quite difficult to implement. The scheme under consideration can be implemented with your own hands. Parts for the installed generator are not in short supply, they can be purchased at a specialized store. Capacitors are also very common, as is the diode bridge. At the same time, when creating a home-made electric spark machine, the following points should be taken into account:

on the capacitor, the indicated voltage should not be less than 320 volts;
the number of energy storage devices and their capacity are selected taking into account the fact that the total capacity should be 1000 microfarads. All capacitors must be connected in parallel. It should be borne in mind that the power of a home-made version increases if it is necessary to obtain a stronger spark strike;
the lamp is installed in a porcelain cartridge. It is necessary to protect the lamp from falling, a circuit breaker is installed with a current strength of 2 to 6 Amperes;
the machine is used to turn on the circuit;
electrodes must have strong clamps;
a screw clamp is used for the negative wire;
The positive wire has a clamp with a copper electrode and a tripod for guiding.

Homemade wire version has a relatively small overall dimensions.

Homemade electric spark machine

The main elements of the scheme of electrospark equipment

The scheme is represented by the following elements:

electrode;
clamp screw used to fix the positive wire and electrode;
sleeve for direction;
housing made of fluoroplast;
hole used to supply oil;
tripod.

The body, which is used to connect all the elements, is machined from fluoroplastic. A grounding pin is used as a bushing, in which a threaded hole is machined along the axis for attaching the electrode. All structural elements are mounted on a tripod, which is made with the possibility of changing the height. A hole is also created through which oil is supplied.

Diagram of an electric spark machine

Often, cutting is carried out using a device that is powered by a starter with a coil connected to 220V. The starter rod can have a stroke of 10 millimeters. The starter winding is connected in parallel with the lamp. That is why at the time of charging the capacitors, the lamp is on, and after this process is completed, it goes out. After the stem has been lowered, a spark charge occurs.

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Do-it-yourself machine for electroerosive processing of metals

The electroerosive machine is designed for cutting metal parts of complex shape. Modern piercing equipment makes it possible to process conductive material along four axes at once, to produce products of any shape, even from hard alloys that are difficult to machine.

Possibilities of EDM machines

EDM wire machine

The EDM machine copes with complex technological tasks:

making recesses and holes of complex configuration, including blind openings;
processing of titanium, tool and alloy steels, hard alloys and hardened steel of the highest hardness;
execution of recesses of various configurations on the internal surfaces of the part;
threaded holes in hard metal blanks;
production of parts that is impossible or difficult on CNC turning and milling machines.

Types of processing

There are several types of electroerosive machining:

combined - performed simultaneously with other types of processing;
electroerosive-abrasive - the material is destroyed by electricity and polished with abrasive particles;
electrochemical - the metal dissolves in the electrolyte under the influence of current;
anode-mechanical - the metal dissolves with the appearance of an oxide film, combined with the electroerosive method;
hardening;
bulk copying - a processing method that allows you to get a projection of the tool on a blank;
marking;
grinding - metal grinding occurs under the influence of electricity;
flashing - the tool cuts into the blank and forms a hole;
cutting - the tool-electrode performs feed movements and is constantly rewound, removes the upper layers of the workpiece, creating the necessary shape;
cut - the division of the blank into separate pieces;
fine-tuning.

The principle of the machine

The primary processing of the blank and the removal of the main volumes of material takes place on a CNC lathe or milling machine. The principle of operation of electroerosive equipment is that the metal is processed by current discharges that appear between the workpiece and the tool. A stretched wire is used as a cutter.

The generator releases current in pulses without changing the properties of the working environment. When the tension between the electrodes is higher than the critical one, a plasma channel is formed that destroys the surface of the workpiece. A small notch appears. The polarity of the current is selected in such a way that the part is destroyed more strongly.

In order to reduce cutter wear, unipolar electric pulses are created. Depending on the length of the pulse, the polarity is selected, since with a short duration the negative electrode wears out faster, with an increased one, the cathode wears out. In fact, both principles of creating unipolar electrical impulses are applied during processing: a variable positive charge and a negative charge are applied to the blank. Water reduces the temperature of the tool (wire) and carries away the destruction products.

Under the influence of high-frequency pulses, erosion passes evenly along the length of the gap, gradually expanding the narrowest point. Gradually, the tool (wire) or part is advanced in the required direction, increasing the area of impact. It is possible to process according to this principle a part from any material that transmits electricity.

The processing time depends on the physical properties of the material (electrical conductivity, thermal conductivity, melting point). The faster the work is done, the more roughness remains on the surface. The best effect is achieved by multi-pass processing with decreasing pulse power.

Machine design

The main elements of the EDM machine:

frame - made of special high-strength cast iron, which gives strength and stability to the structure.
desktop - rectangular shape made of stainless steel;
working stainless steel bath;
the wire feeder consists of drive spools (ceramic), wire guides and drive system;
automatic wire installation device (installed at the request of the customer);
the dielectric block consists of cardboard or paper filters, a dielectric tank and a tank for ion-exchange mass, a pump for running water;
the generator is used anti-electrolysis, which prevents the destruction of the workpiece;
numerical control system with display.

We make a machine with our own hands

spark generator circuit

The main difficulty in making a machine with your own hands is the assembly of a spark generator. For some time, he must accumulate a sufficient amount of electricity and throw it away in one gulp. It is necessary to achieve the shortest period of current surge so that its density is as high as possible. You can pull out the components for it with your own hands from an old TV or buy it.

diagram of a homemade machine: 1 - electrode; 2 - electrode clamp screw; 3 - positive contact clamp screw; 4 - direction sleeve; 5 - body made of fluoroplast; 6 - opening for oil inflow; 7 - tripod

The capacitor must withstand from 320 V, with a total capacity of 1 thousand microfarads. All parts are assembled in an insulated PTFE box. From the grounding pin of the euro socket, you can make a guide sleeve for the electrode. It is moved forward as it evaporates, for which the clamp screw is loosened. The tripod for mounting the entire device must be height-adjustable. A tube is inserted into the hole for the oil inflow, and the directional sleeve drips oil along the longitudinal line of the electrode.

A drive is connected to the electrode (starter with a 230V coil). The stroke of the stem fixes the depth of the hole. While the capacitors are charging, the lamp turns on, and the starter rod is held inside. As soon as the capacitors are sufficiently charged, the lamp goes out, the stem moves down. He touches the workpiece and a discharge occurs in the form of a spark, the cycle repeats. The repetition rate depends on the power of the lamp.

The oil may ignite during operation. It is important to observe safety measures! After all these actions, we will get a do-it-yourself erosion machine.

The video demonstrates the capabilities of the EDM machine:

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How to do. - Erosion machine.

HOW TO MAKE AN ELECTRIC SPARK MACHINE

(garage)

I bought it at the price of scrap, such a tripod. And for a long time my head hurt what to do with it. As they say, the time has come. All this is done so that, in garage conditions, small molds can be made. But in order to achieve good results, you need to work hard and try hard.

The tripod itself. Started making the head. The head consists of coils, yoke and damper device.

The lower part of the head, with two screws, for fixing the soft insert and the electrode. The upper part of the head consists of a U-shaped bracket with a bolt for adjusting the springs. The yoke up to the middle of the coil consists of iron and the continuation of textolite. At the end of the washer and between the washer are two springs.

Head assembled. A groove is made along the yoke in the iron part, into which we screw the stopper.

At the bottom of the bed I made a bath for kerosene. Collected according to this scheme. But the capacitor that stands between the working electrodes is selected during operation. Its capacity depends on many factors.

I assembled the electrical circuit in such a case. But just in case, I put everything in the left side of the locker. Left half of the empty space for an electronic generator for the future.

To check the bronze machine made such an electrode. finished electrode.

Left trace. Far from perfect, but we will work on it.

This should work only with an electronic generator.

See work.

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Small electric spark machine

A simple electric spark setup (Fig. 1) makes it possible to easily and quickly process small parts made of electrically conductive materials of any hardness. With its help, you can get through holes of any shape, remove a broken threaded tool, cut thin slots, engrave, sharpen tools, and much more.

The essence of the process of electrospark processing is the destruction of the workpiece material under the action of a pulsed electric discharge. Due to the small area of the working surface of the tool, a large amount of heat is released at the discharge site, which melts the substance of the workpiece. The processing process is most effective in a liquid (for example, in kerosene), which washes the place of contact between the vibrating tool and the workpiece and carries away the erosion products with it. The tool is brass rods (electrodes), repeating the shape of the intended hole.

Rice. 1. Small-sized electric spark installation: 1 - workpiece; 2 - tool; 3 - electromagnetic vibrator; 4 - clamping device; 5 - bath.

The circuit diagram of the installation is shown in fig. 2. The installation works as follows. The discharge capacitor C1 is connected with its positive terminal to the workpiece 1. Its minus is connected to the tool 2. The electromagnetic vibrator 3 informs the tool of continuous oscillations. This ensures a constant spark at the point of contact and prevents the tool from welding to the workpiece. The workpiece 1 is fixed in the clamping device 4, which has reliable electrical contact with the bath 5.

The power transformer is assembled on a Sh32 core made of ordinary transformer steel. The thickness of the set is 40 mm. The primary winding contains 1100 turns of PEV 0.41 wire with a tap from the 650th turn. The secondary winding has 200 turns of PEV-2 wire with a diameter of 1.25 mm. A shielding winding III is placed between the primary and secondary windings, consisting of one layer wound with a PEV 0.18 wire. The capacity of the discharge capacitor is 400 μF (two capacitors of the KE-2 type 200 x 50 V). Rheostat R1 is designed for a current of 3-5 A. This rheostat is wound with a nichrome wire with a diameter of 0.5-0.6 mm on the resistance BC-2.

Rice. 2. Schematic diagram of the electric spark installation.

Diodes D1-D4 type D304, other types of diodes can be used. At the output of the rectifier, the voltage is about 24-30 V. You can use power supplies with a lower voltage, but with a large current, so that the power consumed by the charge circuit is at least 50-60 watts.

During the operation of the installation, continuous sparking occurs. To reduce the interference generated by the installation, it is necessary to include a simple radio interference filter in its power circuit.

Photo instructions included.

Erosion machine.pdf (542 kB)

Modern devices, machines, devices and mechanisms consist of more complex parts when compared with devices that came out earlier. At this stage of technological progress, devices are required to perform large amounts of work. People tend to mechanize everything in order to simplify their daily lives, as well as to achieve new results in research or in areas such as construction, industry, and so on. Along with the complexity of the details, their processing became correspondingly more complicated.

Various devices are used to process parts. They differ in the principle of operation, and purpose, and in other aspects. But a huge number of specialists emphasize the advantage of using EDM machines, which designed for processing various parts, and with very convincing results and indicators.

Purpose of electroerosive machines

Electroerosive machines are used to cut various workpieces that have a wide variety of shapes and sizes. Processing occurs either at a right angle or at an angle from 1 to 30 degrees. The angle at which workpieces are processed depends primarily on the configuration of the machine. The beginning of the cut can occur from the edge of the workpiece, as well as from the inside through a hole that is pre-drilled. Electroerosive machines are designed for the production of parts with an accuracy of 0.015 millimeters.

The main purpose of EDM machines is to replace stamping. Machines of this type Can cut multiple pieces at once, thanks to the possibility of batch processing. In this case, subsequent milling of the part is not required, since during processing there is no surface deformation of the workpiece being processed.

Also, the machine allows you to produce various matrices and templates. One of its great advantages is that it can be easily and quickly reconfigured. In principle, the entire reconfiguration of the EDM machine consists in performing several operations: first you need to download the required drawing from AUTOCAD, then perform several actions already on the computer, then set up the generator and after that you can start processing the next workpiece. Experienced operators spend an average of only 15 minutes setting up the device.

Machines of this type consist of the following units:

Machine bed

This piece is cast iron. Internal stresses are relieved in the chamber. The interior of the bed designed for installation of electrical equipment, since the bed itself has a box type. The working part of the frame is precisely scraped and polished in some places, namely: on the drum carriage, on the column mounts and on the guides of the desktop.

Machine worktable

This is a very important component of the EDM machine. The working table consists of two plates, which are mounted on ball-roller guides. Plates are installed one above the other.

If there is a need to move the table, then two stepper motors must be used. This is done using two ball screws. Also you can change the position of the desktop manually, while using the feed wheel, which are all fixed on the same shafts of ball screws.

Wire conveyor

This part of the machine consists of a wire drum, as well as a system of roller guides, which are located in the lower and upper sleeves.

The control computer and generator can be placed either in a rack or in a desktop with a pedestal. The differences are only in the cost of the device, the solidity of the layout, as well as in the design of all equipment.

The principle of operation of the electroerosive machine

After the design aspects of existing EDM machines have been considered above, it is necessary to understand the principle of their operation. It is impossible not to mention that the procedures for processing parts that are used on devices of this type make it possible to achieve simply amazing results.

To begin with, a few words about what electrical erosion is, because, as the reader could already guess from the name of the machine, it is this reaction that underlies the operation of such devices.

The destruction of the upper layer of the surface of the material under the influence of external influences carried out by electrical discharges is called electrical erosion. Exactly this process became the basis for the processing of various materials and parts, which is called electroerosive.

EDM itself is carried out by changing the size, shape, roughness and properties of the surface of the workpiece being machined under the influence of electrical discharges as a result of electrical erosion affecting the workpiece during processing.

Due to the fact that very high temperatures (8000 - 12000 degrees Celsius) operate in the discharge zone, the metal undergoes the following changes: heating, then subsequent melting and even partial evaporation. In order to obtain such high temperatures in the discharge zone, a large concentration of energy is created, which is achieved due to the generator of electrical impulses. The process of electroerosive machining itself takes place in the working fluid, namely in distilled water. It fills the space between the existing electrodes. One of these electrodes is the workpiece itself, and the second is the tool electrode (tubular electrode).

Under the action of the forces that arise in the discharge channel, and also due to the fact that the electrode rotates rapidly, the already liquid and vaporous metal is ejected from the discharge zone into the working fluid surrounding it, and then it solidifies in it with the formation of separate small parts. A hole is formed in the workpiece under the action of a current pulse. Besides, you can observe the waste of the electrode-tool occurring parallel to the formation of the hole.

It should be noted that the tool electrode must necessarily be made of a material with high erosion resistance. Such materials that have such an important quality and which are able to ensure the stability of the electroerosion process are: tungsten, graphite, aluminum, brass, copper and graphite materials. Usually in such machines copper or brass tubular electrodes are used.

Parameters that affect the speed and accuracy of processing

In order to better understand the operation of EDM machines and influence its quality, you can specify several important parameters, which directly affect the accuracy and speed of the processing process:

In addition to the above parameters, one more can be named, which can also have a great influence on the EDM process. This parameter is the position of the universal cartridge for fixing electrodes, namely, the straightness of its location relative to the X axis. Therefore, the user of the machine it is highly recommended to check the cartridge on a regular basis.

Possibilities of the EDM machine

After all the subtleties of the machining process on an EDM machine have been discussed, we can mention the capabilities of this very useful device with such impressive functionality.

EDM machine:

conclusions

EDM machines are very useful devices that are capable of doing very complex work. A huge number of users who process various materials on machines of this type testify in favor of such equipment, which has proven itself from the best side.

A number of advantages, as well as an atypical principle of operation, which allows you to achieve outstanding results when processing various workpieces, make this processing equipment a real titanium among other types of devices, but also designed for processing various workpieces.

The ease of operation of EDM machines allows them to work even for those users who previously had no experience or certain skills in working with the same equipment.

The principle of operation of EDM machines, which consists in the use of electrical erosion for processing workpieces, allows you to achieve very high quality results.

Possibilities of EDM machines

The EDM machine copes with complex technological tasks:

making recesses and holes of complex configuration, including blind openings;
, tool and alloy steels, hard alloys and hardened steel of the highest hardness;
execution of recesses of various configurations on the internal surfaces of the part;
threaded holes in hard metal blanks;
production of parts that is impossible or difficult on CNC turning and milling machines.

Types of processing

There are several types of electroerosive machining:

combined - performed simultaneously with other types of processing;
electroerosive-abrasive - the material is destroyed by electricity and polished with abrasive particles;
electrochemical - the metal dissolves in the electrolyte under the influence of current;
anode-mechanical - the metal dissolves with the appearance of an oxide film, combined with the electroerosive method;
hardening;
bulk copying - a processing method that allows you to get a projection of the tool on a blank;
marking;
grinding - under the influence of electricity, metal is polished;
flashing - the tool cuts into the blank and forms a hole;
cutting - the tool-electrode performs feed movements and is constantly rewound, removes the upper layers of the workpiece, creating the necessary shape;
cut - the division of the blank into separate pieces;
fine-tuning.

The principle of the machine

The generator releases current in pulses without changing the properties of the working environment. When the tension between the electrodes is higher than the critical one, a plasma channel is formed that destroys the surface of the workpiece. A small notch appears. The polarity of the current is selected in such a way that the part is destroyed more strongly.

The processing time depends on the physical properties of the material (electrical conductivity, thermal conductivity, melting point). The faster the work is done, the more roughness remains on the surface. The best effect is achieved by multi-pass processing with decreasing pulse power.

Machine design

The main elements of the EDM machine:

frame - made of special extra strong cast iron, which gives strength and stability to the structure.
desktop - rectangular shape made of stainless steel;
working stainless steel bath;
the wire feeder consists of drive spools (ceramic), wire guides and drive system;
automatic wire installation device (installed at the request of the customer);
the dielectric block consists of cardboard or paper filters, a dielectric tank and a tank for ion-exchange mass, a pump for running water;
the generator is used anti-electrolysis, which prevents the destruction of the workpiece;
numerical control system with display.

We make a machine with our own hands

diagram of a homemade machine: 1 - electrode; 2 - electrode clamp screw; 3 - positive contact clamp screw; 4 - direction sleeve; 5 - body made of fluoroplast; 6 - opening for oil inflow; 7 - tripod

The oil may ignite during operation. It is important to observe safety measures! After all these actions, we will get a do-it-yourself erosion machine.

The video demonstrates the capabilities of the EDM machine:

It is advisable to assemble a home-made EDM machine if high-precision work with metal is performed frequently and in relatively large volumes. This is a difficult to manufacture equipment that is rarely used in everyday life. It is justified in metalworking shops and workshops as a finishing tool for processing workpieces after milling or turning machines or manufacturing small parts of complex configuration.

The principle of operation of the EDM machine requires the manufacture of both an electronic circuit that generates a high-power pulsed current, and a complex mechanical part that ensures the movement of the electrode (wire or piece). The main difficulty is to make a generator that can accumulate enough charge for a breakdown in a short time, throw it away in a split second and restore it in an equally short period. With insufficient current density, EDM is not possible even on thin parts made of soft metals.

The main parts of a homemade wire EDM machine:

bed - cast iron or steel;

desktop - durable plastic or stainless steel;

bath for the dielectric, serving as a working area;

wire feed system (two coils, electric motor, drive, guides);

· electrode control system (for piercing);

start and stop system

dielectric pumping unit - pump, filters, pipelines;

generator;

· control system.

The last point is one of the most difficult, it is necessary to synchronize the wire feed in speed and direction, the pulse frequency and the feed of the dielectric liquid. It should be taken into account that during operation the liquid is ionized, and its properties change significantly.

Advantages of EDM

Such work should be carried out only on special equipment under the obligatory supervision of a qualified specialist, having the appropriate permission. Although this method makes the workpiece more accurate and of high quality, industrial enterprises prefer to use metal machining.

Therefore, it is necessary to note the main advantages of electroerosive action on various types of workpieces.

Using this method, it is almost always possible to achieve the highest quality of the metal surface, as a result of which it becomes as accurate and uniform as possible. This completely eliminates the need for finishing processing. Also, this method ensures that the output surface of a variety of structures.

Also, the advantages of electroerosive metal processing include the ability to work with a surface of any hardness and the absence of noise when working on special equipment.

Electroerosive action completely eliminates the occurrence of surface deformation in parts with a small thickness. This is possible due to the fact that with this method there is no mechanical load, and the working anode has minimal wear. In addition, electrical discharge machining helps to obtain a surface of various geometric shapes and configurations with minimal effort.

Disadvantages of EDM

There are certain disadvantages that determine the lack of the possibility of widespread use of electrical discharge machining. The main disadvantages include:

1. Low performance. To change the shape or size, the quality of the surface requires a fairly long exposure to an electric discharge. Most of the equipment has the following performance indicator: 10 millimeters per minute.

2. High power consumption determines that the cost of obtaining parts is very high. Electricity is the most expensive source of energy used in many industries.

3. The complexity of the process determines that only a professional can operate the equipment.

4. There are certain requirements for where the equipment is installed. It should be borne in mind that the technology provides for the supply of current with high current and voltage.