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Instructions on how to make an electroerosive machine. 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 by electroerosion 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.

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.

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.

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.

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.

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.

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.

Some home craftsmen have the idea to make an electroerosive machine with their own hands for their own workshop. The desire is explained by the fact that sometimes it is necessary to process parts with high hardness. It is impossible to anneal to reduce strength. Deformation of the part is possible and the requirements for the quality of the machined surface or other characteristics will be violated.

As a result of spark erosion, through holes are burned or marks are applied. It is possible to process a surface of a complex shape, given by the electrode.

Main features of electroerosion

The principle of operation of an erosive installation for metal parts is based on the removal of the smallest particles of the processed material by a spark discharge. As a result of a single exposure, a small hole remains at the point of contact. The more powerful the spark, the wider and deeper the recess is formed.

If repeated spark treatment is performed, then the process of evaporation of the smallest particles in the spark zone will be more noticeable. The metal will heat up. Therefore, coolant is supplied to lower the temperature.

The wiring diagram of the device provides for the use of:

diode bridge, it rectifies the supplied alternating voltage from the 220 V network;
a 100 W H₁ incandescent lamp represents an active load;
capacitors C₁, C₂, C₃ accumulate energy to produce a single spark discharge.

When the circuit is connected to the network, the H₁ lamp lights up, an electric charge accumulates on the capacitors C₁, ..., C₃. When the capacitors are fully charged, the flow of electric current through the circuit stops. The H₁ lamp goes out, which serves as a signal for the possibility of obtaining a spark.

The electrode is brought to the workpiece. There remains a gap through which the breakdown occurs. A small hole is burned on the metal.

To produce the next electric discharge and burn out another portion of the metal, it is necessary to remove the electrode from the part. Then the capacitors are charged again.

These actions happen over and over again. With each subsequent action, the electrode penetrates the metal more strongly, pulling out particles at a greater depth.

The above scheme for a full charge of capacitors requires about 0.5 ... 0.7 s of time. The value of the current in the charge circuit is approximately 0.42 ... 0.47 A. When contact is made in the discharge zone, the current increases to 7000 ... 9000 A. At such a high value, 0.010 ... 0.012 g of metal (steel) evaporates.

For high current values it is necessary to use copper wires with a cross section of 8…10 mm². To burn a hole, the electrode is made of thick brass wire. To start a continuous process of work, it is necessary to bring the electrode to the workpiece with a frequency of about 1 Hz.

Terms of reference for the design of a homemade machine

To make a homemade EDM machine, you need to make a number of devices that will help automate the production process.

We need a frame, it will house the mechanism for moving the electrode.
You will need the mechanism itself, which allows you to periodically supply and remove the electrode to the material being processed.
To burn holes of various shapes, you need to have a set of electrodes. Experts recommend using molybdenum wire.
For different types of main tool, you will need to change the power of the device and the amperage. Under different operating modes, the circuit diagram should allow for the regulation of the magnitude of the discharge on the electrode. It must provide for a change in the voltage ripple frequency.
To cool the part (hardened steel cannot be overheated, tempering occurs with a decrease in hardness), it is necessary to supply coolant to the work area. More often use ordinary water or salt solutions. Water along the way washes away the sludge (destroyed metal particles).

Attention! In industrial installations, for example, the Japanese machine tool firm Sodick uses shock-resistant glass baths. They organize the flow of liquid into the treatment area, as well as the removal of waste water and subsequent filtration.

Development of a horizontal EDM machine

The installation diagram includes the main components and parts:

1 - electrode;
2 - screw fixing the electrode in the guide sleeve;
3 - terminal for fixing the positive wire from the voltage converter;
4 - guide sleeve;
5 - body made of fluoroplast;
6 - hole for supplying lubricant;
7 - bed.

Small size installation that can be installed on the table. In the housing 5, the guide sleeve 4 can move in both directions. To drive it, you need a special mechanism or device.

Electrode 1 is attached to sleeve 4, the positive wire is also connected using terminal 3. It remains only to assemble the proposed circuit into a real installation at home. It uses the simplest equipment.

Brief description of homemade installation

Electrode 1 is installed in housing 2. Its reciprocating movement is performed by an electromagnet from coil 7. Terminal 3 is connected to the guide sleeve (positive potential is applied).

On the desktop 4, the part to be processed is attached. There is terminal 5 on the table, a negative conductor is connected to it. Lubricant is supplied through the tube 6 inside the housing.

A voltage converter is connected through the filters, from which the positive and negative wires are connected to the corresponding terminals 3 and 5. A part is fixed on table 4, in which various types of processing can be carried out, for example, burn a hole in a hardened part.

By turning on the converter, the operating voltage will be obtained on the current-carrying wires. Additionally, voltage is applied to the induction coil 7. It creates vibration of the electrode 1, directing its movement to the right and left. Electrode 1 touches the workpiece. A current of 7000 ... 9000 A appears in the contact zone.

With each movement of the tool towards the part, a small amount of metal is burned. Within 10 ... 12 minutes of the EDM machine, a through hole will be obtained in the part. A hole has been made in the drill shank. It is quite difficult to drill such a hole in the usual way.

How to improve the machine?

The simplest machine made is a working model. Its purpose is the formation of holes in hardened parts.

In the future, you need to consider the option with a vertical arrangement of the electrode. Then you can install a bath under it. The process will take place without possible malfunctions associated with the presence of unremoved sludge from the working area.

It is also necessary to consider additional mechanisms for smooth tool feed. It may be necessary to carry out not only axial movement, but also movement of the electrode in a horizontal plane in order to carry out a three-dimensional surface treatment.

Any simple machine gives thoughts on how to further improve it and create a more convenient unit. The main thing is to take the first step and try to make the first sample.

Video: homemade electric spark machine.

Conclusion

The machine for electroerosive processing of metal allows you to refine hardened parts without reducing their strength.
Even the simplest machine, made from improvised materials, allows you to perform a number of operations that cannot be performed with other tools and devices.

For the manufacture of non-standard equipment or products in production (at a factory, in a factory, in an industrial workshop), they usually do not think for a long time, and if they cannot make something themselves and on their own, then they order this equipment or products on the side, regardless of the costs. For a craftsman, this option for acquiring a non-standard product is not always acceptable.
So what to do?
Do not lose heart and remember that any technical problem has many solutions and you just need to find the most acceptable solution suitable for use in your particular case.
Example: You need to make a couple of products, the size of a medium-sized basin, from sheet steel.
For the sake of manufacturing two or three parts, which, quite possibly, will subsequently need a radical alteration or even a new design, renting a press and making a stamp (with alteration) for a craftsman can turn out to be an expensive pleasure. But you should not give up what you have planned, especially if you know how to work not only with your hands, but also with your head. In the middle of the last century, an electro-hydraulic effect was discovered, a spark in water excited a hydraulic shock with which you can stamp quite large and complex products on relatively simple equipment.
Hydraulic shocks for stamping have been used for a relatively long time. During the conquest of the American wild west, handicraftsmen stamped saucepans, bowlers and other products in primitive stamps, shooting into the water (stamp) from rifles or revolvers.
The device of the stamp was as follows: A sheet blank was attached to the matrix, so that water did not get under the sheet blank, then the whole assembly was immersed in a thick-walled vat of water and fired. Hydraulic shocks gradually pressed the sheet of metal against the inner surface of the matrix. Air was bled from the matrix cavity through a special hole. Then, for the same purposes, instead of shooting, they began to blow up mini charges of explosives. The equipment was compact and simple, although a bit "" dangerous.
Would you say primitive? But it's simple. Bodies for ultra-long limousines are still stamped in this way, using water and explosives. It turned out that for the manufacture of such bodies it is too expensive to make a special press even for reputable firms. With the help of approximately the same equipment, ship armor is cut to size (thickness up to 0.8 meters), ore is crushed, etc. and so on.
In our beloved Land of Prohibitions, no one will allow production pranks with firearms and explosives to a lone master, so for the execution of what was conceived at home, an electro-hydraulic effect would be very useful. Not prohibited, adjustable in power and relatively cheap. The matrix is easy to make from ordinary polymer-coated concrete. As you can see, this idea is quite realistic in the end.
More details for those interested in the book: Yutkin L.A. ,Electrohydraulic effect and its application in industry.""
The following examples:
Processing of metals by electrical means.
These are electrochemical, electroerosive and electrocontact methods of dimensional processing of metals and metal alloys of any hardness. Dimensional and volume cutting and processing, punching of simple and extra-deep, profiled holes, cavities. Milling, marking, sharpening, grinding, polishing, etc. In relation to the usual methods of processing (cutting), the tool used (for electrical processing) can be cheaper, home-made and from non-deficient materials, the machines are simpler, compared to the usual ones, to manufacture .
A well-known method is the electrochemical dissolution of a metal under the action of an electric current. If two metal electrodes are connected to a direct current source and the electrodes are lowered into the electrolyte solution, then the positive electrode (workpiece) will begin to dissolve, and the negative electrode (tool), depending on the electrolyte used, will remain unchanged or begin to be covered with a layer of metal dissolved in the electrolyte. In our case, only the dissolution of the metal on the workpiece is welcome, the dissolved metal precipitates and the unchanged state of the tool electrode. For this, a 25% solution of table salt is used as an electrolyte. The closer the electrode-tool is to the electrode-workpiece, the more accurate is the imprint "" of the tool on the workpiece. In reality, the distance between the tool electrode and the workpiece electrode is from hundredths of a millimeter and more.
The main difficulties are:
to keep the tool electrode at the same distance from the workpiece electrode during the entire processing process, the dissolution of the metal leads to a change in the dissolution area and other changes in various parameters.
remove dissolved metal from the processing zone and prevent its deposition on the workpiece and tool. This is usually done by supplying electrolyte under high (up to 20 atmospheres) pressure to the working gap.
The advantages of such processing are a relatively cheap and practically eternal tool, the ability to process metals of any hardness with very high accuracy, without subsequent changes in their properties and hardening in particular.
A simpler way to process metals is electroerosive. In essence, this is a continuation of the electrochemical method. When the gap between the tool electrode and the workpiece electrode approaches, a breakdown spark occurs. Holes appear on both electrodes at the place where the spark originated, but the hole is slightly larger on the workpiece. The metal in this case does not dissolve in the electrolyte, but evaporates and then condenses in the form of tiny metal balls in the working fluid. For electroerosive machining, it is no longer a conductive electrolyte that is used, but liquid dielectrics (or working fluids): engine oil, kerosene, descillated water, etc. Liquid dielectrics prevent the evaporated metal of the workpiece electrode from settling on the electrode tool. Thus, both the tool and the workpiece are destroyed, but the workpiece at the point of contact is destroyed more, and so after a series of contacts, the workpiece is eventually processed.
Wear (destruction) of the tool up to 30-80 percent in relation to the destruction on the workpiece. However, the tool can often be made from tin or pieces of non-deficient wire of the required diameter, for shaped cutting and punching complex and deep holes, not only in ordinary iron, but also for processing other metals, up to super-hard pobedite soldering. The punching of ultra-deep holes is carried out with a constant rotation of the tool and the supply of working fluid under low pressure. The processing accuracy is relatively low, but the processing itself is quite simple.
The machine for electrical discharge machining resembles a desktop drilling machine. Only the tool is attached to the solenoid connected in parallel to the electromagnetic coil. During the contact of the electrodes, the tool and the workpiece come into contact, the electrical circuit closes, a current appears in the coil, the electromagnetic coil raises the solenoid and the tool above the workpiece. But at this time, the electrical circuit is de-energized and the solenoid (and the tool) falls under its own weight down onto the workpiece and everything repeats. Repeats automatically as long as there are conditions for tool-to-workpiece contact.
Disadvantages: The tool quickly loses its original shape, which leads to a large distortion of the workpiece shape. Therefore, processing is sometimes carried out in several steps and with different tools, first in a draft version, then in a finishing one.
The electro-contact method of metal processing is even simpler. As a working fluid, a solution of liquid glass (sodium or potassium silicate) is already used. The tool is a metal, rotating disc made of thick tin. A solution of liquid glass (better known as clerical glue) forms an insoluble film on the metal, but microroughnesses on the metal tool peel off the film on the workpiece and immediately a discharge of electricity levels the protrusion on the tool and makes a new recess on the workpiece. And so continuously, at different points of contact, while the tool disk rotates and comes into contact with the workpiece. A solution of sodium silicate (potassium) is either poured into the contact zone, or both the workpiece and the tool are immersed in the solution. In an electro-contact way, you can cut and process metal in much the same way as a grinder or on an emery wheel.
Machine tools for electro-contact processing of metals are the simplest in design and must ensure the rotation of the tool, and the supply of high currents by the tool to the processing zone. Tool wear is significant, but finishing is carried out with the same tool as roughing.
Electro-contact grinding and polishing irregularities on the guide surfaces of metalworking machines. In this case, the cast-iron plate (tool) and the frame (workpiece) are connected to a low-voltage direct current source and poured with liquid glass (manually rubbed) grind the surface of the guides.
If you think that any of the above metal processing methods will suit you, then of course my description will not be enough for a serious study of this topic. But in essence, the machines are quite simple, and all of the above is not so difficult to use at home.