Parts and components of modern machines and devices are distinguished by a wide variety of designs and materials used, including those whose shaping by known methods of machining is difficult, and sometimes impossible. This is due to the increasing use of EDM processes. “The possibilities of EDM machines are endless!” - such a phrase can often be heard from machine users just a month after the equipment is put into operation.

Classification
According to the technological purpose, machines for electrical discharge (EE) processing are divided into two main types - copy-piercing and wire-cutting.
Copy-piercing machines allow processing shaped holes and cavities, internal and external surfaces of bodies of revolution, grinding, cutting. It is possible to obtain helical and involute surfaces, as well as various internal shaped holes and cavities with a straight, reverse and variable cone. In copy-piercing machines, the electrode-tool is shaped, its shape is a reverse copy of the cavity to be processed.
EE wire-cutting machines are used for the manufacture of parts for stamps, copiers, templates, shaped cutters, patterns and other tooling. The electrode-tool in cut-out machines is a continuously rewound wire. The design features of the machines determine their technological advantages: no shaped tool is required, no need to make adjustments for electrode wear, it is possible to obtain small parts of complex shape, including parts with an equidistant profile (matrices, punches) using one CNC program.

Stages of progress
EE treatment both in the world and in our country is no longer an unconventional treatment method. Currently, EE equipment is the fourth most used in the world after milling, turning and grinding. Sales of EDM machines increased from 0.5% in 1960 to over 6% of the MEO market in 2000.
The priority in the discovery of electrical erosion belongs to Russia. The first practical research in this area was made in the Urals at the end of the 30s by the spouses B. and N. Lazarenko while studying the problems of contact erosion. The discovery was registered in 1943. The world's first EE cutting machine was manufactured at a factory in Fryazino, Moscow Region in 1954. But, unfortunately, the production of EE equipment in the Soviet Union did not receive proper development.

EE wire cut
EE cutting on wire-cutting machines appeared in the early seventies and is continuously progressing in several directions.
Cutting speed increased from about 10 mm 2 /min. in the early seventies up to 35 mm 2 /min. in the mid-eighties, and now has reached 330-360 mm 2 /min. The increase in speed was achieved primarily by washing the working surface with liquid under high pressure and the use of more efficient pulse generators that allow you to set the optimal parameters. The increase in speed is also facilitated by an improvement in the quality of the electrodes.
Reliable and efficient automatic wire threading, wire break prevention and automatic part loading have been developed to take advantage of high speed cutting and eliminate machine downtime.
Max Height matrices and punches of stamps, processed at the beginning on erosion machines, was in the range from 50 to 100 mm. However, for the machining of molds, extrusion dies, and various other parts, manufacturers of EDM machines have expanded the range of sizes of parts machined on them.
Initially taper hole angle, equal to 1° for parts with a height of 100 to 125 mm, was practically the maximum possible. To meet customer requirements, 30° angles with a workpiece height of around 400 mm can currently be achieved on most machine models.
Maximum achievable accuracy increased from 25 µm, which was typical for the first machines, to 1 µm - for modern EE machines. Much less effort is required from operators of modern cut-out machines to achieve machining accuracy of the order of 1 μm compared to experienced operators of the first cut-out machines, which received machining accuracy of the order of 5 or 2.5 μm.
This simplification of work to ensure increased accuracy is due to the development of several factors. The technology built into the latest machines ensures that the required contour is cut exactly according to the geometric program. Optical rulers provide stable accuracy regardless of the duration of the machine and large temperature fluctuations.
The most important innovation is the equipping of machines with highly reliable and efficient automatic wire threading devices, which allow the processing of a number of parts without the participation of an operator. The ease of use of the machines makes it possible to increase the cost-effectiveness of machining and maintain more machines in the shop with less effort, even on a day shift.

EE firmware
The most significant improvement in CNC copying and stitching machines compared to manual machines has been the reduction in processing cycle times, and above all, the reduction in operator time. In 1960, the processing of a cavity with a tool electrode required approximately 4 hours of operator work and 4.5 hours of electroerosion time. With the advent of CNC already in the mid-eighties, the required operator time was only 0.5 hours, and the erosion time was about three hours.
New stage time reduction processing cycles began in 1999 by equipping copy-piercing machines with adaptive pulse generators. Compared to previous generations, these generators have the ability to optimize the machining process based on its continuous monitoring. Such a generator also adapts the current density during processing in roughing modes, which greatly contributes to an increase in the productivity of processing with electrodes of any shape. When machining in finishing modes, the system provides process control to protect the quality and uniformity of the machined surface using a more advanced sensor for contamination of the interelectrode gap. All this increases productivity by 10 times in comparison with the previous generators.
Businesses are turning to robotic machine loading systems to increase machine tool uptime. deserted mode, increasing productivity per machine and reducing tool change times. The robot is built into the machine, the CNC system provides direct control of the machine and the robot. Other benefits of this system are adaptive control, a 50% reduction in electrode change time and a reduction in floor space.
New control systems provide opportunities easier programming, contributing to the reduction operator hours. The generic control system allows the operator to perform offline programming on personal computer and then download the program to the machine. This results in a reduction of approximately 25% in programming time and EDM time for most operators.
Machining accuracy on copy-piercing machines largely depends on the accuracy of the electrode. The advent of affordable high-speed graphite electrode milling machines has made it easier for businesses to efficiently process large quantities of precision electrodes.
The accuracy of the latest models of copy stitching machines has also been improved. This applies in particular to micromachining. For example, when electroerosive machining of square cavities, the area of ​​which is equal to 60 mm 2, using the latest pulse generators, a cavity profile with a corner radius of 0.025 mm is obtained, due to a 65% reduction in electrode wear in these corners. This allows six times fewer electrodes to be used.
With increasing processing speed, size and complexity of workpiece shapes, increased accuracy achievable, easier machine operation, unattended operation, user education, customer support and affordability, EDM has established its position in the tool industry and is increasingly being used in mainstream manufacturing. .
Today, no enterprise can ignore the possibilities of electroerosion, which can solve many production problems.
Turning directly to the analysis of EE equipment, let us dwell on several fundamental issues that significantly determine the effectiveness of EE processing.

Linear drives
EE feed drives of CNC machines are built according to the traditional scheme. More reliable and modern drives are made without a belt drive. In these drives, the power stepper motor is directly connected to the lead screw. The disadvantages of these drives are well known:

• a large number of intermediate elements from the energy source to the working body (RO);
• the enormous inertia of these elements, which is especially noticeable in large machine tools;
• the presence of gaps in the transmitting devices;
• friction of mating parts, which changes dramatically when the system moves from a state of rest to a state of motion;
• temperature and elastic deformations of almost all transmission links;
• wear of mating elements during operation and loss of initial accuracy;
• errors in lead screw pitch and accumulated length error, etc.

Since these shortcomings reduce the main quality characteristics of the drives (accuracy and uniformity of the stroke of the working body, the amount of backlash during reverse, permissible accelerations and speeds of the RO), the design thought of machine tool builders has long been trying to somehow reduce their influence. For example, instead of a lead screw with a nut, an expensive and complex ball screw connection is used to reduce friction; in order to eliminate gaps, special devices for tensioning the connection are introduced into the connection of the screw with the nut; lead screws of highly precise machine tools are made according to the standard class; screw pitch errors are reduced using compensators; Sophisticated cooling systems are created to combat temperature deformations. Nevertheless, it is clear that the problems of drives with lead screws cannot be solved in principle because of their physical and technical nature.
The task was to radically replace the typical drives of metalworking machine tools with some other ones. And such a solution was the use of linear motors (LD). The principle of operation of such an engine has a number of advantages: there are no intermediate elements between the energy source and the RO, energy is transferred through the air gap, nothing needs to be rotated, it becomes possible to implement the main task - the longitudinal movement of the RO. All elements of electroautomatics, electric brake systems, protection systems, special shock-type equipment, etc. have been operating on this principle for decades. The vast experience in using electromagnetic systems has revealed their advantages: amazing simplicity of design and use, the possibility of almost instantaneous stop and reverse, quick response, large forces generated, ease of adjustment.
The promise of the solution, of course, was immediately appreciated. There was only one thing missing - the possibility of regulating the speed of the RO in the electromagnetic system. And without this, it was impossible to use an electromagnetic drive as a mover for a RO machine.
Particularly intensive research in this direction was carried out in Japan, where the linear drive was first used as a mover for bullet trains. In the same place, attempts were made to create linear drives for metalworking machine tools, but the first developed samples had significant drawbacks: they created strong magnetic fields, overheated, and most importantly, they did not ensure the uniformity of the RO movement.
Only on the threshold of the new millennium, mass-produced machines (so far only EDM) began to be equipped with a new generation LD, which is distinguished by the uniform movement of machine carriages with ultra-high precision, a large range of speed control, huge accelerations, instant reverse, ease of maintenance and adjustment, etc. In principle, the design LD hasn't changed much. The engine consists of two elements: a fixed flat stator and a flat rotor with an air gap between them. Both the stator and the rotor are made in the form of flat, easily dismantled blocks. The stator is attached to the rack (base) of the machine, and the rotor to the working body. The rotor is elementary simple, it consists of a set of rectangular bars, which are strong permanent magnets. The latter are fixed on a thin slab of special mineral-ceramics, the coefficient of thermal expansion of which is two times less than that of granite, and the hardness is close to that of sapphire.

With or without bath
EE wire-cutting machines without a bath (cutting only in a jet) have been produced and operated for a long time. Machines without a bath are 15-25 thousand dollars cheaper than machines with a bath (plunge cutting). If the enterprise has a sufficiently large area of ​​EDM machines, a part of the machines without a bath is a justified solution. If there is only one machine, it is worth considering what it should be.
Machines without a bath (jet) significantly limit the technological possibilities:

• it is impossible (or extremely difficult) to cut contours in parts such as a hollow pipe;
• it is impossible (or extremely difficult) to make contour cutting of multilayer slabs with voids between layers and in parts with holes, “pockets”, etc.;
• jet machines are suitable only for cutting parts of simple stamps, but do not ensure the stability of the environment of electric spark discharges for complex tasks;
• only during blasting, air cannot be completely expelled from the cavities, which leads to increased formation of abnormal discharges and as a result to wire breaks, scrap, cutting instability;
• without a bath, it is impossible to ensure temperature stability if the room temperature fluctuates significantly during the day; this is especially dangerous when cutting dies of multi-window sequential dies. In a water jet, taper cutting with angles greater than 15° is unstable at a large thickness.

Water or oil
Oil is a delicate and friendly medium for metal EDM. The high resistivity makes it possible to generate ultra-small spark discharges. The electric spark gap when cutting in oil is much less than in water.
In EE wire cutting, the tool size is the wire diameter plus 2 gaps. Since an EE discharge in water requires a larger gap, the size of the EE tool in water is always larger. In other words, for the same wire diameter, the resulting cut is wider in water than in oil. In addition, water is an aggressive medium for metal, which creates known problems. And these problems are all the more serious, the smaller the dimensions of the elements of the cut contour.
The main reason why water is used in EE machines is speed. Modern EE wire-cutting machines allow cutting at speeds up to 360 mm2/min. However, speed in microcutting is a secondary indicator.
Oil as an EE cutting medium is much more attractive than water. In addition to smaller gaps, the oil is completely free of electrolytic erosion and surface corrosion. The quality and durability of the tool surface after cutting in oil is significantly higher than after cutting in water. In oil, the cutting speed is stable even with a wire with a diameter of 0.025-0.03 mm.
Oil is an indispensable medium for EDM cutting of precision tools and small parts.

Manufacturers
The field of play (that is, the EDM market) is large and there are many players on this field, however, as the famous Dutch footballer Marco Van Basten said, 22 people play football, and the Germans always win. So in the production of EDM equipment, there are many manufacturers, and there are two clear leaders: the Japanese company Sodick and the Swiss AGIE Charmilles Group, which includes the companies AGIE and Charmilles. AGIE Charmilles Group and Sodick account for over 60% of global EDM sales.
On Russian market The products of such foreign companies as Fanuc, Hitachy, Mitsubishi (Japan), Dekkel, Diter Hansen (Germany), CDM Rovella (Italy), Electronica (India), Maurgan, Joemars Machinery (Taiwan), CJSC MSHAK (Armenia)…

Expert opinions

Michael Riedel, Head of Special Tools Department at SCOB (Germany): “Because PKD (polycrystalline diamond) as a material has a hardness similar to diamond, almost all traditional processing technologies are not applicable to it. As a method of processing products from this material, only electroerosive action can be used.

Rudolf Eggen, director of Kroeplin GmbH (Switzerland): “There are three possibilities for manufacturing contact levers for linear measuring instruments: casting, laser cutting and electroerosive cutting. We chose EDM because casting with an annual production of 6,000 pieces per model is too expensive, and laser cutting due to insufficient repeatability of the results, the required accuracy is not achieved. In addition, due to the short duration of preparatory and final operations and the high autonomy of processing during night shifts and on non-working days, EDM is more economical than other methods.”

Frank Haug, Managing Director of Frank Haug GmbH (Germany): “The possibilities of using EDM are endless. Our expectations for its use and accuracy have been greatly exceeded. Thanks to this technology, today we can produce many products in tight deadlines.”

Walter Gunter, owner of Ganter Werkzeug (Germany): “Thanks to the rational use of electrical discharge cutting, we can manufacture microtomes with high precision with their components from the most the best materials and meet tough market demands that unnerve our competitors.”

Advantages of wire EE processing

New opportunities in the manufacture of parts

Various wire diameters and the high suitability of EE wire machines for processing internal shapes allow you to produce parts that are impossible with traditional processing methods:

• obtaining deep grooves;
• production of parts with minimal internal radii;
• production of die equipment with high accuracy without manual finishing.

Reduced processing time

Obtaining a finished part from a heat-treated workpiece without the use of intermediate operations, achieving the required surface roughness without the use of manual finishing, manufacturing parts from hard alloys, ease of mounting workpieces on the machine due to the absence of loads on the workpiece during processing - all these advantages can radically reduce manufacturing time and enterprise costs compared to traditional processing methods.
Savings are achieved through:

• material savings (whole waste, not chips);
• use of one machine with one tool for the manufacture of the finished part;
• no need for intermediate operations for heat treatment of blanks;
• the possibility of manufacturing thin-walled parts and parts from brittle materials without the use of complex and expensive tooling.

decline labor costs when operating the machine

EE machines are designed for autonomous operation, which allows one operator to operate several machines at the same time.

Reliability and high accuracy

Due to the absence of mechanical loads on the workpiece and the constant updating of the tool - wire - the dimensions of the resulting part are not distorted. Each part, manufactured according to the corresponding program, can be repeated any number of times, changes in size or configuration can be made, if necessary, in a matter of seconds.

A bit of physics

The principle of electroerosive machining is based on the destruction and removal of material by the thermal and mechanical action of a pulsed electric gas discharge directed to the treated area of ​​the workpiece in the liquid. At the same time, complex physicochemical processes occur in the discharge channel, in the workpiece, in the working fluid and in the tool electrode, which determine technological characteristics shaping process.
When the electrode-tool and the workpiece, immersed in the working fluid (dielectric or weak electrolyte), approach each other, discharges are initiated between them under the action of the pulsed voltage of the generator. The formation of discharges depends on the processing mode. An electrical discharge is a highly concentrated in space and time impulse electrical energy, converted into heat between the electrode-tool and the electrode-workpiece. After the breakdown, a discharge channel is formed, surrounded by a gas bubble, both expanding as the discharge develops. When the electrode surface is bombarded with electrons and discharge ions, a concentrated heat release occurs, causing the appearance of holes with molten metal, some of which is overheated and can evaporate. A significant part of the metal is removed at the end of the current pulse due to a sharp decrease in pressure in the discharge channel, accompanied by mechanical impacts. Thus, electrical erosion of the conductive material is carried out.
The materials from which the tool electrode is made must have high erosion resistance. The best indicators in this sense are copper, brass, tungsten, aluminum, graphite. Working fluids must meet a number of requirements: low corrosiveness to the materials of the electrode-tool and the workpiece, high flash point and low volatility, good filterability, no smell and low toxicity.

In the direction of metalworking, the method of electrical discharge machining (EDM) has become widespread. The electroerosive processing method was discovered by Soviet scientists in 1947.

This technology was able to greatly facilitate the process of metal processing, especially it helped in the processing of high-strength metals, in the manufacture of parts of complex design, as well as in other areas.

The operation of the method is based on the impact on the part by electric discharges in a dielectric medium, as a result of which the metal is destroyed or its physical properties change.

Application of the EEE method:

• When processing parts made of metals with complex physical and chemical properties;
• In the manufacture of parts of complex geometric parameters, with complex machining;
• When alloying the surface to improve wear resistance and give parts the required qualities;
• Improving the characteristics of the upper layer of the metal surface (hardening) due to the oxidation of the material under the influence of an electric discharge;
• Marking products without harmful effects, which is present in mechanical branding.

Used to perform various operations different types electroerosive processing. Numerical devices are installed on industrial machines. program control(CNC), which greatly simplifies the use of any type of processing.

Types of electroerosive processing of material:

• The electric spark type of processing is used when cutting hard-alloy materials, figured cutting and for making holes in high-strength metals. Gives high accuracy, but the speed is low. It is used in stitching machines.
• The electrocontact processing method is based on the local melting of the metal by arc discharges, followed by the removal of the spent material. The method has a lower accuracy, but more high speed work than the electrospark method. It is used when working with large parts made of cast iron, alloy steel, refractory and other metals.
• The electric pulse method is similar to the electric spark method, but arc discharges with a duration of up to 0.01 seconds are used. This gives high performance with relatively good quality.
• The anodic-mechanical method is based on a combination of electrical and mechanical effects on the metal. The working tool is a disk, and the working medium is liquid glass or a substance similar in characteristics. A certain voltage is applied to the workpiece and the disk, during the discharge the metal is melted, and the sludge is mechanically removed by the disk.

In industry, machines are used that work on the basis of the method of electroerosive metal processing. They are classified according to several parameters: principle of operation, control, availability of CNC, etc.

Types of machines operating on the principle of EDM:

• EDM wire machine;
• Electroerosive wire-cutting machine;
• Electroerosive piercing machine.

Due to its versatility, the EEO machine is needed on the farm, and sometimes it cannot be replaced at all. Everyone would like to have such a device in their garage. Unfortunately, buying such a factory-assembled machine is very expensive and often not possible. There is a way out of this situation - to collect with your own hands.

Cutting and stitching machine

Contrary to preconceived notions about the complexity and impossibility of such a task, this is not the case. This is quite a feasible task for a simple layman, although everything is not so simple. The simplest type of machine is a cut-out machine, designed for processing parts made of alloyed, refractory and other durable metals.

The electrical circuit contains: a power source, a diode bridge, a light bulb and a set of capacitors connected in a parallel circuit. An electrode and a workpiece are connected to the output. Note again that this circuit diagram for a figurative concept of the principle of operation of the device. In practice, the scheme is supplemented with various elements that allow you to adjust the piercing machine to the required parameters.

General requirements for the electrical circuit of the cutting machine:

• Consider the required power of the machine when choosing a transformer;
• The voltage on the capacitor must be greater than 320 V;
• The total capacitance of the capacitors must be at least 1000 uF;
• The cable going from the circuit to the contacts must be only copper and with a cross section of at least 10 mm;

One example of a working scheme:

As you can immediately see, the scheme differs significantly from the principle one, but at the same time it is not something supernatural. All the details of the electrical circuit can be found in specialized stores or simply in old electronic devices that have long been gathering dust somewhere in the garage. An excellent solution is to use CNC to control the machine, but this method of control costs a lot, and connecting it to homemade machine requires certain skills and knowledge.

Machine design

All elements of the electrical circuit must be securely fixed in a dielectric housing; it is desirable to use fluoroplastic or another with similar characteristics as a material. You can display the necessary toggle switches, regulators and measuring instruments on the panel.

On the bed, you need to fix the holder for the electrode (must be fixed movably) and the workpiece, as well as the dielectric bath, in which the whole process will take place. As an addition, you can put an automatic electrode feed, it will be very convenient. The working process of such a machine is very slow, and it takes a long time to make a deep hole.

DIY wire machine

The electrical circuit of the wire machine is the same as on the cut machine, with the exception of some nuances. Consider other differences of the wire machine. Structurally, the wire machine is also similar to the cut-out machine, but there is a difference - it is a working element of the machine. On a wire loom, unlike a cut one, it is a thin copper wire on two drums, and in the process of work the wire is rewound from one drum to another.

This was done to reduce tool wear. A fixed wire will quickly become unusable. This complicates the design with a wire movement mechanism that must be installed on the frame for convenient processing of parts. At the same time, it gives the machine additional functionality. When cutting complex elements the best option will put the CNC, but, as mentioned above, this is due to some difficulties.

• Electroerosive wire-cutting machines with CNC Balt-System (Russia) jet type DK77-MS series
• Electroerosive wire-cutting machines of the jet type DK77 series in stock in Moscow
• Electroerosive copy-piercing ZNC machines with a controlled Z-axis series D71 in stock in Moscow
• EDM wire-cutting machines ACCUTEX, Taiwan
• Electroerosive wire-cutting machines of submersible type (СW series) Aristech, Taiwan
• Electroerosive wire-cutting machines of submersible type with automatic wire threading (СW-S series) Aristech, Taiwan
• Electroerosive copy-piercing machine (LS series) Aristech, Taiwan
• Electroerosive piercing machines with CNC (CNC series) Aristech, Taiwan
• EDM Super Drills
• MAXSEE CNC Elevating Bath EDM, Taiwan
• Precision stitching machines NEU-AR
• Electroerosive extractor. Removal of drills and taps by NPP "MEATEK". Available in a warehouse in Moscow.

Electroerosive wire-cutting machines of the jet type DK77 series in stock in Moscow

Price: from $11,500 including VAT

Installation of servo drives on the DK77 series machine.

Wire EDM machines are designed for manufacturing parts of various shapes and sizes, such as tools, machine parts, jewelry, dies, gears, slots, etc. These machines allow you to process parts made of steel of various grades, high-strength composite alloys, titanium, graphite and much more. Models differ in the amount of movement along the axes, the dimensions of the desktop, the type of processing - "single-pass" or "multi-pass". All models of machines are designed to process any conductive materials with high precision and excellent surface quality.

Application area:

When designing machine tools LLC NPP "MEATEK", the accuracy of processing, ease of operation, labor savings and long service life were taken as the basis, which undoubtedly affected the popularity this equipment and its wide application in enterprises of various levels. These machines are mainly used in the production of dies and molds, because. accuracy is the main advantage of these models. With only one tool required to get the job done, this machine is your affordable alternative to milling, turning and grinding equipment.

Processing scheme.

Advantages of our equipment:

• Processing of any conductive materials of any hardness.
• No chips (metal melts and evaporates).
• Absence of thermal and mechanical influence on the structure (the surface is not deformed).
• The minimum cut thickness equal to 0.2 mm allows you to effectively save the material being processed.
• The possibility of obtaining parts of complex shape and very small sizes, the production of which by other methods is difficult.
• Processing holes of small diameters and roundings of small internal and external radii.
• Possibility of batch processing.
• Due to the low cost of the machining process and the elimination of the problems of manufacturing expensive punching dies, the machine is the best replacement for punching.
• The possibility of short-term payback of equipment in the presence of problematic parts due to the overall low cost of processing, quick changeover of equipmentfrom one product to another.
• The simplicity of the machine design increases its reliability.
• The presence of a wire drum that rotates in different directions and at different speeds, thereby providing a rough and finishing cut.
• Repeated use of a wire electrode reduces the cost of processing.
• Rational use of consumables.
• Simplicity and clarity of creating complex contours and surfaces using the popular CAM / CAD programs "Compass" and "AutoCAD".

Made in Russia LLC NPP "MEATEK".

Wire-cut EDM machines of the jet type of the DK77 series work on molybdenum wire. Unlike wire electroerosive machines of submersible type of the SV series, jet-type machines of the DK77 series are equipped with an open work table, on which the workpiece is placed for processing without immersing it directly in the working fluid.

Coolant liquid is supplied to the molybdenum wire through a nozzle, directly into the zone EDM, which leads to cooling in the region EDM cutting and leaching of erosion products.

Advantages of jet-type EDM machines:

• Precision machining of any conductive materials
• Low cost of processing
• Fast payback of equipment
• No need for additional accessories
• Processing of large workpieces

What is used to make:

• matrices
• Punches
• Stamps
• injection molds
• Gears
• impeller
• Keyways
• cutting tooth
• Trim along the contour of the product

What should you pay attention to when choosing?

It's no secret that the accuracy indicators directly depend on the quality of the frame and the ball screw, when choosing an EDM machine, special attention must be paid to the maximum load on the desktop, maximum height blanks, diameter of ball screws and rail guides. Differences in the maximum load on the desktop are explained by the use of the frame of the younger model of the EDM machine - this certainly reduces the cost of the machine, but entails the use of a smaller diameter of the ball screw and rail guides, which undoubtedly affects the durability of the equipment. For example: Tosun DK7732 has a maximum worktable load of 500kg, while DK7725 has a maximum load of 300kg, which is in line with China's standard.

All of our equipment is used in own production, so we are always ready to demonstrate distinctive features, perform electroerosive machining and measurement of machining results.

Installation Features

The main tool is a stretched wire, which acts as one of the electrodes, the second is the workpiece itself. The high-frequency pulses supplied from a special generator are regulated according to the conditions of the task being performed and the set processing parameters. able to work with workpieces of various thicknesses. The movement of the part, controlled by automation, occurs according to the program laid down by the operator. Polarity allows you to process parts with minimal consumption. The presented equipment is efficient, reliable and economical.

All our machines are multi-pass.

Demonstration of the work of the wire machine

Metal processing on our machines

Although at present there are many methods and principles of metal processing, not all of them are universal. Even fewer methods are available for general use due to the high cost of specialized units and tools. The wire cutting machine is of the type that can guarantee high accuracy and work efficiency, regardless of the hardness of the material, because even the most stable alloys are subject to electroerosive processes.

Features of the impact allow you to vary the speed and accuracy, thereby determining the productivity and quality of processing. The widest customization options, combined with a carefully debugged and well-proven action scheme, have already made the corresponding installations extremely popular in the segment of manufacturing complex volumetric components with curved surfaces. The product is not only affordable, but also inexpensive to operate. That significantly increases the profitability of its use. Electronic control systems allow the smallest and most complex parts to be consistently produced.

The device of the wire-cutting machine

The flexibility of using the equipment is based on modern systems positioning of the conductive wire. The working tool is stretched between the base lower and upper guides. Uniform rewinding is provided by a drive shaft with a connected electric motor. Guides are made of materials with increased wear resistance, in particular, diamond or sapphire. The reusable working tool is looped and is changed only in the event of a break or before a large amount of work. The elements of the path are isolated and protected from breakdown to the body. The flush circulation system directs a specialized electrolyte with specified electrical conductivity characteristics into the gap between the wire and the workpiece. The products of combustion and melting of the workpiece are separated by coolant filters, after which the composition is again sent to work by pumping components. key element is a process current generator that provides voltage generation with specified power and frequency characteristics. Modern machines controlled by electronic components under software numerical control, and informative screens form the basis of the display system.

The process of electrical discharge machining (EDM) of conductive materials is based on the principle of directed destruction of the anode (workpiece), which is in a liquid dielectric medium, as a result of the passage of a high-power electric discharge between it and the cathode (working tool). In view of the significant technological possibilities method, it is implemented on electroerosive machines of various designs.

Structure and types of equipment for EEE

A typical EDM machine includes:

1. several autonomously operating from each other electric motors;
2. node for supplying the electrode-tool;
3. a bath with a working environment;
4. table for placing the workpiece;
5. control scheme.

The classification of the equipment in question is carried out according to the following criteria:

• Technological purpose. It is possible to single out universal, specialized and special machines for EEE;
• According to the principle of layout of the main nodes. It can be made horizontal and inclined, but vertical layout is more commonly used;
• By type of table: fixed or coordinate;
• By type of bath - removable or rising;
• According to the degree of accuracy - equipment for work of ordinary accuracy and precision;
• According to the principle of excitation and subsequent regulation of the parameters of the electric discharge.

The size range of types of domestically produced EDM equipment is determined by the requirements of GOST 15954.

Methods for obtaining an electric discharge in the working circuits of machine tools

Dimensional processing can be performed by spark, pulse and arc discharges. In the first case, a spark discharge of low duty cycle is formed between the cathode and anode, but with precisely specified characteristics of the interelectrode gap. Such machines are compact, they are distinguished by high work accuracy and surface quality after electroerosion, ease of regulation of technological indicators, but at the same time they have low power and, consequently, productivity. The areas of expedient use of such machines are the precise cutting of hard-to-cut materials (in particular, hard alloys), the production of parts with complex contours. They can also be used to retrieve broken tools and the like.

An increase in the energy of an electric discharge is achieved by introducing a pulse generator into the circuit, which increases the interval between adjacent discharges and simultaneously increases the thermal power during a single electroerosive act. As a result, work productivity increases, but accuracy decreases, and the surface of the machined part can have a rather extended heat-affected zone, which is not always acceptable. Electropulse machines are used where more significant metal removal per unit time is required.

If it is necessary to provide an even higher metal removal (and not only to shape the original workpiece, but also to harden it), electric arc machines are used. The productivity of such equipment increases by several tens of times, since the arc, unlike other types of electric discharge, burns continuously. To control the technological parameters of the arc discharge, it is compressed by a transverse flow of the dielectric medium, which is constantly and under high pressure pumped through the arc burning zone by a pumping unit provided in the machine circuit. Electric arc machines can produce large blanks for rolls, hammer dies hot stamping etc.

The use of electroerosive machines of various types

Of the equipment of the electric spark type, one of the most accurate is the MA4720 copy-stitching machine. It is designed to work with difficult-to-cut workpieces of complex configuration, for example, for hard-alloy die equipment, molds, molds. The productivity of the machine does not exceed 70 mm 3 /min, but it is possible to achieve an accuracy of 0.03 ... 0.04 mm, with a rather low roughness of the final surface (not higher than Rz 0.32 ... 0.4 μm in finishing processing modes). The movement of the desktop is made by the CNC system. The dimensions of the working table and the allowable range of values ​​of the interelectrode gap between the anode and cathode do not allow to obtain products with overall dimensions of more than 120 × 180 × 75 mm on this machine.

An example of an electric pulse machine is the common model 4E723, also equipped with a CNC. Higher values ​​of power density make it possible to achieve the efficiency of EEE up to 1200 m 3 /min, with processing errors in finishing modes within 0.25 ... 0.1 mm. Higher accuracy is achieved with EDM of shaped surfaces. The machine is also used mainly in tool making, however, the surface roughness increases markedly - up to Ra 2.5 µm, so grinding is required after processing in most cases. On the machine, it is possible to perform EDM of parts with overall dimensions of 620 × 380 × 380 mm, as well as cutting shaped grooves.

These types belong to universal electroerosive machines. An example of specialized equipment is the Model 4531 EDM, which profiles complex contours using a non-profiled electrode. The 4531 machine uses brass wire that is continuously rewound across the interelectrode gap, initiating a discharge between the cathode and anode. With a relatively low productivity (no more than 16 ... 18 mm 3 /min for steel; for hard alloy, the productivity is even lower), the 4531 machine, in principle, allows for an error of ± 0.01 mm, so the equipment in question is effective in the production of punching die matrices of a particularly complex configuration and templates. The maximum dimensions of the contour to be cut out are 100 × 60 mm.

Principles for the optimal choice of technology and machine size for EDM

The initial data are the accuracy of the contour, the dimensions (depth) of the thermally modified zone, as well as the desired value of removal per unit of time. For machine tools that work with non-profiled electrodes, it is important to have devices for automatic wire threading, and for pulse machines, generators that allow the use of bimetallic wire, which increases the performance of EDM.

To improve the quality of the process and reduce the erosive wear of the electrode-tool, it is better to use oil as working media (the most common mixture of industrial-20 oil with kerosene). In principle, for products with increased tolerances, it is also possible to use water.

The technological capabilities of electroerosive machines are significantly expanded by the presence of additional devices (for example, to obtain conical surfaces).

For metal removal from 20000 mm 3 /min and above, only electric arc machines should be used. The smallest error in the operation of such equipment is achieved at reverse polarity when graphite electrodes are used. At the same time, a relatively high surface roughness - not lower than Rz 0.8 ... 1.6 μm - makes it necessary to provide for fine grinding of the resulting contour after EEA with an arc discharge. The pumping pressure of the working medium must be at least 50 ... 60 kPa.