Electric wire cutting on cnc machines
Electric wire EDM machine
Processing of metals of different hardness levels with high accuracy is possible using unconventional methods. This includes cutting, grinding, and surface hardening by electric discharge. The electric discharge machine was invented quite a long time ago, but has only become widespread in recent decades.
The first industrial machine tool was developed by CHARMILLES TECHNOLOGIES in 1952, and the NC wire EDM was introduced in 1969. Compared with the traditional methods of metal processing. forging, casting, grinding, milling. the electrospark method can be considered innovative. The first references to forged and cast products are several thousand years old.
Electric discharge machining is such machining in which changes in shape, size, quality of workpiece surface occur under the action of electrical discharges, which leads to destruction of surface. During this machining process, the workpiece material is melted and/or corrected and removed in a liquid and/or vapor state. The removal usually has an explosive (impulse) character running in a short space of time on a small area of surfaces, in the place of discharge channel localization. The discharge channel is a cylindrical area of small cross-section filled with plasma.
Plasma. ionized gas heated to high temperature. And the result of the breakdown and formation of the discharge channel is the destruction of the electrode surface metal in the places of localization of the channel. electric erosion of the metal. The intensity of destruction of each of the electrodes is different and, under other conditions, depends on the polarity of the electrodes, the shape and duration of discharge current pulses. Accordingly, the workpiece to be treated is connected in such a way that its fracture (machining) intensity is always higher than the fracture (wear) intensity of the electrode-tool.
By feeding electrical discharges or pulses onto the spark gap, we get an effect on the metal. For a better result of machining one chooses accordingly more suitable way of its performance. So, the important element of this effect is that the workpiece can be machined in different directions at the same time.
The piercing machine is designed for machining both internal and external spherical elements, working along a 3-dimensional linear path. It is also possible to produce electric-spark piercing.
The first Soviet electric-spark machine in the world was designed for removal of a broken tool stuck in the workpiece. Since then, a great number of EDM machines of various applications, productivity and design have been produced in Russia and abroad.
Purpose of electric-spark machines
Electric-spark machines are used for cutting various workpieces of most diverse shapes and sizes. Machining is done either at a right angle or at an angle from 1 to 30 degrees. The angle at which the workpieces are machined depends primarily on the equipment of the machine. The beginning of the cut can be from the edge of the workpiece, but also from inside through a pre-drilled hole. Electroerosion machines are intended for producing parts with an accuracy of up to 0,015 millimeters.
The main purpose of electric-spark machines is considered as the replacement of stamping. Machines of this type can cut several workpieces at the same time, thanks to batch processing. No subsequent milling of the workpiece is required, since the machining process does not cause any surface deformation of the workpiece.
Different dies and templates can also be produced. One of its great advantages is that it can be easily and quickly reconfigured. Basically the whole re-equipment of the machine consists of several operations: first of all the required drawing is loaded from AUTOCAD, then some actions are done on the computer and after that the generator is set and the next workpiece is ready for machining. Experienced operators spend on average only 15 minutes to set up the device.
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Electric discharge metal cutting
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Continental” electrical discharge cutting
Our company provides services for electrical discharge metal cutting in a short time. The equipment we use allows us to work with almost any metal. Qualified personnel provide the necessary accuracy and quality of processing, controlling the processing at all stages of production.
With the help of electrospark machining it is possible to perform a wide range of works, for example:
- Machining of complex shaped parts;
- Machining of spur gears and sprockets;
- Cutting of key and slotted grooves in bores;
- Cutting complex contours with high accuracy requirements.
Field of application of EDM technology:
toolmaking, keyways, gears, sprockets, crowns, shafts, racks, gearboxes, housings, split rings, stator plates, junction disks, punches, dies, dies.
Any conductive material. structural, tool and alloy steels, stainless steel, hard alloys, non-ferrous metals, hardened steel.
At the Kopeyskiy branch, the production department of Continental LLC, a high-speed electroerosion CNC wire-cutting machine DK7763 was put into operation.
Characteristics of CNC machine DK7763:
|Table size, mm||1070х680|
|Table displacement, mm||850х650|
|Maximum thickness, mm||600|
|Maximum weight of workpiece, kg||950|
|Roughness at single pass cutting, μm||Ra 3.2|
|Best roughness for multi-pass cutting, μm||Ra 0.8. 1.6|
Machine can be used for making punches, press-molds, gear wheels, slotted holes, keyways and other details with complicated profile, big working depth (up to 600 mm) or internal sharp angles.
In addition, the hardness of the material is not important for electrical discharge machining (electro-sparking). It can be raw or hardened steel, stainless, alloyed steel, titanium, tungsten, aluminum, hard alloy. The machine’s ability to machine parts while they are hardened makes it possible to cut e.g. a keyway after the heat treatment, which reduces the risk of cracks.
Surface distortion of thin parts is completely eliminated. This is because the method does not imply any mechanical loading.
The possibilities of the machine and the high professionalism of the specialists of the Kopeyskiy branch will allow to solve the most different tasks of our customers: from urgent production of single pieces to serial production of parts.
Advantages of electrical discharge machining
We are sure that nothing is impossible for us and our CNC-machines. We always undertake the most technically complicated serial orders and perform the tasks on time. If you need mass electrospark machining, feel free to contact us!
We are convenient and reliable to work with, because we:
- experienced specialists,
- take on tasks of any complexity,
- work with all kinds of metal,
- We have the most innovative technological base,
- are aimed at long-term cooperation.
To find out the price of electrical discharge machining, contact us by phone or leave a request in the special feedback form. we will promptly calculate the cost of your work!
Let’s see how our Fanuc ROBOCUT α-C400iB EDM machine works.
Electric discharge machining
Details and units of modern machines and devices are characterized by a great variety of constructions and applied materials, including such materials, which shaping by the known methods of machining is difficult and sometimes impossible. Related to this is the increasing use of electrical discharge machining processes. “The possibilities of electrical discharge machines are limitless!”This is a phrase you often hear from machine users just a month after commissioning.
Classification According to the technological purpose machines for electrical discharge machining are divided into two main types. copy-piercing and wire-cutting. Piercing machines can machine shaped holes and cavities, the inner and outer surfaces of bodies of revolution, grinding and cutting. Spiral and involute surfaces as well as a variety of straight, inverted and variable cone internal bores and cavities can be produced. In copy-piercing machines the electrode-tool is shaped; its shape is an inverse copy of the cavity to be machined. EE wire-cutting machines are used for manufacturing parts of dies, gauges, templates, shaped cutters, templates and other tooling equipment. Electrode-tool in cut-out machines is a continuously rewound wire. Design features of the machines determine their technological advantages: shaped tools are not required, there is no need to make corrections for electrode wear, it is possible to produce small parts of complex shape, including parts with equidistant profile (dies, punches) using one CNC program.
Progress stages EE machining is no longer a non-traditional method of machining both in the world and in our country. Currently, EE equipment is the fourth most used in the world after milling, turning and grinding. Sales of electric erosion machines increased from 0.5% in 1960. To more than 6% of the EE market in 2000. The priority in the discovery of electric erosion belongs to Russia. The first practical research in this field was done in the Urals at the end of the 30s by the couple B. and H. Lazarenko in his study of contact erosion problems. Discovery registered in 1943. The world’s first wire-cutting machine was built in the German plant in Halle-Vilvo in Berlin. Fryazino, Moscow region in 1954. But, unfortunately, the production of energy-saving machines in the Soviet Union was not duly developed.
EE wire cutting EE cutting on wire-cutting machines appeared in the early seventies and is continuously progressing in several directions. The cutting speed increased from about 10 mm 2 /min. at the beginning of the seventies to 35 mm 2 /min. in the middle of the eighties, and now reached 330-360 mm 2 /min. The increase in speed was mainly achieved by flushing the working surface with liquid under increased pressure and the use of more productive pulse generators which allowed to set the optimum parameters. Improved electrode quality also contributes to the speed increase. Reliable and efficient automatic wire threading devices, wire break prevention devices and automatic part loading devices have been developed to take advantage of high speed cutting and to avoid machine downtime. The maximum height of dies and punches machined at the beginning on erosion machines was in the range of 50 to 100 mm. But in order to machine casting molds, extrusion dies, and a variety of other parts, machine tool manufacturers have expanded the size range of their workpieces. Originally, a tapered hole angle of 1° for workpieces between 100 and 125 mm high was just about all that was possible. In order to meet the requirements of the customers, an angle of 30° with a workpiece height of about 400 mm can now be achieved on most machine models. The maximum achievable accuracy is increased from 25 µm, which was typical of the first machines, to 1 µm. for modern EE machines. The operators of today’s cutting machines need far less effort to achieve machining accuracies on the order of 1 µm than the experienced operators of the first cutting machines, which achieved machining accuracies of 5 or 2.5 µm. Several factors have contributed to this simplification of precision work. The technology built into the latest machines makes it possible to cut the contour exactly as specified by the geometry program. Optical rulers provide stable accuracy regardless of the duration of machine operation and significant temperature fluctuations. The most important innovation is the provision of highly reliable and efficient automatic wire threading systems that enable the machine to machine a number of parts without operator intervention. The machines’ ease of use allows for more economical machining and for more machines in the shop to be operated with less manpower, even during the day shift.
EE piercing The most significant improvement on CNC copy-piercing machines compared to hand-controlled machines was the reduction in cycle times, and above all the reduction in operator work time. In 1960. The machining of the cavity with the electrode tool required about 4 hours of operator time and 4.5 hours of erosion 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. A new era in the reduction of machining cycle times began in 1999. Equipping copy-piercing machines with adaptive pulse generators. Compared to earlier 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 roughing, which greatly contributes to the productivity of machining with electrodes of any shape. For finish machining, the system monitors the process to protect the quality and consistency of the surface finish using a more advanced electrode gap sensor. All of this increases productivity by a factor of 10 compared to previous generators. Enterprises are turning to robotic machine loading systems to increase idle time, increase productivity per machine and reduce tool change times. The robot is integrated into the machine, CNC controlling the machine and robot directly. Other benefits are adaptive control, up to 50% shorter electrode change times, and a smaller footprint. New control systems allow easier programming which reduces operator time. The typical control system allows the operator to program off-line on a personal computer and then load the program into the machine. This provides a reduction in programming time and electroerosion time of approximately 25% for most operators. The precision of the copy-piercing machines depends to a large extent on the accuracy of the electrode. The appearance on the market of affordable high-speed milling machines for machining graphite electrodes has made it possible for companies to simplify the task of efficiently machining a large number of precision electrodes. The accuracy of the latest models of copy-piercing machines is also improved. This applies in particular to micromachining. For example, in the electrical discharge machining of cavities with a square cross-sectional area of 60 mm 2. the newest pulse generators make it possible to obtain a cavity profile with a corner radius of 0.025 mm, thanks to a 65% reduction of the electrode wear in these corners. This allows six times fewer electrodes to be used. Due to the increase in machining speed, sizes and complexity of processed parts, increase in achievable accuracy, facilitation of machine operation, possibility of unattended operation, user training, customer support and availability, electrospark machining has consolidated its position in tool production and is more and more used in mainstream production. Today no enterprise can not ignore the possibilities of electromachining that allow to solve many production problems. Turning directly to the analysis of EE equipment, let us consider a few principle issues that essentially determine the efficiency of EE machining.
Electric discharge machining is used today for a wide variety of applications because it is an expedient way to produce parts with complex parameters. Among the advantages of this method should be highlighted:
- Ability to create maximum sharp angles on the outside and inside of the workpiece;
- The permissibility of processing hardened steel, as well as all kinds of alloys;
- The depth of cut, which reaches 400 mm;
- Capability to cut closed channels.
Among other things, we guarantee that our machine tool for electrical discharge metal cutting is reliable in use. Our company uses only high-tech modern equipment, which demonstrates high efficiency in operation.
SUPPORTING SYSTEM OF THE MACHINE
The EEP machine bed in order to perform its functions, namely for the installation of electrical units, must not only give the structure stability, but also be characterized by high rigidity. The base of our machines is designed as a box. The most critical parts of the bed (drum carriage, column mounts, table guides) are scraped and polished.
Materials with high strength and low coefficient of thermal expansion are used for the bed. Originally, a special type of cast iron was used for the bed of an EEP machine. high-strength. At the present time the productivity of machines is increasing sharply and thus the effort in EE processing increases, and this, in turn, leads to increased loads and increases the thermal impact on the bed.
High-strength cast iron no longer satisfies manufacturers of EBM machines, and many companies use other materials for bed construction. For example, machines by “EXERON” (Germany) are distinguished by the base, made of mineral casting, and machines by “Maurgan” (Taiwan) have a base made of polymer concrete.
Electrical discharge machines
The appearance of new cutting tools in recent years has allowed high-speed milling to compete quite strongly with electrical discharge technology, especially in the manufacture of dies and molds. However, for many technological operations, including a number of designs of molds and dies, use of electric-spark machines remains not only more efficient but also has no alternative.
Let us have a look at the general trends of electromachining equipment perfection, analysis of this equipment market in Russia, world novelties and experience of using electric-spark machines.
Such foreign companies as Agie and Charmilles Technologies (Switzerland), Sodick and Mitsubishi Electric (Japan), Opa (Spain), Taiwanese Joemars, Maurgan are among well-known manufacturers of electric-spark machines in the Russian market. Recently Italian CDM Rovella, American-German Ingersoll, Indian Electronica, Taiwanese Sevenspark, Jiten, Chmer EDM, Polish ZAP In.P., American Hardinge (series of machines collectively called Hansvedt). The products of German Wollmer-Werke and Matra-Werke, British Derek Robinson, Japanese Makino, Seibu Electric. And products of American companies Toolmaster Technology and Methods EDM are almost totally unknown. Russia in the list of electroerosion machine tools producers is represented by OOO NPK Delta-Test (Fryazino, Moscow region, oblast, Russia), OOO TeliaSonera (Kuzbass, Russia), OOO TeliaSonera (Moscow region, Belarus), as well as by the following companies. Fryazino, Moscow reg.), Spetspromoborudovanie LLC (Moscow region), Spetspromoborudovanie LLC (Moscow region) and Spetspromorudovanie LLC (Moscow region). Ulyanovsk), Stankokonstruktsiya Plant (Moscow), CNITI (Moscow), SPb. Precision Machine-Tool Plant”, JSC “Troitsk Machine-Tool Plant” (Moscow, Russia). Troitsk, Chelyabinsk reg.). And, with a few exceptions, all the above companies produce both basic types of electric-spark machines. wire-cutting as well as coordinate-piercing machines. In short, there is a choice, especially considering the significantly lower demand for electric-spark equipment compared to the demand for lathes or mills. Machines that perform the same functions, similar in size of the parts to be machined, differ significantly in their technological indicators, level of reliability, degree of automation and autonomy and, as a consequence, in the price. For example, basic price of piercing machine of BP-97 model made by Polish company ZAP В.Р. The basic price of the sewing machine of model Gantry 500 by Ingersoll company is 29500 euro, and machine of model Gantry 500 by Ingersoll company costs 152100 euro without a delivery cost, custom duties and the VAT. Approximately the same level of for machines from leading world manufacturers (Agie and Charmilles Technologies, Sodick and Mitsubishi Electric). Naturally, such a significant difference in cost cannot be explained only by a brand. Let’s try to find out the difference between machines made by the world leading manufacturers, and what are the general trends of development and perfection of electric-spark technique. This is where we will start. Since both types of electric-spark machines are different in their purpose and execution, we will take the following order of presentation: in the first part we will consider the cutting machines, in the second. the piercing machines.
Rather solid, if not more, cost of the best samples of such equipment and tough competition are forcing the leading manufacturers to constantly improve the design, expand the technological capabilities, improve the reliability of machines and ease of their operation. Nowadays the best models of cut-out machines enable to achieve very high technological indicators. productivity of processing up to 330 sq. m. / min. mm/min. (in some cases up to 360), minimum surface roughness Ra up to 0,03-0,05 microns, machining accuracy up to 1-2 microns. Consider the almost mandatory list of features and characteristics of a really great machine. Rigidity of design. a prerequisite for accuracy and durability. Used materials and design optimized according to many criteria allow to load heavy workpieces providing specified accuracy. The frame is made of special materials, providing high strength, rigidity and durability, high electrical insulation characteristics, low coefficient of thermal expansion. Sodick’s FineXCera structural ceramics are a typical example. Achievement of virtually mirror-like surfaces is due to the use of special modes, CNC-controlled process generators that exclude electrolysis and anodic dissolution, and the use of special working fluids, such as oils or hydrocarbon fluids with metallic powder additives. Control systems and level of automation are constantly being improved. The software of CNC systems allows to achieve maximum productivity. For example, the software includes programs that select the sequence of machining operations and optimize cutting modes based on the priorities set by the operator in terms of speed, accuracy and surface finish; automatic control of machining and immediate response to changing machining conditions, thus eliminating the risk of wire breaks; adjustment of machining parameters and wire tension at each change of direction, resulting in accurate execution of the ost. The cutting machines are enhanced by a range of options such as precision contact positioning, controlled turning of workpiece and spindle, which enable cutting at any freely definable angle without wire tilt, and the possibility of cutting any kind of grooves on round workpieces, including helical ones. Provides universal machine-to-machine connectivity. Software support for a range of peripheral devices. in addition to floppy and CDROM drives, local network connectivity is included, as are internal robots and other manipulators. Ethernet port allows both program and process files to be downloaded from and sent to the host computer. Considerable attention is paid to increasing the autonomy of machines and individual assemblies. For this purpose, machines are equipped with robots, devices for automated change of fixture-satellites with details, etc. Control programs have been developed that enable continuous operation of the machines in automatic mode and control groups of machines within a site. The machining process is monitored from the control room using diagnostic data from the central computer and data from the video cameras installed in the machining area. And just a few more words: