What is WEDM?

Question1:What is the history of WEDM?

In the mid-20th century, the Lazarenko couple in the Soviet Union, while studying the phenomenon and causes of switch contacts being corroded by spark discharge, found that the instantaneous high temperature of spark could melt, oxidize and corrode local metals, thus creating and inventing the EDM method. The WEDM machine tool was also invented by the Soviet Union in 1960. At that time, a projector was used to watch the left and right hands move back and forth in front of the outline for processing. In fact, people think that although the processing speed is slow, it can process fine shapes that are not easy to process by traditional machinery. A representative example is the machining of special-shaped holes of chemical weaving nozzles. At that time, mineral oil (lamp oil) was used as the processing fluid. High insulation, small distance between poles, lower processing speed than existing machinery, and limited practicability.

The model machined by NC in deionized water (close to distilled water) was exhibited by Swiss EDM Machinery Factory for the first time at 1969 Paris Machine Tool Exhibition, in order to improve the machining speed and establish the safety of unmanned operation. However, the manufacture of CNC paper tape is very laborious, and it will be a great burden for users if there is no automatic programming by large computers. Before the appearance of cheap automatic programming tool APT, its popularity was very slow.

The WEDM machine developed by Japanese manufacturers by automatic programming with small computers is cheap, which accelerates its popularization. The machining shape of WEDM is a two-dimensional contour. Simple APT is widely used in automatic programming equipment (APT language is simpler than formal model), and the appearance of simple APT is an important factor in the development of WEDM.

Basic principles of WEDM

In WEDM, copper wire is used as the tool electrode, and a pulse voltage of 60~300V is applied between the copper wire and the workpiece material such as copper, steel or superhard alloy, and a gap of 5~50um is maintained. The gap is filled with insulating media such as kerosene and pure water, which causes spark discharge between the electrode and the workpiece, mutual consumption and corrosion. Numerous pits are etched on the surface of the workpiece, which are monitored by numerical control and executed by servo mechanism.

The physical principle of EDM is as follows:

In order to generate an electric spark between two electrodes, the voltage between the two electrodes must be higher than the gap (electrode-workpiece) breakdown voltage, which depends on:

1) the distance between the electrode and the workpiece;

2) Insulation capacity of dielectric liquid (water resistivity);

Pollution status of gap (corrosive waste).

The discharge first occurs at the point with the strongest electric field, which is a complicated process. Free positive ions and electrons accumulate in the electric field and soon form ionized conductive channels; At this stage, an electric current is formed between the two plates. It leads to numerous collisions between particles, forming plasma, which quickly rises to the high temperature of 8000 to 12000 degrees, instantly melting some substances on the surfaces of the two conductors, and at the same time, bubbles are formed due to the vaporization of the electrode and dielectric liquid, and its pressure rises regularly until it is very high; Then the current is interrupted and the temperature drops suddenly, so that the bubbles explode inward, and the generated power throws the dissolved substances out of the crater, and then the corroded substances re-condense into small balls in the dielectric liquid and are discharged by the dielectric liquid; The asymmetry of corrosion pair between electrode and workpiece mainly depends on the thermal conductivity of electrode, melting point of material, duration and discharge density. What happens on the electrode is called loss, and what happens on the workpiece is called material removal.

job/work safety

In order to ensure the healthy and comfortable working environment of operators and machine tools under the best safety conditions, and to maintain the original machining performance and accuracy of machinery and equipment for a long time and prolong the service life, we must abide by the safety rules of WEDM.

I. Environment:

The selection of environment is directly related to WEDM equipment and its operators, and the quality of environment selection has the following effects: First, it damages the performance and accuracy of equipment and shortens the life of its machine tools; Secondly, it affects the machining accuracy of the workpiece and causes poor quality; Third, it is also harmful to the safety and health of operators. Therefore, please refer to the following items for the selection of environmental sites:

1. Space size meeting the requirements of WEDM;

2. Choose a place that can bear the weight of the machine tool;

3. Choose a place without vibration and shock.

WEDM is a high-precision machining equipment. If there is vibration and impact at the place where it is placed, it will cause serious damage to the machine, thus seriously affecting its machining accuracy. & gt

Question 2: What is wire cutting for? WEDM is an electro-machining machine tool, which cuts metals (especially hard materials and linear complex parts) by electro-corrosion with molybdenum wires.

WEDM, sometimes called WEDM. Its basic working principle is to use thin metal wire (called electrode wire) which moves continuously as electrode to remove metal and cut workpiece by pulse spark discharge. It is mainly used to process various complex and precise workpieces, such as punches, dies, punches, fixed plates, discharge plates, etc. Forming tools, templates, metal electrodes for EDM, all kinds of fine holes, grooves, arbitrary curves, etc. It has the outstanding advantages of small machining allowance, high machining precision, short production cycle and low manufacturing cost, and has been widely used in production.

According to the different wire speed and machining quality, WEDM machine tools are usually divided into three categories: the first category is WEDM-HS, whose wire speed is 8 ~ 10m/s in general, and the wire can be reused, so the machining speed is high, but it is easy to cause wire jitter and reverse pause, which reduces the machining quality. The second type is WEDM-LS, in which the electrode wire moves in one direction at a low speed, and the linear speed is generally lower than 0.2m/s, and the electrode wire is no longer used after discharge. The work is stable and uniform, with small jitter and good processing quality, but the processing speed is low, so it is the main model produced and used abroad. The third medium-speed WEDM machine tool should be accurately called "multi-speed WEDM". It is original in China, and the principle is to cut the workpiece repeatedly. At the beginning, it was cut with faster spool speed and stronger high frequency, just like the current high-speed wire cutting, and the last knife was polished with slower spool speed and weaker high frequency current, thus improving the machining smoothness. Moreover, after the linear speed is reduced, the jitter of the guide wheel and bearing is smaller and the machining accuracy is improved; In addition, the first knife has the fastest cutting speed, and the subsequent cutting and grinding amount is very small. Therefore, the total time of three-knife cutting is generally faster than that of one-knife cutting of fast-moving line.

According to the different control forms of electrode wire motion trajectory, WEDM machine tools can be divided into three types: one is profiling control, in which a die with the same shape as the workpiece is made in advance before on-line cutting, and the workpiece blank and the die are clamped on the workbench of the machine tool at the same time during machining, and the electrode wire moves close to the edge of the die during cutting, so as to cut the workpiece with the same shape and precision; The other is photoelectric tracking control. Firstly, according to the part pattern before wire cutting, the photoelectric tracking diagram is drawn according to a certain amplification ratio. During machining, the pattern is placed on the photoelectric tracking table of the machine tool, and the photoelectric head on the tracking table always follows the trajectory of the ink line pattern. Then, with the help of electrical and mechanical linkage, the machine tool workbench and the workpiece are controlled to do similar movements relative to the electrode wire, so that the workpiece with the same pattern shape can be cut. The other is digital program control, which uses advanced digital automatic control technology to drive the machine tool to automatically complete the machining according to the NC machining program pre-programmed according to the geometric parameters of the workpiece before machining, without making templates or drawing enlarged drawings. Compared with the first two control forms, the machining accuracy is higher and the application scope is wider. At present, more than 95% WEDM machine tools at home and abroad have adopted numerical control.

Wire cutting belongs to the field of electrical machining and was invented by the former Soviet Union. China was the first country to use it in industrial production. It was jointly produced by Fudan University and Suzhou Changfeng Machinery Factory. This is the earliest model, called Fudan model. On this basis, we developed China's fast wire cutting system (HS). Europe, America and Japan have developed the Slow Travel System (LS).

The main difference is 1. Tungsten-molybdenum alloy wire is used as electrode wire in China and brass wire is used abroad. 2. Soap chemicals are used at home and deionized water is used abroad; 3. The linear speed in China is about 1 1 m/s, and it is about 3~5 m/min abroad. Our electrode wire is reused until it is broken, which is not reused abroad. 5. Our accuracy is not as high as that of foreign countries ... >>

Question 3: What are the basic steps of 3:WEDM? Information 0bbs/group _ thread/view/ID-408 1 3 Basic steps and precautions of WEDM operation1. Read the drawings carefully, master the most basic cutting requirements, and find the shortest and simplest cutting line. 2. painting; Turn on the computer, select the wire cutting software on the desktop, right-click to start drawing, and form a trajectory transmission program. 3. Select the transmission command in the correct transmission process, select the transmission file (generally select current) and then double-click the Enter key; The controller clicks the standby gear 1b to start transmission; Do not touch the keyboard and mouse during transmission. 4. Choose the clamping method. The clamping of WEDM workpiece requires a small basic force and can be attracted by magnets. Bolts can also be used for bolt reinforcement of general large workpieces. In any case, there is only one clamping principle: cutting can complete the whole gauge at one time; Thereby conveniently solving the problems of short circuit, broken wire and the like in cutting. 5. Selecting cutting parameters; Because of the different thickness of materials and the different roughness of cutting surfaces, the cutting parameters of each workpiece are very different. Generally, the voltage for cutting workpieces below 50 meters is below 70 volts. The voltage higher than 70 mm is above110v; There are four steps between pulses; They are 1248 four single-pole switches. These four switches can only be matched with 1 and 4 or 8, otherwise no current will be formed. In principle, the fewer switches, the faster the speed and the worse the finish. However, the pulse width and voltage are matched. Generally, two 14 single switches are selected below 50 mm, and the pulse width selection range is 4.8. 1632. The current also increases, but generally only 32 single switches are selected. Voltage: Voltage has six unipolar switches. The more switches are selected, the higher the voltage. The magnitude of current and large voltage depends on the thickness and material of the workpiece. Under 50 mm, generally choose three 122 single switches; Or 1222 four single switches. It is best to use 122 single switch three in the initial running state of new molybdenum wire, which can prolong the service life. The current of the new molybdenum wire is preferably 50% of the normal current. 6. The relationship between pulse width and pulse interval and voltage and current is very important. These theoretical knowledge can only be understood by practitioners who can operate machine tools and can't cut wires. The larger the pulse width, the smaller the current (assuming other parameters are unchanged). Under normal circumstances, the working current of the current should be below the ammeter indication 2 (except for the workpiece with a thickness of more than 50 meters). The normal indication is as follows: the peak current indicates that the cutting pointer decreases downward after 2 revolutions, which is the best processing state simply from the service life of molybdenum wire. 7. Try not to change the cutting parameters when cutting the machine tool, because the sudden change of current and voltage is likely to cause the failure of the high-frequency control cabinet (it is best to burn out the circuit board and capacitor, etc.). ). It is best to select the parameters before the machine tool commutation interval or machining. When checking the pointer of the workbench, shake it to the wire feed point. Start the machine tool and turn on the high frequency of the wire feed point. Everything is ready. Turn on the water pump, feed and process. 9. Coolant must be replaced after a week of continuous use at most, especially when machining workpieces with large cutting area and thickness exceeding 50 mm, to prevent short circuit and broken wires during cutting. Trouble. Generally speaking, the ratio is 1:20, that is 1 container of pure liquid to 20 containers of water. The demand for water is very high. If conditions permit, the cutting effect with pure water will be very good. It is not easy to short circuit and disconnect. Because the minerals contained in the water have a great influence on the electrical corrosion in the cutting process. About single chip microcomputer controller; The controller should stop working in thunderstorm weather, because this will lead to the breakdown of the circuit board inside and the controller will be scrapped. (Its price is around 800 yuan) 1 1. On the problem of single-sided wire tightening, both new wires and molybdenum wires used for a period of time are faced with the problem of wire tightening, because if the molybdenum wire is too loose, it is not only easy to break, but also easy to deviate to form waste products and damage the molybdenum wire. Therefore, after using them for a period of time, you should always check them ...&>

Q 4: What is the general charging standard of 4:WEDM? General charging standard for WEDM: WEDM is generally calculated by area. WEDM universal parts are charged according to the cutting area (square millimeter) *0.008 yuan. For parts that need threading, add 5 yuan to each threading hole.

Other related expenses:

First, the method of pricing by working hours:

Z25 drilling machine, CA6 140 lathe planer grooving sawing machine will be charged per hour 15 yuan.

Vertical and horizontal milling, wire cutting, large lathe and gantry milling are charged at 20 yuan per hour.

The locksmith generally charges for maintenance per hour 15 yuan.

The timing unit starts the takeover process and ends the acceptance process.

Second, according to the requirements of parts, quantity and accuracy, charging method:

1, drilling general materials

The depth-diameter ratio is not more than 2.5 times, and the diameter below 25MM is calculated as the bit diameter *0.05.

According to the drill bit diameter of 25-60 *0. 12 (the minimum hole is not lower than 0.5 yuan).

General materials with depth-diameter ratio greater than 2.5 are charged according to base price * depth-diameter ratio *0.4.

If the aperture accuracy is required to be less than 0. 1MM or the center distance is required to be less than 0. 1MM, it will be charged at the base price of *5.

Tapping fee is calculated as tap diameter *0.2 (calculated as cast iron, steel is * 1.2).

For batch processing, the standard base price is *0.2-0.8 (depending on batch size and processing difficulty).

2, lathe processing general precision optical axis processing.

If the aspect ratio is less than 10, it will be charged according to the blank size of the workpiece *0.2 (minimum 5 yuan).

If the aspect ratio is greater than 10, the basic price of the general optical axis * the number of aspect ratios *0. 15.

If the accuracy is required to be within 0.05MM or the taper is required, it will be charged according to the general optical axis base price of *2.

General stepped shafts (fan shaft, pump shaft, reducer shaft, grinding wheel shaft, motor shaft, spindle, etc.). ) are all processed with general precision optical axis. The basic price is *2. If the stepped shaft has taper and internal and external threads, it will be machined with general precision optical axis.

Basic price *3 expenses

General screws are charged according to the basic price of general precision optical axis processing *4.

General flange parts shall be charged according to the material diameter of *0.07, and those with a diameter greater than 430MM shall be charged according to the material diameter of *0. 12.

General round nut parts are charged according to the diameter of *0.25 (including materials).

For general trapezoidal and triangular nut parts, the diameter is *0.3 (excluding materials).

General shaft sleeve parts (diameter less than 100, diameter-length ratio less than 2) are charged according to the external diameter of materials *0.2, and those with diameter-length ratio exceeding 2 are charged according to diameter-length ratio * base price *0.6.

Generally, each 5 yuan with a wear amount of less than 2MM, a diameter of less than 40MM and a width of less than 25MM needs to be mounted on the center frame, or the with a length of more than 1.7m will be charged at the base price of *2. If the diameter is greater than 40MM, it will be charged according to the diameter *0.2.

3, milling machine processing general keyway processing.

Key slot width *0.5 (aspect ratio less than 10) (minimum 5 yuan). If the aspect ratio exceeds 10, it will be charged according to the aspect ratio * base price *0. 1 If there are strict location requirements, it will be charged at the base price of *2. Materials with hardness greater than HRC40 shall be processed according to the reserve price *2. For general spline machining (the aspect ratio is less than 5), it is calculated as spline shaft outer diameter *0.8 (minimum 15 yuan), and for general gear machining, it is calculated as modulus * number of teeth *0.5 yuan. Worm gear is charged according to cardinal number * 1.2. Bevel gears, bevel gears and modified gears are charged at the base price of *2. Ordinary plane machining is charged at per square decimeter 1.5 yuan (minimum 5 yuan), and ordinary boring is charged at aperture *0.25.

4. The cutting of general round steel, thick-walled tube and square steel for band saw processing is calculated according to 5 yuan per square decimeter (minimum 5 yuan), and the cutting, slicing and opening of general steel plate is calculated according to per square decimeter 10 yuan (minimum 10 yuan).

5. The cutting area of WEDM universal parts is (square millimeter) *0.008 yuan. For parts that need threading, add 5 yuan to each threading hole.

6. Ordinary covered electrode with a diameter of 3.2 1 yuan and TH506 welded castings/3 yuan are welded, gas cut and plasma cut. Gas cutting processing: plasma cutting stainless steel is calculated according to the thickness of iron plate MM* cutting length m, and charged according to the basic price of gas cutting *3, and cutting carbon steel is charged according to the basic price of gas cutting *2.

7. With regard to urgent parts and overtime parts, the definition of receiving urgent parts according to the standard base price of *2 is to arrange maintenance or manufacture emergency parts for specific customers at the first time. Overtime parts refer to parts that must be manufactured continuously outside normal working hours.

Optical tool curve grinding 60 yuan/hour.

200 lathes, 20 yuan per hour.

More than 300 lathes per hour 30 yuan.

Milling machine 20 yuan &; ......& gt& gt

Question 5: What are the main contents of 5:WEDM process indicators? Accuracy, line speed

Question 6: What gear needs wire cutting According to my working experience, it is more convenient to use wire cutting for single and small pieces, such as non-standard module pinion. If it is a standard module and a batch of workpieces, it is better and faster to use a hobbing machine.

Question 7: How many kinds of wire cutting are there? There are two kinds of wire cutting: wire cutting and brass wire cutting.

WEDM is a kind of WEDM, and X is abbreviated as WEDM-LS. It uses thin metal wire (called electrode wire) which moves continuously as electrode to remove metal and cut workpiece by pulse spark discharge. Mainly used for processing all kinds of complex and precise workpieces.

Question 8: How is the 8:WEDM fee calculated? 1, single piece or small amount:

WEDM fee = (cross-sectional area/1200)*5

Note: 1 hour WEDM 1200mm2, generally charged according to 5 yuan. Speed: 80 mm 2/ sec.

2, large quantity: the price can be lower than this standard.

Question 9: How to calculate the cost of WEDM? Additional subscription fee for wire cutting = product perimeter (unit /mm) x product height (unit /mm)/1200 X 3 yuan or 3.5 yuan. Where 1200 is 1 working hour. Generally, if the product quantity is large, 1200=3 yuan, if the product quantity is small, 1200=3.5 yuan, copper and aluminum parts =4 yuan or 4.5 yuan, molds, 1200=5 yuan. Please refer to the product size for details. Wuxi and Changzhou can refer to this charging standard. If you still don't understand, you can ask me.