• 한국정밀공학회지
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• 제21권11호
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• pp.171-178
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• 2004

This paper presents vibration characteristics of a wire cut discharge machine in which an electro-rheological brake actuator is used to control the wire tension. The ER brake actuator has several advantages including design simplicity, fast response time and real-time controllability. On the basis of the tension level required in the machine an appropriate size of the ER brake actuator is devised. The ER brake actuator is then incorporated with the machine and the field-dependent wire tension is experimentally evaluated. The straightness of the workpiece is also empirically investigated by changing the intensity of the electric field.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.1167-1169
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• 1996

As electrical discharge machinery(EDM) is industrial process which is manufactured by discharge energy, by producing discharge, EDM process finished material at the little micrometer air gap. Especially, EDM is used for the characteristic of heat-resisting material, it puts to use air-space industrial element, confusing shaping material such as jet engine, rocket elements. Working performance. is changed by environment of working, discharge current voltage and duration of discharge pulse. Evaluation of performance working is work speed, clearance smoothing of product surface, wasting of pole. In this paper, this machine is compensated by adaptive controller which corrects the weak points of classical machine which is observed and operated working condition by user in hands. The previous purpose is main object in this thesis. The adaptive controller automatically detect abnormal condition and working conditions. To improve performance, surface smoothing and working speed, the adaptive controller uses fuzzy control strategy. To evaluate performance, this controller is implemented by microprocessor i80c196 and is applied real experimental machine.

• 한국기계가공학회지
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• 제4권3호
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• pp.32-38
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• 2005

Electrical discharge machining is the method of using thermal energy by electrical discharge. Generally, if the material of workpiece has conductivity even though very hard materials and complicated shape which are difficult to cut such as quenching steel, cemented carbide, diamond and conductive ceramics, the EDM process is favorable one of possible machining processes. But, the process is necessarily required of finish cut and heat treatment because of slow cutting speed, no mirror surface, brittleness and crack due to the residual stress for manufactured goods. In this experimental thesis, the super EDM drilling was developed for high precision semiconductor die steel and for minimization of leadframe width. It was possible to development of EDM drilling machine for high precision semiconductor die with the electrode guide and its modelling and stress analysis. The development of electrode with the copper pipe type was conducted to drill the hole from the diameter of 0.1mm to 3.0mm with the error of from 0.02mm to 0.12mm. From the SEM and EDX analysis, the entrance of the EDM drill was found the resolidification of not only the component of tungsten but also the component of copper.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.383-386
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• 2007

In this study, the analysis was carried out for Electrical Discharge Machining (EDM) characteristics of the Cu electrodes by LIGA process. The shape of electrodes has 324 pins for the cavity of BGA(Ball Grid Array) type test socket mold. BGA test sockets are used in the inspection process of the semi-conductor I.C chip manufacturing. In the work, the machining performance for EDM of the electrodes was analyzed on dimensional accuracy and wear rate. The dimensional accuracy was measured for dimension of the pins, pitch size between the pins and the roundness of corner edge using optical measuring machine.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 추계학술대회 논문집
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• pp.43-47
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• 1997

Advances in EDM power supplies have made the process competitive in some areas dominated by conventional and numerically controlled machines. This paper will produce more comprehensive data than are presently available and will use this data in applying concepts of optimization based on manufacturer's guide lines utilizing neural networks. A method will be developed for determining the machining parameters of the EDM process considering the conflicting desirability of good surface finish, low tool wear and high rates of metal removal. By the proposed method, one can select machining parameters that can maintain permissible tool wear and obtain maximum machining rates on the system represented by the data.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.1154-1158
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• 1995

Electrical Discharge Machining, with its ability to machine hard metals and tough shapes has become a very desirable process. In the past few years, Electrical Discharge Machining (EDM) has been solidly established in tool-room and large-scale production. However, in spite of its indispensability in many areas of metal removal applications, the theoretical basis of EDM process is yet to be established. More importantly, the information regarding essential technology parameters such as machining rate and resulting surface roughness integrity, has not been raised to the level of a general technical science. The paper presents a method, which can be determining approprate machining parameters for the given parameters such as electrode wear and surface roughness based on machining guideline utilizing neural networks.

• International Journal of CAD/CAM
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• 제6권1호
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• pp.167-172
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• 2006

Recently, wire-EDM became a necessity for many engineering applications, particularly in the dies making. No-Core cut process is helpful for operations in which falling slug can jam the machine or wire. In this paper a proposed CAM system (called NCPP) is introduced, to overcome the limitations of the existing CAM systems in the machining of No-Core cut. The proposed CAM system (NCPP) provides pocketing of No-core cut and optimal selection of the position of starting hole (wire threading point), to minimize toolpath length. It was written for data exchange between CAD-CAM-CNC machines. This data model will become part of the ISO (Data model for Computerized Numerical Controllers) international standard. The NCPP system has been implemented in Visual C++. Many examples are used to illustrate NCPP system. The results show that, NCPP saves the machining time by significant value. This value depends on the shape and complexity of the workpiece that is being cut.

• 한국공작기계학회논문집
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• 제14권5호
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• pp.13-20
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• 2005

Micro EDM process is generally used for machining microholes, cavities, and three dimensional shapes. For machining micro structures, first of all, micro tool electrode is indispensable and WEDG system is proposed for tool fabrication method. When using WEDG, its machining characteristics are highly affected by many EDM parameters such as applied voltage, current, rotation speed, capacitance, and pulse duration. Therefore, the design of experiment is introduced to fully understand the effect of the EDM parameters on machining tool electrode. And an attempt has been made to develop the mathematical model for predicting the size of the tool electrode by calculating spark distance. The suggested model was verified with experiment and predicted working gap distance is in good accord with the measured value.

• 한국생산제조학회지
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• 제6권4호
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• pp.130-137
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• 1997

The demand for wire-cut EDM is increasing rapidly in the die and tool making industry. In this study machining characteristics such as machining rate, surface roughness, hand drum form and hardness of machined material are investigated experimentally under the conditions varing pulse on time, pulse off time, peak voltage, wire tension after fixing other conditions in SKD 11 and brass and brass workpiece. It was found that various operating conditions had significant influences on machining characteristics. But the hardness of workpiece was uneffected by operating conditions. Also it was obtained experimentally that brass workpeice had better machinability than SKD 11 one.dition according to the current(Ip) in an electric spark machine : 1) Electrode is utilized Cu and Graphite. 2) Work piece is used the material of carbon steel. The condition of experiment is : 1) Current is varied 0.7(A) to 50(A) and the time of electric discharging to work piece in each time is 30(min) to 60(min). 2) After the upper side of work piece was measured in radius(5$\mu$m) of stylus analyzed the surface roughness to ade the table and graph of Rmax by yielding data. 3) Electro wear ratio is : \circled1Cooper was measured ex-machining and post-machining by the electronic balance. \circled2The ex-machining of graphite measured by it, the post-machining was found the data from volume $\times$specific gravity and analyzed to made its table and graph on ground the data. 4) In order to keep the accuracy of voltage affected to the work piece was equipped with the A.V. R and the memory scope was sticked to the electric spark machine. 5) In order to preserve the precision of current, to get rid of the noise occured by internal resistance of electric spark machine and to force injecting for the discharge fluid , it made the fixed table for a work piece to minimize the work error by means of one's failure during the electric discharging.

• 대한치과보철학회지
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• 제39권1호
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• pp.1-13
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• 2001

An absolutely passive fit at the interface with the superstructure and the abutment cylinders is need for implant longevity. In this study, a method of cast framework correction using spark erosion technology was evaluated. Electric discharge machining(EDM) is a process that uses electrical discharges, or sparks, to machine metal, The surface being machined is bombared with high-intensity electrical energy pulses that gradually melt away the stock until the desired configuration is obtained. Master model was fabricated by using metal block impression analogue, which fired 5 Branemark squared impression coping in an arc shaped metal block. Then framework using 4mm standard gold cylinder and type IV gold alloy was fabricated. In order to measure the fit of the framework we used both contact and noncontact coordinate measurement machine and data was processed by computer program. After superimposition of gold framework and master model numeric image data the distances between gold cylinder bearing surfaces and abutment replica bearing surfaces, and the angle deviations between gold cylinder and abutment replica centroid points were calculated. The results were as follows 1 The total mean distance (p<0.01) and standard deviation (p<0.001) between the gold cylinders and abutment bearing surfaces were significantly decreased after EDM 2. The total mean of maximum distances was significantly decreased after EDM (p<0.05). 3. After EDM, the mean angle deviation between centroid points was decreased.