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Dissertations / Theses on the topic 'Electrochemical Discharge Machining (ECDM)'
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Jui, Sumit Kumar Narendrakumar. "Study of Micro-Electrochemical Discharge Machining (ECDM) Using Low Electrolyte Concentration." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384870046.
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Kolhekar, Ketaki R. "Study of Gas Film and its Effect on the Electrochemical Discharge Machining Process." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1522419144100495.
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Schöpf, Martin. "Electro Chemical Discharge Machining (ECDM) : Neue Möglichkeiten zum Abrichten metallgebundener Diamantschleifscheiben /." Zürich, 2001. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=14120.
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Dahmani, Rabah. "Optimisation d’un procédé d’usinage par microélectroérosion." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10058/document.
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L’objet de cette thèse est d’étudier un procédé de fraisage par microélectroérosion (μEE), qui est un procédé sans contact permettant d’usiner tous les matériaux durs conducteurs d’électricité à l’aide d’un micro-outil cylindrique ultrafin. Le principe consiste à créer des micro-décharges électriques entre le micro-outil et une pièce conductrice immergés dans un diélectrique liquide. En faisant parcourir à l’outil un parcours 3D, il est possible de creuser une forme complexe dans la pièce avec des détails à fort rapport d’aspect. Dans ce travail, nous avons tout d’abord amélioré un procédé d’élaboration de microoutils cylindriques ultrafins par gravure électrochimique de barreaux de tungstène. Des outils de diamètre 32,6 ± 0,3 μm sur une longueur de 3 mm ont été obtenus de manière automatique et reproductible. L’écart type a été divisé par 2 par rapport à l’état de l’art antérieur. Des outils de diamètre inférieur ont été obtenus avec une intervention de l’opérateur, et ce jusqu’à 3 μm de diamètre. Puis ces micro-outils ont été mis en oeuvre pour usiner des pièces avec le procédé de fraisage par microélectroérosion. Pour ce faire, une machine de 2ème génération a été entièrement développée sur la base de travaux antérieurs. Il a été possible d’usiner de l’acier inoxydable dans de l’eau déionisée avec des micro-outils de 3 μm de diamètre sans détérioration de l’outil. Par ailleurs, Le procédé de μEE a été caractérisé en termes de résolution d’usinage, taux d’enlèvement de matière et usure de l’outil. Un générateur de décharges original a permis d’usiner avec des micro-décharges de 1 à 10 nJ / étincelle avec une diminution très sensible de l’usure de l’outil par rapport à l’état de l’art. Un procédé original de caractérisation en ligne des décharges et de cartographie dans l’espace a aussi été développé<br>This work aims at studying Micro Electrical Discharge Milling (μEDM milling), which is a non-contact process allowing machining all hard and electrically conductive materials with a cylindrical ultrathin tool. The principle is based on the creation of electrical micro discharges between the tool and an electrically conductive part immersed in a liquid dielectric. By means of a 3D path, the tool machines a complex shape in the part with high aspect ratio details. In this work, we have firstly improved a process for making cylindrical ultrathin micro-tools by electrochemical etching of tungsten rods. Tools with a diameter of 32.6 ± 0.3 μm and a length of 3 mm have been obtained with an automated and reproducible process. Standard deviation has been divided by 2 by comparison with the previous state of the art. Tools with diameter as low as 3 μm have been fabricated with the help of the machine operator Then these micro-tools have been used for machining parts with the μEDM milling process. To do so, a second generation machine has been entirely developed on the basis of previous work. It has been possible to machine stainless steel in deionized water with 3 μm micro-tools without damaging the tools. In other respects, the μEDM milling process has been characterized in terms of machining resolution, material removal rate and tool wear. An innovative generator of discharges allow machining with 1 to 10 nJ / spark with a reduced tool wear by comparison to the state of the art. An innovative process for the on line characterization of discharges with spatial distribution capability has been developed
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Girardin, Guillaume. "Développement d’un procédé d’usinage par micro-électroérosion." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10315/document.
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L’électroérosion (EE) est une technique d’usinage sans contact de matériaux conducteursd’électricité ; elle particulièrement bien adaptée à l’usinage de matériaux durs. Le principe consiste àcréer des décharges électriques érodantes entre un outil et une pièce à usiner, toutes deuximmergées dans un diélectrique. Dans cette thèse, nous avons étudié la miniaturisation de ceprocédé, la microélectroérosion (μEE), qui se présente comme un procédé complémentaire destechniques de micro-usinage mécanique, laser, ou encore des techniques issues de lamicrotechnologie du silicium (RIE, DRIE, LIGA). Toutefois, la résolution de la μEE est limitée.Dans ce travail, nous avons tout d’abord développé un procédé original d’élaboration de microoutilscylindriques en tungstène par gravure électrochimique. Celui-ci permet d’obtenir de manièrereproductible des micro-outils de diamètre 15 μm et de rapport hauteur sur diamètre supérieur à 50.Des micro-outils plus fins ont aussi été obtenus (jusqu’à 700 nm) mais avec des problèmes dereproductibilité. Par ailleurs, un prototype de machine de fraisage par μEE a été développé avec uneélectronique entièrement caractérisée. Des micro-canaux de 40 μm de largeur ont été obtenus dansl’acier d’inoxydable et 25 μm dans le titane ; une rugosité Ra de 86 nm a été atteinte dans des cavitésde 600 x 600 x 30 μm. Les limitations du dispositif expérimental ont aussi été mises en évidence.Dans la dernière partie de ce travail, nous avons procédé à l’étude des microdécharges et du microplasmas’établissant entre micro-outil et pièce à l’aide de caractérisations électriques. La résistanceet l’inductance des décharges ont été déterminées expérimentalement puis intégrées dans unmodèle permettant de prévoir la durée des impulsions de courant et leur intensité. Des pistes pourl’amélioration de la résolution d’usinage sont proposées en conclusion de ce travail<br>Electro Discharge Machining (EDM) is a non-contact technique allowing machining of electricallyconductive materials; it is well adapted for the machining of hard materials. The principle is based onthe creation of eroding electrical discharges between a tool and a piece, both immersed in adielectric. In this thesis, we have the studied miniaturization of the process, called micro electrodischarge machining (μ-EDM), which is considered as a complementary technique of mechanical orlaser micro-machining techniques and silicon micro technology processes (RIE, DRIE, LIGA)..However, the resolution of μEDM is limited.In this work, we have firstly developed an original method for making tungsten micro-tools withcylindrical profile by electrochemical etching. This method allows the reproducible fabrication ofmicro-tool with 15-μm diameter. Thinner micro-tools were also obtained (down to 700 nm) withreproducibility problems. Furthermore, a prototype machine for milling μ-EDM was developed with afully characterized electronics. Micro channels were obtained respectively in stainless steel with awidth of 40μm and in titanium with a width of 25μm; a surface roughness Ra of 86 nm was achievedin 600 x 600 x 30 μm cavities. Besides, the limitations of the apparatus were highlighted. In the lastpart of this work, we have studied the micro-discharge and the micro-plasma between the micro-tooland the part with electrical characterization. The resistivity and the inductance of the sparks weremeasured and integrated in a numerical model in order to explain the duration of the microdischarges and their intensity. Solutions for improving the machining resolution are also discussed atthe end of this work
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Chen, Han-wei, and 陳翰威. "Studies on Discharge Behavior of Electrochemical Discharge Machining." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/02314434462019715171.
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碩士<br>國立中山大學<br>機械與機電工程學系研究所<br>93<br>Because of the exceptional physical, chemical, electric and mechanical properties of hard and brittle materials, such as ceramics, glass and diamond film etc, those are considerably valued in high technology industry. Although those materials can be machined using the ECDM method, but mostly used for machining hole and wire cutting, there is few application in the polishing aspect. In this study, a high-precision dynamic electrical pitting tester is employed, the electrolyte is KOH(eq), investigate the behavior of static electrochemical discharge of supply voltage and electrolyte highly to the steel ball/glass, and analysis it’s machining characteristic.
From the experimental results, which are SEM pictures of machined glass and variations of current and force , we can clearly infer the electrochemical discharge machining mold, and establish electrochemical I-V curve under different electrolyte highly, and furthermore machining area classify for (1) non-machining district (2) precision machining district (3) middle machining district (4) heavy machining district. The experimental results shows, the pitting of damage width and depth and supply voltage are relation in direct ratio. Under three different electrolytes highly, shows the critical voltage of pitting damage are all the same value, namely 29V, and electrolyte highly will be influenced real machining time and damaged form of surface. In the precision machining district, can get the surface roughness (Ra) reach 0.02μm, machining depth of surface damage reach 0.3649μm after machined for 60 seconds under the optimum operating parameter.
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Zhong, Sen-fu, and 鍾森富. "A study on sapphire machining by electrochemical discharge machining." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/58492169465648903283.
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碩士<br>國立中央大學<br>機械工程學系<br>102<br>Sapphire is excellent mechanical properties that used as substrate of light-emitting diode epitaxial and screen protective film of cell phone, but it is quite difficult machining. This study used a different voltage, the time and the proportion of the electrolyte,A study on sapphire machining by electrochemical discharge machining.
Observation and comparison of experimental results and found that the voltage 80 voltage, 60 seconds and electrolyte mixture of phosphoric acid and sulfuric acid, sulfuric acid, accounting for 55.56%, the mechining depth is 24.4663μm, that is the largest working depth of the study, and this mechining efficiency is also higher than the industry using sapphire machining by wet etching, and no heat affected zone, such as laser processing, sapphire able to prove the feasibility of electrochemical discharge machining methods of processing.
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Huang, Chun-Yi, and 黃俊益. "Ultrasonic Vibration Assisted Electrochemical Discharge Microhole Machining." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/94263852294442434628.
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碩士<br>逢甲大學<br>機械與電腦輔助工程學系<br>105<br>In this study, electrochemical discharge processing technology assisted with ultrasonic vibration, coating diamond abrasive on the spiral tungsten steel electrode for micro-drilling experiments. Electrochemical discharge during the drilling process promote the electrolyte to chemically etch the workpiece, and thus shorten the drilling time, smoothen the cracks generated during the processing. This process smoothens the micro-hole entrance, and improve machining accuracy of the drilling hole.
In the process of high aspect ratio micro-hole drilling process, the debris generated during the process can’t be eliminated, resulting in continuous processing to the debris, which greatly extended the drilling time. Additional ultrasonic vibration can significantly reduce the friction coefficient of the drill so that the debris can not be accumulated in the drill or the hole. It reduced the secondary processing of the debris, thereby reducing the drilling time. After that, the electrochemical discharge time was controlled to reduce its reaming, improving the accuracy of the micro-hole after drilling. In order to solve the problem of the fracture of the drilling hole, the weight was adjusted to reduce the pressure of the tool on the glass, thereby reducing the fracture of the hole generated by the micro-drilling processing.
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Huang, Yan-shuo, and 黃彥碩. "Microfabrication of Quartz by Electrochemical Discharge Machining." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/79349271879001810812.
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碩士<br>東南科技大學<br>機電整合研究所<br>98<br>In recent years, electrochemical discharge machining (ECDM) has become the preferred non-traditional processing technology, which is mainly applied to machining non-conductive hard brittle materials.
This study investigated the precision and stability of quartz fabricated by ECDM and explored the optimal processing parameters including size of electrode, machining speed as well as pulse-on and pulse-off duration. Microgrooves machined under the optimal processing parameters with adjusted rotational speed and feed rate were examined to understand the effect of different ECDM parameters on machining performance.
Results indicate that micro-holes of better morphology could be obtained under pulse voltage of 40 V, electrolyte concentration of 5 M, electrode size of 125 μm. Moreover, rotational speed of 1500 rpm and pulse-on/pulse-off (ms) ratio of 1:0.6 gave higher machining accuracy with smaller hole diameter and shorter machining time. Finally, microgrooves machined under the optimal processing parameters showed the best accuracy in dimension and cross-sectional morphology at rotational speed of 2500 rpm, pulse-on /pulse-off (ms) ratio of 1:1.6, and feed rate of 3000 μm/min.
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Yang, Cheng-Kuang, and 楊程光. "Study on Micro-Machining of Quartz by Using Electrochemical Discharge Machining." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/77442819014742331487.
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博士<br>國立中央大學<br>機械工程研究所<br>99<br>Quartz is the critical material used in MEMS due to its beneficial properties, such as piezo-electric effect and stable chemical properties. However, it is difficult to machine between the efficiency and accuracy using conventional methods. Electrochemical discharge machining (ECDM) is an emerging non-traditional machining process that involves high-temperature melting assisted by accelerated chemical etching. However, the electrochemical reaction affects the coalesce status of gas film in ECDM. The structure of gas film is in turn affected by efficiency and accuracy. Therefore, this research uses different methods to improve the stability of gas film and machining efficiency in ECDM.
First, discharge energy varies with tool material of electrode. Different tool materials have different transition voltages, which determine the gas film formation, and hence the hole diameter and average current achieved. Otherwise, Surface roughness of tool electrode is key determinant of gas film formation. Poor surface roughness increases contact angle of gas bubbles adhered on electrode surface, causing them to coalesce and form a thicker gas film, resulting in largest hole diameter machined. During machining process, there is no significant tool wear observed after repeated gravity-feed machining of 50 micro-holes by using tungsten carbide tool electrode.
In ECDM process, the stability and formation of gas film is in turn affected by the machining efficiency and quality. In order to improve the stability of gas film structure, this study attempt to use the magnetic effect keeps bubbles move quickly form the tool electrode. According to the experimental results, the stability of standard deviation in hole diameter was increased by 80.7% while hole diameter was also decreased by 24.6%. Besides, both machining efficiency and accuracy were found to worse with increasing machining depth. In particular, the machining gap between the electrode and micro-hole is completely filled up by the gas film when using the cylindrical tool electrode. To solve these problem, this study proposed using a tool electrode with a spherical end whose diameter (150 μm) is larger than that of its cylindrical body (100 μm). In other words, during machining by the spherical end, the thickness of gas film formed on the surface of electrode body would be smaller than that of the micro-hole machined. Comparison between machining depth of 500 μm achieved by conventional cylindrical tool electrode and the proposed spherical tool electrode shows that machining time was reduced by 83% while hole diameter was also decreased by 65%.
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Yang, Jhih-Yu, and 楊智宇. "Characteristics of Zirconia processed by electrochemical discharge machining." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/41319168814827718973.
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碩士<br>東南科技大學<br>機械工程研究所<br>103<br>In this study, electrochemical discharge machining (ECDM) is applied to drilling process of zirconia material. ECDM is a commonly used processing technique for insulation with hard and brittle property in recent years. It is not affected by the mechanical properties of the workpiece and is well suited for machining materials of high hardness, toughness and strength. ECDM involves high-temperature melting and accelerated chemical etching under the high electrical energy discharge on the electrode tip during electrolysis for material removal.
The workpiece used in the study is black zirconia of more than 96 % purity and mohs scale 8.7. With its hardness only lower than diamond and much higher than stainless steel, zirconia is replacing the metal material used in dental implant. Experiments were conducted using tungsten electrodes of 0.2 mm diameter, cut from 1 mm, at various applied voltages, mole concentrations and spindle speeds. Changes in ECDM efficiency of alpha-Al2O3 ceramic under difference parameter settings were examined using a white light interferometer and the variations in surface morphology were observed with a scanning electron microscope.
Experimental results show that a minimum hole diameter of 224 μm and depth of 122.9 μm can be obtained under the optimal machining conditions of applied voltage, 85 V ; mole concentration of phosphoric acid, 5M ; and spindle speed, 1000 rpm if under such conditions for 20 minutes. To achieve a better result, conditions are further changed to voltage, 83 V ; mole concentration of phosphoric acid, 15 M ; and spindle speed, 1000 rpm for 40 minutes, eventually boring through the zirconia with diameter of 304 μm at the front and 113 μm at the back of the hole respectively.
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Lin, Jui-che, and 林瑞哲. "Improving machining characteristics of quartz in electrochemical discharge machining by spherical electrode." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/18702598629509550494.
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碩士<br>國立中央大學<br>機械工程研究所<br>98<br>Electrochemical discharge machining（ECDM）is used high-temperature melting assisted by accelerated chemical etching, hence it is well suitable for quartz material precisely machining. During ECDM, gas film will be formed on the tool electrode surface due to electrochemical reaction and then result in discharge phenomenon. Therefore both the structure and stability of gas film have significant effect factors on the efficiency and precision of machining. For this reason, first we will discuss the influence of different gas film structure on machining characteristics in this study. And then in order to improve the machining characteristics which is processed the quartz material. Try using the spherical electrode to improve present electrochemical discharge machining which has the problem about efficiency on the deep hole.
Experimental results show the coalesce status of gas film in the cylinder electrode decreased the machining efficiency because of the short time of gas film. Compact and stability of gas film lead to influence of machining characteristics. Moreover, current waveform and appearance of micro-hole can analyze the difference of different coalesce status of gas film structure on discharge frequency and machining precision. The electrolyte concentration will also influence the gas film structure. Therefore this study is using spherical electrode to overcome such problem mention above. Compare with the cylinder electrode, the machining time is decreased 83%, the micro-hole diameter is reduced 65%. Meanwhile after passes through the perforation hole processing, the exit of micro-hole can not break to effect its quality. It can get higher straight of hole wall cross-section, and obtain the high-accuracy micro-hole in quartz.
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Lin, Yung-wei, and 林詠偉. "Studies on the Machining Characteristics of Diamond Film in Electrochemical Discharge Machining." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/20765362934087061471.
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碩士<br>國立中山大學<br>機械與機電工程學系研究所<br>94<br>The exceptional physical, chemical, electric, and mechanical properties of ceramics, glass and diamond film make them receive much attention in high-tech industry. Although the electrochemical discharge machining (ECDM) can be used to process those materials, most ECDM are used for machining micro-holes and wire cutting. However, the application on the polishing aspect is still scarce in the literature. In this study, a high-precision dynamic electrical pitting tester with the electrolyte of KOH is employed to investigate the behavior of static electrochemical discharge in terms of supply voltage and gap distance between the steel ball and the diamond film. Furthermore, its machining characteristics are also analyzed.
According to the current waveform, the I-V curve is plotted. Results show that the current value of glass is higher than that of diamond film and acrylic. This indicates that the glass is easily to be ionized. According to the observation on the surface of machined diamond film by using SEM, the machined status can be divided into four regimes. In the first regime, the supply voltage is less than 100V where the machined mark on the diamond film cannot be found. Hence, it is called non-machined regime. In the second regime, the supply voltage is in the range between 100 and 107V, where only very slight damage can be observed on the diamond film. Hence, it is called the fine machined regime. In the third regime, the supply voltage is in the range between 107 and 110V, where the machined status on the diamond film is unstable. Hence, it is called the transition regime. In the fourth regime, the supply voltage is larger than 110V, where the machined damage is very heavy. Hence, it is called the rough machined regime. At the supply voltage 105V with the gap less than 80μm, the annular shape of the machined damage on the surface of the diamond film can be observed. However, when the gap is in the range between 80μm and 95μm, the annular shape of the machined damage disappears, but there is still slight damage at the asperity of the diamond film. When the gap is larger than 95μm, the machined damage is invisible. Hence, the critical gap is defined as 95μm for the supply voltage of 105V. At the supply voltage of 105V, the gap of 90μm, and the machining time of 10 min, only the asperity of diamond film shows machined mark, but the surface is flatter. Therefore, it is possible to conduct the fine machining process by using ECDM on diamond film.
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Yang, Ching-Tang, and 楊景棠. "Improving Machining Precision of Pyrex Glass by Using Micro Electrochemical Discharge Machining." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/79558434618278043759.
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博士<br>國立中央大學<br>機械工程研究所<br>95<br>Electrochemical discharge machining (ECDM) is new and developing technology to non-conductive hard brittle materials. The advantage of the technology is no limitation on brittleness and electrical conductivity. Since the complexity of ECDM involves the interdependency of thermal, electrochemical and mechanical effects, the machining quality can’t reach the application in industry. In view of such drawbacks, this study aims to investigate the machining mechanism in ECDM and enhance the precision quality of micro-holes and micro-slits machined by ECDM.
Real time photographs and the current response were taken to observe the transition process in ECDM. The effects of chemical etching were studied by comparing three surface morphologies, high temperature chemical etching, electrical discharge machining (EDM) and ECDM. The machining mechanism can be further analyzed. Micro-holes of glass with diameter less then 0.3mm and thickness 1.5mm were developed. This study proposed using Al2O3 electrophoretic deposition grinding (EPDG) to further improve taper and surface roughness of the microholes. The surface roughness and taper angle can be improved to 5nm Ra and 0.2o after 500 sec grinding time, respectively. In the wire cut application, it is important to decrease the saw mark and kerf loss. This study proposed adding SiC abrasives in the electrolyte to improve the micro-slits quality. The expansion of micro-slit and surface roughness achieved were 0.024mm and 0.84μm Ra, respectively.
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Wu, Tien-yi, and 吳添益. "Studies on the Mechanism of Static Electrochemical Discharge Machining." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/34354616541519068356.
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碩士<br>國立中山大學<br>機械與機電工程學系研究所<br>92<br>Because of the exceptional physical, chemical, electric and mechanical properties of hard and brittle materials, such as ceramics, glass and diamond film etc, those are considerably valued in high technology industry. Although those materials can be machined using the ECDM method, its machining mechanism is still indeterminate. In this study, a static electrical pitting tester is employed, the electrolyte is KOH(eq), the workpiece is glass, and we change the parameters, such as supply voltage, supply current and machining gap to investigate the mechanism of static Electrochemical Discharge Machining.
From the experimental results, which are SEM pictures of machined glass and variations of current, we can clearly infer the mechanism of static-ECDM. Moreover, the most important reason for damaging glass is supply voltage. Even increasing supply voltage can make glass cleave. And the main factor to make the loop become insulating is supply current. While the supply voltage is 50V, the supply current is 8A, and in different machining gap condition, the results show that it has a certainly gap to discharge during the machining process, and the particular gap is about 49μm. The results also show that the machining model has two kinds of types. When the machining gap is shorter than 49μm, the machining model is from ring to circle; contrarily, when it is longer than 49μm, the machining model is circle directly.
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Zhou, Cheng-Han, and 周承翰. "Characteristics of alumina material processed by electrochemical discharge machining." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/48731853386745886160.
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碩士<br>東南科技大學<br>機械工程研究所<br>101<br>In this study, electrochemical discharge machining (ECDM) is applied to processing of alumina material. ECDM is a commonly used non-traditional processing technique. It is not affected by the mechanical properties of the workpiece and is well suited for machining materials of high hardness, toughness and strength. ECDM involves high-temperature melting and accelerated chemical etching under the high electrical energy discharged on the electrode tip during electrolysis for material removal.
The workpiece in this study is made of alumina (Al2O3), which is known to possess good mechanical strength, high corrosion and wear resistance as well as high electrical insulation. The effects of various parameters including applied voltage, mole concentration, spindle rotational speed, and discharge frequency on processing efficiency and surface roughness are examined to determine the optimal machining conditions. Surface morphologies are observed using white light interferometer and scanning electron microscopy (SEM).
Experimental results show that the optimal machining conditions are applied voltage, 85 V; phosphate mole concentration, 10 M; spindle rotational speed, 1000 rpm; and discharge frequency, 1k. ECDM with a 200-μm-diameter electrode under such conditions for 30 min achieves the minimum hole enlargement in the alumina workpiece, yielding a hole diameter of 224 μm with a smooth surface profile.
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Wang, Wei-kai, and 王威凱. "The Investigation of Gas Film and Machining Precision in the Electrochemical Discharge Machining." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/57852695838762713452.
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碩士<br>國立中央大學<br>機械工程學系<br>102<br>Electrochemical discharge machining (ECDM) is one of the novel technologies applied on machining non-conductive materials. ECDM has serveral advantages, such as low residual stress on the surface, high quality, high machining rate and low tool electrode wear.Since previous references discussed about little the effects of machining mechanism, on the machining result so this thesis emphasizes how to control the radius of gas film formed on the tip of electrode.
In this thesis Tungsten Carbide knife with diameter of 100m is used as the electrode, and KOH added Ethanol as electrolyte, to drill the quartz glass by electrochemical discharge machining. High speed camera is used to record the gas film under different supply voltages, frequencies, and magnetic field etc. The effects of gas film of thickness on the micro hole machining is analyzed.
Experimental results show that gas film on the tip of electrode has the biggest radius as the supplied voltage is 40V. By increasing the supplied voltage, the gas film’s radius becomes smaller. The applied frequency and gas film’s radius are inversely proportional. Adding a proper magnetic field can decrease the overcut, taper, and enhance the roundness of micro hole.
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Lin, Yu-sen, and 林愈森. "The Study of Drilling on Quartz by Electrochemical Discharge Machining." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/58062730073854055355.
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碩士<br>國立中央大學<br>機械工程研究所<br>99<br>The optical materials such as Pyrex and quartz are widely used with enormous potentialities and highly added value. However, the machining of non-conductive brittle materials is remaining as a big concern. The new developed technology, electrochemical discharge machining (ECDM), is a promising process for machining non-conductive brittle materials.
In present thesis quartz is machined by ECDM. A tungsten carbide cylinder with diameter of 100 micro-meters is selected as the electrode tool. KOH is selected as the electrolyte. In this research, the single variable method and Taguchi statistical method are used to analyze the influence of the parameters(such as applied voltage, concentration of electrolyte, pulse frequency, duty, current waveform, tool feeding rate, etc) on the over cut of the drilling and the relative importance among parameters.
From experimental results, it shows that applied voltage has relatively large influence on machining. The optimal parameters are taken for drilling the quartz, and a hole with diameter of about 166 μm is obtained. Finally, it is successful in reducing the gas film thickness when the liquid soap is added to mix with the KOH electrolyte, and the hole with diameter of about 143 μm is obtained.
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Cheng, Chih-Ping, and 鄭志平. "Microstructuring of Borosilicate Glass by Using Micro Electrochemical Discharge Machining." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/03644658991338982593.
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博士<br>國立中央大學<br>機械工程研究所<br>96<br>Borosilicate glasses (Pyrex glass) are becoming very important in MEMSs and many modern industries due to their anodic bonding properties, transparency and corrosion resistance. However, the inert nature of glass possesses challenges for machining these materials with high accuracy and efficiency, especially in micromachining process. Recently, electrochemical discharge machining (ECDM) has demonstrated to be a potential process for microstructuring of Pyrex glass. However, the key to widening ECDM application lies in how to obtain both high efficiency and machining accuracy. In ECDM process, the discharge phenomenon is closely related with the machining quality and efficiency. The main factors are concluded that the gas film stability and gas film size, in which discharge take place around electrode. This study uses different machining parameters, in order to investigate their inferences on the gas film integrity and to further seek solving tactics.
In the drilling process, to improve the quality of ECDM microhole, a flat sidewall-flat front tool electrode was designed to reduce taper phenomena due to the sidewall discharge. Besides, a pulse voltage is applied to improve the heat-affected zone in the rectified DC voltage. The experimental results show that the combination of flat sidewall-flat front tool and pulse voltage conspicuously increases the machining accuracy. The taper angle can be improved to 3 degree. In the microstructuring application, the results indicate that optimum combinations of both pulse voltage and tool rotational rate will realize better machining accuracy. The feasibility of 3-dimensional microstructure machining was demonstrated by a layer-by-layer ECDM micromilling machining.
Although pulse voltage is favorable for improving the machining quality, it is hard to obtain an efficient machining rate. The pulse-off (Toff) duration allows the gas film structure to be re-constructed, which makes the sustainability of a dense gas film difficult and results in unstable and unpredictable discharges. In this study a novel pulse voltage configuration, called offset pulse voltage, was applied in the ECDM process to enhance gas film stability and to further promote the discharge performance. Results also show that both the mean machining time and time deviation were decreased around 60 % without sacrificing machining accuracy by an adequate offset voltage.
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Chin, Kuan-Hwa, and 金冠樺. "Characteristics of alpha-Al2O3 ceramic processed by electrochemical discharge machining." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/40784033174381545811.
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碩士<br>東南科技大學<br>機械工程研究所<br>102<br>Abstract
In this study, Electrochemical Discharge Machining (ECDM), a non-traditional but commonly used processing technique, is applied to processing of alumina material. The alumina material used is alpha-Al2O3 ceramic of more than 99.9% purity sintered under temperature of 1650-1990℃ and has a transmission wavelength of 1-6 μm. Its good light transmittance and high corrosion resistance render it an ideal material for making sodium lamps. It is also used in electronic industry for making integrated circuit board and for high-frequency insulation because of its superior mechanical strength, strong erosion and abrasion resistance, and high electrical insulation properties.
Experiments were conducted using tungsten electrodes of 200 μm diameter at various applied voltages, mole concentrations and spindle speeds. Changes in ECDM efficiency of alpha-Al2O3 ceramic under different parameter settings were examined using a white light interferometer and the variations in surface morphology were observed with a scanning electron microscope.
Experimental results show that a minimum hole diameter of 200 μm can be obtained under the optimal machining conditions of applied voltage, 85 V per minute gradually increased to 105 V in 20 minutes; mole concentration of phosphoric acid, 5M, and spindle speed, 1000 rpm. Moreover, EDM performed under magnetic assistance and with hydrochloric acid can achieve greater machining depth of 101.8 μm and a more flat bottom.
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Su, Tsung-Kai, and 蘇琮凱. "Investigation of Electrochemical Discharge Machining by Using Diamond Coated Tool." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/17482254384988333618.
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碩士<br>逢甲大學<br>機械與電腦輔助工程學系<br>104<br>The research focus on the machining of diamond grit assisted Electrical chemical discharge machining method against optical glass, exploring the effect of machining accuracy and surface roughness under various electrode rotating speed, and the generating mechanism of bubbles through camera. As a result, the best surface quality appeared using diamond assisted tool electrode under parameters of 40V and 2,000 rpm, however the minimum expansion was found under 40,000 rpm reaching 1.069mm of diameter and 7 minutes 37 seconds of machining time. Operating under high rotating speed will massively reduce the expansion of the hole, and reduce the roundness errror to 3.7%. In order to achieve higher efficiency, diamond coated rod had been chosen as electrode. Resulting the highest machining efficiency under 40,000 rpm reaching 1.097mm of diameter and 2 minutes 51 seconds of machining time.
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Lin, Chun-yi, and 林軍屹. "Study on Machining of Quartz by Using Adjustable Magnetic Field Assisted in Electrochemical Discharge Machining." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/97075951966144456631.
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碩士<br>國立中央大學<br>機械工程研究所<br>100<br>Since quartz is a hard and brittle material, it is difficult to achieve high efficiency and high reliability using conventional methods, especially in the manufacturing of micro parts and components. Electrochemical discharge machining (ECDM) is an emerging non-traditional machining process that involves high-temperature melting assisted by accelerated chemical etching. During ECDM, gas film will be formed on the tool electrode surface due to electrochemical reaction and then result in discharge phenomenon. Therefore both the structure and stability of gas film have significant effect factors on the efficiency and precision of machining. During ECDM, the impact of high heat discharged and the differences in electrolyte cycle cause gas film to be irregular in structure and unstable in status. As a result, both the quality and efficiency of ECDM are undermined. Therefore, this study will first explore the effect of different electrode types for processing performance, and in order to improve the stability of gas film structure, this study attempt to use the tunable magnetic field (electromagnet) effect keeps bubbles move quickly form the tool electrode. both the stability of gas film structure and the efficiency of electrolyte cycle in micro holes are greatly enhanced.
According to the experimental results, by changing the electrode shape, that machining time was reduced by 73.8%, can be substantially improved processing efficiency. Then increase the tunable magnetic field, that machining time was reduced by 49.5%, and the standard deviation of the processing time achieve 91.8%. Finally, tunable magnetic field generated by asymmetric gas film type, further enhance the capacity of the electrolyte cycle. Thus machining time was reduced by 24.4% again.
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Song, Shang-Lin, and 宋尚霖. "The effect of electrolyte mixed SiC on Wire Electrochemical Discharge Machining." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/78863863797120403600.
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Wu, Ming-Hao, and 吳明豪. "Forming Research of Plane Glass Groove Using ElectroChemical Discharge Machining Method." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/41109505972102856969.
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He, Jia-Jhe, and 何嘉哲. "The effect of electrolyte powder-mixed on Wire Electrochemical Discharge Machining." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/82344320796346244619.
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碩士<br>國立中央大學<br>機械工程學系<br>101<br>In this experiment, the process is added with a new effect of the electrolytic solution by letting the electrolytic solution to coat on a quartz glass in the shape of a droplet while dripping down, in order to avoid the bubbles released during the electrolysis accumulating at the inlet and outlet of the processing area and affecting the gas film stability and developing slit expansion phenomenon, therefore, to increase the process efficiency. Although the process has pretty good features, however, the surface of the slit is less refined after the process. Therefore, graphite powder and silicon carbide abrasive granules are added separately in the electrolytic solution. Using transport lines to bring the granules into the thin fine slit to perform the polishing process, hopefully to improve the surface fineness after the polishing process and to investigate whether, after adding the granules, other types of process and process features can be added.
The wire electrode used in this study is a brass wire with φ0.15mm in diameter; the selected work piece is the quartz glass of 1.1mm thickness. In the experiment, the process voltage, the feed rate and the electrolytic solution flow volume are selected for a series of discussions in relevant to the process feature of electrochemical discharge wire cutting process. Finally, based on the experimental results, the scale of the process voltage directly impact the processing depth and slit fineness. When the feed rate (f) = 300 μm/min; the electrical energy discharged and materials removed under such feed rate are arranged appropriately; and the wire electrode does not crush the insulating gas film, a better process quality is obtained. When the electrolytic solution flow volume is equal to 4 c.c/min, the electrolytic solution response rate is able to fully supplement the process area in order to maintain the gas film stability and to achieve a better process efficiency. The graphite powder can diversify the electrical energy discharged and stabilize the electrical current during the electrical energy discharge. In addition, the accession of the polishing mechanism by adding silicon carbide abrasive granules can reduce the surface roughness of the slit and the expansion of the slit.
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Chang, Kuang-hua, and 張光華. "Study on texturing of mono-silicon by using Electrochemical Discharge Machining." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/20830703287553681299.
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碩士<br>國立中央大學<br>機械工程學系在職專班<br>102<br>In order to improve the light conversion efficiency of solar cells, recently processing method use the strong chemical substances to etch silicon surface. Although acid or alkaline texturing can increase the frequency of the light reflecting, this kind of texturing process not only has long processing time but also is harmful to the environment. Compared with the conventional surface texturing process which generates chemical etched pyramid structure or crater structure , this study proposes texturing P type mono-crystalline silicon by electrochemical discharge machining (ECDM). ECDM method has the advantage of short processing time and can generate a higher surface roughness and the porous structure.
In this study, stainless steel was used as negative electrode. The graphite was used as the positive electrode acting as the auxiliary electrode. The potassium hydroxide was used as the electrolyte. The processing parameters include the machining voltage, the processing time, the machining gap, the electrolyte concentration, the additive agent concentration, pulse frequency and duty factor, etc. The surface roughness was measured using surface roughness tester. The surface morphology was observed using SEM and three-dimensional laser scanning microscope.
The result of experiments reveals that appropriate concentrations of ethanol can expand the size of the pores and enhance surface roughening effect. The appropriate processing parameters are a machining gap of 200μm, voltage of 48V, concentration of potassium hydroxide of 3M, concentration of ethanol of 4%. The electrochemical discharge machined surface roughness was increased from 0.417μm to 0.915μm using one minute processing time. The average reflectance rate of the textured surface was decreased from 29.6% to 12.7% measuring by using integration spectroscopic reflectometer.
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Yeh, Chin-chang, and 葉金璋. "Processing Characteristics of Polycrystalline Silicon by Wire Electrical Discharge Machining and Electrochemical Grinding." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/13731829407360907827.
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博士<br>國立中央大學<br>機械工程學系<br>102<br>Nowadays, the researches and developments of renewable energy have become the universal consensus. Among them, the developments of solar cell attract the greatest attention. In the process of making solar cell, the cutting process of silicon ingot is the key to determine the cost. Multi-wire saw has been used in the traditional cutting to conduct machining process. Its advantage is to multi-wire-type processing, which heighten the processing efficiency. However, multi wire requires great tension and produces stress that could easily damage the silicon ingot. In addition, during the process, abrasive could not be used completely. The complicated recycle processes of abrasive contaminate the environment. Thus, in recent years, related research proposed in the literature, by using wire electrical discharge machining (WEDM) cutting silicon ingot, this method can effectively improve the shortcomings multi-wire saw. WEDM has been applied onto the single-crystal silicon cutting. Most researches adopted single-crystal silicon as the process material. However, it is hard to find a literature review on the machining characteristics of a polycrystalline silicon surface and the quality improvements after processing. The main reasons of polycrystalline silicon are changing boundaries, high electrical resistance and other characteristics, which lead WEDM can not be process smoothly. Polycrystalline silicon manufacturing process is simple, lower cost, stable photoelectric efficiency and other advantages. Therefore, a new method to improve the polycrystalline silicon processing problems needs to be developed.
This thesis adopts machining characteristics of polycrystalline silicon research by WEDM and electrochemical grinding (ECG) these two methods. This paper divided into two research directions. The first part discusses when the polycrystalline silicon by using WEDM processing, the impact of discharge parameters on the polycrystalline silicon and the adjustments of phosphorous dielectric improve its processing efficiency and processing characteristics. The second part is the application of ECG surface defects after WEDM be grinded, it improves the removal of surface roughness and affected layer by using Taguchi-method experiment planning, the main factor affects the analysis process to get through. Follow added graphene in dielectric. By using the high hardness and high lubricity of graphene to improve processing characteristics of the original surface and explore the impact of process parameters for the processing.
After the experiments by this thesis, it is sure that in the WEDM processing, phosphorous dielectric improves the discharge process effectively and makes the discharge energy booster to enhance conductivity. Under the no-changing existed processing parameters condition, it improves the cutting speed and reduces kerf loss. In the ECG processing, by adding graphene, the surface problems effectively improved after WEDM machining residues and reduce friction force during processing and it enhances the grinding tool life. It is expected the results of this thesis could be referenced for the future research in both industrials and academic field.
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Hsu, Yu-shan, and 許玉山. "A study on improvement Pyrex glass machinability by using magnetism assisted electrochemical discharge machining." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/45706008916026715489.
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碩士<br>國立中央大學<br>機械工程研究所<br>96<br>Electrochemical Discharge Machining (ECDM) can be use for manufacture non-conductors brittle material, but the forming contours and dimension precision will effect industry application, a purpose on improve Pyrex glass forming precision and stability, using magnetism assisted in the experiment is new technology for ECDM. In the study, we find the discharge current density and spark distributable will effect forming precision and reliability but the most important key point is bubble geometry and dimension which will influence the stability of insulation gas film.
According to the result, when voltage arrival 38 V、electrolyte concentrate at 6 M, and change electrode geometry from cylindrical tool to flat sidewall-flat front tool can improve microhole reaming arrival 4 %, and than combination of magnetism to increase the machining precision and reliability, improve microhole reaming achieve 26.7 %, machining efficiency achieve 72 %.
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Kuo, Kuan-yuan, and 郭寬淵. "Study of Wire Electrochemical Discharge Machining (WECDM) of Quartz Glass with Titrated Electrolyte Flow." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/91357165184471106269.
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博士<br>國立中央大學<br>機械工程學系<br>103<br>Quartz has excellent properties, but its brittleness property results in the difficulty of balance between efficiency and precision for traditional machining method. ECDM aids in machining with high temperature fusion and etching, and is very appropriate for quartz material. In WECDM machining system, uneasy control of insulation gas film structure and difficult electrolyte circulation in machining zone. Therefore, thesis topic is to explore WECDM machining mechanisms, development new methods and improve the micro slit surface quality.
First, investigate the flow of electrolyte influence on the processing of quartz glass, adding graphite powder or silicon carbide powder of composite processing methods to improve the processing efficiency and accuracy. From experimental results, the surface roughness value for electrolyte WECDM machining without adding any powder under the same condition is Ra＝1.13μm, while the surface roughness may achieve Ra＝0.36μm as 0.4wt％ of graphite is added into electrolyte . The improvement rate is 68%. As 5wt％ of silicon carbide is added into electrolyte, the surface roughness can achieve Ra＝0.22μm, that is, the improvement rate is 80%. Furthermore, electrolyte is used very few under the best appropriate condition. It is proved that the utilization of graphite or silicon carbide characteristics for local machining of quartz glass in titration electrolyte is advantageous of improving surface quality effectively, reducing environmental pollution, lowering cost, and achieving one-time machining to reduce machining procedures.
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Cheng, Wei-Hsin, and 鄭偉欣. "A Study on the Microchannel Machinability of Pyrex Glass by Using Electrochemical Discharge Machining." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/95080296435987511224.
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碩士<br>國立中央大學<br>機械工程研究所<br>95<br>Electrochemical discharge machining (ECDM) is demonstrated to be a potential process for 3D-microstructuring of Pyrex glass. However, it is difficult to obtain an accurate machining shape with a good surface quality because it is difficult to control the discharge characteristics near the tool tip. To improve the machining quality of the ECDM micromilling process, microgroove machining experiments were conducted in this study. Three factors affecting ECDM micromillimg performance, pulse voltage, rotational rate of tool and feed velocity of tool were taken up as machining parameters to investigate their influences on machining performance.
The results indicate that optimum combinations of both pulse voltage (40V, Ton：Toff = 2 ms：2 ms) and rotational speed (1500 rpm) will realize better machining accuracy. The feasibility of 3-dimensional microstructure machining was demonstrated by a layer-by-layer ECDM micromilling machining. Complex structures were made to demonstrate the great potential for the 3D microstructuring of Pyrex glass of the ECDM micromilling process.
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Liu, Yu-hsiu, and 劉育修. "Effect of the geometry of the electrode on the bubble formation in electrochemical discharge machining." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/j6skb7.
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碩士<br>國立中山大學<br>機械與機電工程學系研究所<br>95<br>A static electrochemical discharge machining (ECDM) tester, where the tungsten needle is used as the cathode and the platinum as the anode and the glass as the specimen, and the depth of electrode is set to be 1mm in the aqueous electrolyte of 30wt% KOH at the test time of 10s, is employed to investigate the influence of geometry and size of the electrode, supply voltage and gap on the characteristic of electrochemical discharge machining.
According to the current/voltage measurements combined with the photographs of the bubble layer on the cathode and the behavior of discharge under different geometry and size of the electrode during the ECDM process, three regimes have been identified as: (I): non-machining. (II): glow discharge. (III): spark discharge. From the observation on the surface of machined glass specimen by using SEM, the experimental result show that damage of the glass increases with the increase of supply voltage.
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HUANG, HONG-YU, and 黃泓諭. "Observation Survey of the Bubbles and the Gas Film Evolution of Electrochemical Discharge Machining Using Transmission Microscope." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/6x4g3s.
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碩士<br>國立臺北科技大學<br>光電工程系<br>107<br>In this thesis, an electrochemical discharge machining transmission microscope, which composed of an transmission microscope, electrochemical discharge machining system, and image analysis system, was proposed for observing the formations of bubbles and the gas film during the machining. The mechanisms and relationships of the bubbles and the gas film evolution between their status and current signals need to be further investigated. An experimental setup with a conical/columnar electrode was constructed for the observations when there were with/without samples. Furthermore, a photograph of 10,000 shots per second by a high speed camera was taken to observe the status of the bubble and the the gas film evolution. As the result of the experimental, it showed that the bubbles and the gas film evolution was highly correlated with current signals. In the case of a columnar electrode, the largest volume was 3-17 seconds slower than the volume at the moment of the largest current. In the case of a conical electrode, the largest volume was 3-13 seconds slower than the volume at the moment of the largest current. Besides, the gas film of conical electrode was stable more fast than the columnar electrode, and the condition without quartz glass became stable more fast than the condition with quartz glass. From the images we got, it could be observed that of gas film broken and discharged was also observed, then the gas bubble was simultaneously produced to repair the defective gas film.
In this thesis, the microscopic observation system we mentioned was described first, and then we discussed the the bubbles and the gas film evolution with the microscopic observation system we mentioned. Finally, the results of the observation were discussed, and then the conclusions and future prospects were presented.