It has been established that the formation of an electrically conductive layer on an insulator is a precondition for electrical discharge machining of insulating ceramics by an assisting electrode method. However, the details of the formation mechanism of the electrically conductive layer are not well understood. In this paper, the morphology and components of the machined surface layer are analyzed under different machining conditions of electrode moving speed and voltage threshold for discharge detection. We describe an idea for the formation mechanism of the electrically conductive layer in the machining of insulating Si3N4 machining by using a machine tool made especially for our experiments. : insulating ceramics, electrical discharge machining, formation mechanism, Si3N4
{"title":"Consideration of Formation Mechanism of Conductive Layer in Electrical Discharge Machining of Insulating Si 3 N 4 Ceramics","authors":"Hiromitsu Gotoh, T. Tani, N. Mohri","doi":"10.2526/JSEME.50.112","DOIUrl":"https://doi.org/10.2526/JSEME.50.112","url":null,"abstract":"It has been established that the formation of an electrically conductive layer on an insulator is a precondition for electrical discharge machining of insulating ceramics by an assisting electrode method. However, the details of the formation mechanism of the electrically conductive layer are not well understood. In this paper, the morphology and components of the machined surface layer are analyzed under different machining conditions of electrode moving speed and voltage threshold for discharge detection. We describe an idea for the formation mechanism of the electrically conductive layer in the machining of insulating Si3N4 machining by using a machine tool made especially for our experiments. : insulating ceramics, electrical discharge machining, formation mechanism, Si3N4","PeriodicalId":269071,"journal":{"name":"Journal of the Japan Society of Electrical-machining Engineers","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131804831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Goto, T. Moroi, Masato Uematsu, N. Saito, N. Mohri, T. Yuzawa
In this study, Electrochemical Machining (ECM) phenomena of sintered carbide are investigated. One of the biggest problems in ECM of sintered carbide is the elution of cobalt, which is the binder of the material. When too much cobalt is eluded, the strength of the material is deteriorated and it cannot be used as a die, particularly in cold forging. In this report, the prevention technology of Co elution is discussed. First, the authors have conducted a simple experiment with a beaker and the results indicated the possibility of inhibiting cobalt elution by adding Co ion into the electrolyte. Then, a machining experiment was carried out with electrolyte flushing, and it was shown that sintered carbide can be machined without excessive Co elution.
{"title":"Electrochemical Machining of Sintered Carbide (1st Report): - Prevention of Excessive Co Elution -@@@－Coの溶出防止の方法－","authors":"A. Goto, T. Moroi, Masato Uematsu, N. Saito, N. Mohri, T. Yuzawa","doi":"10.2526/JSEME.49.117","DOIUrl":"https://doi.org/10.2526/JSEME.49.117","url":null,"abstract":"In this study, Electrochemical Machining (ECM) phenomena of sintered carbide are investigated. One of the biggest problems in ECM of sintered carbide is the elution of cobalt, which is the binder of the material. When too much cobalt is eluded, the strength of the material is deteriorated and it cannot be used as a die, particularly in cold forging. In this report, the prevention technology of Co elution is discussed. First, the authors have conducted a simple experiment with a beaker and the results indicated the possibility of inhibiting cobalt elution by adding Co ion into the electrolyte. Then, a machining experiment was carried out with electrolyte flushing, and it was shown that sintered carbide can be machined without excessive Co elution.","PeriodicalId":269071,"journal":{"name":"Journal of the Japan Society of Electrical-machining Engineers","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115369324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"形彫り放電加工特性に及ぼす放電加工油物性の影響(第1報) : 導電性材料の放電加工の場合","authors":"花岡 大生, 渡邉 利行, 福澤 康, 北村 友彦","doi":"10.2526/JSEME.47.81","DOIUrl":"https://doi.org/10.2526/JSEME.47.81","url":null,"abstract":"","PeriodicalId":269071,"journal":{"name":"Journal of the Japan Society of Electrical-machining Engineers","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114042674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In electrolyte jet machining, by using a film flow formed after an electrolyte jet collides with a workpiece, the workpiece can be machined locally in the area of collision with the electrolyte jet by applying an electric current to the region. However, when the electrolyte flow rate is low, a hydraulic jump occurs near the jet and the film flow cannot be formed, thereby the workpiece cannot be machined locally. To solve this problem, we introduced an assist air jet coaxial to the electrolyte jet. The effect of the assist air jet on accelerating the radial flow of the electrolyte was clarified by hydrodynamic simulation. Machining experiments showed that the assist air jet has beneficial effects on machining stability at lower electrolyte flow rates, enabling higher aspect ratios in hole drilling and fabrication on concave surfaces.
{"title":"Study on effect of assist gas in electrolyte jet machining","authors":"Shoya Kai, M. Kunieda","doi":"10.2526/JSEME.47.97","DOIUrl":"https://doi.org/10.2526/JSEME.47.97","url":null,"abstract":"In electrolyte jet machining, by using a film flow formed after an electrolyte jet collides with a workpiece, the workpiece can be machined locally in the area of collision with the electrolyte jet by applying an electric current to the region. However, when the electrolyte flow rate is low, a hydraulic jump occurs near the jet and the film flow cannot be formed, thereby the workpiece cannot be machined locally. To solve this problem, we introduced an assist air jet coaxial to the electrolyte jet. The effect of the assist air jet on accelerating the radial flow of the electrolyte was clarified by hydrodynamic simulation. Machining experiments showed that the assist air jet has beneficial effects on machining stability at lower electrolyte flow rates, enabling higher aspect ratios in hole drilling and fabrication on concave surfaces.","PeriodicalId":269071,"journal":{"name":"Journal of the Japan Society of Electrical-machining Engineers","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126718892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Shida, Okihara Shin-ichiro, K. Suda, K. Haraguchi, Y. Kato
{"title":"Nanometer-Resolution Cross Sectional Observation of the Changes in Multilayer Thin Films and Substrates due to Laser Ablation","authors":"S. Shida, Okihara Shin-ichiro, K. Suda, K. Haraguchi, Y. Kato","doi":"10.2526/JSEME.46.66","DOIUrl":"https://doi.org/10.2526/JSEME.46.66","url":null,"abstract":"","PeriodicalId":269071,"journal":{"name":"Journal of the Japan Society of Electrical-machining Engineers","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128139264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The purpose of this study is to develop a new type of coated wire electrode for fine-wire EDM. A piano wire with a very high tensile strength is coated with an electrically conductive brass layer to achieve high-speed and high-precision wire EDM. In our previous studies, by using a thin wire of 50 μm in diameter, the thickness and quality of the brass coating layer were optimized, and the effect of surface unevenness was also discussed. In this paper, the effects of the oxidation of the wire surface and high-resistance layer on the wire electrode were experimentally investigated. It was found that more sparks occur selectively in front of the wire and less sparks on the side surface of wire with the high-resistance layer on the wire surface. Consequently, the kerf width decreased and the removal rate increased with the optimum thickness of the layer. Also, the occurrence of a short circuit between the wire and the machined surface was reduced because of presence of a high-resistance layer on the wire surface.
{"title":"ワイヤ放電加工用高性能ワイヤ電極の開発に関する研究（第４報） －ワイヤ表面の高抵抗層が放電加工特性に及ぼす影響－","authors":"晃 岡田, 俊之 山内, 正典 中澤, 敏明 清水, 義幸 宇野","doi":"10.2526/JSEME.45.64","DOIUrl":"https://doi.org/10.2526/JSEME.45.64","url":null,"abstract":"The purpose of this study is to develop a new type of coated wire electrode for fine-wire EDM. A piano wire with a very high tensile strength is coated with an electrically conductive brass layer to achieve high-speed and high-precision wire EDM. In our previous studies, by using a thin wire of 50 μm in diameter, the thickness and quality of the brass coating layer were optimized, and the effect of surface unevenness was also discussed. In this paper, the effects of the oxidation of the wire surface and high-resistance layer on the wire electrode were experimentally investigated. It was found that more sparks occur selectively in front of the wire and less sparks on the side surface of wire with the high-resistance layer on the wire surface. Consequently, the kerf width decreased and the removal rate increased with the optimum thickness of the layer. Also, the occurrence of a short circuit between the wire and the machined surface was reduced because of presence of a high-resistance layer on the wire surface.","PeriodicalId":269071,"journal":{"name":"Journal of the Japan Society of Electrical-machining Engineers","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126924204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the automobile industry, increasing the demands for better environment protection and resource conservation entails for lowering both fuel cost and exhaust emission. This is because combustor efficiency is markedly influenced by grain size, spray pattern, and the injection volume of fuel atomization. Therefore, to increase combustor efficiency it is effective to improve the size, pattern, and accuracy of nozzle holes. In mass production, conventional processing methods for nozzle holes include stamping and drilling. Noncontact processes such as electric discharge machining (EDM) has the advantages of smaller size, better pattern flexibility and better accuracy, however, they are not suitable for mass production. In this study, we introduced a new EDM method with both good accuracy and good productivity that are suitable for the finish machining of microholes having a diameter less than 0.2 mm. We found that for finish boring by EDM, the smaller the depth of cut, the lower the processing efficiency. Thus, to solve this problem, we suggested a new method that entails overlaying high frequency vibration to the electrode, and verified the effectiveness of the method by experiments. We verified the effective use of a high-frequency electrode feeding device together with the direct drive method for improving the processing efficiency. The finish EDM developed method is now in practical use in the mass production of fuel injection nozzle holes, which start as preholes made using a YAG laser.
{"title":"Study of High-Speed Microhole Drilling by Combined Process using Laser and EDM-Apply for fuel injection nozzle-","authors":"H. Morita, Tetsuji Yamaguchi, N. Mohri","doi":"10.2526/JSEME.44.45","DOIUrl":"https://doi.org/10.2526/JSEME.44.45","url":null,"abstract":"In the automobile industry, increasing the demands for better environment protection and resource conservation entails for lowering both fuel cost and exhaust emission. This is because combustor efficiency is markedly influenced by grain size, spray pattern, and the injection volume of fuel atomization. Therefore, to increase combustor efficiency it is effective to improve the size, pattern, and accuracy of nozzle holes. In mass production, conventional processing methods for nozzle holes include stamping and drilling. Noncontact processes such as electric discharge machining (EDM) has the advantages of smaller size, better pattern flexibility and better accuracy, however, they are not suitable for mass production. In this study, we introduced a new EDM method with both good accuracy and good productivity that are suitable for the finish machining of microholes having a diameter less than 0.2 mm. We found that for finish boring by EDM, the smaller the depth of cut, the lower the processing efficiency. Thus, to solve this problem, we suggested a new method that entails overlaying high frequency vibration to the electrode, and verified the effectiveness of the method by experiments. We verified the effective use of a high-frequency electrode feeding device together with the direct drive method for improving the processing efficiency. The finish EDM developed method is now in practical use in the mass production of fuel injection nozzle holes, which start as preholes made using a YAG laser.","PeriodicalId":269071,"journal":{"name":"Journal of the Japan Society of Electrical-machining Engineers","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129282912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Okada, T. Yamauchi, Masayuki Higashi, Toshiaki Shimizu, Y. Uno
The purpose of this study is to develop a new type of coated wire electrode for fine wire EDM. Piano wire with a very high tensile strength is coated with an electrically conductive brass layer to achieve high-speed and high-precision wire EDM. In our previous papers, using a thin wire of 50μm diameter, the thickness and quality of the brass coating layer were optimized and the effect of the tensile strength of the piano wire used as the core wire was discussed. In this report, the effect of unevenness of the brass wire electrode surface was experimentally investigated. As a result, it was found that by using wire with relatively large surface unevenness, the machining rate increased because of the high discharge frequency. Also, a more uniform distribution of the discharge location was confirmed by high-speed observation of the working gap during the process. In addition, the electrostatic field in the gap between the wire electrode and workpiece surface was analyzed and the reason for the high machining rate for the wire with relatively large surface unevenness was discussed from the viewpoint of the distribution of electric intensity distribution on the wire surface.
{"title":"Development of Coated Wire Electrode for High-Performance WEDM (3rd Report)-Effects of wire surface unevenness on wire EDM characteristics-","authors":"A. Okada, T. Yamauchi, Masayuki Higashi, Toshiaki Shimizu, Y. Uno","doi":"10.2526/JSEME.43.179","DOIUrl":"https://doi.org/10.2526/JSEME.43.179","url":null,"abstract":"The purpose of this study is to develop a new type of coated wire electrode for fine wire EDM. Piano wire with a very high tensile strength is coated with an electrically conductive brass layer to achieve high-speed and high-precision wire EDM. In our previous papers, using a thin wire of 50μm diameter, the thickness and quality of the brass coating layer were optimized and the effect of the tensile strength of the piano wire used as the core wire was discussed. In this report, the effect of unevenness of the brass wire electrode surface was experimentally investigated. As a result, it was found that by using wire with relatively large surface unevenness, the machining rate increased because of the high discharge frequency. Also, a more uniform distribution of the discharge location was confirmed by high-speed observation of the working gap during the process. In addition, the electrostatic field in the gap between the wire electrode and workpiece surface was analyzed and the reason for the high machining rate for the wire with relatively large surface unevenness was discussed from the viewpoint of the distribution of electric intensity distribution on the wire surface.","PeriodicalId":269071,"journal":{"name":"Journal of the Japan Society of Electrical-machining Engineers","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2009-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121894621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The micro-EDM process with deionized water as a dielectric fluid is used for nozzle production because of its high speed and low tool wear benefits. However, this process causes the formation of defects due to the electrolysis corrosion and processing limitation of applicable materials. It was considered that the electrolysis corrosion is induced by the ion produced as a result of the electro-discharge process. The process mechanism is considered in line with the theory indicating that electrolysis occurs in the deionized water when a high voltage is applied. Oxygen and H are formed at the anode surface during electrolysis, the carbon in the anode is oxidized, and part of the metal is corroded. For tungsten carbide, the corrosion is severe. A pulse shorter than 40ns can inhibit electrolysis and allow a highly precise micro-EDM to use deionized water with tungsten carbide. The tool wear ratio is 0.025% by volume and the processing speeds that are 150 times higher than those under the same conditions using oil as a dielectric fluid are verified. In addition, the mechanism of the electrolysis corrosion in stainless steel and the capability of the improved surface quality to control the generated electrolysis are explained. Micro-EDM, deionized water, electrolysis, tungsten carbide Vol.43, No.104 (2009)
{"title":"Study of precision micro-Electro-Discharge Machining (3rd Report)-Analysis of micro-EDM process with deionized water-","authors":"T. Masaki, T. Kuriyagawa","doi":"10.2526/JSEME.43.163","DOIUrl":"https://doi.org/10.2526/JSEME.43.163","url":null,"abstract":"The micro-EDM process with deionized water as a dielectric fluid is used for nozzle production because of its high speed and low tool wear benefits. However, this process causes the formation of defects due to the electrolysis corrosion and processing limitation of applicable materials. It was considered that the electrolysis corrosion is induced by the ion produced as a result of the electro-discharge process. The process mechanism is considered in line with the theory indicating that electrolysis occurs in the deionized water when a high voltage is applied. Oxygen and H are formed at the anode surface during electrolysis, the carbon in the anode is oxidized, and part of the metal is corroded. For tungsten carbide, the corrosion is severe. A pulse shorter than 40ns can inhibit electrolysis and allow a highly precise micro-EDM to use deionized water with tungsten carbide. The tool wear ratio is 0.025% by volume and the processing speeds that are 150 times higher than those under the same conditions using oil as a dielectric fluid are verified. In addition, the mechanism of the electrolysis corrosion in stainless steel and the capability of the improved surface quality to control the generated electrolysis are explained. Micro-EDM, deionized water, electrolysis, tungsten carbide Vol.43, No.104 (2009)","PeriodicalId":269071,"journal":{"name":"Journal of the Japan Society of Electrical-machining Engineers","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2009-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113936428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Keigo Nishimoto, Takeo Ikai, Kiyoto Hashiguchi, Y. Uno
The kind of electrode and its internal structure affect greatly electrical discharge characteristics such as metal removal rate and surface roughness. A new electrode, in which the insulator plate is inserted between thin copper plates, was proposed in this study, in order to achieve a high removal rate without deteriorating the surface roughness. The result of an impulse discharge experiment with this new electrode shows that a larger crater was generated compared with that having a copper solid electrode. It is also clarified that, in repetitious discharge machining using this electrode, the surface roughness doe's not increase even in high-removal-rate machining.
{"title":"Electrical Discharge Machining Using Isolated and Bundled Flat Plate Electrode","authors":"Keigo Nishimoto, Takeo Ikai, Kiyoto Hashiguchi, Y. Uno","doi":"10.2526/JSEME.42.58","DOIUrl":"https://doi.org/10.2526/JSEME.42.58","url":null,"abstract":"The kind of electrode and its internal structure affect greatly electrical discharge characteristics such as metal removal rate and surface roughness. A new electrode, in which the insulator plate is inserted between thin copper plates, was proposed in this study, in order to achieve a high removal rate without deteriorating the surface roughness. The result of an impulse discharge experiment with this new electrode shows that a larger crater was generated compared with that having a copper solid electrode. It is also clarified that, in repetitious discharge machining using this electrode, the surface roughness doe's not increase even in high-removal-rate machining.","PeriodicalId":269071,"journal":{"name":"Journal of the Japan Society of Electrical-machining Engineers","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127245055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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