Hidekazu Tsukahara, H. Minami, K. Masui, T. Sone, K. Demizu
In this paper we present a surface modification method for titanium using a scanning electrode during the finishing process of EDM. The effects of several parameters, such as the electrode thickness, scanning speed and scanning pass, on the surface properties were investigated. Using this method, the discharge process can be controlled without any difficulty. Therefore a smooth TiC layer with excellent tribological properties may result. The C/Ti ratio in the TiC layer, which influences the tribological properties of the machined surface, changed with the discharge number. The scanning electrode method proved to be effective for efficient surface modification of titanium.
{"title":"Surface Modification of Titanium Using Scanning Electrode Method by Electro Discharge Machining","authors":"Hidekazu Tsukahara, H. Minami, K. Masui, T. Sone, K. Demizu","doi":"10.2526/JSEME.35.79_24","DOIUrl":"https://doi.org/10.2526/JSEME.35.79_24","url":null,"abstract":"In this paper we present a surface modification method for titanium using a scanning electrode during the finishing process of EDM. The effects of several parameters, such as the electrode thickness, scanning speed and scanning pass, on the surface properties were investigated. Using this method, the discharge process can be controlled without any difficulty. Therefore a smooth TiC layer with excellent tribological properties may result. The C/Ti ratio in the TiC layer, which influences the tribological properties of the machined surface, changed with the discharge number. The scanning electrode method proved to be effective for efficient surface modification of titanium.","PeriodicalId":269071,"journal":{"name":"Journal of the Japan Society of Electrical-machining Engineers","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134030511","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 this paper we describe the analysis of the distribution of discharge location using chaos theory in Electrical Discharge Machining (EDM). Chaos is a nonlinear phenomenon which is determined by a relatively simple rule, although it appears complicated and random. It was found that the discharge location is simply determined by the gap distribution and the debris particle distribution in spite of the complicacy and randomness of these distributions. Namely, the discharge occurs at the location where the gap is narrow and the debris density is high. Consequently, we analyzed the discharge location distribution using chaos theory and found the following: 1) the distribution of discharge location is irregular, 2) a bifurcation is observed, 3) the attractor dimension is relatively small, and 4) at least one of the Lyapunov exponents is larger than zero. By calculating the attractor dimension, we also found that there is a correlation between the attractor dimension and machining stability, that is, the higher the attractor dimension is, the greater the stability of machining is. This means the machining stability, which has not been detectable so far, can be distinguished by calculating the attractor dimension.
{"title":"Distribution of Discharge Location in EDM Using Chaos Theory","authors":"Fuzhu Han, M. Kunieda","doi":"10.2526/JSEME.35.79_16","DOIUrl":"https://doi.org/10.2526/JSEME.35.79_16","url":null,"abstract":"In this paper we describe the analysis of the distribution of discharge location using chaos theory in Electrical Discharge Machining (EDM). Chaos is a nonlinear phenomenon which is determined by a relatively simple rule, although it appears complicated and random. It was found that the discharge location is simply determined by the gap distribution and the debris particle distribution in spite of the complicacy and randomness of these distributions. Namely, the discharge occurs at the location where the gap is narrow and the debris density is high. Consequently, we analyzed the discharge location distribution using chaos theory and found the following: 1) the distribution of discharge location is irregular, 2) a bifurcation is observed, 3) the attractor dimension is relatively small, and 4) at least one of the Lyapunov exponents is larger than zero. By calculating the attractor dimension, we also found that there is a correlation between the attractor dimension and machining stability, that is, the higher the attractor dimension is, the greater the stability of machining is. This means the machining stability, which has not been detectable so far, can be distinguished by calculating the attractor dimension.","PeriodicalId":269071,"journal":{"name":"Journal of the Japan Society of Electrical-machining Engineers","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123840827","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}
Shin-ichiro Kubota, Y. Uno, H. Kuribayashi, S. Yokomizo
This paper deals with fine deep boring of carbide alloys. Fine deep boring by EDM is superior for obtaining a qualitatively machined shape and high surface integrity compared to conventional processes. However, it is difficult to obtain a microhole smaller than 100μm in diameter with an aspect ratio larger than 5, because of remaining bubbles and debris in the small gap between the electrode and workpiece which cause unstable machining. A new fine boring method is proposed in which EDM and laser beam machining are combined. First, a penetrating prehole is machined with a YAG laser. In the next process, micro-EDM boring is carried out on the prehole. By removing the bubbles and debris through the prehole, it is possible to maintain stable EDM. With these two successive processes, a fine deep hole is obtained. The hole made by this method has a good roundness and a high aspect ratio that cannot be achieved using only the EDM process. We applied this method to a superfine grain carbide alloy which is widely used for precise metal molds and cutting tools. The main results of this study are as follows. (1) Using the combined process of EDM and LBM, ∅160μm holes were successfully machined through a 2-mm-thick superfine grain carbide. (2) It is possible to remove the bubbles and debris efficiently by suction flow through the prehole. (3) In the case of EDM boring with a prehole, electrode wear mainly occurs on the side of the electrode. (4) For a 1-mm-thick workpiece, it is possible to bore a microhole with a diameter of 100μm and an aspect ratio of 10.
{"title":"Fine Deep Boring of Carbide by EDM with YAG Laser","authors":"Shin-ichiro Kubota, Y. Uno, H. Kuribayashi, S. Yokomizo","doi":"10.2526/JSEME.35.19","DOIUrl":"https://doi.org/10.2526/JSEME.35.19","url":null,"abstract":"This paper deals with fine deep boring of carbide alloys. Fine deep boring by EDM is superior for obtaining a qualitatively machined shape and high surface integrity compared to conventional processes. However, it is difficult to obtain a microhole smaller than 100μm in diameter with an aspect ratio larger than 5, because of remaining bubbles and debris in the small gap between the electrode and workpiece which cause unstable machining. A new fine boring method is proposed in which EDM and laser beam machining are combined. First, a penetrating prehole is machined with a YAG laser. In the next process, micro-EDM boring is carried out on the prehole. By removing the bubbles and debris through the prehole, it is possible to maintain stable EDM. With these two successive processes, a fine deep hole is obtained. The hole made by this method has a good roundness and a high aspect ratio that cannot be achieved using only the EDM process. We applied this method to a superfine grain carbide alloy which is widely used for precise metal molds and cutting tools. The main results of this study are as follows. (1) Using the combined process of EDM and LBM, ∅160μm holes were successfully machined through a 2-mm-thick superfine grain carbide. (2) It is possible to remove the bubbles and debris efficiently by suction flow through the prehole. (3) In the case of EDM boring with a prehole, electrode wear mainly occurs on the side of the electrode. (4) For a 1-mm-thick workpiece, it is possible to bore a microhole with a diameter of 100μm and an aspect ratio of 10.","PeriodicalId":269071,"journal":{"name":"Journal of the Japan Society of Electrical-machining Engineers","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133746261","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}
Heat-affected zones (HAZs), in which there are many cracks and microcraters, are generated by electrical discharge machining (EDM) of cemented carbides. These defects cause a substantial decrease in the strength of the materials. As one of the countermeasures, HAZs can be removed by polishing, which is dependent on hand finishing. However, it is difficult to remove HAZs completely through polishing. At present, a polishing operator subjectively evaluates whether defects such as cracks exist on a polished surface based on the degree of brilliance of the polished surface. In this study, the relationship between the reflectivity of the polished surface and the transverse rupture strength (IRS) was experimentally examined based on the assumption that polishing to a quasi-mirror-finish surface is not necessarily accompanied by recovery of the strength of the material. Our results showed that the reflectivity of the quasi-mirror-finish surface with surface roughness of 0.2μm Ry is 3-4 percent lower than that of a mirror-finish surface with surface roughness of less than 0.1μm Ry. The IRS ratio of a quasi-mirror-finish surface is 0.7, and that of an electrical discharge machined surface is 0.6 compared with 1.0 for a mirror-finish surface. Thus, we observed that the reflectivity of the quasi-mirror-finish surface is near that of the mirror-finish surface, and that the IRS of the quasi-mirror-finish surface is near that of the electrical discharge machined surface.
{"title":"Surface Integrity of Cemented Carbides Machined by Electrical Discharge Machining after Polishing","authors":"T. Tamura, S. Matsumoto","doi":"10.2526/JSEME.35.12","DOIUrl":"https://doi.org/10.2526/JSEME.35.12","url":null,"abstract":"Heat-affected zones (HAZs), in which there are many cracks and microcraters, are generated by electrical discharge machining (EDM) of cemented carbides. These defects cause a substantial decrease in the strength of the materials. As one of the countermeasures, HAZs can be removed by polishing, which is dependent on hand finishing. However, it is difficult to remove HAZs completely through polishing. At present, a polishing operator subjectively evaluates whether defects such as cracks exist on a polished surface based on the degree of brilliance of the polished surface. In this study, the relationship between the reflectivity of the polished surface and the transverse rupture strength (IRS) was experimentally examined based on the assumption that polishing to a quasi-mirror-finish surface is not necessarily accompanied by recovery of the strength of the material. Our results showed that the reflectivity of the quasi-mirror-finish surface with surface roughness of 0.2μm Ry is 3-4 percent lower than that of a mirror-finish surface with surface roughness of less than 0.1μm Ry. The IRS ratio of a quasi-mirror-finish surface is 0.7, and that of an electrical discharge machined surface is 0.6 compared with 1.0 for a mirror-finish surface. Thus, we observed that the reflectivity of the quasi-mirror-finish surface is near that of the mirror-finish surface, and that the IRS of the quasi-mirror-finish surface is near that of the electrical discharge machined surface.","PeriodicalId":269071,"journal":{"name":"Journal of the Japan Society of Electrical-machining Engineers","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131357019","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}
T. Moro, A. Goto, N. Mohri, N. Saito, H. Miyake, M. Akiyoshi
A surface modification technology with electrical discharge machining has been applied to cutting tools, molds and dies. A Ti-based powder composite structure electrode is used in this method, a highspeed modification technology which can generate a thin and hard layer on a substrate. In this report, experiments using a Tile green compact electrode are described. The results of the experiments are as follows 1) The piled layer is functionally graded in atomic content and hardness which reaches 3000HV at the top of a 10-m-thick layer in spite of voids involved. 2) The thickness and hardness are uniquely determined by the supplied energy density. The wear length of the electrode is reduced according to the decrease of its area due to the bubbles in the gap region. 3) The layer grows rapidly at the beginning of machining and then its hardness increases. After the maximum piling rate, the hardness decreases owing to the change of thermal properties of the piled layer.
{"title":"Surface Modification Process using TiH2 Green Compact Electrode by Electrical Discharge Machining","authors":"T. Moro, A. Goto, N. Mohri, N. Saito, H. Miyake, M. Akiyoshi","doi":"10.2526/JSEME.35.26","DOIUrl":"https://doi.org/10.2526/JSEME.35.26","url":null,"abstract":"A surface modification technology with electrical discharge machining has been applied to cutting tools, molds and dies. A Ti-based powder composite structure electrode is used in this method, a highspeed modification technology which can generate a thin and hard layer on a substrate. In this report, experiments using a Tile green compact electrode are described. The results of the experiments are as follows 1) The piled layer is functionally graded in atomic content and hardness which reaches 3000HV at the top of a 10-m-thick layer in spite of voids involved. 2) The thickness and hardness are uniquely determined by the supplied energy density. The wear length of the electrode is reduced according to the decrease of its area due to the bubbles in the gap region. 3) The layer grows rapidly at the beginning of machining and then its hardness increases. After the maximum piling rate, the hardness decreases owing to the change of thermal properties of the piled layer.","PeriodicalId":269071,"journal":{"name":"Journal of the Japan Society of Electrical-machining Engineers","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121279183","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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