共查询到20条相似文献,搜索用时 31 毫秒
1.
Apiwat Muttamara Yasushi Fukuzawa Naotake Mohri Takayuki Tani 《Journal of Materials Processing Technology》2003,140(1-3):243-247
Electrical discharge machining (EDM) is used as a precision machining method for the electrically conductive hard materials with a soft electrode material. But recently we succeeded to machine on insulating material by EDM. The technology is named as an assisting electrode method. The EDMed surface is covered with the electrical conductive layer during discharge. The layer holds the electrical conductivity during discharge. For micro-EDM, the wear of tool electrode becomes lager ratio than the normal machining. So the micro-machining is extremely difficult to get the precision sample.
In this paper to obtain a fine and precise ceramics sample, some trials were carried out considering the EDM conditions, tool electrodes material and assisting electrode materials. Insulating Si3N4 ceramics were used for workpiece. The machining properties were estimated by the removal rate and tool wear ratio. To confirm the change of micro-machining process, the discharge waveforms were observed. The micro-machining of the Ø0.05 mm hole could be machined with the commercial sinking electrical discharge machine. 相似文献
2.
In recant years, surface modification of metals and machining of insulating ceramics by electrical discharge machining (EDM) have been successfully carried out. In surface modification by EDM with semi-sintered electrodes, worn substances in the gap region form the material source of the layer generated on the work-piece surface. In the machining of insulating ceramics by EDM, a crystallized carbon layer or carbide layer from the working oil covers the surface of the insulator. Increase in the thickness of the generated layer, however, tends to stop at a certain maximum value in both surface modification by EDM with semi-sintered electrodes and machining of insulating ceramics by EDM processes. In these machining operations, accretion and removal phenomena occur alternately. In this paper, the mechanisms of machining insulators and the accretion process are discussed considering the characteristics of the generated layers on the work-piece surface. 相似文献
3.
In traditional electro discharge machining (EDM) the usual practice is to form a 3D female cavity in the work piece by making a corresponding male shaped tool and plunging this into the work piece. Recently, however, computer numerical control (CNC) EDM machines have become available which have the potential to generate a detailed shape without using complex electrodes. This paper describes a novel method of electro discharge machining which makes the generation of linear, circular and curved contours possible without any special electrodes. The experimental work employs CNC EDM, mild steel work pieces and inexpensive “frame type” copper tools. The results indicate, relative to the cavities produced, an improved effective material removal rate (MRR), a better surface finish and a lower powered machine. The paper also introduces the effect of EDM parameters on the process performance by modelling and analysing the experimental results using statistical techniques. Finally, a few applications are discussed. 相似文献
4.
Fabrication of micro-electrodes by multi-EDM grinding process 总被引:1,自引:0,他引:1
Feng-Tsai Weng R.F. Shyu Chen-Siang Hsu 《Journal of Materials Processing Technology》2003,140(1-3):332-334
In this study, a multi-EDM grinding process is adapted to fabricate micro-electrodes. Equipments such as a wire EDM machine and a traditional CNC-EDM machine are used for machining micro-electrodes. Rod electrodes of copper with diameter 3.0 mm were cut to be 0.15 mm on wire-EDM machine at first step. EDM grinding process was used to grind micro-electrodes to fine diameter bellow 20 μm on a CNC-EDM machine at second step. For EDM grinding, rotating mechanisms are mounted on both the WEDM machine and the CNC-EDM machine. A CCD camera is provided for viewing and for on-line dimensional controlling, when micro-electrodes were cutting. Fine electrodes could be processed to a smaller size using proposed two-steps EDM grinding process. Higher L/D ratio could be also achieved by this method. The processed fine electrodes can be used for drilling micro-holes, micro-deep holes, micro-milling, micro-punching, and manufacturing of micro-nozzles. 相似文献
5.
H. C. Tsai B. H. Yan F. Y. Huang 《International Journal of Machine Tools and Manufacture》2003,43(3):593
Electrode materials for electrical discharge machining (EDM) are usually graphite, copper and copper alloys because these materials have high melting temperature, and excellent electrical and thermal conductivity. The electrodes made by using powder metallurgy technology from special powders have been used to modify EDM surfaces in recent years, to improve wear and corrosion resistance. However, electrodes are normally fabricated at high temperatures and pressures, such that fabrication is expensive. This paper proposes a new method of blending the copper powders contained resin with chromium powders to form tool electrodes. Such electrodes are made at low pressure (20 MPa) and temperature (200 °C) in a hot mounting machine. The results showed that using such electrodes facilitated the formation of a modified surface layer on the work piece after EDM, with remarkable corrosion resistant properties. The optimal mixing ratio, appropriate pressure, and proper machining parameters (such as polarity, peak current, and pulse duration) were used to investigate the effect of the material removal rate (MRR), electrode wear rate (EWR), surface roughness, and thickness of the recast layer on the usability of these electrodes. According to the experimental results, a mixing ratio of Cu–0wt%Cr and a sinter pressure of 20 MPa obtained an excellent MRR. Moreover, this work also reveals that the composite electrodes obtained a higher MRR than Cu metal electrodes; the recast layer was thinner and fewer cracks were present on the machined surface. Furthermore, the Cr elements in the composite electrode migrated to the work piece, resulting in good corrosion resistance of the machined surface after EDM. 相似文献
6.
In this paper a new approach for the optimization of the electrical discharge machining (EDM) process with multiple performance characteristics based on the orthogonal array with the grey relational analysis has been studied. A grey relational grade obtained from the grey relational analysis is used to solve the EDM process with the multiple performance characteristics. Optimal machining parameters can then be determined by the grey relational grade as the performance index. In this study, the machining parameters, namely workpiece polarity, pulse on time, duty factor, open discharge voltage, discharge current, and dielectric fluid are optimized with considerations of multiple performance characteristics including material removal rate, surface roughness, and electrode wear ratio. Experimental results have shown that machining performance in the EDM process can be improved effectively through this approach. 相似文献
7.
8.
9.
10.
SeongMin Son HanSeok Lim A.S. Kumar M. Rahman 《Journal of Materials Processing Technology》2007,190(1-3):73-76
Micro EDM is one of the most powerful technologies which are capable of fabricating micro-structure. However, there are many operating parameters that affect the micro EDM process. Since the EDM is basically a thermal process, the supplying electrical condition can be an important factor. The conditions generally consist of several parameters such as electrical current, voltage, pulse duration, spark gap, and others. Those are decisive in removal rate, wear rate, and machining accuracy, which are characteristics of EDM. In this study, the influences of EDM pulse condition on the micro EDM properties were investigated. Voltage, current, and on/off time of the pulse were selected as experimental parameters based on a simple equation for the material removal rate. The pulse condition is particularly focused on the pulse duration and the ratio of off-time to on-time, and the machining properties are reported on tool wear, material removal rate, and machining accuracy. The experimental results show that the voltage and current of the pulse exert strongly to the machining properties and the shorter EDM pulse is more efficient to make a precision part with a higher material removal rate. 相似文献
11.
针对放电诱导烧蚀加工在高效加工的同时易在工件表面产生巨大烧蚀坑的问题,提出了电火花诱导烧蚀磨削修整复合加工方法。对钛合金TC4进行了电火花加工、烧蚀加工、诱导烧蚀磨削修整复合加工的对比实验,研究机械磨削作用对烧蚀性能的影响。在钛合金烧蚀加工实验过程中,用复合机械磨头进行修整能显著提高加工效率,达到1107 mm3/min,是同等条件下电火花加工的6.77倍、烧蚀加工的1.27倍。由于存在机械磨削修整作用,可在线去除烧蚀产物,露出基体材料,工件表面粗糙度优于烧蚀加工,甚至优于同等电参数下的电火花加工,达到了在获得高效加工的同时提升表面质量的目的。 相似文献
12.
13.
Electrical Discharge Surface Alloying of Ti and Fe Workpiece Materials Using Refractory Powder Compact Electrodes and Cu Wire 总被引:1,自引:0,他引:1
The paper reviews the use of metal powders dispersed in the dielectric fluid and refractory PM electrodes, to initiate workpiece surface modification during EDM. Experimental work details the effects of EDM parameters (up to 270 V) on the hardness/composition of the white layer following die sink machining of AISI H13 tool steel and roll texturing of 2% Cr steel using partially sintered PM electrodes. Similar data are presented following EDM scanning and wire cutting of standard TI alloy TI-6AI-4V and a y TIAI. With AISI H13, recast layers were 5-20 μm thick and up to ∼ 1350 HK0.025. When machining TI-6AI-4V with WC/Co electrodes, recast microhardness was 600-2900 HK0.025. Wire cutting y TIAI generated porous alloyed layers up to 115 μm thick with extensive cracks and no increase in bulk hardness. 相似文献
14.
Jose Marafona Catherine Wykes 《International Journal of Machine Tools and Manufacture》2000,40(2):153
Electrical discharge machining (EDM) is widely used in the production of dies. This paper describes an investigation into the optimisation of the process which uses the effect of carbon which has migrated from the dielectric to tungsten–copper electrodes. This work has led to the development of a two-stage EDM machining process where different EDM settings are used for the two stages of the process giving a significantly improved material removal rate for a given tool wear ratio. 相似文献
15.
16.
分析了数控电火花加工特点,介绍了LYNUC数控系统HiPT高速高精度核心控制模块的切削特点。通过实际切削加工案例的分析,证实了在辅助电火花放电加工的切削工序中,HiPT高速高精度模块可以获得高品质的切削电极和放电加工工件,且有效地提高数控电火花加工表面精度和加工效率,降低了生产成本。 相似文献
17.
Machining performance on hybrid process of abrasive jet machining and electrical discharge machining
To develop a hybrid process of abrasive jet machining (AJM) and electrical discharge machining (EDM),the effects of the hybrid process parameters on machining performance were comprehensively investigated to confirm the benefits of this hybrid process.The appropriate abrasives delivered by high speed gas media were incorporated with an EDM in gas system to construct the hybrid process of AJM and EDM,and then the high speed abrasives could impinge on the machined surface to remove the recast layer caused by EDM process to increase the efficiency of material removal and reduce the surface roughness.In this study,the benefits of the hybrid process were determined as the machining performance of hybrid process was compared with that of the EDM in gas system.The main process parameters were varied to explore their effects on material removal rate,surface roughness and surface integrities.The experimental results show that the hybrid process of AJM and EDM can enhance the machining efficiency and improve the surface quality.Consequently,the developed hybrid process can fit the requirements of modern manufacturing applications. 相似文献
18.
A novel high-speed dry electrical discharge machining (EDM) method was proposed in this study. Using this method, the material can be rapidly melted by extremely high discharge energy and flushed out of the discharge gap by high-pressure and high-speed air flow. The material removal rate (MRR) of dry EDM was significantly improved by the proposed method. The MRR of dry EDM is usually in tens mm3/min, whereas the MRR of the proposed method can be as high as 5162 mm3/min, which improves the MRR by 2nd to 3rd order of magnitude. Investigation was conducted systemically. The influences of work piece polarity, discharge current, pulse duration time, gas pressure, and electrode rotation speed on machining performance were studied. The machining mechanism of this method was thoroughly analyzed. Moreover, the re-solidified layer, surface morphology, elementary composition, and phase of AISI 304 stainless steel for high-speed dry EDM were also investigated. Theoretical and technical foundations were laid for the industry application of dry EDM. 相似文献
19.
Fred L. Amorim Leandro J. Stedile Ricardo D. Torres Paulo C. Soares Carlos A. Henning Laurindo 《Journal of Materials Engineering and Performance》2014,23(4):1480-1488
Titanium and its alloys have high chemical reactivity with most of the cutting tools. This makes it difficult to work with these alloys using conventional machining processes. Electrical discharge machining (EDM) emerges as an alternative technique to machining these materials. In this work, it is investigated the performance of three special grades of graphite as electrodes when ED-Machining Ti6Al4V samples under three different regimes. The main influences of electrical parameters are discussed for the samples material removal rate, volumetric relative wear and surface roughness. The samples surfaces were evaluated using SEM images, microhardness measurements, and x-ray diffraction. It was found that the best results for samples material removal rate, surface roughness, and volumetric relative wear were obtained for the graphite electrode with 10-μm particle size and negative polarity. For all samples machined by EDM and characterized by x-ray (XRD), it was identified the presence of titanium carbides. For the finish EDM regimes, the recast layer presents an increased amount of titanium carbides compared to semi-finish and rough regimes. 相似文献