Papers by Keyword: EC-PCD

Abstract: In our previous research, precise groove machining could be achieved on a cemented carbide workpiece by utilizing a combined method of EDM and grinding using only a single tool, i.e. a rotary PCD disc tool acting as an electrode for EDM and as a wheel for grinding. In this study, the authors applied this method to forming a 3D shape on a cemented carbide workpiece. Firstly, an EC-PCD disc-shaped tool of φ33.4mm was mounted on a spindle of the EDM machine vertically to the workpiece. And the tool was rotated to make a spherical concave on the workpiece by EDM. The surface roughness of the workpiece was Rz=6.4μm and no electrode wear resulted at all. Secondly, the EDMed surface was ground with the same PCD tool. As a result, the improved surface roughness of Rz=1.7μm was obtained on the workpiece maintaining the precise tool profile and dimension.

Abstract: Electrically conductive PCD (EC-PCD), which was made of electrically conductive diamond particles, was applied to an electrode for EDM. In this study, properties of EC-PCD electrode in the EDM of cemented carbide were investigated and the results were compared with those of copper-tungsten (Cu-W) electrode and standard PCD (S-PCD) electrode. In terms of EDM speed, 35μm/min with Cu-W electrode, 15μm/min with S-PCD electrode and 22μm/min with EC-PCD were recorded. As for the electrode wear rate, though Cu-W electrode wore by 20-30%, S-PCD and EC-PCD did not wear at all and even the electrode length became longer by several micro meters. Roughness value of the EDMed surface was Rz=8μm with both Cu-W and S-PCD, while it was Rz=3μm in the case of EC-PCD. From the above, it was found that EC-PCD showed excellent performance in the electrode wear rate and the roughness of the EDMed surface, though EDM speed was 0.7 times of Cu-W electrode.

Abstract: It has been made clear that the EC-PCD composed of boron doped diamond particles improves the performance in the die sinking EDM and wire EDM in comparison with the existing standard PCD (S-PCD). However, the effect of the property improvement could not been evaluated quantitatively in the research reports in the past. Therefore, in this study, wire EDM cutting tests were conducted on the specimens of S-PCD and EC-PCD, in addition to the evaluation of cutting efficiency and cutting PCD surface, a detailed investigation of the cut surface properties of the PCD has been performed under the color 3D laser scanning microscope. In order to investigate effects of a grain size of the source diamond, EDM cutting experiments were conducted on the EC-PCD specimens of 4 different grain sizes. As a result, it was found that the cutting speed was higher in the case of EC-PCD than the case of S-PCD, e.g., by 20% and 40% respectively in the sample of 10μm and 25μm particle size. Also, in the case of the cut S-PCD surface, a groove due to the discharge is formed in the boundary of the tungsten carbide layer and the PCD layer. However, in the case of the cut EC-PCD surface, the groove did not appear in the boundary.

Abstract: Electrically conductive polycrystalline composite diamond (EC-PCD), which consists of electrically conductive diamond particles manufactured by doping boron atoms, has recently been developed for the purpose of providing material with both excellent tool properties and good machinability. This paper deals with an investigation into the machinability of EC-PCD by EDM with a copper electrode. As a result, it was found that the material removal rate of EC-PCD made up of diamond particles of 10 and 25 µm in diameter respectively was far higher than that of the conventional PCD. Furthermore, it was confirmed in the single pulse EDM experiment with a needle electrode that the EC diamond region in the EC-PCD was removed together with the cobalt region whereas only the cobalt region of C-PCD was removed when the electrode was set at plus polarity.

Abstract: Polycrystalline Composite Diamond (PCD) is excellent in chipping resistance despite its very high hardness. However, it is not easy to EDM or grind PCD. To realize high efficiency and high quality processing of PCD simply and at low cost, the authors devised new PCD (EC-PCD) by using electrically conductive diamond particles and applied a complex electrodischarge grinding method. In this study, investigation is made on effective grinding condition to realize high efficiency, low and stable grinding force and low wheel wear in complex electrodischarge grinding. As a result, superior grinding property was obtained when the grinding wheel was set at minus polarity, and set peak current of i_P = 4 and 6 A was applied. Furthermore it also became clear that additional conventional grinding process followed after complex electrodischarge grinding improved the surface condition.

Abstract: A new PCD (electrically conductive PCD: EC-PCD) consisting of electrically conductive diamond particles has recently been developed. The authors have proposed a complex grinding assisted with electrical discharge machining (EDM) where discharge machining and grinding are used in combination during material removal to realize high efficiency, low and stable grinding force and low wheel wear for the EC-PCD. In this study, the effect of constant-force grinding in a complex grinding assisted with electrical discharge machining of EC-PCD was investigated. As a result, it was found that higher material removal rate, higher grinding ratio and better surface condition were obtained on EC-PCD compared with standard PCD (S-PCD) in the constant-force grinding.

Abstract: A new PCD material named EC-PCD (Electrically conductive polycrystalline composite diamond), which consists of electrically conductive diamond grits, has recently been developed. This paper deals with an investigation of a complex grinding assisted with electrical discharge machining (EDM) to realize high efficiency, low and stable grinding force and low wheel wear for the new EC-PCD. The effect of complex grinding assisted with EDM is compared experimentally with the standard PCD (S-PCD). The result shows that, in the complex grinding, lower and more stable grinding force is realized thanks to the material removal action in EDM and that lower wheel wear and better surface finish are attained, just when the EC-PCD is selected as a workpiece.

Abstract: Electrically conductive polycrystalline composite diamond (EC-PCD), which consists of electrically conductive diamond grits, has recently been developed for the purpose of providing the material with both excellent tool property and good machinability. This paper deals with an investigation of machinability of EC-PCD by EDM with a copper (Cu) electrode. As a result, it was found that the EDM speed (Material removal rate) for EC-PCD was higher than that of the standard PCD. Although the surface roughness of the standard PCD was 13µm Rzjis at set current ip=3A, the surface roughness of the EC-PCD was 5µm Rzjis at the same current condition. Furthermore, it was observed that the EC diamond particle in EC-PCD was machined by single discharge EDM. Moreover, it was confirmed that EC-PCD was able to be applied a fine discharge profiling or a making fine holes using a rotating electrode.