1. MANUFACTURING OF MICRO V-GROOVE WITH AN ELECTRICALLY CONDUCTIVE DIAMOND ELECTRODE IN EDM
Name：吳涵玉
Date：6/13

2. Outline INTRODUCTION PCD MATERIAL USED
EDM PROPERTIES OF PCD ELECTRODES WITH FLAT SURFACE
EDM PROPERTIES OF PCD ELECTRODE WITH V SHAPE
EXPERIMENTAL RESULTS
CONCLUSION

3. INTRODUCTION
In order to realize successful fine and precise EDM, it is important to minimize the wear of the electrode under the condition of very small pulse duration.
Subsequently, the authors proposed the use of PCD (polycrystalline diamond) material having adequately high thermal conductivity instead of expensive EC-CVD diamond, and have shown that the PCD also has superior wear resistance in EDM on die steel (SKD11 in JIS) similar to the EC-CVD diamond electrode [3].
In this study, fine EDM experiments were conducted using a PCD electrode having a knife edged shape with an included angle of 45°, for the purpose of realizing a practical use of PCD material as an electrode for fine and precise ED machining on tungsten carbide workpiece.

4. PCD MATERIAL USED
Such a superior thermal property is derived from the composition and structure of the PCD materials. Concretely, PCD is composed of micron-size diamond particles that are firmly bonded (intergrowth) with each other during the synthesis process under ultra-high pressure and high temperature with the help of metallic catalyst (cobalt in this case).
TABLE 1. Physical properties of various electrode materials.

5. EDM PROPERTIES OF PCD ELECTRODES WITH FLAT SURFACE(1/2)
Fig 1. Schematic set up for EDM on tungsten carbide
edge with PCD electrode.

6. EDM PROPERTIES OF PCD ELECTRODES WITH FLAT SURFACE(2/2)
Cu-W
EDM conditions
( Recommended from
manufacturer)
Vi＝120V
Ip=1.6A
Te=0.5μs
Fig 2.Comparison of electrode wear ratio.

7. EDM PROPERTIES OF PCD ELECTRODE WITH V SHAPE
Fig 3. V-shaped PCD electrode formed by wire cut
EDM machine.
Fig 4. Experimental setup.
Table 2. Experimental conditions.

8. Experimental results
Fig5 .Cu-W electrode after EDM and groove profile on a workpiece (WC).

9. Effect of no-load voltage
Fig 6.Effect of no load voltage.
Fig 7.Effect of no load voltage. (te/to=15/15μs)

10. Effect of set ED current
Fig 8.Effect of EDM circuit.
Fig 9.Effect of applied set peak current. (te/to=15/15μs).

11. Effect of ED duration Fig 10.Effect of pulse on time.
Fig 11.Effect of pulse on time. (Vi=60V, Ip=2A)

12. CONCLUSION
PCD electrodes with flat surface show an almost zero wear at the long pulse duration and a significantly low wear of 0.6~1.5% at the short pulse duration compared to 10% wear of the Cu-W electrode at suggested condition for EDM on tungsten carbide (G5).
The electrode wear is extremely less with PCD electrode compared to a Cu-W electrode and a zero wear machining is achieved by optimizing the ED conditions (Vi=60V, Ip=2A, te>15μs).
3. Thermal conductivity of PCD is different according to the diamond grain size of the PCD. In this study, it was expected that the electrode with higher thermal conductivity would show less wear. In fact, the result is just as expected, i.e. CTH025 exhibits less wear than CTB010.

13. Thank you for your attention!!