Transcript *** 1

MANUFACTURING OF MICRO VGROOVE WITH AN ELECTRICALLY
CONDUCTIVE DIAMOND ELECTRODE
IN EDM
Name：吳涵玉
Date：6/13
Outline
• INTRODUCTION
• PCD MATERIAL USED
• EDM PROPERTIES OF PCD ELECTRODES
WITH FLAT SURFACE
• EDM PROPERTIES OF PCD ELECTRODE
WITH V SHAPE
• EXPERIMENTAL RESULTS
• CONCLUSION
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.
PCD MATERIAL USED
•
Such a superior thermal property is derived from the composition and
structure of the PCD materials. Concretely, PCD is composed of micronsize 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.
EDM PROPERTIES OF PCD
ELECTRODES WITH FLAT
SURFACE(1/2)
Fig 1. Schematic set up for EDM on tungsten carbide
edge with PCD electrode.
EDM PROPERTIES OF PCD
ELECTRODES WITH FLAT
SURFACE(2/2)
Electrode
EDM conditions
( Recommended from
manufacturer)
Fig 2.Comparison of electrode wear ratio.
Cu-W
Vi＝120V
Ip=1.6A
Te=0.5μs
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.
Experimental results
Fig5 .Cu-W electrode after EDM and groove profile on a workpiece (WC).
Effect of no-load voltage
Fig 6.Effect of no load voltage.
Fig 7.Effect of no load voltage. (te/to=15/15μs)
Effect of set ED current
Fig 8.Effect of EDM circuit.
Fig 9.Effect of applied set peak current.
(te/to=15/15μs).
Effect of ED duration
Fig 10.Effect of pulse on time.
Fig 11.Effect of pulse on time. (Vi=60V, Ip=2A)
CONCLUSION
1. 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).
2. The electrode wear is extremely less with PCD electrode compared to a CuW 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.
Thank you for your attention!!