Alternating Energy EDM is currently a developing type of machining, the results obtained are very enthusiastic. The usage of the sintered electrode is the main reason for the astonishing results, and it's rotation make it even better. WC i.e. Tungsten Carbide has high erosion tendency and low resistivity, whereas PCD i.e. Polycrystalline Diamond has low erosion and high resistivity, due to which plasma channel is more likely to form between WC with Workpiece instead of PCD with Workpiece as the gap between WC as well as PCD with Workpiece is same. But after WC section gets eroded, the gap between WC section with Workpiece is not enough to create and sustain plasma channel, then plasma channel is formed between PCD section with Workpiece and due to low erosion tendency and high resistivity no significant material removal takes place only finishing operation takes place. After eroding of PCD, Diamonds expose to workpiece and micro grind it. Material Removal- WC section Finishing- PCD section Micro grinding- Diamonds (mechanically)

1. Alternating Energy EDM of Ti Alloy using
a WC-PCD Electrode
ABHISHEK GUPTA
2011ME01
Department of Mechanical Engineering,
IIT Patna

2. CONTENT
• Introduction
• Working principle
• Experiment setup
• Results
• Conclusions
• References

3. Introduction
• Alternating Energy EDM (AE-EDM) uses
Tungsten Carbide (WC) and Polycrystalline
Diamond (PCD) sintered electrode.

4. • The work function and resistivity of WC section
is lower than that of PCD.
• If Plasma channel be formed between WC with
workpiece larger energy erosion takes place.
• If plasma channel be formed between PCD with
workpiece smaller energy erosion takes place.
• This Alternate Energy Erosion is due to high
difference of work functions of WC and PCD.

5. Working Principle
• First plasma channel be formed between WC
part and workpiece, due to lower Work function
of WC part compared to PCD part.

6. • After WC part reduces due to erosion, plasma
channel formed between PCD and workpiece.
• Alternate switching of plasma channel between WC
and PCD part with workpiece takes place.
• Diamond crystals used to mechanically grind
softened workpiece.

7. Experiment setup
• WC-PCD electrode was connected to rotary
mechanism.
• Workpiece & WC-PCD both were immersed in
dielectric medium.

8. Results
• The Material Removal Rate (MRR) of normal EDM using Cu is
2.85mg/min but of AE-EDM came to be 2.13mg/min.
• The Relative Electrode Wear (REW) was 35.8% in normal EDM
whereas in AE-EDM it came to be 5.3% only.
• The average roughness of finished surface with AE-EDM was 58.7%
of normal EDM.

9. • The recast layer so formed on finished workpiece
consist of high amount of Tungsten and Carbide.
• Surface hardness of finished workpiece is higher
with AE-EDM than that of normal EDM.

10. • Recast layer of AE-EDM (Fig.b) is thinner than
normal EDM (Fig.a).

11. Conclusions
• The WC-PCD electrode and it’s rotation is the main
mechanism of AE-EDM.
• The voltage to sustain plasma channel is smaller for
PCD compared to metals.
• The WC-PCD electrode produces different type of
craters, using different section of electrode
• High surface finish, high surface hardness, thinner
recast layer and less REW in AE-EDM compared to
normal EDM.

12. References
• Xiangzhi Wang, Chaojiang Li, Hum Guo, Shuang Yi,
Linglei Kong, Songlin Ding Alternating Energy
Electrical Discharge Machining of Ti Alloy Using a
WC-PCD electrode 2020, 1526-6125/© 2020

13. THANK YOU