1. Manufacturing Processes
EDM(방전가공)
Associate Professor Su-Jin Kim
School of Mechanical Engineering
Gyeongsang National University 1

2. EDM (Electrical-Discharge Machining, 방전가공)
Based on erosion of metals by spark discharges.
EDM system consists of electrodes(전극) connected to a DC and placed in a dielectric fluid(방전액).
Electrode
Spark
Workpiece
SME 1min
Ram vs. Wire EDM 4min

3. EDM (Electrical-Discharge Machining)
50~380 V, 0.1~500 A, 50~500 kHz, 1~100 μm3/Hz
Metal removal rate (mm3/min) = Exp const x Current (A) / Meting temperature (°C): MRR = 4x104 I Tw-1.23
1st RC EDM

4. EDM Condition & Results
Experiment and Result of EDM : Current, On time, Off time -> MRR, Wear, Roughness
Current (A)↑  MRR ↑ Quality ↓ (Linear)
On time (us) ↑  MRR ↑ Quality ↓ (Small)
Refer :

5. EDM Condition & Results
Current (A)↑ > On time(us) ↑  MRR ↑

6. EDM Condition & Results
Current (A)↑ > On time(us) ↑  Roughness Ra ↑

7. Ram EDM
Used to machine high hardness metals like as die by copper of graphite electrode.
Machine

8. Wire EDM
A brass wire is fed through the workpiece submerged in a tank of dielectric fluid.
It is used to cut plates as thick as 0.3 m and to make punches, tools, and dies from hard metals.
- Wire electrode
+ Workpiece
WireEDM
WireEDM

9. Small Hole EDM
EDM drill rows of holes into the leading and trailing edges of turbine blades used in jet engines.