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

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 https://youtu.be/L1D5DLWWMp8 SME 1min https://youtu.be/q4FinKsDfww Ram vs. Wire EDM 4min

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

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 : http://edmtechman.com

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

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

Ram EDM Used to machine high hardness metals like as die by copper of graphite electrode. http://ma.gnu.ac.kr/vod/Machining/EDM.WMV Machine

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 http://www.youtube.com/watch?v=pBueWfzb7P0 WireEDM http://ma.gnu.ac.kr/vod/Machining/WireEDM.wmv WireEDM

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