Die Sinker EDM Electrode

At my internship, this week I have been working on machining two identical copper electrodes for one of the lab members to do some testing on the Electron Beam Melting machine. This machine is used to smooth the surface of mold parts created on EDM machines. Its works in vacuum by using a wide beam of electrons to sweep across the part melting the surface on a microscopic level producing a mirror finish. Here are a few shots of the three processes to complete the electrode including roughing, semi-finishing, and finishing. The finishing is done with an R1.5mm ball end mill (3mm diameter) with a 2% step-over (0.06mm step-over) which produced nearly a mirror finish. I accidentally put scratches on the surface by using a rag to wipe off the coolant. Total machining time was a little under 2 hours.