Shown are a couple of electrodes used to EDM a mold cavity. These are machined from copper or graphite and are consumed in the EDM process. The wear on the corners of the blackened electrode on the right is normal for the process; a second or even third electrode must be made and used up to finish the part to correct geometry.Each electrode is time consuming to make and set up in the machine. The process is also intrinsically slow, these electrodes are about 2 inches long and are burned into a hardened steel block about 3/8 inch deep. Each burn took several days to complete and required 3 electrodes to get the detail and finish required in the part.