To start, EDM stands for Electrical Discharge Machining. It is a process that dates back to 1770, when Joseph Priestly noticed that electrical discharges were slowly removing material from the electrodes he used in his experiments. Unlike today, where the process is carefully controlled, this was termed electro-discharge erosion. EDM as we know it today was developed in Russia in 1943 by two scientists, B. R. Lazarenko and N. I. Lazarenko.

EDM provides us with a way to precisely cut small, intricate features into metals and other electrically conductive materials, features that would otherwise be impossible to create with the use of traditional tools or methods.

The workpiece is bombarded by thousands or even millions of sparks every second from the wire (the electrode, or the electrical conductor) and each time this happens, a tiny bit of material is removed.

By submerging both the electrode and the workpiece in dielectric fluid during this process, the tiny pieces of material cool and fall away from the workpiece before they have a chance to 'reattach.'

If you were to watch the EDM process under a microscope, you would see that the wire itself never actually makes contact with the workpiece–the electrical discharges do all the work. The same erosion that crafts the workpiece occurs to the wire, however, so modern EDM machines use a spool of wire to ensure that no part of the wire ever becomes too thin or breaks.