Define the EDM process; what are the process limitations?
Two types of EDM (electro-discharge machining) processes are performed; Wire EDM and Sinker EDM. Sinker EDM is a process typically consisting of a graphite, brass, or copper tube-shaped electrode that is slowly fed into a workpiece that is immersed in oil. A pulsed electrical discharge from the electrode causes sparks to jump to the workpiece, each tearing out a small particle. Oil, also known as cutting fluid, typically flows through the center of the electrode to help flush the particles away from the cutting path. The electrode gradually erodes its way through the workpiece. Surface finishes are typically rougher than in grinding processes, however secondary cuts or slower cutting speeds may improve finish. Tolerances typically range from +/- .001″ to +/- .005″ depending on the material being cut and the length of the cut (or electrode travel). Ceramic magnets cannot be machined utilizing EDM because the material does not allow for the “electrical arcing” to take place between the e
