No longer is EDM a "non-conventional" machining method. It is claimed that EDM is now the fourth most popular machining method. The first three are milling, turning, and grinding. One of the major reasons for the turnaround is today's EDM machines have dramatically increased their cutting speeds. | 1 19 Understanding Electrical Discharge Machining Electrical Discharge Machining No longer is EDM a "non-conventional" machining method. It is claimed that EDM is now the fourth most popular machining method. The first three are milling, turning, and grinding. One of the major reasons for the turnaround is today's EDM machines have dramatically increased their cutting speeds. In today’s highly competitive world, it is essential to understand the electrical discharge machining (EDM) processes. Every manufacturer needs to learn and understand the many advantages of EDM. We will be examining the three basic EDM processes: wire EDM, ram EDM, and small hole EDM drilling. See Figure 1:1. Courtesy Mitsubishi Wire EDM Courtesy Charmilles Courtesy Agie Ram EDM Small Hole EDM Drilling Figure 1:1 The Three EDM Processes Complete EDM Handbook 20 Compliments of Various Electric Discharge Machines The three electric discharge machining methods, wire, ram, and small hole EDM, all work on the principle of spark erosion. As the name indicates, material is eroded from the workpiece by means of electrical discharges that create sparks. A. Wire EDM In wire EDM, the spark jumps from the wire electrode to the workpiece and erodes metal both from the wire electrode and the workpiece. Wire EDM is used primarily for through hole machining as shown in Figure 1:2. Electrode Work piece Figure 1:2 Wire EDM Wire EDM is used primarily for through hole machining. B. Ram EDM Ram EDM, also known as conventional EDM, sinker EDM, die sinker, vertical EDM, and plunge EDM is generally used to produce blind cavities as shown in Figure 1:3. In ram EDM sparks jump from the electrode to the workpiece. This causes material to be removed from the workpiece. Electrode Work piece Figure 1:3 Ram EDM Ram EDM is used primarily for blind hole machining. Understanding Electrical Discharge Machining 21 C. Small Hole EDM Drilling Small hole EDM drilling, also known as fast
