There’s no need to get ahead of ourselves, no desire to put the proverbial cart before the horse, so let’s define an EDM Spark Eroding Machine before taking it apart and explaining its various inner workings. This is Electrical Discharge Machining (EDM), a manufacturing technique that uses a special sparking electrode to cut intricate shapes into hard metal alloys. Without further ado, just how does this tool work?
The Business End: EDM Spark Eroding Electrodes
When hard metal parts require work, it’s tough to accurately subtract smaller sections, as marked on an intricate design. An abrasive blade is no good. It’ll cut rough lines into the dense alloy, and there are all those sharp burrs to remove after the process is complete. EDM Spark Eroding Machines do the job by using a geometrically profiled electrode. A powerful electrical charge leaps across a small gap between the two electrodes. The first terminal is the shaped tool. As for the second electrode, this is the workpiece, an electrically conductive object that’s typically submerged in oil or water. That fluid obviously cools the workpiece as the electronically pulsed charge erodes the dense metal, plus it also acts as a circuit dielectric, a type of electrical insulator.
Watching the Process in Action
The electrode drops down above the workpiece. This gap must be small so that the spark can arc between the tool electrode and the object electrode. Pecking away at the part, the tool profile is cut into its surface. That massive spark is now generating 8000 to 120000°C of electrically-induced thermal energy, so the subject metal is quickly eroded. It melts, but the melted particles, subtracted from the workpiece, are so tiny that they can’t be seen by the human eye. Flushed away by the dielectric fluid, filtered and returned to the tool site, the electrically non-conductive fluid is ready for the next particle and heat flushing cycle. Again, this is a tool bit, a replaceable piece of conductive metal that acts as a shaping or surface-subtractive electrode. Alternatively, wire cutting EDM Machines can slice incredibly intricate designs into the hardest alloys, all while adopting the exact same electrically-active principle.
EDM Spark Eroding Machines excel when abrasive cutting saws fail. They cut tungsten, machine titanium and polycrystalline diamonds, and they do so without producing any waste. Metal burrs do not form when electrodes spark or wire sparking machines perform their subtractive magic. If there is waste, the particles are so fine that they do not interfere with the cutting process. Process complete, the insulating dielectric simply flushes the fine waste towards a filtration mechanism.