Spark Erosion
Spark erosion (sinker electrical discharge machining, cavity type EDM, volume EDM) is an electronic process to cut metal pieces.
Spark erosion is performed in sinker electronic discharge machines, which has an electrode and a workpiece that are lowered in an insulating liquid. Both the electrode and the workpiece are connected to a power supply. The electrode is moved towards the component until a short circuit (or more correctly a dielectric breakdown) appears. Electricity is led from the electrode through the isolating liquid and the component, and the electricity cuts the workpiece. The electricity pulsing, which means the power is rapidly turned on and off. This is measure in on time, when the power creates sparks, and off time, the pause between every spark.
Using spark erosion, it is possible to manufacture complex shapes which are difficult to with conventional machines. It is also possible to get very fine tolerances in very hard materials. In addition, it is possible to machine small and sensitive workpieces, workpieces that any conventional machine would break because of its tool pressure.
Spark erosion is a quite rare manufacturing process, although found in some workshops. The electrical current usually determines the end result; a if it is high, the machining is quick and done rapidly but tolerances are less accurate. On the other hand if the current is low, the machining process is slow but with fine tolerances.
Picture: Aire Erosion