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Spark Erosion

Method description

Electrical discharge machining for high-precision material processing is called “erosion” or “spark erosion”. Here, numerous small discharges between the electrode and work piece, inside the dielectric, erode small pieces of an electrically conductive work piece. For example, a hole can be drilled (drill EDM) or a work piece can be cut by a wire (wire EDM). Thus, a complex tool contour can be negatively reflected (imaged) on a work piece (die sinking EDM). An application that is gaining in popularity is disc eroding which is used for sharpening PCD (poly crystal diamonds) or hard metal saw blades and wood cutting tools. In this application a rotating disk serves as an electrode. The accuracy of these processes depends on the stability of the tool electrode, because the spark also removes electrode material even if it is at a much lower extent. This is why the electrode material from which the electrodes are made is of particular importance. The electrode material determines critical process parameters such as removal rate, wear, burrs, thermal expansion and requirements regarding rinsing.

The high-melting refractory metals tungsten and molybdenum as well as their alloys meet all requirements in this respect. They allow higher tool sharpness than copper and graphite and thus allow a more focused spark, better accuracy, smaller tolerances and form fidelity. Also, the very low tool warpage supported by a balanced temperature contributes to it, as the refractory metals with their high thermal conductivity and low thermal expansion, prevent uneven heat distribution. Homogeneous and fine grain structures improve the machinability of TUCOMET® materials and make it possible to achieve a low roughness and high surface quality of the electrodes.

Accordingly, the material erosion of the tool is lower and, because of more homogenous sparks distribution, finer. Therefore, flushing and removal of erosion are much easier and the risks of short circuits are reduced.

Application areas & Materials


  • EDM-Electrodes
  • EDM-Tubes
  • Threaded Electrodes


We recommend the following materials:

  • TUCOMET® 60
  • TUCOMET® 75
  • TUCOMET® 80
  • TUCOMET® 90
  • Tungsten
  • Molybdenum

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