T4T – Fast EDM Drilling

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The EDM DRILLING process, also known as Fast EDM Drilling or High-Speed EDM Drilling, is, like Plunge EDM, part of the group of material removal processes by EDM and in general of the family of chip removal processes termed “unconventional.”

Like Plunge EDM, it has the same erosive properties generated by electric current: the removal of material from the blank takes place through the passage of current from the machine, which is equipped with a generator, to the electrode system, which is connected to the machine head via an electrode holder.

In this case, unlike Plunge EDM, the electrode holder consists of a rotating spindle and the electrode (a tube of conducting material) must necessarily be cylindrical; its rotary and axial movement driven by the spindle is constrained in axis by an insulating guide made of ceramic material.

EDM Drilling uses deionized water as the insulating liquid and can be done by immersion (in a tank containing such liquid), or by sprinkling, when the electrode is sprayed locally by the liquid, both internally and externally through the spindle.

The material of the electrode is characterized by high conductivity, and for this reason Copper, Copper-Brass alloys and Tungsten alloys (for special applications) are frequently used.

Its use is typical in applications where deep drilling and very small diameters are required: for some types of machines it starts even from an electrode diameter of ø0.25 up to 6mm with depths ranging up to 350/400mm.


  • Very small drilling diameters in absolute terms and in relation to the depth that can be reached
  • Very high drilling depths not achievable by any other conventional drilling process
  • Absence of burrs resulting from stock removal compared to drilling with a conventional cutting tool
  • Absence of both normal and tangential cutting forces
  • Machining does not depend on the mechanical properties of the material (eg hardness, tensile strength) and allows machining of very hard materials that are difficult to machine by conventional stock removal


Unlike Die Sink EDM, in the Fast EDM Drilling process the polarity of the current remains fixed during the removal cycles.


The Die Sink EDM process finds particular application in the Energy and Aerospace sectors: in fact, the use of this technique for the realization of cooling holes in nozzles and turbine blades, and in multiple categories of oil nozzles for the lubrication of components subject to wear (such as stators, bearings and hydraulic cylinder) and fuel injection in the combustion section, is of fundamental importance.