Analysis of sinking EDM electrode deflection measurements for the manufacturing of high aspect ratio cavities

The use of Sinking EDM for the fabrication of filigree structures with high aspect ratio (HAR) geometries is gaining continuously more terrain not only in the area of micro machining but also for the manufacturing of highly precise HAR macro geometries for the mould- and die industry. Fundamental tests have shown that discharge forces caused by the release of energy during the electrical discharge can generate unwanted vibrations on the tool electrode damaging final desired precision of the manufactured workpieces. This work will show results of dynamic lateral deflection of HAR macro Sinking EDM slit-formed graphite electrodes. A highly precise laser-interferometer will be used to measure electrode vibration during a continuous Sinking EDM process. The pulse frequency, as well as the mechanical properties of the electrodes will be taken into account for the analysis of the results. Possible improvement strategies based on analytical modeling of the electrode vibration caused by discharge forces are presented. Further work in the area of process monitoring and control will allow the achievable workpiece precision of the Sinking EDM process to be improved, making it more viable to meet the requirements of the growing precision manufacturing industry. (C) 2013 The Authors. Published by Elsevier B.V. Selection and/or peer-review under responsibility of Professor Bert Lauwers