Fundamental Analysis of High Frequent Electrical Process Signals for Advanced Technology Developments in W-EDM

Technology development in EDM is very time consuming especially for the application of new materials or in the case of unfavorable machining conditions. Due to the large number of influencing factors and their interdependencies it is not possible to predict the machining conditions only by interpretation of the used generator parameters. Therefore it is difficult to link the machining results directly to the parameter setting. As a consequence a large number of test series are typically performed in a trial and error approach to find the ideal set of parameters for each machining task. But in this case the resulting technology is limited to the machining of the same material, geometry and the used machine tool.For an intelligent model based technology development the direct influence of the generator parameters on the actual process conditions need to be identified. In this paper the actual physical values for current and voltage as well as pulse on- and off-time of each discharge is determined by monitoring the electrical process signals. By tracking these values over time the quality of the whole process is evaluated by determination of the actual discharge frequency, the percentage of misdischarges and the resulting duty cycle. These parameters are then linked to the output variables cutting rate and surface roughness. Using this approach the specific influence of the machined material as well as other special machining conditions on the EDM process can be identified. With this fundamental knowledge the needed test series for future developments can be reduced and the transferability of the resulting technology will be improved significantly.