Experimental Characterisation of a High Dynamic Piezo Module for Resource-efficient Electrothermal Precision Ablation

Abstract

In commercial micro electrical discharge machining (micro-EDM) a high process-stability is required, which is mainly determined by the dynamic characteristics of the kinematic system and the process control. To reduce inefficient processing such as open circuits, arcing and short circuiting and thereby increase removal-efficiency, an additional feed-system is required when using industrial EDM machines, since detailed knowledge about the kinematic parameters and the parameters of the electrical control system is limited and usually only comprehensible by analysing voltage and current characteristics.In this study, the dynoMat module as an additional system is presented, which is based on statistical analyses to control the gap between the tool electrode and the work piece by help of a piezo module. A separate monitoring system was realized for process analyses, which is used for fast and direct control of the piezo actuator. The maximal feed of the piezo actuator is less than the minimal step size of the basic feed system, which ensures the applicability in the EDM machine.The fundamental functionality of the dynoMat module is described in this study. Based on an experiment for machining micro-channels, it will be shown that the piezo module ensures a high process-dynamic and thus reduces the number of removal-inefficient pulses, which is verified by analyses of the voltage and current characteristics. From the experimental results it can be determined that the process-efficiency, characterised by the material removal rate and the tool wear rate, as well as the machining precision, characterised by the sparking-gap, are significantly improved.