Video based Process Observations of the Pulse Electrochemical Machining Process at High Current Densities and Small Gaps

Pulse Electrochemical Machining (PECM), a nontraditional process, using pulse-lengths in the low millisecond range as well as feed overlaid mechanical vibration, allows more precise tolerances and geometric precision through narrowing the working gap compared to conventional sinking ECM. With small working gaps in ranges down to 10 μm, the anodic shape evolution during machining is getting difficult to monitor. Therefore understanding the shaping phenomena during the PECM process is key factor in achieving precision during the manufacturing of dies and molds, as well as precision parts in e.g. automotive or aircraft industry. In this contribution an experimental approach towards visual in-process observations of the PECM shaping process during the use of mechanical vibrations up to 50 Hz and high pulsed current densities will be presented. Recording the process with a precisely clocked high speed camera system allowing precise μs shutter times, visual observations are conducted and being used as input for detailed downstream data analysis. The experimental study incorporates one of the most widely used flushing conditions in PECM as well as an outlook into the comparison between recorded in-process data and a static FEM simulation based on the monitored shape are given. In all experiments stainless steel of type AISI 304 (X5CrNi18-10) is used as anode and cathode material and for all PECM experiments a commercially available PEMCenter8000 with sodium nitrate as electrolyte was used. The concept presented will help to better link experiment and modelling of the PECM process, by simultaneously providing process relevant electrochemical data as well as the directly corresponding geometric shaping information during experiments.