Different Influences on the ECF Process

K. Hofmann(a), H. Kück(a)(b) H. Ruoffc, L. Staemmler(b)
a: Institute of Micro- and Precision Engineering (IZFM), University of Stuttgart, 70569 Stuttgart, Germany
b: Hahn-Schickard-Institute for Micro Assembly Technology (HSG-IMAT), 70569 Stuttgart, Germany
c: Institute for Materials Testing, Materials Science and Strength of Materials (IMWF), 70569 Stuttgart, Germany

Abstract

Electrochemical milling with ultra short voltage pulses (ECF) is an innovative technique to machine electrochemically active materials at micrometer feature size, especially very hard materials like steel. The movement of the tool is similar to conventional milling, although it does not rotate. Therefore 3D-forming of the workpiece is possible. The surface of the workpiece is etched by a galvanic current. Due to this neither mechanical forces nor thermal loads are applied to workpiece or tool. The ability to manufacture hard materials like stainless steel at micrometer feature size makes ECF the ideal technique for processing micro moulds. When manufacturing moulds large differences in machining speed and quality of the surface occur. So far possible explanations for this were supposed differences between the machinability of grain boundaries and interior of the grains. But experiments showed no significant influence. Furthermore the dependence of the tool diameter on the working distance was determined. Experiments showed a decreasing working distance with increasing tool diameter. This phenomenon could also be explained theoretically. Finally the influence of the grade of hardness on the ECF process is investigated at the tool steel M 340.