Fabrication of micro-rods with electrostatic induction feeding ECM

• The machinable length limitation peaks at an optimum feed speed.
• The optimum feed speed results good machining accuracy.
• The influences of thickness of the tool electrode on machining accuracy are investigated.
• The influences of top surface area of the tool electrode on machining accuracy are investigated.
• The influences of the current density distribution are calculated.

Micro-rods were machined by electrochemical machining using the electrostatic induction feeding method, with which ultra-short current pulse duration of several tens of ns was obtained. A tungsten plate and stainless steel (SUS304) rod were used as the tool electrode and workpiece, respectively. The rotating workpiece rod was fed axially in the direction normal to the top surface of the tool electrode, thereby the diameter of micro-rod was determined by the depth of cut in the radial direction. The influences of voltage amplitude and the thickness and surface area of the tool electrode on machining characteristics were investigated from the aspects of machinable length limitation, straightness of the micro-rod, pitting corrosion, and surface finish to determine the optimum machining conditions. The results of machining experiments and current density simulation showed that the influence of stray current on machining accuracy markedly decreased with decreasing tool electrode thickness, allowing micro-rods with higher aspect ratio and better surface finish to be fabricated. On the other hand, the influence of the top surface area of the tool electrode on machining accuracy was small due to small changes in the current density on the frontal surface of workpiece, resulting in small changes in the material removal rate (MRR).