Time-Efficient Simulations of Nano-Pulsed Electrochemical Micro- Machining

Abstract

Pulsed electrochemical micromachining (PECMM) is a metal shaping process that exploits the double layer's capacitive effect to confine the machining reaction. By applying nano-second pulses this effect is strongly enhanced and confines the faradaic current to electrode regions where the tool-workpiece gap is the smallest. We offer a solution to calculate the final removal shape and to quantify the confinement with respect to the ideal machining profile. The simulations are conducted on axisymmetric geometries which reflect a real case. We use the potential model with time varying boundary conditions. The double layers are modeled by the capacitor equation in parallel with the Butler-Volmer equation. The temperature in the system is calculated based on the internal energy balance equation, having as natural boundary conditions the heat generated by the electrochemical reactions. The cooling is performed through conduction, having jet specific heat transfer coefficients. For obtaining the mesh deformation according to the electrochemical metal removal, the linear elasticity equations are solved, having the Faraday's law as essential boundary conditions. To handle efficiently the large difference between the time scales of the temperature and mesh deformation on one side and the pulses on the other, we developed an average time stepping algorithm. This enables us to shortcut the full calculation, allowing simulations for longer times, independent of the pulsing time.