Electrochemical machining of a rhombus hole with synchronization of pulse current and low-frequency oscillations

Abstract

Abstract Metal gratings with rhombus holes are widely applied in lightweight aircraft components. Electrochemical machining (ECM) is a nontraditional processing technology with no tool loss and no thermal deformation that has unique advantages for the high-quality processing of rhombus holes. However, the flow paths of the electrolyte in the lateral gap are quite different, and stray corrosion easily occurs on the sidewall due to the different diagonal lengths of a rhombus hole. In this paper, a method was proposed to improve the flow field and processing localization by the synchronization of the pulse power supply and low-frequency oscillations. The on and off positions of the pulse power supply are symmetrical with respect to the wave trough of the oscillation waveform. Based on the coupled simulation of the gas-liquid two-phase flow field and electric field, the effects of assisting oscillations and synchronization of the pulses and oscillations on the void fraction, electrical conductivity, current density, dissolution rate and evolution of the anode profile were investigated. Moreover, the effects of assisting oscillations and synchronization of the pulses and oscillations on the lateral gap, sidewall slope, machining fillet and surface quality were experimentally studied. The experimental results of different ECM methods showed that the coupled simulation was effective and feasible. Moreover, the simulation analysis and experimental results both revealed that the processing accuracy and surface quality of a rhombus hole could be improved by using the synchronized ECM method. The lateral gap at the rhombus hole entrance was only 0.13 mm, the sidewall slope was 0.026 and the surface roughness was Ra0.134 μm under the optimized parameters.