Improvement of Surface Quality of Electrochemical Machining Using Porous Electrode by Mixing Bubbles into Electrolyte

Abstract

In electrochemical machining using a porous electrode, the electrolyte flows through small pores. However, irregularities perpendicular to the direction of the electrolyte flow sometimes occur on the machined surface, resulting in high surface roughness. This is thought to be due to the nonuniformity of the size and density of the pores, which causes a difference in the electrolyte flow velocity, thus resulting in a large difference in the concentration of the electrochemical products and the temperature of the electrolyte. To improve the surface quality, bubbles were mixed into the electrolyte to reduce the influence of the differences in the flow velocity. The observation results of the inter-electrode gap with the bubble-mixed electrolyte show that bubbles move in a short time and the distribution of bubbles on the electrode surface changes at several milliseconds. The machining results show that the surface roughness is significantly reduced by mixing air bubbles. This is because the current density distribution changes for each applied pulse due to the randomly distributed bubbles, and the irregularity of the machined surface owing to the discontinuous flow speed of the electrolyte decreases.