EXPERIMENTAL STUDIES OF MICROCUTING PROCESS IN ELECTROCHEMICAL GRINDING

The results of experimental studies on the combined process of electrochemical grinding, including anodic dissolution of the material being processed and mechanical cutting processes, are presented. The electrochemical effect on the surface layer of the part has a significant impact on the microcutting conditions and the electrochemical grinding process itself. Samples made of corrosion-resistant and heat-resistant steel and titanium deformable alloy were subjected to experimental studies on the designed and manufactured model of a surface grinding machine. 15% aqueous solutions of sodium chloride (NaCl), sodium nitrate (NaNO3), and sodium sulfate (Na2SO4) were used as working media. The research methodology consisted of measuring the forces arising during micro-cutting a surface drawn mechanically to Ra = 0,16 μm and a surface subjected to anodic etching. The study of the electrochemical component has proven that grain boundaries undergo the most intense anodic dissolution; the dependences of grain boundary depth etching on the electrolyte composition and current density are presented. Studies have shown that in an electrolyte containing NaCl, the process of anodic dissolution of steel occurs without the formation of any oxides on the surface of the samples, and in electrolytes based on NaNO3 and Na2SO4 it is accompanied by the formation of oxide films. When processing the titanium alloy in an electrolyte containing NaCl, the maximum etching depth was 7 μm, and in an electrolyte based on NaNO3 it was only 3.8 μm. An increase in current density to 25-40 A/cm2 when processing steel and to 15-20 A/cm2 when processing titanium alloy is accompanied by an increase in the depth of etching; a further increase in the current density in most cases leads to a decrease in the depth of etching. The influence of electrolyte temperature on the depth of etching along grain boundaries is very significant. It was found that due to anodic dissolution, cutting forces were reduced, which extended the service life of abrasive tools and improved the quality of processing.