Capabilities of electrochemical dimensional machining of thin-walled oversized aircraft details using rotating cathode-instrument

This article presents the results of experimental studies of electrochemical dimensional machining model sample in the form of thin-walled hemispherical shell. The studies were carried out using a specially designed and manufactured laboratory installation for local electrochemical machining of details using rotating electrode-instrument. The article presents the main units of used installation for research and the methods of used experiments are decrypted. In this case varying factors during carrying out a series of experiments were composition of electrolyte, electrolyte temperature and also current density. The studies were conducted using as electrolyte an aqueous solution of sodium hydroxide, and also an aqueous solution of ammonium nitrate. When used as an electrolyte 15 % water solution of sodium hydroxide at a rotation speed of the electrode-instrument 20 rpm, at a current density 2-5 A/cm2, temperature of electrolyte 30-40 °С it has been found alignment of the sample surface through the thickness in the radial axes, moreover, the thickness extreme deviations are negligible. Using 15 % of aqueous solution of ammonium nitrate as a main component and 2.5 % of ammonium citrate as a complexing agent does not allow to achieve the desired results. During the analysis of the results extreme deviations in thickness in the radial direction amounted from ±0.05 to ±0.09 mm when removing 0.1 mm of metal. Non-uniformity of metal removal was detected in the axial direction. Thus, it is established, that for carrying out electrochemical machining process of thin-walled oversized details of responsible appointment, which are applied in the aerospace industry, an aqueous solution of sodium hydroxide is most expedient to use as an electrolyte. The main feature of the proposed process is its controllability, efficiency and reducing the environmental impact on the ecological conditions due to lower temperature of used electrolyte and lower concentration of electrolyte.