Selection and Optimization of Electrolyte for Micro Electrochemical Machining on Stainless Steel 304

During the process of micro electrochemical machining (Micro ECM) of metallic alloys, insoluble electrolytic products restrict the depth of micro holes with high aspect ratio. The selection and optimization of composite electrolyte are researched to dissolve and remove electrolytic products smoothly. Composite electrolyte containing neutral salt and complexing agents is adopted, in which the ligands are utilized to generate soluble products with metal ions. To optimize the electrolyte constituent, products deposition on electrode surface, inlet diameter, material removal rate (MRR) and ratio of removal rate to current (MRC) are taken as evaluation criterions. Micro ECM experiments on stainless steel 304 (SS304) are carried out. The electrolyte which contains 1.0 mol/L NaNO3 and 0.01 mol/L sodium citrate is selected as optimal constituent. Micro holes with diameter of 160∼190 μm are achieved on SS304 with 0.5 mm thickness. Experimental results show that the MRR of micro holes with above electrolyte is increased by 35%. Meanwhile, the composite electrolyte maintains its good machining localization and being eco-friendly. No electrolytic products are deposited on the surface of the tool electrode or workpiece. As a result, both machining efficiency and stability are improved by using the composite electrolyte.