Optimization of the operating parameters in a novel electrochemical machining device for titanium alloys

Titanium and its alloys are used in the fields of petroleum refinery, chemical process industry, jewelery, surgical implants, dental implants, food industry, and also widely used in other different sectors because of its properties such as high specific resistance at high temperatures (ratio of strength to weight), high corrosion resistance and low density. Electrochemical machining (ECM) is an unusual machining method that is especially used for difficult-to-machine, rigid, complex shaped and thin materials. It is more advantageous than other conventional and new methods since no mechanical or thermal stress is not applied on the surface, it is cost-effective and ensures high surface quality. In the study, appropriate electrolyte content and concentration were determined by using constant operating parameters in order to machine the Ti6Al4V alloy which is the most commonly produced alloy among the titanium alloys and which is commercially named as Ti5, on a domestic electrochemical machining bench developed in our laboratory. NaCl-NaF was selected as the electrolyte mixture that is required to optimize the developed system which was used to electrochemically machine the Ti5 alloy among the different concentrated solutions of NaCl, NaBr, NaNO3, NaHCO3 and NaF. Response surface methodology and the Design Expert version 11 software was used to determine the content ratios. The concentrations making the material removal rate maximum and the surface roughness minimum were determined as 0.48 M for NaCl and 0.34 M for NaF. The effect of these parameters on the material removal rate and surface quality was investigated by changing the machining gap between the workpiece and the tool end, electrolyte temperature, pH values and pulse frequency while keeping the concentrations constant. Key words: Titanium alloys, Ti6Al4V, Electrochemical machining, Electrolyte, Response Surface Method