Effect of Electrolytes on Surface Integrity in Electrochemical Honing Process

Electrochemical Honing (ECH) is a process of precision finishing of functional surfaces with the use of the electrical and mechanical energy. It is reported that the 90 percent of the material is removed by electrochemical machining (ECM) process and remaining 10 percent by mechanical scrubbing, which shows the electrical energy is the main constituent in the ECH process. Basically, electrical energy is combined with chemical to form an etching reaction to remove material from the workpiece surface. The electrolyte is pumped through the gap between the tool (cathode) and the workpiece (anode) while a continuous DC current is passed through the cell at a low voltage, so as to dissolve metal from the workpiece. Electrolytes are substances that become ions in solution and acquire the capacity to conduct electricity. The electrolyte has three main functions in the electrochemical machining (ECM) zone. It carries the current between the tool and the work piece, it removes the product of the reaction from the cutting region, and it removes the heat produced by the current flow in the operation. Electrolytes must have high conductivity, low toxicity and corrosivity, and chemical and electrochemical stability. The rate of material removal in ECM is governed by Faraday's laws and is function of current density. Primary variables that affect the current density and MRR are voltage, feed rate, electrolyte conductivity, electrolyte concentration/composition, electrolyte flow rate and material of the work piece. Therefore, electrolyte must be selected carefully for better outcomes.