Computation and verification of workpiece shape in electrochemical machining
This investigation was motivated by the need for accurate prediction of electrochemical machined surfaces relative to corresponding tool geometries for given sets of machining parameters. A mathematical model was formulated which simulates the electrochemical erosion achieved by primary current distribution under steady tool feed rate, but with correction for variable efficiency. The equations comprising the mathematical model were programmed for solution by a digital computer, using discrete steps and a quasi-steady approach. The model was not completely analytical; it utilised an empirical values for specific metal removal rates. The efficiency of machining with NaNO₃ electrolyte was estimated from experimental results of other investigators. To assess the validity of the model, drilling test runs were performed with tubular electrodes having two geometries at the leading edge of the tool. Work specimens were made out of EN58J stainless steel, both NaC1 and NaNO₃ electrolytes were used. The correlation between experimentally obtained drilled surfaces and the computer predicted surfaces were satisfactory, justifying the assumptions made during the development of the model and the numerical methods of the solution used. This investigation has provided a method which could be successfully employed to predict the electrochemically machined profiles relative to tool geometries. This undoubtedly helps the production engineer in achieving the desired tolerances of the finished component eliminating the high cost of trial and error techniques.