Effect of grain size on ECM performance

The conditions at the gap in Electrochemical machining (ECM) process are complex and random in nature due to the transient effects of a large number of parameters and their interactions. Therefore, the problems related to work and tool shape prediction and the characterization of surfaces generated by ECM are not completely resolved. This paper examines two aspects of ECM performance. The reduction in the experimentally measured values of the final gap with the increase in work specimen grain size is used to develop a correction factor. The prediction of the anode profile based on the correction factor and the improved cosθ method compares well with the anode cavity profile measured with a specially designed and built instrument. The characterization of the ECM generated surface profiles by Data Dependent Systems (DDS) has led to the characteristic shape or Green's function and a component by component wavelength decomposition. The characteristic shape is correlated with the distribution of potential gradient or current in the gap. The percent contribution by the shorter wavelength to the total power or variance has been found to decrease with the increase in feed rate as well as in grain size.