One of the non-traditional machining processes which has gained momentum for its practical applicability in the current manufacturing scenario is the Electrochemical Machining (ECM) process. ECM has tremendous potential on account of the versatility of its applications, and it is expected that it will be successfully and commercially utilized in modern industries. ECM is based on a controlled anodic electrochemical dissolution process of the work piece (anode) with the tool (cathode) in an electrolytic cell. Based on the past research (Thorpe, 1969), it is understood that during the course of machining, the machining rate at any instant depends not only on the end gap, but also on other process parameters. Also, several works were carried out by various researchers such as Kozak (1971), Kozak and Lubkowski (1972), and Kozak and Lubkowski (1976) to develop models of characteristic for pulse ECM. The aspect of surface formation with electrolyte flow velocity was investigated for good surface formation by Chetty et al. (1979). Sorkhel and Bhattacharya (1981) worked on ECM for accurate job machining and concluded that the increment in gap resistance is due to various causes such as electrolyte heating, gas bubble generation, and sludge formation with respect to an uneven current flow causing poor dimensional control of workpiece due to overcut. Bhattacharya (1983) studied ECM by supplying constant current via an auto tool feed drive control system to improve the production rate. Sorkhel and Bhattacharya (1986) studied ECM parametric control for optimal quality of the workpiece and concluded that better quality of the product can be produced by ECM through combinational control of various process parameters. Various mathematical models for precision process modeling of ECM and computer simulation were attempted by different researchers (Kozak, 1989; and De Silva and Atlena,1991). De Barr and Oliver (1975) stated that the surfaces produced by ECM generally have better fatigue, wear, friction and corrosion resistance properties than those produced by mechanical means. Recent work (Bhattacharya and Sorkhel, 1999) was carried out on ECM for controlling the machining parameters using NaCl solution of varying concentration as electrolyte, because of its high conductivity and non-passive characteristics. A number of research investigations have been carried out on optimization of ECM parameters, but still applied research on parametric optimization of ECM is an ardent requirement to the modern manufacturing engineers.
The main objective of the paper is to develop comprehensive mathematical models for correlating the interactive and higher order influences of the various machining parameters, such as the electrolyte flow rate and concentration, inter electrode gap thickness and the applied voltage on the most dominant machining criteria—MRR and overcut phenomena—for effective machining of E0300 alloy steel by ECM process. Utilizing the experimentally obtained results, the interactive and higher order influences of the various machining parameters are investigated through Response Surface Methodology (RSM). The ECM parameters are optimized for achieving an enhanced production rate with improved profile accuracy. |
