Two phase flow analysis in electrochemical machining for L-shaped Tool: A CFD approach

Abstract

Electrochemical machining (ECM) is a non-conventional machining process based on the principle of reverse electroplating. Some genuine characteristics like negligible tool wear, high precision machining in difficult to cut materials, lower thermal and mechanical stress on work piece etc. makes ECM advantageous over other non-conventional machining processes. Still there are some challenges in ECM like generation of hydrogen bubbles and its effect on Material Removal Rate (MRR), complexity of tool geometry and its effect on various process parameters, prediction of electrolyte flow pattern and its impact etc. In the present study, three dimensional two phase flow pattern of ECM process has been simulated using Computational Fluid Dynamics (CFD) in three different L-shaped tool models. The software used for the analysis was ANSYS 13.0 CFX. Various process parameters like volume fraction profile, velocity profile, and turbulent pattern of electrolyte flow in the Inter Electrode Gap (IEG) etc. have been evaluated from the simulated environment in all the three models. The results indicated generation of hydrogen bubbles in all three cases which in turn reduced the volume fraction of brine at varied rate depending upon the tool geometry. Reduced brine volume fraction led to reduction in MRR. It was also inferred that the same would affect the surface finish as well. As a result of hydrogen bubble formation, temperature towards the boundaries were increased rapidly as gaseous hydrogen bubbles possess sufficiently lower convective heat transfer coefficient as compared to liquid brine. Similarly, the results of static pressure and velocity profiles across tool work piece interface provided a varying pattern depending upon the tool geometry. For validating the simulation results, a set of experiments have been carried out on ECM by fabricating the three tool geometries. The experimental results were analyzed by using MINITAB 16 software.