GEOMETRICAL ANALYSIS OF CENTRIFUGAL FORCE GENERATING ELECTRODE FOR THERMAL ADDITIVE CENTRIFUGAL ABRASIVE FLOW MACHINING PROCESS

Abstract

Abrasive flow machining (AFM) is one of the prominent method to finish the hollow intrinsic surface which are hard to reach by the conventional tools. The process has significant applications but low machining time is the major limitation of the process. To limit this various hybrid have developed and Thermal additive centrifugal abrasive flow machining (TACAFM) is the new name in the list. The TACAFM process uses the advantage of heat energy produced by the spark and the centrifugal force assisted abrasive flow machining process for enhancing the material removal through melting and erosion process. The spark is generated due to the EDM effect produced by supplying pulse DC supply between the workpiece and centrifugal force generating (CFG) electrode placed coaxially between the hollow workpiece whose internal surface is to be machined. This CFG electrode plays vital role in the efficient working of TACAFM process. The media containing the abrasive acts as a dielectric and supports the spark formation. The present investigation deals with the improvement of TACAFM process by improving CFG electrode, fixture design, media and by analyzing computational model of TACAFM process. The initial CFG electrode used in the process is spline shape electrode with straight blade. To improve the working efficiency of the process different geometrical shape of CFG electrode (rectangular, triangular, spline shape with straight blade, spline shape with curve blade) is proposed in this investigation. The experiments were performed on brass workpiece and the media with desirable property is prepared. Different base oil including (transformer oil, engine oil and Hydrocarbon oil) were studied using rheometer and hydrocarbon oil was chosen for media preparation on the basis of viscosity analysis. ANSYS Fluent is used to analyze the spark generation and study the flow parameters. The experimental results were analyzed using central composite design based on response surface methodology. The electrode type, supply current, duty cycle and the rotational speed of electrode is taken as the process parameter and their effect of material removal and percentage improvement in surface finish is analyzed. The simulation results were in agreement with the experimental results. The investigation showed that the spline shape electrode with curved blade showed maximum MR with significant improvement in percentage improvement in surface finish. The morphological study of brass showed the machining marks and spark proof. The different XRD pattern and EDAX also highlights the spark generation process.