ANALYSIS OF EDM PARAMETERS WITH TOOL ROTATION

Abstract

In advanced manufacturing process, the Electric Discharge Machining (EDM) plays a vital role in precision tool room of manufacturing industries such as automobile, aerospace and defence. The manufacturing industries require unique and exact methodology for EDM machining with maximum machining rate, low tool wear rate and high surface finish. EDM with tool rotation facilitates to get maximum material removal rate (MRR), low tool wear rate (TWR) and low surface roughness (Ra) for AISI D3 and EN-31 Steel.

Researchers have tried to investigate and improve the responses i.e. MRR, TWR and Ra of different materials by different EDM processes. The literature reveals that less research has been conducted to maximize MRR and minimize Ra. It is noted that the MRR is very low for significant surface characteristics of the material. It is a well-known fact that good surface quality and high MRR may not be achieved simultaneously.

The present research work involves experimental investigation of the MRR, TWR and Ra for AISI D3 and EN-31 steel with copper tool and input parameters viz. peak current, pulse-on-time and tool rotation. The Central Composite Design (CCD) method of Response Surface Methodology (RSM) was effectively used to develop and analyze the parameters of the model. It is used to reduce the number of experiments. The second-order mathematical model is developed through the regression analysis to predict better performance characteristics.

Sample output to test PDF Combine only ix

The ANOVA predicts Ip is competent variable for MRR having participation of 56.024%, Ton for TWR having participation of 44.95%, TR for Ra having participation of 43.43% for AISI D3 steel. The TR is competent variable for MRR having participation of 44.32%, Ton for TWR having participation of 31.68%, Ip for Ra having participation of 49.72% for EN-31 steel.

The Characterization of the surface is done by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and its spectra mapping. The morphology shows the presence of tungsten carbide and iron carbide on the machined surface, which is responsible for high hardness and providing resistance against hot corrosion and high temperature. Residual stresses are present in tensile (25 MPa to 257 MPa) and compressive (11826 MPa) for AISI D3 steel and tensile (207 MPa to 380 MPa) and compressive (2008 MPa) for EN-31 steel. The discharge pulse formation verified with a Digital Storage Oscilloscope (DSO) and found that current and voltage have fluctuation/disturbance due to the high frequency of charging and discharging. The model adequacy is established by the correlation of predicted and actual values of the MRR, TWR and Ra.