Papers by Author: M. Murali

Abstract: Silicon Nitride-Titanium Nitride ceramic composites are newly advanced material having the properties of high hardness, strength, toughness and low density. These kinds of materials are challenging to machine by conventional machining process because it causes severe tool wear due to its properties. Since the materials can be machined by non-conventional machining process like laser cutting and water jet, but these processes are limited. Electric discharge machining shows higher capability for cutting complex shapes with high accuracy. The present work focuses to optimize the process parameter for maximum material removal rate and minimum electrode wear rate. The experimental studies were conducted under varying pulse on time, pulse off time, dielectric pressure and discharge current. Taguchi L₉ orthogonal array was used to design the experiments. Grey relational analysis and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was used to optimize the process parameter and the results were validated by the confirmation tests. Thus the machining parameter for electric discharge machine was optimized to achieve higher material removal rate and lower rate on electrode. The result shows that the proposed technique is being effective to optimize the machining parameter for electric discharge machining process.

Abstract: Micro electro discharge machining is an important unconventional metal micromachining technology. The performance of micro EDM depends on the combination of the tool and work materials used. In the absence of a comprehensive theoretical model to predict the effect of electrode materials on the performance of EDM, experimental investigations as described in this paper become useful. The work materials studied include ferrous, non-ferrous and exotic material (XW42, Ti6Al4V, WC) and the tool electrode materials include the commonly used EDM tool materials namely tungsten, copper and graphite. It is found that in the microgroove machining by micro EDM using foil electrodes, graphite consistently provides higher material removal rate than tungsten and copper tool electrodes and hence it is useful for the rough machining. On the other hand tungsten tool electrode is preferable for finish machining as it provides the least surface roughness.