Electrochemical Discharge Machining Lab Report

Abstract- Electrochemical Discharge machining is an innovative spark based non-conventional machining method. It uses Electrochemical Discharge phenomenon to generate a stable spark at threshold voltage which has sufficient thermal energy to melt and vapourise the workpiece. Along with it, chemical erosion of the workpiece also plays a role in machining. In the present work, an attempt is made to understand the contribution of various parameters for slotting operation. Experiments are carried according to Taguchi design of experiment. L9 orthogonal array is used to represent the experiments for three different levels of three different parameters. Contribution of each parameter towards MRR is calculated using ANOVA. The confirmation test run

EXPERIMENTAL SETUP

Experimental setup consists of stainless structure with motors to actuate the tool in lateral direction. The tool can be moved in x and y directions. The work piece having dimensions 40x10x1.5 mm is of soda lime glass. NaOH is used as electrolyte for the experimentation. Stirrer is used for the circulation of the electrolyte. Gearboxes of gear ratio 1500:1is used to reduce the speed of the motor and it actuates the rack and pinion. Variac is used to provide AC power which is converted to DC by a rectifier. Digital ammeter and voltmeter is added in series and parallel respectively to find out the current and voltage readings. The spark is initiated at threshold voltage of about 27V. The tool is dipped to 1-2 mm from level of electrolyte and the gap between the electrode tool and workpiece is about a few micrometers. The electrolyte used was NaOH at room temperature. Prior to each experimentation tool was ground to ensure that tool tip is very small. The tool is made up of tungsten and anode is that of graphite. The graphite electrode is such that its surface area is about hundred times greater than the surface area of tool electrode. Tungsten tool is used because of its low wear

CONCLUSION

Widespread use of non conducting materials like ceramic, glass etc. led to the development of one of the important micro machining technique called Electro Chemical Discharge Machining which has features of both Electro Chemical Machining (ECM) and Electric Discharge Machining (EDM) . For optimization of various machining parameters like inter-electrode gap, voltage and concentration of electrolyte Taguchi method of Parametric Optimization is used. From the experimental analysis and study using MINITAB 17 software following conclusions are drawn-

1. Among three important parameter concentration of electrolyte has largest contribution on MRR which is 37.8268%. after that voltage plays vital role on slotting operation.

2. Optimum values for maximum MRR are observed at 60V applied voltage, 50% electrolytic concentration and 25mm inter-electrode gap.

3. From the confirmation test we observed that MRR at optimum parametric condition is 2.489 times than that of initial parametric condition which is at 50V applied voltage, 40% electrolytic concentration and 30mm inter electrode