Improvement of surface quality of inconel-625 using utility method in edm machining by varying current densities

Abstract

Electro discharge machining (EDM) process is an advanced machining process because of burrs free, less metallurgical damage, stress free and very precise machining. It produces mould cavity, deep holes, complex shapes and sizes by spark erosion process in all types of electroconductive materials. This process is used to make dies of different shapes and sizes and also used in various industries like automobiles, aerospace, nuclear reactor and surgical instruments. The operating temperature of the super alloys varies from 1200F to 1300F. Nickel based super alloys widely used for aerospace engine components, power-generation turbines, rocket engines, chemical processing plants, petrochemical, food processing, nuclear reactor, pollution control equipment and other tough environments applications. INCONEL 625 used in this process due to their high hardness and high wear resistant properties. In the present study, INCONEL 625 workpiece material is machined by EDM using two different diameters of copper tool such as 10mm and 15mm. The experiment are carried out economically by varying the input current, pulse on time, pulse off time and flushing pressure according to Taguchi’s orthogonal array. Four output parameters such as: surface roughness, crackwidth, surface crack density and hardness are optimized simultaneously using the Utility optimization method to obtain the best level of input parameters. When the diameter are varied, a better result is found out based on the value of signal to noise ratio. Then ANOVA method is used to find out the most effective input parameter. Finally, a confirmation test is carried out to obtain the best diameter of copper tool. This technique can also be extended for other process optimization and helpful for industry personnel to select appropriate process parameters for making a die of long life.