EXPERIMENTAL INVESTIGATIONS ON MRR AND SURFACE ROUGHNESS OF EN 19 & SS 420 STEELS IN WIRE- EDM USING TAGUCHI METHOD C. BHASKAR REDDY * V. DIWAKAR REDDY C. ESWARA REDDY Ph.D. Scholar Associate Professor Professor Department of Mechanical Engineering, Sri Venkateswara University TIRUPATI – 517 502, INDIA. e-mail : cbhaskarreddy321@gmail.com ABSTRACT Quality and sophistication of the parts / products are the main requirements of the customer in the present global market. Therefore, the manufacturing / Production industries are searching for un-conventional machining processes to achieve production requirements. One among such production processes is the Wire- EDM. As such, a solemn attempt is made in this paper to investigate the response parameters, viz., Material Removal Rate (MRR) and Surface Roughness (Ra) a by experimentation on EN 19 & AISI 420 (SS420) Steels in Wire-EDM process. The Design of experiments is carried-out considering Taguchi Technique with four input parameters, namely, pulse-on, pulse-off, Bed speed and Current. The experiments are conducted considering the above two materials for L 16 and then the impact of each parameter is estimated by ANOAVA. Then the regression analysis is carried-out to find the trend of the response of each material. A comparison made between the two materials indicates that the EN 19 Material is more suitable for better MRR and AISI 420 for better Surface finish. Key Words: Wire-EDM, Taguchi Technique, MRR, Ra, EN19, SS420, Experimental Parametric Values, Regression Analysis. 1. INTRODUCTION Wire-EDM is one of the most popular techniques of the Unconventional Production / Manufacturing processes in the present global manufacturing scenario. The Wire-EDM utilises the wire which acts as a tool upon passing the current so as to erode the work material by the generation of spark(s) between the work and tool. The work and the tool are immersed in a die-electric fluid and then allowed to pass through to remove the material by erosion and such machining helps to produce parts with good surface quality and dimensional accuracy. The experimental investigation on P20 Die - Tool Steel reveals that the current applied and pulse-on and pulse-off duration influence the out-put of MRR and Surface Quality, [Bhaskar Reddy et al. (2102)]. The other important capabilities of wire-EDM in production of parts are: (i) micro-level accuracy [Ravindra et al. (2008)], (ii) improved productivity, [Nixon and Ravindra (2011)] and in the reduction of cutting speeds in machining AlSI7 Mg / Al 2 O 3 Steels. Thus, in the present paper, the experiments are conducted on two different AISI steels materials to estimate the MRR and quality surface. Effect of two machining methods and dry and wet EDM and surface integrity and the effect of pulse current and gap voltage on surface roughness during wet and dry wire EDM of stainless steel are investigated, [Abdul Kareem, et al. (2011)]. As such, the Wire-EDM is gaining importance in the present modern manufacturing industry to meet the not only the customer demand but also at the Global level. Therefore, the present work is taken-up to conduct experiments on two different materials. 2. LITERARTURE REVIEW AND OBJECTIVE Research on Wire-EDM is an unending process and many researchers are doing the experimental works and modelings to establish the response parameters depending on the necessity. In the research, it is common to bring-out the review on the relevant research from time-to-time and to note worthy are (i) State of the Art in Wire-EDM, [ Ho (2004)] and (ii) Growth of EDM and its applications, [Bhaskar Reddy, et al. (2012)]. A careful analysis reveals that the response parameters, such as MRR, Surface Roughness, Dimensional Accuracy, oversize, etc., are studied by changing input parameters, namely, Voltage, Current, Pulse-on, Pulse- off, wire speed and so-on either by experimentation and or modeling. In the process, multiple performance characteristics like MRR and Surface finish are investigated on different Die-steels by experimentation on (i) high Chromium and high Carbon Die-tool steel [Puri and Deshpande (2004)], (ii) Press tool steel with coated C. Bhaskar Reddy et al. / International Journal of Engineering Science and Technology (IJEST) ISSN : 0975-5462 Vol. 4 No.11 November 2012 4603