OCTOBER 19-20, 2012 - YMCA University of Science & Technology

Proceedings of the National Conference on
Trends and Advances in Mechanical Engineering,
YMCA University of Science & Technology, Faridabad, Haryana, Oct 19-20, 2012
EFFECT OF WEDM PARAMETERS ON MACHINABILITY OF
NIMONIC-90
Vinod Kumar 1 , Kamal Jangra 2 , Vikas Kumar 3
1 Research Scholar, Deptt. of Mechanical Engg., YMCA University of Science and Technology, Faridabad
2 Assistant Professor, Deptt. of Mechanical Engg., YMCA University of Science and Technology, Faridabad
3 Associate Professor, Deptt. of Mechanical Engg., YMCA University of Science and Technology, Faridabad
1* E-mail: Vinod_kumar9400@yahoo.com
Abstract
Nimonic-90 is a nickel based super alloy which is specifically used in aerospace industry for jet engines, valves,
blades etc owing to its high strength at high temperature, fatigue and corrosion resistance. Present work focuses
on machinability of Nimonic-90 with wire electrical discharge machining (WEDM) process. Cutting speed is
considered as machinability attribute in present work. Influence of WEDM parameters namely discharge current
(Ip), pulse on time (Ton), pulse off time (Toff), servo voltage (SV) and wire feed rate (WF) has been investigated
on cutting speed of Nimonic-90.
Keywords: WEDM, Nimonic-90, Machinability, cutting speed
1. Introduction:
Nickel based super alloy are widely used in high temperature and high corrosion environment application such as
aerospace industry, various thermal processing, marine engineering, crude petroleum stills and chlorinated
solvent. In last few years different grades of nickel super alloy have been developed such as Inconel 601, Inconel
718, Nimonic-80, Nimonic-90, and Monel etc. Machining characteristics of nickel alloys can significantly affect
the working life of its components. Several attempts have been made to evaluate the machining characteristics of
nickel based super alloys with conventional machining methods. Kortabarria et al., (2011) reported on residuals
stress profiles on Inconel 718 developed by dry face turning. Surface integrity condition has been directly
affected by the machine parts fatigue life. Different dry facing turning conditions were used for developing
different residual stress profile. Then they were compared by using X- ray diffraction method, hole drilling
method and Finite element method. Aspinwall et al., (2007) presented the experimental data for Nickel based
super alloy when machining with profiled super abrasive grinding wheels. The tool wear of grinding wheel CBN
is lower as compared to diamond (D46) grinding wheel at the high rotation speed with lower value of surface
roughness. Wei, (2002) has been reported on feasibility of using milling or grinding as alternatives for the
current EDM process to machine shaped hole in Inconel 718 super heat resistant alloy. The result shows that
milling process of Inconel 718 can produce shaped hold with an acceptable surface roughness and geometrically
accuracy efficient after optimizing the cutting condition.
Soo. et al., (2011) evaluated the machinability and surface characteristics of RR1000 Nickel based super alloy in
drilling and milling process. Experimental data for drilling showed that flank wear < 100 μm, when operating at
45 m/min and measured thrust forces were 1600-1800 N. which is generally used the high pressure compressor
and turbine parts. The roughness of end mill specimens achieved up to 0.8 µm when a new tool is to be used.
The significant burr increased micro hardness and white layer formation when we are using worn tools. Kwong
et al., (2009) concluded the influence of major flank wear of drilling tools on the work piece surface integrity and
residual stress distribution for RR1000 a Nickel based super alloy. Hughes et al., (2004) had reported on the
effect of cutting tools and edge geometry on tool life and surface integrity in turning of Nickel based super alloy.
Surface integrity investigation on nickel based super alloy RR1000 have been published by Herbert et al., (2009)
for hole making and also present a comprehensive analysis and discussions of the influence of the drills minor
cutting edge to work piece surface integrity and residual stress distribution for RR1000.Imrarn et al., (2011)
conducted micro drilling in Inconel 718 alloy under wet condition and analysis three different zones namely,
nanostructurered surface layer, a deformed subsurface layer and an unaffected parent metal during micro drilling.
The microstructure crystal misorientation, nanohardness, plastic deformation was to be studied.
Wire electrical discharge machining (WEDM) process is best non-conventional machining process to machine
complex geometries in high strength, high hardness materials with high precision. Several investigations have
also been carried out on EDM and WEDM. Kang et al., (2003) investigated the EDM characteristics of Nickel
based heat resistance alloy Hastelloy–X. Pulse on time was the main factors that affect the surface integrity of
the work material. Rajesha et al., (2010) reported the machining of EDM of Inconel 718 with hollow Tools. The
most influential factor on MRR was discharge current and duty factor. High value of discharge current was
suggested for obtaining high MRR. Krishan, (2004) reported on the performance of two graphite electrode Poco
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