International Review of Mechanical Engineering (I.RE.M.E.), Vol. 6, N. 7 ISSN 1970 - 8734 November 2012 Manuscript received and revised October 2012, accepted November 2012 Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved 1418 Experimentation and Prediction of Surface Roughness of the Machining Parameter with Reference to the Rake Angle in End Mill G. Mahesh 1 , S. Muthu 2 , S. R. Devadasan 3 Abstract – This paper presents the effect of process parameter in end milling operation to predict surface roughness. An experiment has been conducted to observe the significance of process parameters and influence of the radial rake angle of the tool in end mill cutter. Mathematical model has been developed to predict surface roughness in terms of machining parameters such as spindle speed, feed rate, radial, axial depth of cut, and rake angle of cutting tool. The second-order mathematical models, in terms of the machining parameters, have been developed using Response surface methodology (RSM)by designing five factors, five level central composite rotatable design matrixes with full replication. The experiment is conducted on aluminum Al 6063 by HSS end mill cutter, the surface roughness is measured by using Surftest SJ- 201.The direct and interaction effects of the machining parameter with surface roughness are analyzed using design expert software. It is found that spindle speed and radial rake angle are major factors influencing the surface roughness followed by radial depth of cut, feed rate and axial depth of cut. The developed mathematical model is verified by confirmatory test and found to be acceptable for the prediction of surface roughness. Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved. Keywords: Radial Rake Angle, Surface Roughness, RSM, DoE, Vertical Milling Machine Nomenclature N Spindle speed in m/min Z Feed rate per tooth in mm/rev X Axial depth of cut in mm Y Radial depth of cut in mm γ Radial Rake angle in degree RSM Response Surface Methodology Al-SiC Aluminum silicon carbide particulate composite MMX Metal matrix DOE Design of Experiments Ra Surface roughness I. Introduction In machining operations surface quality is one of the most pertinent aspects as it is employed as the final stage in the production cycle for improving the surface finish, dimensional and geometrical properties of the product [1]-[36]. Surface roughness is the most important parameter which determines the quality of the product. The surface quality of the orthopedic prostheses is a parameter influencing in their life time [10]. Surface roughness is primarily dependent on production process [30]. Surface roughness is expressed as the irregularities of material resulted from various machining operations. Average surface roughness (Ra) is the arithmetic average value of departure of the profile from the mean line throughout the sampling length. Ra is also an important factor in controlling machining performance. Surface roughness is influenced by many factors such as spindle speed, feed rate, radial and axial depth of cut, radial rake angle, helix angle etc. The experiments were designed taking into an account, that the majority of parameters will affect the surface roughness [5]. In manufacturing industry, end milling is one of the most widely used metal removal process. The quality of surface is important as it plays a key role for the improvement of corrosion resistance, fatigue strength and creep life to name a few. The study on the effect of process parameters on surface roughness is essential in order to set the required process parameter on the machine. Recent investigation has revealed that when cutting speed is increased, productivity can be maximized and surface quality can be improved [1]. The authors [2] stated that the surface roughness increased with increase in the feed or axial depth of cut, whilst decreased surface roughness arrived at increase in cutting speed. Among the various machining parameters, most literature sources revealed that feed rate has the greatest influence on the surface roughness [7]; [8]; [27]; [15]. However, the study by [11] proved that that the combined variation of both feed rate and cutting speed are able to increase the surface finish.