DOI 10.1515/jmsp-2013-0019 J. Manuf. Sci. Prod. 2014; 14(1): 23 – 30 Suha K. Shihab*, Zahid A. Khan, Aas Mohammad and Arshad Noor Siddiquee Investigations on the Effect of CNC Dry Hard Turning Process Parameters on Surface Integrity: A Multi-performance Characteristics Optimization Abstract: The cutting parameters such as the cutting speed, the feed rate, the depth of cut, etc. are expected to affect the two constituents of surface integrity (SI ), i.e., surface roughness and micro-hardness. An attempt has been made in this paper to investigate the effect of the CNC hard turning parameters on the surface roughness average (R a ) and the micro-hardness ( μh) of AISI 52100 hard steel under dry cutting conditions. Nine experi- mental runs based on an orthogonal array of the Taguchi method were performed and grey relational analysis method was subsequently applied to determine an opti- mal cutting parameter setting. The feed rate was found to be the most influential factor for both the R a and the μh. Further, the results of the analysis of variance (ANOVA) revealed that the cutting speed is the most significant con- trolled factor for affecting the SI in the turning operation according to the weighted sum grade of the surface rough- ness average and micro-hardness. Keywords: CNC dry hard turning, hard steel, grey rela- tional analysis, optimization PACS ® (2010). 81.20.Wk *Corresponding author: Suha K. Shihab: Department of Mechanical Engineering, Jamia Millia Islamia (A Central University), New Delhi, India. E-mail: suhakarim_10@yahoo.com Zahid A. Khan, Aas Mohammad, Arshad Noor Siddiquee: Department of Mechanical Engineering, Jamia Millia Islamia (A Central University), New Delhi, India 1 Introduction AISI 52100 hardened steel finds its application in the manufacturing of automotive components, gear, bearing, tool and die etc. Manufacturing industries use automated and flexible manufacturing systems, including CNC ma- chines to manufacture high quality products with low cost and reduced time. In recent times, researchers have shown immense interest in hard turning of steel to be used for industrial production of several components, since it offers a number of potential advantages such as lower equipment costs, shorter setup time, high accuracy, fewer process steps, greater part geometry flexibility, and no use of cutting fluid during turning. It is reported that if hard turning is used to fabricate complex parts, manufacturing costs could be reduced by up to 30 times [1, 2]. Hard turning avoids the use of subsequent finish- ing processes as this process is characterized by a high level of accuracy in terms of the form and size, high quality of surface finish and surface integrity (SI ) in workpieces [3–5]. The establishment of adequate machining guide- lines requires the study of several factors (roughness, hardness, residual stresses, micro-structural changes, etc.) that define the surface integrity generated in the part by a machining operation. SI generated after machining is important, as it determines the functional behaviour and reliability of the components such as fatigue life and wear resistance when they are put to use. Maintaining surface integrity is one of the most critical requirements [6–8]. In order to maintain a high production rate with an accept- able quality level and SI of the machined parts, it is im- portant to select the optimum combination of cutting pa- rameters such as cutting speed, feed rate, depth of cut and cutting fluid as these parameters have impact on multi performance characteristics like surface roughness, strain hardening, micro-hardness and microstructure which are indeed constituents of SI [9]. Among the several SI param- eters, R a and the μh are very important as they correlate with the surface profiles in order to better characterize the different machining processes. R a plays an important role in many areas and is a factor of great importance in the evaluation of machining accuracy. Many researchers have reported the effect of several hard turning parameters on R a . Derakhshan and Akbari [10] explored the effects of independent parameters such as hardness of parts and cutting speeds on the surface quality during CNC turning of AISI 4140 alloy steel with CBN tool. Fnides et al. [11] in- vestigated the effect of cutting parameters (cutting speed, feed rate and depth of cut) on surface roughness during hard turning of X38CrMoV5-1 hot work tool steel using a whisker ceramic tool under dry condition and found that the feed rate is the dominant factor for affecting surface Brought to you by | Stockholms Universitet Authenticated Download Date | 7/12/15 11:10 PM