634 Vol. 41, No. 4 (2019) 634-647, DOI: 10.24874/ti.2019.41.04.15 Tribology in Industry www.tribology.rs Evaluation of the Surface Roughness of Ti-6Al-4V for Surface Grinding under Different Cooling Methods Using Conventional and Vegetable Oil-based Cutting Fluids K.N. Ronoh a, *, N.W. Karuri a , F.M. Mwema a,b , H.T. Ngetha c , S.A. Akinlabi d , E.T. Akinlabi b a Department of Mechanical Engineering, Dedan Kimathi University of Technology, Nyeri, Kenya, b Department of Mechanical Engineering Science, University of Johannesburg, Johannesburg, South Africa, c Department of Electrical and Electronics Engineering, Dedan Kimathi University of Technology, Nyeri, Kenya, d Department of Mechanical and Industrial Engineering Technology, University of Johannesburg, Johannesburg, South Africa. Keywords: Ti-6Al-4V Cutting fluids MQL Taguchi Signal-to-noise ratio ANOVA Surface roughness A B S T R A C T In this research study, the surface roughness of medical grade Ti-6Al-4V alloy was evaluated to understand the effects of cutting fluids, cooling methods, and grinding depths after surface grinding with alumina wheel. Three cutting fluid types namely sunflower oil, sunflower oil-based cutting fluid, and conventional cutting oil were applied to the grinding zone using two cooling methods: minimum quantity lubrication and wet cooling methods. The grinding was undertaken at grinding depths of 0.005, 0.010, and 0.015 mm. The surface roughness of the ground surfaces was determined using a surface profiler. An analysis of variance demonstrated that the individual contributions of cutting fluid types, cooling methods and grinding depths to surface roughness were 42.7 %, 8.46 % and 40.61 % respectively. The design of the experiment was done using Taguchi L9 orthogonal array to determine the collective contributions of the grinding parameters. The analysis of the signal-to-noise ratio shows that the optimal surface roughness of Ti-6Al-4V was obtained with sunflower oil-based cutting fluid, a minimum quantity lubrication of 0.67L/h and a grinding depth of 0.005 mm. This study provides novel evidence of how grinding parameters can be used collectively to optimize Ti-6Al-4V machining. © 2016 Published by Faculty of Engineering * Corresponding author: Kipkurui Nickson Ronoh E-mail: kipkurui.ronoh@dkut.ac.ke Received: 7 June 2019 Revised: 28 July 2019 Accepted: 18 September 2019 1. INTRODUCTION Biomaterials have received much support and have been used in the manufacture of the biomedical devices [1,2]. Modern metallic biomaterials used for making orthopaedic medical implants include titanium-based alloys [1,3]. Ti-6Al-4V is a titanium alloy applied widely in medical industries due to its superior biocompatibility [4], high resistance to corrosion RESEARCH