1. Introduction End milling process is one of the common metal cutting operations used for machining parts in manufactur- ing industry. It is usually performed at the final stage in manufacturing a product and surface roughness of the produced job plays an important role. In general, the sur- face roughness affects wear resistance, ductility, tensile, fatigue strength, etc., for machined parts and cannot be neglected in design. 1 In End Milling, the cutter, called end mill, has a diam- eter less than the work piece width. e cutter generally rotates on an axis vertical to the work piece. It can be tilted to machine tapered surfaces. Cutting teeth are located on both the end face of the cutter and the periphery of the cutter body. End mills with flat ends (so called squire- end mills) are used to produce pockets, closed or end key slots, etc. e depth of the feature may be machined in a single pass or may be reached by machining at a smaller axial depth of cut and making multiple passes. End milling is one of the important machining opera- tions, widely used in most of the manufacturing industries due to its capability of producing complex geometric surfaces with reasonable accuracy and surface finish. However, with the invention of CNC milling machine, the flexibility has been adopted along with versatility in end milling process. In order to build up a bridge between quality and productivity and to achieve the same in an economic way, the present study highlights optimization of CNC end milling process parameters to provide good surface finish and high Material Removal Rate (MRR). e surface finish of the machined surface has been identified as quality attribute whereas MRR has been treated as performance index directly related to pro- ductivity. Attempt has been made to optimize quality and productivity in a manner that these multi-criterions Abstract Objectives: The objective of the present work is to assess the effects of machining parameters in milling on surface roughness and metal removal rate of AISI H11 steel. It is used in the manufacturing industries for making die casting moulds, extrusion dies, moulds for glass industry, punches, piercing tools, mandrels etc. Methods/Statistical Analysis: The objective of the study was carried out by machining experiments which were conducted on CNC vertical milling machine whose maximum speed was 6000 RPM. Design of experiments based on Taguchi grey relational analysis with three independent factors (cutting speed, feed rate and depth of cut), three levels L27 orthogonal array has used to develop relationships for predicting surface roughness and metal removal rate. Findings: The surface roughness was measured using surface roughness tester (Mitutoyo surftest-4) and the averages were calculated to obtain the surface roughness of the samples. Metal removal rate was calculated using the formula in terms of width of cut, depth of cut and table feed rate. Improvements: Model significance tests were conducted using ANOVA table and effects of various parameters were investigated. Indian Journal of Science and Technology, Vol 10(31), DOI: 10.17485/ijst/2017/v10i31/113896, August 2017 ISSN (Print) : 0974-6846 ISSN (Online) : 0974-5645 Optimization of Surface Roughness and Metal Removal Rate in End Milling using Taguchi Grey Relational Analysis Amardeep S. Kang, Gurmeet S. Cheema and Varun Gandhi Bhai Gurdas Institute of Engineering and Technology Sangrur – 148001, Punjab, India; amardeepkang@gmail.com, gcheemamand@gmail.com, varun_gandhi_86@gmail.com Keywords: AISI H11, ANOVA, Metal Removal Rate, Surface Roughness *Author for correspondence