© Faculty of Mechanical Engineering, Belgrade. All rights reserved FME Transactions (2020) 48, 636-650 636 Received: March 2020, Accepted: May 2020 Correspondence to: Dr Dhananjay R. Mishra, Mechani- cal Engineering Department, Jaypee University of Engineering and Technology, Guna-473226, India E-mail: dm30680@gmail.com doi:10.5937/fme2003636G Girish Dutt Gautam Research Scholar Department of Mechanical Engineering Jaypee University of Engineering and Technology, Guna-473226, Madhya Pradesh India Dhananjay R. Mishra Assistant professor (SG) Department of Mechanical Engineering Jaypee University of Engineering and Technology, Guna-473226, Madhya Pradesh India Multiple Kerf Quality Optimization in Laser Cutting of BFRP Composite using Grey Relational based Genetic Algorithm In laser beam machining, the geometrical precise cutting of fiber reinforced polymer (FRP) composite materials is a challenging task in order to produce a higher quality cut. The aim of the present research is to determine optimum levels of cutting parameters able to provide geomet- rically accurate cut for 1.60 mm thick Basalt Fiber Reinforced Polymer (BFRP) composite laminate. The total of 42 experiments have been perfor- med on a 250W pulsed Nd:YAG laser system. During experimentation, the lamp current, pulse width, pulse frequency, compressed air pressure and cutting speed have been varied to evaluate different kerf quality characteristics such as top and bottom kerf width, top & bottom kerf deviation, and kerf taper. Experimental results have been used to single index optimization of evaluated multiple kerf quality characteristics. A hybrid grey relational analysis coupled with genetic algorithm approach has been adopted for the optimization. The optimum levels of cutting parameters have been found at moderate lamp current (184.5 Amp), lower pulse width (2 ms), compressed air pressure (8 kg/cm 2 ) and cutting speed (50 mm/min) and higher pulse frequency (30 Hz). Finally, confirmation experiments have been conducted and it has been observed that optimal levels of cutting parameters are able to improve top kerf width, bottom kerf width, top kerf deviation, bottom kerf deviation, and kerf taper by 13.33 %, 13.29 %, 23.52 %, 23.07 %, and 10.83 %, respectively. From the experimental results, it has been found that lamp current is the most significant parameter for all kerf quality characteristics. Keywords: Nd:YAG laser; Basalt fiber; Kerf characteristics; optimization; Grey relational analysis; Genetic algorithm. 1. INTRODUCTION In recent decades, the interest of researchers focused on basalt fibers due to their higher mechanical performance and eco-friendly nature. These fibers are obtained from melted basalt rocks by an energy efficient extrusion process [1]. Silicon dioxide (SiO 2 ) and aluminium oxide (Al 2 O 3 ) are the main constituents of basalt fibers. Superior thermal, electrical, abrasion, corrosion, and chemical resistant properties with higher shear and compression strength make basalt fibers and its compo- sites suitable for a wide range of applications in auto- mobile, aircraft, and manufacturing industries. Basalt fibers have a wide range of working temperature from - 269 ºC to 650 ºC. Their composites are widely used for the production of car headliners, disc brake pads and clutch facing components, engine insulator due to their higher frictional, thermal and shock resistance proper- ties in the automotive industries. Nowadays basalt fibers are increasingly replacing E-glass fibers and carbon fibers as a reinforcing agent of polymer matrix com- posites due to its greater tensile and compressive pro- perties and low cost. It has a similar chemical structure to the glass with slightly higher density and higher sta- bility in an acidic environment. Basalt composite pipes are stronger as compare to glass fiber pipes for corrosive liquids and gases transportation [2]. In recent years, the applications of BFRP composites are increased in various engineering sectors. Machining of these composites is required for their structural appli- cations. In their conventional machining, various fric- tional forces are developed and reduce their cut quality. Matrix cracking, thermal damages, whiskers formation, fiber losing and fiber delamination around cutting edges are some of the major drawbacks of conventional machining of BFRP composites. Advanced machining processes such as laser beam machining (LBM), water jet machining, plasma arc machining etc. compared to the conventional machining techniques provide superior cut quality during FRP composite machining. These processes also improve the production rate. [3]. Laser beam cutting (LBC) proves its wide accep- tability for machining of FRP composites to obtain precise and complex profile cut. It provides a better cut quality and operation preciseness with low cost and improved machinability. In LBC, a high energy focused laser beam is utilized for removal of material from the work surface through melting and evaporation caused