Carbon Fiber Reinforced Polymer (CFRP) composites are widely used in aerospace industry in lieu of its high strength to weight ratio. This study is an attempt to evaluate the machinability of Bi-Directional Carbon Fiber–Epoxy composite and optimize the process parameters of cutting speed, feed rate and drill tool material. Machining trials were carried using drill bits made of high speed steel, TiN and TiAlN at different cutting speeds and feed rates. Output parameters of thrust force and torque were monitored using Kistler multicomponent dynamometer 9257B and vibrations occurring during machining normal to the work surface were measured by a vibration sensor (Dytran 3055B). Linear regression analysis was carried out by using Response Surface Methodology (RSM), to correlate the input and output parameters in drilling of the composite in the longitudinal and transverse directions. The optimization of process parameters were attempted using Genetic Algorithm (GA) and Particle Swarm Optimization–Gravitational Search Algorithm (PSO–GSA) techniques

Carbon Fiber Reinforced Polymer (CFRP) are widely used in many engineering applications as replacement for various other elements to make use of the advantage of its high strength-weight ratio, durability and high corrosion resistance. The paper herein is an attempt to evaluate the drilling characteristics of CFRP by means of three different drill bit types (HSS, TiAlN and TiN) using Taguchi L₂₇ (3¹³) orthogonal array under dry condition. Firstly, the machining process parameters (cutting speed and feed rate) are optimized with multiple performance characteristics using Multi-objective Taguchi technique and TOPSIS. Secondly, mathematical model is developed to correlate the machining process parameters and the performance characteristics (surface roughness, circularity and cylindricity) using response surface analysis. ANOVA is used to validate the developed mathematical model of the responses. The investigation reveals that the results of TOPSIS technique are in good agreement with the multi-objective Taguchi technique and also feed rate is the most predominant factor which affects the responses.

Purpose: This paper aims to attempt to use grey relational analysis (GRA) coupled with Taguchi technique for the optimization of machining parameters (cutting speed, feed rate and drill bit type) with multiple performance characteristics of delamination factor, surface roughness and circularity in drilling of carbon fiber-reinforced polymer (CFRP) along the fiber direction. Design/methodology/approach: Machining trials involved drilling of 6-mm diameter holes on 8-mm-thick CFRP plates was performed according to L27 (313) Taguchi’s orthogonal array technique using the drill material of high speed steel (HSS), Titanium Nitride (TiN) and Titanium Aluminium Nitride (TiAlN). Analysis of variance has been used find the effect, percentage contribution and significance of the process parameters, namely, cutting speed, feed rate and drill bit type. Findings: The Taguchi technique is combined with the GRA to find the optimum process parameter which minimizes the delamination factor, surface roughness and circularity within the range of parameters investigated. The effective implementation of the hybrid approach helps to produce quality and defect free holes. Originality/value: Experimental investigation on delamination factor, surface roughness and circularity in drilling of CFRP along the fiber direction using Taguchi-GRA was seldom reported.