ORIGINAL ARTICLE A novelty optimization approach for drilling of CFRP nanocomposite laminates Halil Burak Kaybal 1 & Ali Ünüvar 2 & Murat Koyunbakan 3 & Ahmet Avcı 2 Received: 21 March 2018 /Accepted: 8 October 2018 # Springer-Verlag London Ltd., part of Springer Nature 2018 Abstract Numerous problems are encountered in drilling of carbon fiber-reinforced polymer composite materials (CFRP) such as delam- ination, tool wear etc. Delamination has been recognized as a major damage encountered when drilling composite laminates. In the present study, machinability and the effects of cutting speed and feed rate upon thrust force and delamination formation in carbon nano tube (CNT)-added carbon fiber-reinforced plastics (CFRP) and CFRP were investigated. With this purpose, the experiments were planned. The response surface analysis has been carried out to study the main and the interaction effects of the machining parameters. By using the Taguchi method, cutting parameters’ degrees of influence were determined. A new multi- objective optimization for the appropriate drilling process of these composite materials was proposed and an analytical optimi- zation technique was applied. Appropriate cutting parameters of thrust force and delamination factor were found and the optimization results showed that the combination of low feed rate with high cutting speed is necessary to minimize delamination in drilling of CFRP.The machinability refers to the relative ease or difficulty under certain cutting conditions. So, it is very important to understand the factors that affect the machinability and to evaluate their effects. Machinability of Epoxy/CF and CNT-Epoxy/CF was investigated. It was aimed to evaluate the machinability of these materials. A new machinability index has been developed in current study. It was found out that machinability of Epoxy/CF is better than CNT-Epoxy/CF. Keywords CFRP . Nanocomposite . RSM . Taguchi methods . Drilling . Thrust force . Optimization . Machinability 1 Introduction Carbon fiber-reinforced polymer (CFRP) composites are well recognized for their superior mechanical properties such as low weight, high strength and stiffness, excellent fatigue and corrosion resistance, and low thermal expansion. CFRP com- posite laminates play a tremendous role in aerospace indus- tries, defense, marine, automobiles, machine tools, transpor- tation structures, power generation, and oil and gas industries. The applications require high-quality machined surfaces, in- cluding dimensional accuracy and surface integrity by using appropriate tools and cutting parameters [1]. Machining of CFRP composites is often needed to fulfill the requirements related to tolerances of assembly needs. Among all machining processes, drilling is one of the most indispensable methods for fabrication of products with composite panels. The perfor- mance of these products is mainly dependent on surface qual- ity and dimensional accuracy of the drilled hole. The quality of drilled hole is influenced by the cutting conditions, tool material, and geometry [2–4]. Davim et al. presented a study of the cutting parameters (cutting velocity and feed rate) on power (P c ), specific cutting pressure (K s ), and delamination in CFRPs [3]. Rahman et al. developed a feasible technique for machining CFRP [5]. Three types of cutting tool inserts, namely uncoated tungsten carbides, ceramic, and cubic boron nitride (CBN), were used to machine two types of specimens, short (discontinuous) and long (continuous) fiber carbon ep- oxy composites. For short carbon fiber composites, experi- mental data shows that the tool wear, the surface finish, and the cutting force fluctuate with respect to the depth of cut, the feed rate, and the cutting speed. However, for long fiber car- bon composites, for a fixed material removal rate, the tool wear was minimized when the CFRP composites were * Ali Ünüvar aunuvar@selcuk.edu.tr 1 Department of Mechanical Engineering, Amasya University, Amasya, Turkey 2 Department of Mechanical Engineering, Selcuk University, Konya, Turkey 3 Department of Manufacturing Engineering, Dumlupinar University, Kütahya, Turkey The International Journal of Advanced Manufacturing Technology https://doi.org/10.1007/s00170-018-2873-1