ORIGINAL ARTICLE On machining of Ti-6Al-4V using multi-walled carbon nanotubes-based nano-fluid under minimum quantity lubrication H. Hegab 1,2 & H. A. Kishawy 1 & M. H. Gadallah 2 & U. Umer 3 & I. Deiab 4 Received: 5 January 2018 /Accepted: 9 April 2018 # Springer-Verlag London Ltd., part of Springer Nature 2018 Abstract Titanium alloys are the primary candidates in several applications due to its promising characteristics, such as high strength to weight ratio, high yield strength, and high wear resistance. Despite its superior performance, some inherent properties, such as low thermal conductivity and high chemical reactivity lead to poor machinability and result in premature tool failure. In order to overcome the heat dissipation challenge during machining of titanium alloys, nano-cutting fluids are utilized as they offer higher observed thermal conductivity values compared to the base oil. The objective of this work is to investigate the effects of multi- walled-carbon nanotubes (MWCNTs) cutting fluid during cutting of Ti-6Al-4V. The investigations are carried out to study the induced surface quality under different cutting design variables including cutting speed, feed rate, and added nano-additive percentage (wt%). The novelty here lies on enhancing the MQL heat capacity using nanotubes-based fluid in order to improve Ti- 6Al-4V machinability. Analysis of variance (ANOVA) has been implemented to study the effects of the studied design variables on the machining performance. It was found that 4 wt% MWCNTs nano-fluid decreases the surface roughness by 38% compared to the tests performed without nano-additives, while 2 wt% MWCNTs nano-fluids improve the surface quality by 50%. Keywords Multi-walled carbon nanotubes (MWCNTs) . Average surface roughness . Ti-6Al-4V alloy . Nano-cutting fluids . Analysis of variance (ANOVA) 1 Introduction Titanium alloys are broadly used in different industrial appli- cations within the military, aerospace, power generation, au- tomotive, and other fields due to their promising mechanical, physical, and chemical characteristics; for example, high yield strength, high strength to weight ratio, high toughness and high creep, corrosion, and wear resistance [1]. These materials also retain their hardness and strength at high temperatures [2], which make them one of the primary candidates for aerospace, nuclear, power generation, and automotive applications. However, despite the abovementioned superior character- istics, titanium alloys are inherently difficult-to-cut materials due to high stresses and high cutting temperatures generated when they are being machined. This is mainly attributed to low thermal conductivity of titanium that adversely affects the tool life and can lead to premature tool failure. Because of their low thermal conductivity, the generated heat during ma- chining titanium alloys is mainly dissipated through the cut- ting tool and cooling media other than the workpiece or chip. In addition, titanium alloys become chemically reactive at a high cutting temperature and react with some tool materials, which also deteriorate the cutting tool and fasten the tool fail- ure. Moreover, the resultant chip shape in titanium machining is serrated or saw-toothed as localized adiabatic shear bending and intense shear strain rate exist in the primary shear zone due to the high temperature at the chip–tool interface. Some other properties that make titanium alloys difficult-to-cut and impose barriers towards their widespread applications are low elastic modulus, strain hardening, tendency to adhesion, and forming built-up edge [3, 4]. * H. Hegab Hussien.Hegab@uoit.ca 1 Machining Research Laboratory, UOIT, Oshawa, Ontario, Canada 2 Mechanical Design and Production Engineering Department, Cairo University, Giza, Egypt 3 Advanced Manufacturing Institute, King Saud University, Riyadh, Saudi Arabia 4 Advanced Manufacturing Laboratory, Guelph, Ontario, Canada The International Journal of Advanced Manufacturing Technology https://doi.org/10.1007/s00170-018-2028-4