The dispersion, evaluation, and exploration of behavioral science throughout its application has necessitated the characterization of metal working fluids nowadays. Alternative lubricants particularly vegetable oil-based lubes are majorly researched by the tribologists which has led to the concept of developing eco-friendly lubricants. Nano additive based veg-oil cutting fluids are outperforming most of the conventionally available metal working fluids in major aspects like friction modification, surface roughness minimization, cutting force reduction and tool wear aspects. This study focuses on evaluating the characters of bio-based (veg-oil; coconut oil-oleic acid) nano fluids with respect to two families of nano particles. Metal-oxide based and carbon-based are the two families which are usually considered. A novel concept of tri-hybridizing nano particles has been explored and the results has been evaluated and presented in a detailed manner. The size and shape morphology were studied using scanning electron microscope images. The rheological and physio-chemical properties of the prepared nano fluids like density, viscosity, thermal conductivity was also studied and presented. The behavioral analysis was performed to explore its fluidic characteristics in which contact angle, zeta potential analysis, flash point and film thickness analysis was done and presented. In addition, surface morphology studies were performed to evaluate the tribological performance of the nano fluids in end milling of AA7075. The results obtained has proved that both metal-oxide and carbonaceous nano cutting fluids are capable for tribological applications and can be considered as a proven alternative for the conventional lubricants. Around 20% improvement has been found in the cutting parameters and surface roughness. Graphical Abstract

Finding an alternate solution for supplanting the existing conventional lubricant in machining is a challenge. This work narrows the search down to the use of nano-cutting fluids, as they exhibit excellent properties such as high thermal conductivity and good lubricity. A technical analysis of the performance of hybrid nano-cutting fluids in the end milling of AA6082 aluminium alloy in a constrained end milling condition is presented. Alumina and carbon nanotubes were chosen in this study for their better physical characteristics and compatibility during machining. Coconut oil was chosen as the base fluid (dispersal medium) as it provides good lubricity and better dispersion of nanoparticles due to its excellent rheological behaviour. The hybrid nanofluid was prepared by mixing alumina-based nanofluid with carbon nanotube nanoparticles in different volumetric concentrations. The thermo-physical properties of the prepared hybrid nanofluid were tested. Furthermore, they were tested for their spread-ability and other mechanical properties. Later, their performances as cutting fluid were studied with the minimum quantity lubrication (MQL) technique, wherein nanoparticle mist was formed and evaluated in the end milling of AA6082 aluminium to reduce the quantity of nanofluids’ usage during end milling. The controllable parameters of speed, feed rate, and type of cutting fluid were chosen, with the levels of cutting speeds and feed rate at 75–125 m/min, and 0.005–0.015 mm/tooth, respectively, and the response parameters studied were surface roughness and tool wear. The results show that better performance is achieved in hybridized nano-cutting fluid, with a sharp improvement of 20%, and 25% in tool wear and surface roughness when compared to the base fluid. This study has explored the concept of hybridization and the capability of nanofluids as cutting fluids that can be used as eco-friendly cutting fluids in manufacturing industries.

This paper is concentrated on the exploration of carbonaceous nanocutting fluids with the concept of tri-hybridization with improved lubricative and cooling properties by using multi-walled carbon nanotubes, hexagonal boron nitride , and graphene nanoparticles with neat cold-pressed coconut oil in a fixed volumetric proportion. The rheological properties of the nanofluids were studied to assess their performance in real-time end milling operations using an AA7075 work piece on a CNC lathe machine under a minimum quantity lubrication environment. At the outset, the carbonaceous nanofluids gave good performance when compared to conventional cutting fluids. Furthermore, the surfaces of the tribo-pairs and the chips formed were analyzed using a profilometer and high-end microscopes. The results obtained from the experiments confirm that the tri-hybridized carbonaceous nanolubricant has reduced the cutting force, tool wear, and surface roughness when correlated to monotype nanofluids. The scanning electron microscope images of the surface and tool were studied and it was found that the surface quality was maintained while end milling with tri-hybridized carbonaceous nanofluid. Improvement of ∼17%, 20% and 25% in cutting forces, surface roughness and tool wear was found in tri-hybrid fluid when compared to other fluids. Thus, the present work indicates that the addition of carbon-based nanoparticles with coconut oil has offered better performance and is found to be a credible alternative to existing conventional cutting fluids.

In this paper Response surface methodology (RSM) based multi-objective approach is applied in order to predict optimal machining parameters and better cutting environment for the end milling process of OHNS (Oil Hardened Non-Shrinking Die Steel) using both coated and uncoated carbide tools of 8 mm diameter inserted into an end miller in both dry (without coolant) and wet (milling with coolant) environment. Optimization is carried out using parametric model based on input cutting parameters such as cutting speed, feed rate and depth of cut and exploiting the capabilities of statistical approaches (Taguchi and RSM) in constrained machining. The objective function is to minimize the surface roughness and finding the better end milling tool-type and cutting environment. The optimized parameters carrying the major objective function (minimizing surface roughness) for different tooling and cooling condition is identified. It was observed that the best optimized configuration for end milling of OHNS was found in carbide coated tool in both dry and wet cutting environment.