Tool steel play a vital role in modern manufacturing industries due to its excellent properties. AISI D3 is a cold work tool steel which possess high strength, more hardenability and good wear resistance properties. It has a wide variety of applications in automobile and tool and die making industries such as blanking and forming tools, high stressed cutting, deep drawing and press tools. The novel ways of machining these steels and finding out the optimum process parameters to yield good output is of practical importance in the field of research. This research work explores an attempt to identify the optimized process parameter combinations in end milling of AISI D3 steel to yield low surface roughness and maximum dish angle using trochoidal milling tool path, which is considered as a novelty in this study. 20 experimental trials based on face centered central composite design (CCD) of response surface methodology (RSM) were executed by varying the input process factors such as cutting speed, feed rate and trochoidal step. Analysis of variance (ANOVA) was adopted to study the significance of selected process parameters and its relative interactions on the performance measures. Desirability-based multiple objective optimization was performed and the mathematical models were developed for prediction purposes. The developed mathematical model was statistically significant with optimum conditions of cutting speed of 41m/min, feed rate of 120 mm/min and trochoidal step of 0.9 mm. It was also found that the deviation between the experimental and predicted values is 6.10% for surface roughness and 1.33% for dish angle, respectively.

Researchers have been greatly encouraged to utilize nanofluids as an alternative cutting fluid during machining with minimum quantity lubrication conditions in recent decades due to their desirable qualities such as enhanced wetting and spreading ability, acceptable rheological behavior with varying nanoparticle parameters, and dispersion methods. The thermophysical values of nanofluids considerably impact their heat transfer capability. Viscosity is a crucial thermophysical property that is influenced by several factors. The viscosity of the nanofluid increases with increasing particle concentration and reduces with increasing particle size. Surfactants can aid in the reduction of nanofluid viscosity. Furthermore, the effects of particle type, shape, and dispersion in the base fluid on the viscosity of nanofluids deserve further investigation. Due to a lack of information on nanoparticle parameters and their preparation method, the experiments that utilize them often seem untrustworthy, contradictory, not similar, and not reproducible. As a result, defining the minimum amount of information required to characterize the nanofluid fully is critical to assure its composition and property measurements’ reproducibility. This review focuses on how the viscosity of nanofluids is affected by the base fluid, concentration, and nanoparticle parameters such as size, shape, material, and dispersion mechanism. The influence of viscosity on the machining performance in surface roughness as well as tool wear is also studied. In conclusion, some recommendations have been made for the least amount of information that should be provided on a nanofluid to recreate the same nanofluid across all laboratories.

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