Experimental investigation of effects of nano-fluid usage on cooling in machining

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Güldaş A., Bilen K., Kızılkaya H. Z.

ISI BILIMI VE TEKNIGI DERGISI/ JOURNAL OF THERMAL SCIENCE AND TECHNOLOGY, cilt.46, sa.1, ss.79-89, 2026 (SCI-Expanded, Scopus)

Özet

Application of nano-fluids in machining processes is becoming increasingly common due to their enhanced thermo-physical characteristics. Previous studies indicate that adding nano-particles such as Al2O3, MWCNT, or TiO2 into base fluids improves properties like density, viscosity, and thermal conductivity. This experimental study investigates the impact of addition of these nano-particles at concentrations of 0.5%, 1%, and 1.5% into a boron oil–water mixture. The research was carried out in three main phases: Nano-fluid preparation, thermo-physical property evaluation, and machining experiments on Ti-6Al-4V alloy. The results showed that increasing the nano-particle concentration led to a consistent rise in fluid density at 24.5 °C. However, similar trends were not observed for dynamic viscosity and thermal conductivity, which began to decline beyond 1% concentration of nano-particles. This decrease was attributed to fluid instability issues like precipitation and sedimentation. Furthermore, the use of nano-fluids significantly marked down temperature at the tool–workpiece interface. For instance, a 0.5% concentration of MWCNT particles reduced this temperature by approximately 18%. On the other hand, higher concentrations resulted in increased interface temperatures and worsened surface roughness due to particle deposition. Specifically, the use of 0.5% MWCNT improved surface finish by around 25%. The study concluded that machining performance benefits from nano-fluids only when used at optimal concentrations, as excessive amounts of nano-particles degrades performance-a finding supported by SEM analyses of the cutting inserts.