Influence of Al2O3 and TiO2 nanofluid on hard turning performance

The current paper emphasized on preparation methodology of aqueous Al2O3-water and TiO2-water nanofluids and its application as the coolant in hard turning operations. The nanofluids are prepared through the two-step process, dispersing nanoparticles of Al2O3 (average diameter 44 nm) and TiO2 (average diameter 27 nm) in deionized water at three different % weight concentrations (0.005, 0.01, and 0.05). Air-assisted nanofluid is impinged through spray impingement setup in hard turning of AISI D2 steel (55 HRC) using multilayer (TiN/TiCN/Al2O3)-coated carbide tool. Application of nanofluid through spray impingement technique in hard turning is a novel work which is rarely found in the literature. Also, there is no literature available which presented the comparative hard turning performance under lower weight % concentration of Al2O3 and TiO2 nanofluid although the cost of the nanoparticle is high. Further, flank wear (VBc), cutting temperature (T), average surface roughness (Ra), and chip morphology have been investigated as the cutting responses. Abrasion is the dominant wear mechanism identified for both types of nano cutting fluids. TiO2-water nanofluid attributes enhanced machinability compared with that of Al2O3-water nanofluid due to higher lubricious characteristics of TiO2 which significantly reduces the chip-tool friction thus reduces the cutting heat. The most favorable results are noticed at 0.01% weight concentration of TiO2 and at this condition, compared with the same concentration of Al2O3 nanofluid, 29% reduction in tool-flank wear, 9.7% drop in cutting temperature, and 14.3% reduction in surface roughness are found. Tool life at 0.01 wt% concentrations of TiO2 nanofluids is found to be 154 min taking flank wear criteria of 0.3 mm, which is 2.52 times more than the tool life obtained under dry cutting and 1.47 times higher than the tool life obtained under air-water spray impingement due to excellent wettability, lubrication, and heat dissipation capability of TiO2 nanofluid. However, the employment of deionized water-based TiO2 nanofluid in spray impingement cooling hard machining can be very promising for a practical manufacturing concern.