Effect of nanoparticles as a lubricants in nano-MQL machining of metallic materials: A review

Nanofluids with minimal lubrication (MQL) are drawing attention with laws and regulations that improve environmental protection. Researchers have focused on a variety of issues concerning the performance and application of nanofluids in MQL processing. This review effort attempts to evaluate some of these researches in order to understand the influence of nanoparticles, as well as the kind and on the machinability performance of metallic materials. Furthermore, it has been found that the rise of unique types of nanoparticles and/or nanofluids combined with other types of nanoparticles considerably alters MQL processing performance (hybrid nanofluids). It has been observed that graphene oxide, paraffin wax, and soy-based nanofluids, as well as MoS2 nanoparticles and hybrid nanofluids, such as multi-layer aluminum carbon nanotubes and alumina graphene, provide effective lubricating and cooling effects in MQL processing. However, to optimize their application in machining operations, the thermophysical and wettability features of hybrid nanofluids during aging, as well as difficulties associated to nanoparticle clustering at greater concentrations, must be explored. This paper finally lists several types of nanoparticles that can be used for further machining studies to achieve collaborative effects on MQL processing performance.