An optimization study on Al ₂ O ₃ nanoparticle concentration, air pressure, and air flow rate in MQL hard turning

Minimum quantity lubrication (MQL) using nano cutting oil has gained much attention and is an up-to-date research topic. The suspension of nanoparticles not only improves the cooling lubrication of MQL technique but also creates the secondary lubrication mechanisms in contact zone. The main objective of this paper is to study the hard turning performance under Al 2 O 3 nanofluid MQL environment using CBN inserts. Box – Behnken response surface methodology was used to investigate the impacts of nanoparticle concentration (NC), cutting speed ( V ), and feed rate ( f ) on surface roughness R a and cutting forces ( F y and F z ). The obtained results indicated that the cutting efficiency of 90CrSi tool steel was improved, thanks to the enhancement of cooling lubrication of MQL using Al 2 O 3 nano cutting oil. The applicability of vegetable oils like soybean oil was enlarged for the hard turning process. The findings indicate that Al 2 O 3 nanoparticle concentration has the highest percentage contribution rate on R a , while air pressure is the most dominant effect on the cutting force F y . Moreover, the provision of the appropriate ranges and optimal set of investigated variables obtained in this paper will be the useful guides for further studies and different industrial applications.