Influence of Al2O3/MoS2 hybrid nanofluid MQL on surface roughness, cutting force, tool wear and tool life in hard turning

The improvement of hard machining efficiency has been a growing concern in the production practice while the environmental friendly characteristics have to be guaranteed. The application of nanofluid minimum quantity lubrication (NF MQL) technique was considered to be as a promising approach to obtain the cooling and lubrication effectiveness in the cutting area. In this present study, the MQL hard turning performance using CBN inserts under different cooling lubrication conditions (dry, Al₂O₃ nano cutting oil, and Al₂O₃/MoS₂ hybrid nano cutting oil) was investigated through evaluating the cutting force, tool wear, tool life, and surface roughness. Based on the obtained results, the normal force component F_y has the large values and the increasing rate is closely related to the flank wear, so it can be used as a criterion to evaluate the tool life. In addition, cutting force coefficient $K_F$ not only presents the relative increase of the normal force F_y compared to the tangential force F_z but also can be used for machining performance evaluation. The wear modes are mechanical scratching and chipping, and the wear land on rake and flank faces is concentrated on the main cutting edge, which is the distinguishing feature of hard machining with conventional cutting. In addition to cutting parameters, tool wear was proven to be affected by the cooling lubrication condition. Furthermore, the machined surface roughness was improved and tool life was prolonged under Al₂O₃/MoS₂ hybrid nanofluid MQL condition when compared to those in dry and Al₂O₃ nanofluid MQL due to the cooling and lubrication effectiveness.