Tribological study of nano lubricant integrated soybean oil for minimum quantity lubrication (MQL) grinding

The application of minimum quantity lubrication (MQL) in high energy abrasive machining processes requires lubricants with enhanced tribological properties to survive severe thermo-mechanical effects. Nano lubricants’ containing inorganic MoS2 nanoparticles encapsulated by organic molecular layers of triglycerides and phospholipids is one such novel formulation, as demonstrated by successful experiments in high energy MQL grinding process in the authors’ previous research (Shen et al., 2008). Nano lubricants in MQL application showed superior grinding performance by reducing the tangential grinding force and the specific grinding energy and by delivering high grinding (G)-ratios as compared to that of MQL applications of pure base oils and flood cooling using a typical water based grinding fluid. In the current study, the performance enhancement by nano lubricants in MQL grinding is investigated by systematic tribological testing under a simulated machining interaction between abrasive crystals and a workpiece in a surface grinding process. It is found that nano lubricants effectively reduce sliding frictional losses by a continuous supply of active lubricant additives and by forming a stable, low friction tribofilm at the sliding interface of the abrasive grit and the workpiece surface.