Effects of Lubrication on the Friction in Nanometric Machining Processes: A Molecular Dynamics Approach

Abstract

Abstract. Physical phenomena in a nanometric machining process were studied by molecular dynamics simulations. A cylindrical tool was indented and then moved laterally on an initially flat workpiece. The focus of the study is on the effect of lubrication on the nanoscale. Therefore, the indentation and the scratching were studied both in vacuum and submersed in a lubricant. All materials were modeled by Lennard-Jones truncated and shifted potential sites. It is observed, that in the lubricated case, a substantial part of the cutting edge of the tool is in dry contact with the workpiece. Nevertheless, compared to the dry scenario, the lubrication lowers the coefficient of friction. However, the work which is needed for the indentation and the scratching is not reduced. The processed surface is found to be smoother in the lubricated case. As expected, the lubrication has an important influence on the temperature field observed in the simulation.

Vapor−Liquid Interface of the Lennard-Jones Truncated and Shifted Fluid: Comparison of Molecular Simulation, Density Gradient Theory, and Density Functional Theory

“…The LJTS potential, is probably the simplest and computationally least expensive that describes properties of simple fluids well. [22][23][24][25][26][27][28][29] The vapor-liquid interfacial properties of the Lennard-Jones (LJ) and the LJTS fluid have been investigated many times in the literature. 19,28,[30][31][32][33][34][35][36] But to the best of our knowledge no systematic comparison between the three different methods MD, DGT, and DFT has yet been conducted for this fluid or any other fluid on a consistent basis (force field, EoS and functional).…”

Molecular Dynamics Simulation Study of Mechanical Effects of Lubrication on a Nanoscale Contact Process

“…There have also been attempts to link atomistic simulation with experiments in that field [32][33][34][35]. In most of these studies, lubrication was only considered by including adsorbed layers of fluid molecules on the substrate in the simulation, while studies in which the contact is truly immersed in a liquid are rare [36][37][38]. An interesting finding is the squeeze-out of the lubricant from the contact zone which has been observed both in simulations in which the lubricant was only a thin adsorbed fluid layer [39,20], as well as in previous works from our group in which the indenter was immersed in the lubricant [37,38].…”

“…In some studies, the solids were modeled by only a few atom layers [39,20]. Cross-interactions resulting from the simultaneous presence of the bulk fluid phase and the bulk substrate have to the best of our knowledge only been investigated by Rentsch et al [36] and in previous studies of our group [37,38]. Also the influence of the solid-fluid interaction energy on the lubricated nanoscopic contact process has not yet been investigated systematically.…”

A review on micro-milling: recent advances and future trends

“…The molecular dynamic is a widely used simulation method due to its special circumstances. The method based on the solving of Newton's movement equations, and it describes the interactions of the particles in the atomic level [279]. There are many papers in the case of nano-scale machining [279][280][281][282]; however, its application is very limited in the studies, which aim the investigation of the macro or micro-milling processes.…”

“…The method based on the solving of Newton's movement equations, and it describes the interactions of the particles in the atomic level [279]. There are many papers in the case of nano-scale machining [279][280][281][282]; however, its application is very limited in the studies, which aim the investigation of the macro or micro-milling processes. Xiao et al [283] investigated the transition mechanism from brittle to ductile mode at machining brittle material (6H SiC) with molecular dynamics method.…”