Effect of Fluid Media on Material Removal and Subsurface Defects Evolution of Monocrystal Copper in Nano-Cutting Process

Abstract

The effect of fluid media on material removal and subsurface defects evolution in nano-cutting process of single-crystal copper is investigated by means of molecular dynamics simulation. In this paper, the removal mechanism of the chip and formation mechanism of machined surface are investigated by analyzing the atomic migration and dislocation evolution of workpiece during nano-cutting process with the use of aqueous media. The distribution of temperature and subsurface defect crystal structural transformation are investigated, which are analyzed by centro-symmetry parameter and common neighbor analysis methods. The results show that the workpiece material is removed by the extrusion shearing action of the cutting tool. The lubrication of the aqueous media can reduce the cutting force and lower the height of cutting chip. Particularly, the cooling action of the fluid media results in the formation of a typical defect “similar-to-grain boundary” in subsurface of the workpiece. And the temperature of workpiece has a distinct decrease during nano-cutting process with the use of fluid media.

Triple Effects of the Physicochemical Interaction between Water and Copper and Their Influence on Microcutting

“…Whether the water was applied on the second half of the surface or the full surface, a consistent 26% reduction in cutting force and 23% reduction in thrust forces can be observed. The reduction in cutting forces with applied water is consistent with the conclusions reached through MD simulations . Additional benefits of water application can be seen through improvements in machined surface quality where a lower roughness of 0.876 μm R a can be obtained with applied water as compared to normal cutting that produces a roughness of 1.328 μm R a (Figure b).…”

“…Researchers are, therefore, heavily reliant on theoretical calculations and simulations to identify the root causes for the experimental findings. In the context of water on copper, previous reports have largely focused on lubrication, cooling, ,− and microcorrosion − effects, as detailed in Table .…”

“…Wang and Shi reported an increase in hardness and a decrease in Young’s modulus during indentation simulation tests on copper with water. Wang et al observed the decrease in cutting forces and extended tool life with molecular dynamics (MD) simulations of copper with a water film. It was reported that heat was removed from the tool-workpiece interface to the cutting chip under the influence of the water film.…”

Study on Chip Formation Mechanism of Single Crystal Copper Using Molecular Dynamics Simulations

“…The dislocation distribution in chip was perpendicular to the cutting direction when the cutting direction is ( 1 1 0) [1 1 0]. Wang et al [20] studied the influence of fluid media on chip formation process of single crystal copper. It is found that the presence of water causes the hot zone in the chip to move from the tool-chip contact zone to the top of the chip.…”

Effect of Machining-Induced Subsurface Defects on Dislocation Evolution and Mechanical Properties of Materials via Nano-indentation

“…The subsurface defects not only solely affect the processing accuracy and surface quality, but also critically affect the mechanical properties and service life of nano-components. Many studies about subsurface defects have been carried out by molecular dynamics (MD) method, mainly focusing on the formation and evolution of subsurface defect s[6, 7], the thickness of subsurface defects (SSD) layer [8, 9], and the influence subsurface defects on surface integrity [10, 11]. However, the effect of subsurface defects on mechanical properties of workpiece materials is less studied.…”