Study of Effect of Impacting Direction on Abrasive Nanometric Cutting Process with Molecular Dynamics
Li et al. Nanoscale Research Letters
Study of Effect of Impacting Direction on Abrasive Nanometric Cutting Process with Molecular Dynamics
Junye Li 0
Wenqing Meng 0
Kun Dong 0
Xinming Zhang 0
Weihong Zhao 0
0 College of Mechanical and Electric Engineering, Changchun University of Science and Technology , Changchun 130022 , China
Abrasive flow polishing plays an important part in modern ultra-precision machining. Ultrafine particles suspended in the medium of abrasive flow removes the material in nanoscale. In this paper, three-dimensional molecular dynamics (MD) simulations are performed to investigate the effect of impacting direction on abrasive cutting process during abrasive flow polishing. The molecular dynamics simulation software Lammps was used to simulate the cutting of single crystal copper with SiC abrasive grains at different cutting angles (0o-45o). At a constant friction coefficient, we found a direct relation between cutting angle and cutting force, which ultimately increases the number of dislocation during abrasive flow machining. Our theoretical study reveal that a small cutting angle is beneficial for improving surface quality and reducing internal defects in the workpiece. However, there is no obvious relationship between cutting angle and friction coefficient.
Molecular dynamics; Nanometric cutting; Impacting direction; Monocrystalline copper
Background
In modern ultra-precision machining, material removal
technologies play an important role in microelectronics,
micromechanical, and optical element manufacturing.
The demand of miniaturized devices with high
dimensional accuracy and quality surface, making
ultraprecision processes the major choice in the mentioned
field [
1
]. Moreover, the changes of surface components
and sub-surface structure are at the nanometer length
scale. Abrasive particle flow polishing technology plays an
important role in many fields of precision machining and
is just like other non-traditional finishing technologies
which improve surface quality. This technology has
attracted lots of researchers due to its significant role. E.
Uhlmann and other researchers have reported the
computer simulation of abrasive grain polishing ceramic
surface for the designed experiments to verify the grinding
fluid flow of various processing factors on the effect of
cutting materials [
2
]. Sehijpal Singh and other researchers
use the abrasive flow polishing technology for cutting
copper and aluminum materials. From scanning electron
microscopic analysis, they found a deep groove surface of
their workpiece [
3
]. G. Venkatesh and other researchers
have reported ultrasonic assisted abrasive grain polishing
technology for the conical gear on the complex surface of
finishing process. In this technique, the abrasive grain
velocity is higher than the conventional abrasive grain
flow to collide with the surface of workpiece, which can
improve the processing efficiency. From their experimental
and theoretical methods, they found that this technology is
one of the best choices for gear blade finishing [
4, 5
]. K.
Kamal et al. studied the rheological properties of the
abrasive liquid in the fluid abrasive viscosity, shear rate,
and creep time [6]. However, most of the abrasive flow
polishing studies are based on macro level and very rare
attention has been paid to micro level. In the abrasive flow
polishing process, the suspended particles in the medium
will flow along the media, at a certain speed with the
impact of micro cutting workpiece surface (Fig. 1).
As the shape of the abrasive grains is not regular,
having certain edges and corners which act on the
surface of the workpiece, similar to the tool. But the cutting
process is on the atomic scale which is obviously
different from the material removal process. A nanoscale
cutting involves few nanometers or less of the material
surface, but it is very difficult to observe this process by
experiments. Therefore, MD simulation as a theoretical
investigation method is very useful in studying the
nanometric cutting process. Molecular dynamics as a
computer simulation technique, which uses a time-based
statistical mechanics method to study the interrelation
of atoms for conditions prediction and analysis. This is
also a powerful tool for simulating and understanding
materials removal processes. In the literature, there exist
numerous studies regarding MD as a tool to investigate
precision machining. Oluwajobi and Chen have done
extensive work on MD simulation of nanoscale
machining of copper [
7
]. In their studies, they investigated
various parameters for nanomachining such as minimum
cut depth, geometry, and interatomic potential [
8
]. In
addition, MD simulations results have also been
successful in the past to address number of problems
concerning the nanometric cutting process of brittle materials
such as silicon [
9
]. Komanduri et al. conducted an MD
simulation for nanometric cutting of single-crystal of
pure silic (...truncated)