An atomistic investigation of nanometric cutting process using a multi-tip single crystal diamond tool

In recent years great efforts are being made for the design and fabrication of periodic nanostructures used in emerging nano-products, such as plasmonic lens, nano-grating and high density hard disk etc. In our previous research work, a deterministic fabrication approach to cost-effectively manufacturing nano gratings over large area has been developed through single point diamond turning by using a multi-tip nano-scale single crystal diamond tool fabricated by FIB (Focus Ion Beam). However, the machining mechanism and technical limits of this approach i.e. the minimum dimension of nanostructures that can be obtained has not known yet. Due to the limitation of real-time detect equipment as well as the high research cost, it is difficult to obtain a quick answer through experimental work. On the other hand molecular dynamics (MD) simulation provides a cost-effective solution for this problem. Based on the merit offered by the large-scale molecular dynamics simulation method and new progresses made in high performance computing (HPC) technique, this paper proposes a new MD model for nanometric cutting process using a multi-tip single crystal diamond (SCD) tools to machine single crystal copper workpieces. By using centrosymmetry parameter (CSP) method and combining it with the dislocation nucleation and propagation theory, the machining mechanism and generation of nanostructures are studied through MD simulation. In order to reveal the dependence of the depth of cut on the integrality of generated nanostructures, a number of MD simulations have been carried out under depth of cut varying from 0.5, 1.0, 1.5, 2.0, and 3.0nm. The simulation results show that the depth of cut has significant influence on the integrality of the machined nanostructured surfaces and cutting force. A concept of maximum depth of cut to obtain high precision nanostructured surfaces in a single cutting pass is proposed based on analysis of the dimensional accuracy of the integrality machined nanostructures. In all simulations the cutting forces fluctuate around a constant value after chip formation.