Is There a Limit to Nanoscale Mechanical Machining?
AO Oluwajobi and X Chen, PRECISION MACHINING VII, 581, 316-321 (2014).
The Moore's law which predicts that the number of transistors which can be integrated on the computer chip will double every 24 months and which has been the guiding principle for the advancement of the computer industry, is gradually reaching its limit. This is due to the limitations imposed by the laws of physics. Similarly, in the machining sector, Taniguchi predicted an increasing achievable machining precision as a function of time in the 1980s and this prediction is still on course. The question also is, is there a limit to machining and to material removal processes; and how far can this prediction be sustained? In this paper, the molecular dynamics (MD) simulation was employed to investigate this limit in the nanomachining of a copper workpiece with a diamond tool. The variation of the depth of cut used was from 0.01m to 0.5nm. The Embedded Atom Method (EAM) potential was used for the copper-copper interactions in the workpiece; the Lennard- Jones (LJ) potential was used for the copper-carbon (workpiece-tool interface) interactions and the tool (carbon-carbon interactions) was modelled as deformable by using the Tersoff potential. It was observed from the simulation results that no material removal occurred between 0.01m 0.25nm depth. At the depth of cut of 0.3nm, a layer of atoms appears to be removed or ploughed through by the tool. At a depth of cut less than 0.3nm, the other only phenomenon observed was the squeezing of the atom. The 0.3nm depth of cut is around the diameter of the workpiece- copper atom. So, it may be suggested that the limit of machining may be the removal of the atom of the workpiece.
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