Investigation of tool geometry in nanoscale cutting single-crystal copper by molecular dynamics simulation

Abstract

Molecular dynamics has been employed in this paper to investigate the nanoscale cutting process of single-crystal copper with a diamond tool. The behavior of the workpiece during material removal by diamond cutting has been studied. The effects of tool geometry including rake angle, clearance angle, and edge radius are thoroughly investigated in terms of chips, dislocation movement, temperature distribution, cutting temperature, cutting force, and friction coefficient. The investigation showed that an appropriate positive rake angle ([Formula: see text]), a suitable clearance angle ([Formula: see text]), or a smaller edge radius tip resulted in a smaller cutting force and a better subsurface finish. It was found that a tool with a rake angle of [Formula: see text] generated more chips, had a higher cutting efficiency, and produced a lower temperature in the workpiece, but a smaller rake angle tip was more conducive to protecting the groove compared to a large rake angle tip. Compared with a tool with a small clearance angle, the tool with a larger clearance angle generated more chips and caused a lower temperature rise in the copper workpiece, and prolonged its lifetime. In addition, a larger clearance angle tip was more conducive to protecting the groove. A smaller edge radius tip reduces the cutting heat during the nanoscale cutting process, while the volume of chips decreases. These results indicated that it is possible to control and adjust the tool parameters according to the tool rake angle, clearance angle, and edge radius during the machining of single-crystal copper, and a set of tool parameters were obtained: [Formula: see text] rake angle, [Formula: see text] clearance angle, and 0 nm edge radius which could reduce surface damage and the required cutting force.

Molecular Dynamics Study of the Effect of Abrasive Grains Orientation and Spacing during Nanogrinding

“…From Figure 6 , it can be seen that both F y and F z values increase as rake angle values increase in magnitude and eventually, F z values become greater than F y values. The increasing trend for both force components is consistent with every relevant work in the literature [ 10 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 ]. Moreover, a slower increase is attested for F y than for F z , as F z values increase 2.62 times, whereas F y values increase only 1.14 times, as it was also observed in several works, such as [ 38 , 39 , 43 , 48 ].…”

“…It can be directly seen from Figure 9 that the height of the chip is considerably reduced for rake angle values up to −30° and then it remains practically stable. The reduction of chip height, with higher negative rake angle was also observed in several works in the relevant literature [ 34 , 35 , 36 , 37 , 38 , 40 , 43 ] due to the increased compression of the removed atoms by the abrasive grain face which contacts them at a highly inclined configuration.…”

“…In this set of simulations, the effect of abrasive grain rake angle is investigated for negative values starting from −5° to −60°. Although no similar works regarding the rake angle of abrasive grains are reported, this range of values was selected in accordance with the relevant literature on nanocutting simulations with negative rake angle tools [ 10 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 ]. More specifically, most authors have chosen negative rake angle values up to −45° [ 34 , 43 , 45 ] or −60° [ 10 , 35 , 38 ], and Lai et al [ 37 ] pointed out that the critical rake angle for formation of chip is −65°, as they proved that higher negative rake angles resulted in plastic deformation of the substrate without a pileup of atoms.…”

“…Thus, the value predicted in the current work is in compliance with these works. On the other hand, Dai et al [ 34 , 40 ] reported higher values of tangential force at least until −45° and Zhao et al [ 36 ] reported a value of 0.55 at −40°. The reason for these variations is perhaps that friction coefficient is dependent on other process parameters to some extent, such as cutting speed, depth of cut, tool radius, and so, simulations conducted under different values of these parameters yield different results on the critical rake angle value which leads to μ > 1.0.…”

“…A few works in the relevant literature also indicate this trend in nanocutting processes. Dai et al [ 34 , 40 ] observed variations in the number of atoms pertinent to intrinsic stacking faults [ 34 ] during nanocutting of copper or in the number of atoms with different coordination during nanocutting of silicon [ 40 ]. Lai et al [ 37 ] found out that plastic deformation was more intense in the workpiece with a decrease of rake angle towards highly negative values and that a lot of dislocations were concentrated in the subsurface area for these rake angle values.…”