Molecular dynamics simulation of the elliptical vibration-assisted machining of pure iron

Abstract

It is well known that diamond wears out rapidly (within several metres of cutting length) when machining low carbon ferrous alloys and pure iron. The past few years have seen a growing interest in the field of elliptical vibration-assisted machining (EVAM) due to it being successful in the micromachining of difficult-to-cut materials including steel. During EVAM, a cutting tool is prescribed an oscillatory motion perpendicular to the direction of cutting, thereby causing the tool to be relieved intermittently from chemical and physical contact with the workpiece. This phenomenon serves as a guideline to develop the simulation test bed for studying EVAM in this work to compare it with conventional cutting. The pilot implementation of the EVAM came as a quasi-3-dimensional (Q3D) elliptical cutting model of body-centred cubic (BCC) iron with a diamond cutting tool using molecular dynamics (MD) simulation. The developed MD model supplemented by the advanced visualization techniques was used to probe the material removal behaviour, the development of the peak stress in the workpiece and the way the cutting force evolves during the cutting process. One of the key observations was that the cutting chips of BCC iron during conventional cutting underwent crystal twinning and became polycrystalline, while EVAM resulted in cutting chips becoming highly disordered, leading to better viscous flow compared to conventional cutting.

Designing nanoindentation simulation studies by appropriate indenter choices: Case study on single crystal tungsten

“…This assumption has been implemented by following either of the three cases: (a) by assuming a rigid diamond indenter (DI), (iii) The microstructure underneath the deformation zone of the substrate showed BCC vacancy while indenting with a rigid diamond indenter, BCC divacancy (2nd NN type) while using a rigid tungsten indenter and twin boundaries while using a purely repulsive indenter. The formation of prismatic dislocation loops underneath the indenter in conjunction with the twin planes in W is directly analogous to similar previous findings for BCC iron [56].…”

The Critical Raw Materials in Cutting Tools for Machining Applications: A Review

“…This methodology reduces the physical hardness of the workpiece, making it more compliant to cutting by reducing the specific cutting energy (i.e., the work done by the tool in removing a unit volume of the material). [47]; (c) schematic diagram to illustrate the mechanism of vibration-assisted machining [48].…”

“…Cryogenic cooling has been executed in cutting operations in different ways by using liquid nitrogen for precooling the workpiece, cooling the chip, and cooling the cutting tool and cutting zone [51]. Numerous studies have compared conventional cutting strategies and cryogenic cooling [47]; (c) schematic diagram to illustrate the mechanism of vibration-assisted machining [48].…”

The importance of wavelength for tight temperature control during μ-laser-assisted machining

“…Other advantages of µ-LAM are reduced surface roughness, which Mohammadi et al (2015) found when turning silicon. More recently, the technique is being proposed to be capable of machining stainless steel almost at the traditional speeds of SPDT thereby being more productive than techniques like ultrasonic elliptical vibration assisted machining (UEVAM) where the speed of cutting needs to be lowered significantly [9].…”