Molecular Dynamics (MD) Simulation of Multi-pass Nanometric Machining – The Effect of Machining Conditions

Title:Molecular Dynamics (MD) Simulation of Multi-pass Nanometric Machining – The Effect of Machining Conditions

Volume: 13 Issue: 1

Author(s): Akinjide Olufemi Oluwajobi and Xun Chen

Affiliation:

Keywords: Depth of cut, feed rate, materials behaviour, molecular dynamics, multiple pass, nanometric machining, nano surfaces.

Abstract: Background: The material removal in ultra precision machining is often at the nanometre scale with stringent form and surface finish accuracy. Currently, it is very difficult to observe nanometric phenomena through experiments, but the MD method has proved helpful in this respect. Many current MD simulation studies on nanometric cutting have been focused on single cutting pass or simple line-type groove. In practice, many machining processes involve the use of multiple passes to create a new surface. In this study, the effect of depth of cut and scribing feed on the simulation of multi-pass cutting, was investigated in the surface creation process, as in single point diamond turning.

Methods: The MD method was employed in studying the effects of machining parameters in multipass nanometric machining of copper workpiece with a diamond tool. The copper-copper interactions were modelled by the EAM potential and the copper-diamond interactions were modelled by the Morse potential. The diamond tool was modelled as a deformable body and the Tersoff potential was applied for the carbon-carbon interactions.

Results: The simulation results show the material removal mechanisms at the different depths of cut. For the first pass, the diamond tool approaches the workpiece at the onset of the simulation, and as the tool touches the workpiece, there is momentary adhesion of the tool atoms and the workpiece atoms. As this is overcome, the tool moves through the workpiece, by ploughing and cutting, depending on the depth of cut, At the cutting depth of 0.5nm, only ploughing occurs and at 1.5nm and 2.5nm, chip formation takes place.

Conclusion: It has been observed that the average tangential and normal components of the cutting forces increase with increase in depth of cut and they reduced in consecutive cutting passes for each depth of cut. The ratios of the tangential to the normal force components decrease as the depth of cut increases, but remain constant after the depth of cut 1.5nm. The magnitudes of the cutting forces decrease from pass 1 to pass 2, but they are identical for both pass 2 and pass 3. The least resistance to cutting was observed at 2.0nm, which may indicate the existence of a critical depth of cut for tool wear reduction. With the variation of the cross feed, after the first pass, the average tangential and normal components of the cutting forces increase with increase in the feed. Also, there is always an increase in friction from pass 1 to pass 2. When carrying out multipass processes, the arrangement should be effected with minimum overlap in the runs, for efficient machining.

Cite this article as:

Oluwajobi Olufemi Akinjide and Chen Xun, Molecular Dynamics (MD) Simulation of Multi-pass Nanometric Machining – The Effect of Machining Conditions, Current Nanoscience 2017; 13 (1) . https://dx.doi.org/10.2174/1573413712666160530123245

DOI https://dx.doi.org/10.2174/1573413712666160530123245	Print ISSN 1573-4137
Publisher Name Bentham Science Publisher	Online ISSN 1875-6786