Abstract
In this work, we present a fully atomistic approach to modeling a finishing process with the goal to shed light on aspects of work piece development on the microscopic scale, which are difficult or even impossible to observe in experiments, but highly relevant for the resulting material behavior. In a large-scale simulative parametric study, we varied four of the most relevant grinding parameters: The work piece material, the abrasive shape, the temperature, and the infeed depth. In order to validate our model, we compared the normalized surface roughness, the power spectral densities, the steady-state contact stresses, and the microstructure with proportionally scaled macroscopic experimental results. Although the grain sizes vary by a factor of more than 1,000 between experiment and simulation, the characteristic process parameters were reasonably reproduced, to some extent even allowing predictions of surface quality degradation due to tool wear. Using the experimentally validated model, we studied time-resolved stress profiles within the ferrite/steel work piece as well as maps of the microstructural changes occurring in the near-surface regions. We found that blunt abrasives combined with elevated temperatures have the greatest and most complex impact on near-surface microstructure and stresses, as multiple processes are in mutual competition here.
Highlights
Machining processes like grinding are often the only mechanical finishing processing options able to meet the given precision requirements, which is why they are part of almost all manufacturing processes [1, 2]
Http://friction.tsinghuajournals.com∣www.Springer.com/journal/40544 | Friction obtained in the molecular dynamics (MD) simulations as a function of the grinding distance
Note that since the grinding tool is represented by three abrasive grains, each of which passes through the entire width of the simulation box approximately 9 times due to the periodic boundary conditions, every point on the work piece is machined by all three abrasives on average
Summary
Machining processes like grinding are often the only mechanical finishing processing options able to meet the given precision requirements, which is why they are part of almost all manufacturing processes [1, 2]. There is one unifying concept behind all chip formation: A detachment of material has to be provoked by force, which usually forms alongside the primary deformation zone, defined as a shear plane or shear zone, with a certain angle towards the machined work piece surface [6, 17] This is defined by multiple process parameters, most importantly the involved geometries, the sharpness of the tool, which is defined by the rake angle, the work piece material, cutting speed, infeed depth, and many more, which are mutually interdependent [11, 18]. Not every set of parameters will form a proper chip at all, because additional effects of deformation are involved These effects are friction, furrowing, and plowing, which will all result in an increase of heat and pressure, but do not contribute to efficiently grinding the work piece. We go on to study and discuss aspects of near-surface work piece development that are laborious to measure experimentally or even impossible to observe insitu, namely stresses within the work piece and its microstructural evolution
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