Abstract
Nanoscale manufacturing imposes demands on prediction of cutting processes on small scales. Predictive modeling schemes based on the underlying physical mechanisms could potentially be more generally applicable in manufacturing. In this work, the experimental and numerical studies on polymethyl methacrylate (PMMA) nanocutting are reported. The cutting experiments were performed on an ultramicrotome instrumented with piezoelectric transducers to measure the cutting forces on cutting down to about 60 nm thickness. Using atomic force microscopy, the surface damage was identified as shear yield bands triggered by adiabatic heating. A suitable physical model including these observed phenomena made it possible to link the processing conditions with the onset of damage, i.e., the transition between a high-quality transparent surface and a damaged uneven surface. Finite element analysis was carried out to investigate the deformation modes of PMMA under different cutting conditions and to predict the formation of the undesired shear bands. From an engineering perspective, such an approach could be potentially useful in improving manufacturing control.
Highlights
The fast development in device miniaturization demands increased abilities to manipulate matter at nanoscale and even atomic level
As cutting goes down to small scales, the mechanical mechanisms related to material volume are increasingly restricted, while the mechanisms related to surface area become relatively more significant [2]
It shows that the formed polymethyl methacrylate (PMMA) chips had integral shapes, which implies that the nanocutting was governed by a ductile deformation mechanism [2, 9]
Summary
The fast development in device miniaturization demands increased abilities to manipulate matter at nanoscale and even atomic level. With chain molecules sliding past each other over relatively large distances. When the temperature approaches about 0.8Tg, the molecules gain some mobility and polymers exhibit certain ductility. When the temperature approaches Tg, the chain molecules become more mobile and can rearrange under loading. If the temperature exceeds Tg, the molecules obtain very high mobility and polymers show relatively viscous behavior. Increasing the strain rate may lead to the isothermal–adiabatic transition. Under high rate plastic deformation, the heat converted from the plastic work in polymer cannot dissipate to the surrounding regions rapidly due to the low thermal diffusivities (~ 10−7 m2/s, two orders of magnitude lower than metals [5]), and it results in thermal softening, which can lead to brittle-ductile deformation transition [6]. A glassy polymer exhibits apparent scale effects (or cube–square scaling effects) [2]; namely it tends to deform
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