Investigation of the cutting mechanisms and the anisotropic ductility of monocrystalline sapphire

Mizumoto, Yuta; Maas, Philipp; Kakinuma, Yasuhiro; Min, Sangkee

doi:10.1016/j.cirp.2017.04.018

Cited by 47 publications

(16 citation statements)

References 16 publications

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“…It needs to be mentioned that the stress distribution in Figure 1 is a simplified illustration, whereas the actual stress distribution would be much more complicated. The stress distribution in a practical machining process would not only be influenced by the machining conditions, but also be affected by the crystal anisotropy [ 5 , 38 , 40 , 41 , 42 , 43 , 44 ]. Nevertheless, compression and tension would still exist in the zones before and behind the tool respectively.…”

Section: Mechanics Of Brittle–ductile Cutting Mode Transitionmentioning

confidence: 99%

“…Brittle–ductile cutting mode transition is an important phenomenon in the ultra-precision machining of brittle materials [ 1 , 2 , 3 , 4 ]. Almost all the brittle materials could be machined in the ductile mode when the undeformed chip thickness (

) decreases to be sufficiently small, typically at submicron level [ 5 , 6 , 7 ]. The mechanism of brittle–ductile cutting mode transition has been a hot topic over the past two decades, and has been explained from several perspectives, including the energy of the material removal, the effects of the preexisting microdefects, and the effective rake angle at small undeformed chip thickness, etc.…”

Section: Introductionmentioning

confidence: 99%

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A Study of Mechanics in Brittle–Ductile Cutting Mode Transition

Xiao

Ren

2018

Micromachines

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This paper presents an investigation of the mechanism of the brittle–ductile cutting mode transition from the perspective of the mechanics. A mechanistic model is proposed to analyze the relationship between undeformed chip thickness, deformation, and stress levels in the elastic stage of the periodic chip formation process, regarding whether brittle or ductile mode deformation is to follow the elastic stage. It is revealed that, the distance of tool advancement required to induce the same level of compressive stress decreases with undeformed chip thickness, and thereby the tensile stress below and behind the tool decreases with undeformed chip thickness. As a result, the tensile stress becomes lower than the critical tensile stress for brittle fracture when the undeformed chip thickness becomes sufficiently small, enabling the brittle–ductile cutting mode transition. The finite element method is employed to verify the analysis of the mechanics on a typical brittle material 6H silicon carbide, and confirmed that the distance of the tool advancement required to induce the same level of compressive stress becomes smaller when the undeformed chip thickness decreases, and consequently smaller tensile stress is induced below and behind the tool. The critical undeformed chip thicknesses for brittle–ductile cutting mode transition are estimated according to the proposed mechanics, and are verified by plunge cutting experiments in a few crystal directions. This study should contribute to better understanding of the mechanism of brittle–ductile cutting mode transition and the ultra-precision machining of brittle materials.

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Section: Mechanics Of Brittle–ductile Cutting Mode Transitionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Study of Mechanics in Brittle–Ductile Cutting Mode Transition

Xiao

Ren

2018

Micromachines

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“…Wen Gu et al improved the assessment of the brittle-ductile transition based on the surface conditions using a method of changing the position to observe the two-dimensional plane with an optical microscope and then calculating the BDTD of the material by extracting the envelope curve [ 19 ]. Three-dimensional microscopic measurement methods mainly use a scanning electron microscope (SEM), atomic force microscope (AFM), transmission electron microscope (TEM), etc., as well as a white light interferometer, laser confocal measuring instrument, or other three-dimensional scanning equipment for performing measurements; then, according to the three-dimensional information, the position of the brittle-ductile transition point is judged, and the BDTD is obtained [ 20 , 21 , 22 , 23 ]. For example, Fang et al used an SEM and AFM to observe a surface after taper cutting and obtained the critical cutting thickness of the brittle-ductile transition during the nano-cutting of single-crystal silicon [ 24 , 25 ].…”

Section: Introductionmentioning

confidence: 99%

A Self-Established “Machining-Measurement-Evaluation” Integrated Platform for Taper Cutting Experiments and Applications

Yang

Zhu

et al. 2021

Micromachines

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Taper-cutting experiments are important means of exploring the nano-cutting mechanisms of hard and brittle materials. Under current cutting conditions, the brittle-ductile transition depth (BDTD) of a material can be obtained through a taper-cutting experiment. However, taper-cutting experiments mostly rely on ultra-precision machining tools, which have a low efficiency and high cost, and it is thus difficult to realize in situ measurements. For taper-cut surfaces, three-dimensional microscopy and two-dimensional image calculation methods are generally used to obtain the BDTDs of materials, which have a great degree of subjectivity, leading to low accuracy. In this paper, an integrated system-processing platform is designed and established in order to realize the processing, measurement, and evaluation of taper-cutting experiments on hard and brittle materials. A spectral confocal sensor is introduced to assist in the assembly and adjustment of the workpiece. This system can directly perform taper-cutting experiments rather than using ultra-precision machining tools, and a small white light interference sensor is integrated for in situ measurement of the three-dimensional topography of the cutting surface. A method for the calculation of BDTD is proposed in order to accurately obtain the BDTDs of materials based on three-dimensional data that are supplemented by two-dimensional images. The results show that the cutting effects of the integrated platform on taper cutting have a strong agreement with the effects of ultra-precision machining tools, thus proving the stability and reliability of the integrated platform. The two-dimensional image measurement results show that the proposed measurement method is accurate and feasible. Finally, microstructure arrays were fabricated on the integrated platform as a typical case of a high-precision application.

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“…Although comprehensive research has been carried out to study elastic-plastic deformation behavior in the static state by indentation, few studies have concentrated on sapphire anisotropy under the dynamic state [ 11 , 12 ]. Mizumoto, et al [ 13 ] discussed the anisotropic deformation behavior of monocrystalline sapphire by plunge-cut tests in brittle–ductile transition. Nanoscratch is becoming a promising characterization method to analyze wear behavior and the nano-tribological property of a material under the dynamic state [ 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Nanoscratch Mechanism of C-Plane Sapphire with the Aid of Molecular Dynamics Simulation of Hcp Crystal

et al. 2021

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In this study, single groove nanoscratch experiments using a friction force microscope (FFM) with a monocrystalline diamond tip were conducted on a c-plane sapphire wafer to analyze the ductile-regime removal and deformation mechanism including the anisotropy. Various characteristics, such as scratch force, depth, and specific energy for each representative scratch direction on the c-plane of sapphire, were manifested by the FFM, and the results of the specific scratch energy showed a trend of six-fold symmetry on taking lower values than those of the other scratch directions when the scratch directions correspond to the basal slip directions as 0001⟨112¯0⟩. Since this can be due to the effect of most probably basal slip or less probably basal twinning on the c-plane, a molecular dynamics (MD) simulation of zinc, which is one of the hexagonal close-packed (hcp) crystals with similar slip/twining systems, was attempted to clarify the phenomena. The comparison results between the nanoscratch experiment and the MD simulation revealed that both the specific scratch energy and the burr height were minimized when scratched in the direction of the basal slip. Therefore, it was found that both the machining efficiency and the accuracy could be improved by scratching in the direction of the basal slip in the single groove nanoscratch of c-plane sapphire.

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Investigation of the cutting mechanisms and the anisotropic ductility of monocrystalline sapphire

Cited by 47 publications

References 16 publications

A Study of Mechanics in Brittle–Ductile Cutting Mode Transition

A Study of Mechanics in Brittle–Ductile Cutting Mode Transition

A Self-Established “Machining-Measurement-Evaluation” Integrated Platform for Taper Cutting Experiments and Applications

Analysis of Nanoscratch Mechanism of C-Plane Sapphire with the Aid of Molecular Dynamics Simulation of Hcp Crystal

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