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Significance statement
Along with the development of cutting technology from conventional scale to micro scale, and even down to nanometric scale, the undeformed chip thickness is reducing and machining accuracy is increasing. Due to the size effect, the material removal mechanism of nanometric cutting shows dramatic difference from that of conventional cutting. Molecular Dynamics (MD) simulation has been widely used to explore the nanometric cutting mechanism. To clarify the nanometric material removal mechanism and relevant research results from MD analysis, a new nanometric cutting device that employs a high precision motion stage to provide nanoscale motions under a scanning electron microscope (SEM) was developed. The device used inside a SEM can realize the online observation of the nano-cutting process, which can be used to effectively study the nanoscale material removal mechanism experimentally for various types of materials. The developed device can be used to realize a displacement of 7 μm, with a closed-loop resolution of 0.6 nm in both the cutting direction and the depth direction. Cutting behavior and chips obtained from various undeformed chip thickness were studied during the cutting process. The undeformed chip thickness of less than 10 nm could be obtained using a cutting tool with an edge radius of 43 nm. Using the device, various nano-cutting experiments can be performed by controlling the parameters quantitatively, such as chip deformation coefficient of different materials, critical undeformed chip thickness of brittle to ductile transition under different cutting edge radii and cutting speeds, etc. The experimental results demonstrated that the material removal in nanoscale below a critical range is by extrusion rather than shearing. The research would also be beneficial to the nano mechanical machining fundamental study and other studies relevant to material behavior in nanoscale.
Figure Legend: Figure a and b show the platform of nanometric cutting device and the cutting process viewed by online SEM observation. Figure c shows SEM micrographs of the chips on silicon substrate formed by using the diamond cutting tool with an edge radius of 43 nm, where the undeformed chip thickness was 5 nm, 10 nm and 20 nm, respectively. Figure d shows the silicon tapper cutting results achieving on this online nanometric cutting device.
A nanometric cutting device developed under the SEM online observation and its cutting results.
Journal Reference
Precision Engineering, Volume 41, July 2015, Pages 145–152. Fengzhou Fang1,2, Bing Liu1,2, Zongwei Xu1
- State Key Laboratory of Precision Measuring Technology & Instruments, Tianjin University, Tianjin 300072, China
- School of Mechanical Engineering, Tianjin University, Tianjin 300072, China.
Abstract
A nanometric cutting device under high vacuum conditions in a scanning electron microscope (SEM) was developed. The performance, tool-sample positioning, and processing capacity of the nanometric cutting platform were studied. The proposed device can be used to realize a displacement of 7 μm, with a closed-loop resolution of 0.6 nm in both the cutting direction and the depth direction. Using a diamond cutting tool with an edge radius of 43 nm formed by focused ion beam (FIB) processing, nanometric cutting experiments on monocrystalline silicon were performed on the developed cutting device under SEM online observation. Chips and machining results of different depths of cut were studied during the cutting process, and cutting depths of less than 10 nm could be obtained with high repeatability. Moreover, the cutting speed was found to exhibit a strong relationship with the brittle–ductile transition depth on brittle material. The experimental results of taper cutting and sinusoidal cutting indicated that the developed device has the ability to perform multiple degrees of freedom (DOFs) cutting and to study nanoscale material removal behaviour.
