The Experts below are selected from a list of 11064 Experts worldwide ranked by ideXlab platform
Yilong Wang - One of the best experts on this subject based on the ideXlab platform.
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ultra precision machining of fresnel microstructure on die steel using single crystal Diamond Tool
Journal of Materials Processing Technology, 2011Co-Authors: Yilong Wang, Qingliang Zhao, Yuanjiang Shang, Ing Guo, Lingling ZhaoAbstract:Abstract With the increasing demand for the replication of structured optical elements such as Fresnel lenses and prism arrays, more attention is being paid to the development of ultra-precision Diamond machining technology for the fabrication of die steel molds. However, the machining process would be a catastrophic failure because of rapid and excessive Tool wear if a Diamond Tool is used to machine die steel. In the present paper, a micromachining method for fabricating microstructures on die steel using single crystal Diamond Tool is presented. The presented technology is based on a thermochemical technique that uses plasma nitriding treatment to suppress the rapid and excessive Tool wear in the Diamond machining of steel. Experimental findings revealed that severe chemical Tool wear, which is the main wear mechanism in the Diamond machining of steel, was reduced significantly after plasma nitriding treatment, and a mirror-quality surface with an average surface roughness of 20 nm root-mean-square (RMS) was achieved over a cutting distance of approximately 5.4 km. Furthermore, a Fresnel microstructure with surface roughness RMS better than 40 nm was precisely fabricated on AISI 4140 die steel using single crystal Diamond Tool.
Xichun Luo - One of the best experts on this subject based on the ideXlab platform.
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the investigation of influence of Tool wear on ductile to brittle transition in single point Diamond turning of silicon
Wear, 2016Co-Authors: Amir Mir, Xichun Luo, Jining SunAbstract:Abstract Single point Diamond turning (SPDT) of large functional surfaces on silicon remains a challenge owing to severe Diamond Tool wear. Recently, tremendous efforts have been made in understanding the machining mechanics, especially wear mechanism of Diamond Tools in SPDT of silicon. However, the localised transition of machining mode from ductile to brittle as a result of progressive Tool wear has not been well understood yet. In this paper both experimental and numerical simulation studies of SPDT were performed in an effort to reveal the underlying phenomenon of ductile to brittle transition (DBT) as a consequence of Diamond Tool wear. Series of facing and plunging cuts were performed and the profile of machined surface was evaluated together with the progression of Tool wear. The transition stages from ductile to brittle were identified by analysing the surface profiles of plunging cuts using a scanning electron microscope (SEM) and a 2D contact profilometer and a white light interferometer. The progressive degradation of the cutting edge of Diamond Tool and its wear mechanism was determined using Least Square (LS) arc analysis and SEM. The study reveals that at initial Tool wear stage, the ductile to brittle transition initiates with the formation of lateral cracks which are transformed into brittle pitting damage with further Tool edge degradation. Numerical simulation investigation using smoothed particle hydrodynamics (SPH) was also conducted in this paper in order to gain further insight of variation of stress on the cutting edge due to Tool wear and its influence on brittle to ductile transition. A significant variation in frictional resistance to shear deformation as well as position shift of the maximum stress values was observed for the worn Tools. The magnitude and distribution of hydrostatic stress were also found to change significantly along the cutting edge of new and worn Diamond Tools.
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influence of temperature and crystal orientation on Tool wear during single point Diamond turning of silicon
Wear, 2012Co-Authors: Saurav Goel, Xichun Luo, R L Reuben, Hongming PenAbstract:Owing to the capricious wear of cutting Tools, ultra precision manufacturing of silicon through single point Diamond turning (SPDT) operation becomes a challenging task. It thus becomes non-trivial to understand the contribution of temperature and crystal orientation during the SPDT process in order to suppress Tool wear. Molecular dynamics (MD) simulation is an appropriate Tool to study nanoscale processes occurring at the femtosecond/picosecond timescale which cannot otherwise be studied experimentally or by the finite element method (FEM). Accordingly, MD simulation has been deployed with a realistic analytical bond order potential (ABOP) formalism based potential energy function to simulate the single point Diamond turning operation of single crystal silicon in order to understand the influence of temperature and crystal orientation on the Tool wear mechanism. Results showed the strong influence of crystal orientation on the wear resistance of a Diamond Tool; cubic orientation performed better than dodecahedral orientation. It was also observed that high pressure phase transformation (HPPT) in the cutting zone was accompanied by the formation of dangling bonds of silicon. Under the influence of cutting temperature, the newly formed dangling bonds of silicon chemically combine with the pre-existing dangling bonds on the surface of the Diamond Tool resulting in the formation of silicon carbide (SiC), the main appearance of which was evident at the Tool flank face. Continuous abrasion of the Diamond cutting Tool with SiC causes sp3–sp2 disorder of the Diamond Tool. Hence, both these processes proceed in tandem with each other. The mechanism proposed here is in good agreement with a recent experimental study, where silicon carbide and carbon like particles were observed using X-ray photoelectron spectroscope (XPS) technology after machining a silicon wafer with a Diamond Tool.
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molecular dynamics simulation model for the quantitative assessment of Tool wear during single point Diamond turning of cubic silicon carbide
Computational Materials Science, 2012Co-Authors: Saurav Goel, Xichun Luo, R L ReubenAbstract:Silicon carbide (SiC) is a material of great technological interest for engineering applications concerning hostile environments where silicon-based components cannot work (beyond 623 K). Single point Diamond turning (SPDT) has remained a superior and viable method to harness process efficiency and freeform shapes on this harder material. However, it is extremely difficult to machine this ceramic consistently in the ductile regime due to sudden and rapid Tool wear. It thus becomes non trivial to develop an accurate understanding of Tool wear mechanism during SPDT of SiC in order to identify measures to suppress wear to minimize operational cost. In this paper, molecular dynamics (MD) simulation has been deployed with a realistic analytical bond order potential (ABOP) formalism based potential energy function to understand Tool wear mechanism during single point Diamond turning of SiC. The most significant result was obtained using the radial distribution function which suggests graphitization of Diamond Tool during the machining process. This phenomenon occurs due to the abrasive processes between these two ultra hard materials. The abrasive action results in locally high temperature which compounds with the massive cutting forces leading to sp3–sp2 order–disorder transition of Diamond Tool. This represents the root cause of Tool wear during SPDT operation of cubic SiC. Further testing led to the development of a novel method for quantitative assessment of the progression of Diamond Tool wear from MD simulations.
Toshimichi Moriwaki - One of the best experts on this subject based on the ideXlab platform.
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Tool wear control in single crystal Diamond cutting of steel by using the ultra intermittent cutting method
International Journal of Machine Tools & Manufacture, 2009Co-Authors: Youngchan Song, Kentaro Nezu, Chunhong Park, Toshimichi MoriwakiAbstract:Abstract Excessive Tool wear is a major drawback to the ultraprecision cutting of steel with geometrically defined single-crystal Diamond Tools. This paper presents a new approach to reduce this wear. In general, the wear of the Diamond Tool is due to chemical reactions such as diffusion into the steel, oxidation, graphitization, and carbide formation under cutting conditions of high temperature and high pressure. To suppress these types of chemical reactions, the contact time between the Diamond Tool and the steel in the cutting process was controlled by intermittent cutting method such as fly-cutting or milling. A series of intermittent cutting experiments were carried out to control the Tool–workpiece contact time in one cutting cycle by changing the cutting speed and cutting length in each cutting cycle. The experimental results showed that the Diamond Tool wear was highly dependent on the Tool–workpiece contact time, regardless of the cutting speed, and that the wear was greatly reduced by decreasing the contact time to less than 0.3 ms under these cutting conditions. It is expected that steel can be successfully cut with a single-crystal Diamond Tool by controlling the Tool–workpiece contact time.
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Ultra-Precision Cutting of Brittle Materials with Ultrasonic Vibrated Diamond Tool
Materials Science Forum, 2006Co-Authors: Eiji Shamoto, Nan Liu, Toshimichi MoriwakiAbstract:The influence of the ultrasonic vibrated Diamond Tool on the transition of ductile cutting to brittle cutting of the glasses is investigated by facing turning. It is understood that the critical depth of cut for the ductile cutting of the brittle materials is increased obviously by the ultrasonic vibrated Diamond Tool. The optical quality surface of the glasses is obtained, the surface roughness of which is less than0.03m. Finally, the relation between the roughness of machined surface and the cutting distance is studied experimentally.
Hongming Pen - One of the best experts on this subject based on the ideXlab platform.
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influence of temperature and crystal orientation on Tool wear during single point Diamond turning of silicon
Wear, 2012Co-Authors: Saurav Goel, Xichun Luo, R L Reuben, Hongming PenAbstract:Owing to the capricious wear of cutting Tools, ultra precision manufacturing of silicon through single point Diamond turning (SPDT) operation becomes a challenging task. It thus becomes non-trivial to understand the contribution of temperature and crystal orientation during the SPDT process in order to suppress Tool wear. Molecular dynamics (MD) simulation is an appropriate Tool to study nanoscale processes occurring at the femtosecond/picosecond timescale which cannot otherwise be studied experimentally or by the finite element method (FEM). Accordingly, MD simulation has been deployed with a realistic analytical bond order potential (ABOP) formalism based potential energy function to simulate the single point Diamond turning operation of single crystal silicon in order to understand the influence of temperature and crystal orientation on the Tool wear mechanism. Results showed the strong influence of crystal orientation on the wear resistance of a Diamond Tool; cubic orientation performed better than dodecahedral orientation. It was also observed that high pressure phase transformation (HPPT) in the cutting zone was accompanied by the formation of dangling bonds of silicon. Under the influence of cutting temperature, the newly formed dangling bonds of silicon chemically combine with the pre-existing dangling bonds on the surface of the Diamond Tool resulting in the formation of silicon carbide (SiC), the main appearance of which was evident at the Tool flank face. Continuous abrasion of the Diamond cutting Tool with SiC causes sp3–sp2 disorder of the Diamond Tool. Hence, both these processes proceed in tandem with each other. The mechanism proposed here is in good agreement with a recent experimental study, where silicon carbide and carbon like particles were observed using X-ray photoelectron spectroscope (XPS) technology after machining a silicon wafer with a Diamond Tool.
Lingling Zhao - One of the best experts on this subject based on the ideXlab platform.
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ultra precision machining of fresnel microstructure on die steel using single crystal Diamond Tool
Journal of Materials Processing Technology, 2011Co-Authors: Yilong Wang, Qingliang Zhao, Yuanjiang Shang, Ing Guo, Lingling ZhaoAbstract:Abstract With the increasing demand for the replication of structured optical elements such as Fresnel lenses and prism arrays, more attention is being paid to the development of ultra-precision Diamond machining technology for the fabrication of die steel molds. However, the machining process would be a catastrophic failure because of rapid and excessive Tool wear if a Diamond Tool is used to machine die steel. In the present paper, a micromachining method for fabricating microstructures on die steel using single crystal Diamond Tool is presented. The presented technology is based on a thermochemical technique that uses plasma nitriding treatment to suppress the rapid and excessive Tool wear in the Diamond machining of steel. Experimental findings revealed that severe chemical Tool wear, which is the main wear mechanism in the Diamond machining of steel, was reduced significantly after plasma nitriding treatment, and a mirror-quality surface with an average surface roughness of 20 nm root-mean-square (RMS) was achieved over a cutting distance of approximately 5.4 km. Furthermore, a Fresnel microstructure with surface roughness RMS better than 40 nm was precisely fabricated on AISI 4140 die steel using single crystal Diamond Tool.