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Optimal tool design in micro-milling of difficult-to-machine materials

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Advances in Manufacturing 2023年第2期11卷 222-247页

作者： Lorcan O'Toole feng-zhou fang Centre of Micro/Nano Manufacturing Technology(MNMT-Dublin) University College DublinDublin 4Ireland State Key Laboratory of Precision Measuring Technology and Instruments Laboratory of Micro/Nano Manufacturing Technology(MNMT)Tianjin UniversityTianjin300072People's Republic of China

The limitations of significant tool wear and tool breakage of commercially available fluted micro-end mill tools often lead to ineffective and inefficient manufacturing,while surface quality and geometric dimensions remain unacceptably *** is especially true for machining of difficult-to-machine(DTM)materials,such as super alloys and *** conventional fluted micro-tool designs are generally down scaled from the macro-milling tool ***,simply scaling such designs from the macro to micro domain leads to inherent design flaws,such as poor tool rigidity,poor tool strength and weak cutting edges,ultimately ending in tool ***,in this article a design process is first established to determine optimal micro-end mill tool designs for machining some typical DTM materials commonly used in manufacturing orthopaedic implants and micro-feature *** design process focuses on achieving robust stiffness and mechanical strength to reduce tool wear,avoid tool chipping and tool breakage in order to efficiently machine very hard ***,static stress and deflection finite element analysis(FEA)is carried out to identify stiffness and rigidity of the tool design in relation to the maximum deformations,as well as the Von Mises stress distribution at the cutting edge of the designed *** analysis and further optimisation of the FEA results,a verified optimum tool design is established for micro-milling DTM *** experimental study is then carried out to compare the optimum tool design to commercial tools,in regards to cutting forces,tool wear and surface quality.

关键词： Precision machining Micro-milling Difficult-to-machine(DTM) Tool wear Micro-tool design Surface quality

Nanometric polishing of lutetium oxide by plasma-assisted etching

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Advances in Manufacturing 2020年第4期8卷 440-446页

作者： Peng Lyu Min Lai feng-zhou fang State Key Laboratory of Precision Measuring Technology and Instruments Centre of Micro/Nano Manufacturing Technology(MNMT)Tianjin UniversityTianjin 300072People’s Republic of China Centre of Micro/Nano Manufacturing Technology(MNMTDublin) School of Mechanical and Materials EngineeringUniversity College Dublin.Dublin 4Ireland

Plasma-assisted etching,in which the irradiation of hydrogen plasma and inorganic acid etching are integrated,is proposed as a novel polishing method for sesquioxide *** means of this approach,low damage and even damage-free surfaces with a high material removal rate can be achieved in lutetium oxide surface *** of transmission electron microscopy and X-ray photoelectron spectroscopy reveal that plasma hydrogenation converts the sesquioxide into hydroxide,which leads a high efficient way to polish the *** influences of process conditions on the etching boundary and surface roughness are also qualitatively investigated using scanning electron microscope and white light *** newly developed process is verified by a systematic experiment.

关键词： Plasma-assisted etching Lutetium oxide Surface roughness Subsurface damage

State of the art of bioimplants manufacturing： part II

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Advances in Manufacturing 2018年第1期6卷 137-154页

作者： Cheng-Wei Kang feng-zhou fang Centre of MicroNano Manufacturing Technology (MNMT- Dublin) University College Dublin Belfield Ireland State Key Laboratory of Precision Measuring Technology & Instruments Centre of MicroNano Manufacturing Technology Tianjin University Tianjin 300072 People's Republic of China

The manufacturing of bioimplants not only involves selecting proper biomaterials with satisfactory bulk physicochemical properties, but also requires special treatments on surface chemistry or topography to direct a desired host response. The lifespan of a bioimplant is also critically restricted by its surface properties. Therefore, developing proper surface treatment technologies has become one of the research focuses in biomedical engineering. This paper covers the recent progress of surface treatment of bioimplants from the aspects of coating and topography modification. Pros and cons of various tech- nologies are discussed with the aim of providing the most suitable method to be applied for different biomedical products. Relevant techniques to evaluate wear, corrosion and other surface properties are also reviewed.

关键词： Bioimplant Precision manufacturing Surfacetreatment Evaluation

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In vitro evaluation of artificial joints: a comprehensive review

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Advances in Manufacturing 2019年第1期7卷 1-14页

作者： Gang Shen Ju-Fan Zhang feng-zhou fang Centre of Micro/Nano Manufacturing Technology (MNMTDublin) University College Dublin Dublin Ireland State Key Laboratory of Precision Measuring Technology and Instruments Centre of Micro/Nano Manufacturing Technology (MNMT) Tianjin University Tianjin 300072 People's Republic of China

Development of artificial joints is a great progress for joint replacement operations of human being, but the short longevity of prostheses has concerned both industries and researchers since the advent of modem implants. Thus, continuous improvements have been made alongside the clinical applications. The methodologies to inspect the potential properties of new designs have also seen many advances. The test machines have evolved from easy pin-on-disk configuration to the modem joint simulator. Besides, various wear traces provided by testing machines are investigated greatly, and multi-directional files are recommended as motion profiles for in vitro testing. The typical testing parameters, like sliding speed or loading profile, are discussed in this article, and their working mechanisms are described in detail. Meanwhile, the calf or bovine serum has been regarded as the gold standard for testing lubricant, and the future trend of fluid will be focused on investigating the effects of lubricant composites on the tribological properties. Hard particles and proteins are discussed as well, and their effects on the wear mechanisms are the focus. Finally, various approaches to measure the wear rate, wear factor and the thickness of lubricant film are presented, and suggestions are given for the development in future.

关键词： Artificial joint Methodology Testing parameter Wear rate

Material removal at atomic and close-to-atomic scale by highenergy photon:a case study using atomistic-continuum method

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Advances in Manufacturing 2022年第1期10卷 59-71页

作者： Hao-Jie An Jin-Shi Wang feng-zhou fang State Key Laboratory of Precision Measuring Technology and Instruments Laboratory of MicroNano Manufacturing Technology(MNMT)Tianjin UniversityTianjin 300072People’s Republic of China Centre of MicroNano Manufacturing Technology(MNMTDublin) School of Mechanical and Materials EngineeringUniversity College DublinDublin 4Ireland

Extreme ultraviolet(EUV)light plays an important role in various fields such as material characterization and semiconductor *** is also a potential approach in material fabrication at atomic and close-to-atomic ***,the material removal mechanism has not yet been fully *** paper studies the interaction of a femtosecond EUV pulse with monocrystalline silicon using molecular dynamics(MD)coupled with a two-temperature model(TTM).The photoionization mechanism,an important process occurring at a short wavelength,is introduced to the simulation and the results are compared with those of the traditional *** processes including photoionization,atom desorption,and laser-induced shockwave are discussed under various fluencies,and the possibility of single atomic layer removal is *** show that photoionization and the corresponding bond breakage are the main reasons of atom *** method developed can be further employed to investigate the interaction between high-energy photons and the material at moderate fluence.

关键词： Extreme ultraviolet(EUV) Molecular dynamics(MD) Two-temperature model(TTM)Photoionization Atomic and close-to-atomic scale manufacturing(ACSM)

Precision micro-milling process:state of the art

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Advances in Manufacturing 2021年第2期9卷 173-205页

作者： Lorcan O’Toole Cheng-Wei Kang feng-zhou fang Center of Micro/Nano Manufacturing Technology(MNMT-Dublin) University College DublinDublin 4Ireland State Key Laboratory of Precision Measuring Technology and Instruments Center of Micro/Nano Manufacturing Technology(MNMT)Tianjin UniversityTianjin 300072People’s Republic of China

Micro-milling is a precision manufacturing process with broad applications across the biomedical,electronics,aerospace,and aeronautical industries owing to its versatility,capability,economy,and efficiency in a wide range of *** particular,the micro-milling process is highly suitable for very precise and accurate machining of mold prototypes with high aspect ratios in the microdomain,as well as for rapid micro-texturing and micro-patterning,which will have great importance in the near future in bio-implant *** is particularly true for machining of typical difficult-to-machine materials commonly found in both the mold and orthopedic implant ***,inherent physical process constraints of machining arise as macromilling is scaled down to the *** leads to some physical phenomena during micromilling such as chip formation,size effect,and process *** dynamic physical process phenomena are introduced and discussed in *** is important to remember that these phenomena have multifactor effects during micro-milling,which must be taken into consideration to maximize the performance of the *** most recent research on the micro-milling process inputs is discussed in detail from a process output perspective to determine how the process as a whole can be ***,newly developed processes that combine conventional micro-milling with other technologies,which have great prospects in reducing the issues related to the physical process phenomena,are also ***,the major applications of this versatile precision machining process are discussed with important insights into how the application range may be further broadened.

关键词： Precision machining Micro-milling Size effect Deflection Runout Tool wear

Numerical study via total Lagrangian smoothed particle hydrodynamics on chip formation in micro cutting

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Advances in Manufacturing 2020年第2期8卷 144-159页

作者： Jin-Shi Wang Xiao-Dong Zhang feng-zhou fang State Key Laboratory of Precision Measuring Technology and Instruments Centre of Micro/Nano Manufacturing Technology(MNMT)Tianjin UniversityTianjin 300072People's Republic of China Centre of Micro/Nano Manufacturing Technology(MNMT-Dublin) University College DublinDublinIreland

Numerical simulation is an effective approach in studying cutting *** widely used methods for cutting simulation include finite element analysis and molecular ***,there exist some intrinsic shortcomings when using a mesh-based formulation,and the capable scale of molecular dynamics is extremely *** contrast,smoothed particle hydrodynamics(SPH)is a candidate to combine the advantages of *** is a particle method which is suitable for simulating the large deformation process,and is formulated based on continuum mechanics so that large scale problems can be handled in *** a result,SPH has also become a main way for the cutting *** some issues arise while using conventional SPH to handle solid materials,the total Lagrangian smoothed particle hydrodynamics(TLSPH)is *** instabilities would still occur during the cutting,which is a critical issue to *** paper studies the effects of TLSPH settings and cutting model parameters on the numerical instability,as well as the chip formation *** deformation,stress field and cutting forces are analyzed as *** shows that the hourglass coefficient,critical pairwise deformation and time step are three important parameters to control the stability of the simulation,and a strategy on how to adjust them is provided.

关键词： Cutting Total Lagrangian smoothed particle hydrodynamics(TLSPH) Numerical instability Chip formation

Molecular dynamics study on surface formation and phase transformation in nanometric cutting of β-Sn

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Advances in Manufacturing 2022年第3期10卷 356-367页

作者： Zhi-Fu Xue Min Lai Fei-Fei Xu feng-zhou fang State Key Laboratory of Precision Measuring Technology and Instruments Laboratory of Micro-Nano Manufacturing TechnologyTianjin UniversityTianjin 300072People's Republic of China

Atomic motion and surface formation in the nanometric cutting process ofβ-Sn are investigated using molecular dynamics(MD).A stagnation region is observed that changes the shape of the tool edge involved in nanometric cutting,resulting in a fluctuation in the cutting *** is found that single-crystal tin releases the high compressive stress generated under the tool pressure through slip and phase *** tin transformation proceeds from aβ-Sn structure to a bct-Sn *** effects of the cutting speed,undeformed chip thickness(UCT)and tool edge radius on material removal are also explored.A better surface is obtained through material embrittlement caused by a higher *** addition,a smaller UCT and sharper tool edge help reduce subsurface damage.

关键词： β-Sn Molecular dynamics(MD) Nanometric cutting Surface formation Phase transformation

Chiral surface waves supported by biaxial hyperbolic metamaterials

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Light(Science & Applications) 2015年第1期4卷 187-191页

作者： Wen-Long Gao feng-zhou fang Yong-Min Liu Shuang Zhang State Key Laboratory of Precision Measuring Technology and Instruments Tianjin UniversityTianjin 300072China School of Physics&Astronomy University of BirminghamBirmingham B152TTUK Department of Mechanical and Industrial Engineering Northeastern UniversityBostonMA 02115USA Department of Electrical and Computer Engineering Northeastern UniversityBostonMA 02115USA

We discover a new kind of surface wave on biaxial hyperbolic metamaterial,which,in the k-space,connects the two diabolical points(or conical singularities)of the equifrequency ***,the propagation of such surface wave is found to be sensitive to the refractive index of the surrounding dielectric medium,showing a convex,concave or flat phase front when the refractive index is ***,the surface wave shows an elliptically polarized state,in which helicity is dependent on the propagation *** feature can be utilized for the spin-controllable excitation of surface waves,opening a gateway towards integrated photonic circuits with reconfigurable functionalities.

关键词： metamaterial spin orbital coupling surface wave