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Magnetohydrodynamic‑based Internal Cooling System for a Ceramic Cutting Tool:Concept Design,Numerical Study,and Experimental Evalidation

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Nanomanufacturing and Metrology 2023年第4期6卷 60-80页

作者： John O’Hara fengzhou fang Center 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 UniversityTianjin 300072China

The efective removal of the heat generated during mechanical cutting processes is crucial to enhancing tool life and produc-ing workpieces with superior surface fnish.The internal cooling systems used in cutting inserts employ a liquid water-based solvent as the primary medium to transport the excess thermal energy generated during the cutting process.The limitations of this approach are the low thermal conductivity of water and the need for a mechanical input to circulate the coolant around the inner chamber of the cutting tool.In this context,this paper proposes an alternative method in which liquid gallium is used as the coolant in combination with a magnetohydrodynamic(MHD)pump,which avoids the need for an external power source.Using computational fuid dynamics,we created a numerical model of an internal cooling system and then solved it under conditions in which a magnetic feld was applied to the liquid metal.This was followed by a simulation study performed to evaluate the efectiveness of liquid gallium over liquid water.The results of experiments conducted under non-cooling and liquid gallium cooling conditions were analyzed and compared in terms of the tool wear rate.The results showed that after six machining cycles at a cutting speed Vc=250 m min−1,the corner wear VBc rate was 75µm with the coolant of and 48µm with the MHD-based coolant on,representing a decrease of 36%in tool wear.At Vc=900 m min−1,the corner wear VBc rate was 75µm with the coolant of and 246µm with the MHD-based coolant on,representing a decrease of 31%in tool wear.When external cooling using liquid water was added,the results showed at Vc=250 m min−1,the diference between the tool wear rate reduction with the internal liquid gallium coolant relative to the external coolant was 29%.When the cutting speed was increased to Vc=900 m min−1,the diference observed between the internal liquid gallium coolant relative to the external coolant was 16%.The study proves the feasibility of using liquid gallium as a coolant to efectively remove the

关键词： Internal cooling Heat transfer Liquid metal Magnetic feld Cutting tool

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Advances in polishing of internal structures on parts made by laser-based powder bed fusion

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Frontiers of Mechanical Engineering 2023年第1期18卷 93-114页

作者： Mingyue SHEN fengzhou fang Centre of Micro/Nano Manufacturing Technology University College DublinDublin 4Ireland State Key Laboratory of Precision Measuring Technology and Instruments Laboratory of Micro/Nano Manufacturing TechnologyTianjin UniversityTianjin 300072China

The internal structures of metallic products are important in realizing functional applications.Considering the manufacturing of inner structures,laser-based powder bed fusion(L-PBF)is an attractive approach because its layering principle enables the fabrication of parts with customized interior structures.However,the inferior surface quality of L-PBF components hinders its productization progress seriously.In this article,process,basic forms,and applications relevant to L-PBF internal structures are reviewed comprehensively.The causes of poor surface quality and differences in the microstructure and property of the surface features of L-PBF inner structures are presented to provide a perspective of their surface characteristics.Various polishing technologies for L-PBF components with inner structures are presented,whereas their strengths and weaknesses are summarized along with a discussion on the challenges and prospects for improving the interior surface quality of L-PBF parts.

关键词： laser-based powder bed fusion polishing internal structures surface quality surface features post process additive manufacturing

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Nanometric Cutting Mechanism of Cerium-Lanthanum Alloy

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Chinese Journal of Mechanical Engineering 2023年第4期36卷 155-166页

作者： Chenyu Zhao Min Lai fengzhou fang State Key Laboratory of Precision Measuring Technology&Instruments Laboratory of Micro/Nano Manufacturing Technology(MNMT)Tianjin UniversityTianjin 300072China Centre of Micro/Nano Manufacturing Technology(MNMT-Dublin) University College DublinDublin 4Ireland

Cerium-lanthanum alloy is widely used in the green energy industry,and the nanoscale smooth surface of this material is in demand.Nanometric cutting is an effective approach to achieving the ultra-precision machining surface.Molecular dynamics(MD)simulation is usually used to reveal the atomic-scale details of the material removal mechanism in nanometric cutting.In this study,the effects of cutting speed and undeformed chip thickness(UCT)on cutting force and subsurface deformation of the cerium-lanthanum alloy during nanometric cutting are analyzed through MD simulation.The results illustrate that the dislocations,stacking faults,and phase transitions occur in the subsurface during cutting.The dislocations are mainly Shockley partial dislocation,and the increase of temperature and pressure during the cutting process leads to the phase transformation ofγ-Ce(FCC)intoβ-Ce(HCP)andδ-Ce(BCC).β-Ce is mainly distributed in the stacking fault area,whileδ-Ce is distributed in the boundary area between the dislocation atoms andγ-Ce atoms.The cutting speed and UCT affect the distribution of subsurface damage.A thicker deformed layer including dislocations,stacking faults and phase-transformation atoms on the machined surface is generated with the increase in the cutting speed and UCT.Simultaneously,the cutting speed and UCT significantly affect the cutting force,material removal rate,and generated subsurface state.The fluctuations in the cutting force are related to the generation and disappearance of dislocations.This research first studied the nanometric cutting mechanism of the cerium-lanthanum ally,providing a theoretical basis for the development of ultra-precision machining techniques of these materials.

关键词： Cerium-lanthanum alloy Molecular dynamics simulation Nanometric cutting Subsurface damage

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On the Three Paradigms of Manufacturing Advancement

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Nanomanufacturing and Metrology 2023年第4期6卷 92-94页

作者： fengzhou fang State Key Laboratory of Precision Measuring Technology and Instruments Laboratory of Micro/Nano Manufacturing Technology(MNMT)Tianjin UniversityTianjin 300072China Center of Micro/Nano Manufacturing Technology(MNMT-Dublin) University College DublinDublin 4Ireland

Good morning!Before we begin our discussions,I would like to share my thoughts regarding the three paradigms of manufacturing advancement.Since my college days and even earlier,I have been fas-cinated by the concept of a“salon”,a gathering of like-minded people.My interest was rooted in my impression of the Copenhagen group,which organized a salon that allowed everyone to freely express their thoughts on a particular topic.

关键词： everyone gathering discussions

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Fundamentals of atomic and close-to-atomic scale manufacturing:a review

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International Journal of Extreme Manufacturing 2022年第1期4卷 1-20页

作者： Jian Gao Xichun Luo fengzhou fang Jining Sun Centre for Precision Manufacturing DMEMUniversity of StrathclydeGlasgow G11XJUnited Kingdom State Key Laboratory of Precision Measuring Technology&Instruments Laboratory of Micro/Nano Manufacturing Technology(MNMT)Tianjin UniversityTianjin 300072People’s Republic of China Centre of Micro/Nano Manufacturing Technology(MNMT-Dublin) University College DublinDublin 4Ireland School of Mechanical Engineering Dalian University of TechnologyDalian 116024People’s Republic of China

Atomic and close-to-atomic scale manufacturing(ACSM)represents techniques for manufacturing high-end products in various fields,including future-generation computing,communication,energy,and medical devices and materials.In this paper,the theoretical boundary between ACSM and classical manufacturing is identified after a thorough discussion of quantum mechanics and their effects on manufacturing.The physical origins of atomic interactions and energy beams-matter interactions are revealed from the point view of quantum mechanics.The mechanisms that dominate several key ACSM processes are introduced,and a current numerical study on these processes is reviewed.A comparison of current ACSM processes is performed in terms of dominant interactions,representative processes,resolution and modelling methods.Future fundamental research is proposed for establishing new approaches for modelling ACSM,material selection or preparation and control of manufacturing tools and environments.This paper is by no means comprehensive but provides a starting point for further systematic investigation of ACSM fundamentals to support and accelerate its industrial scale implementation in the near future.

关键词： manufacturing ACSM quantum mechanics first-principles atomic interaction energy-matter interaction mechanisms

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Cutting of Graphite at Atomic and Close-to-Atomic Scale Using Flexible Enhanced Molecular Dynamics

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Nanomanufacturing and Metrology 2022年第3期5卷 240-249页

作者： Jinshi Wang fengzhou fang Luan Li State Key Laboratory of Precision Measuring Technology and Instruments Laboratory of Micro/Nano Manufacturing Technology(MNMT)Tianjin UniversityTianjin 300072China Centreof Micro/Nano Manufacturing Technology(MNMT-Dublin) University College DublinDublin 4Ireland

Atomic and close-to-atomic scale manufacturing is the key technology for the production of next-generation devices with atomic precision.As an important approach of mechanical processing,cutting has evolved as a potential candidate to generate an atomically smooth surface;thus,exploring its ultimate capability is significant.In this paper,single-crystal graphite,whose lattice structure and chemical bond property are of representation for demonstration,is selected to study the mechanism of atomic layer removal using molecular dynamics.A localized workpiece,which is dynamically updated on the basis of the tool position,is used to improve the computation efficiency.The principle and bullet points of this modeling method are first introduced,followed by a series of simulations under various undeformed chip thicknesses and tool edge radi.In addition,different potentials for the tool-workpiece interaction are tested,and the effect on the material response is presented.Based on the analysis of deformation,the number of carbon layers removed,and cutting forces,the chip formation mechanism and further understanding of the controllability of cutting at atomic and close-to-atomic scale can be achieved.

关键词： Atomic and close-to-atomic scale Cutting Enhanced molecular dynamics Graphite ACSM

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Numerical Analysis of Microchannels Designed for Heat Sinks

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Nanomanufacturing and Metrology 2022年第4期5卷 354-369页

作者： Matthew McCormack fengzhou fang Jufan Zhang Centre of Micro/Nano Manufacturing Technology(MNMT-Dublin) School of Mechanical&Materials EngineeringUniversity College DublinDublin 4Ireland State Key Laboratory of Precision Measuring Technology and Instruments Laboratory of Micro/Nano Manufacturing Technology(MNMT)Tianjin UniversityTianjin300072China

Conjugate heat transfer is numerically investigated using a three-dimensional computational fluid dynamics approach in various microchannel geometries to identify a high-performance cooling method for piezoelectric ceramic stacks and spindle units in high-precision machines.Straight microchannels with rectangular cross sections are first considered,showing the performance limitations of decreasing the size of the microchannels,so other solutions are needed for high applied heat fluxes.Next,many microchannel designs,focusing on streamwise geometric variation,are compared to straight channels to assess their performances.Sinusoidally varying channels produce the highest heat transfer rates of those studied.Thus,their optimization is considered at a channel width and height of 35 and 100μm,respectively.Heat transfer increases as the amplitude and spatial frequencies of the channels increase due to increased interfacial surface area and enhanced Dean flow.The highest performance efficiencies are observed at intermediate levels of amplitude and frequency,with efficiency decreasing as these geometric parameters are increased further at the onset of flow separation.The sinusoidal channel geometries are then optimized with respect to minimizing the system’s pressure drop for all applied heat fluxes between 5690 and 6510 kW/m2.Doing so created an optimal geometry curve and showed that all geometries in this region had amplitudes close to 40μm.Therefore,imposing a fixed heat flux requirement for a case study of cooling piezoelectric ceramics,the optimized sinusoidal geometry decreases the system pressure drop by 79%relative to a straight channel while maintaining a larger minimum feature size.

关键词： Microchannel Heat sink Conjugate heat transfer Numerical simulation

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Sub-nanometer finishing of polycrystalline tin by inductively coupled plasma-assisted cutting

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Frontiers of Mechanical Engineering 2023年第3期18卷 233-249页

作者： Peng LYU Min LAI Yifei SONG Zhifu XUE fengzhou fang State Key Laboratory of Precision Measuring Technology&Instruments Laboratory of MicroNano Manufacturing TechnologyMNMTTianjinUniversityTianjin300072China Centre of MicroNano Manufacturing Technology-MNMT-Dublin School of Mechanical&Materials EngineeringUniversity College DublinDublin4Ireland

Polycrystalline tin is an ideal excitation material for extreme ultraviolet light sources.However,the existence of grain boundary(GB)limits the surface roughness of polycrystalline tin after single-point diamond turning(SPDT).In this work,a novel method termed inductively coupled plasma(ICP)-assisted cutting was developed for the sub-nanometer finishing of polycrystalline tin.The relationship between ICP power,processing time,and modification depth was established by thermodynamic simulation,and the fitted heat transfer coefficient of polycrystalline tin was 540 W/(m2·K).The effects of large-thermal-gradient ICP treatment on the microstructure of polycrystalline tin were studied.After 0.9 kW ICP processing for 3.0 s,corresponding to the temperature gradient of 0.30 K/μm,the grain size of polycrystalline tin was expanded from a size of approximately 20-80μm to a millimeter scale.The Taguchi method was used to investigate the effects of rotational speed,depth of cut,and feed rate on SPDT.Experiments conducted based on the ICP system indicated that the plasma-assisted cutting method promoted the reduction of the influence of GB steps on the finishing of polycrystalline tin,thereby achieving a surface finish from 8.53 to 0.80 nm in Sa.The results of residual stress release demonstrated that the residual stress of plasma-assisted turning processing after 504 h stress release was 10.7 MPa,while that of the turning process without the ICP treatment was 41.6 MPa.

关键词： plasma-assisted cutting polycrystalline tin single-point diamond turning surface roughness

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Tribological study on the surface modification of metal-on-polymer bioimplants

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Frontiers of Mechanical Engineering 2022年第2期17卷 103-115页

作者： Gang SHEN Jufan ZHANG David CULLITON Ruslan MELENTIEV fengzhou fang Centre of Micro/Nano Manufacturing Technology(MNMT-Dublin) School of Mechanical and Materials EngineeringUniversity College DublinDublin 4Ireland Department of Aerospace Mechanical and Electronic EngineeringInstitute of Technology CarlowCarlowIreland State Key Laboratory of Precision Measuring Technology and Instruments Centre of Micro/Nano Manufacturing Technology(MNMT)Tianjin UniversityTianjin 300072China

The tribological performance of artificial joints is regarded as the main factor of the lifespan of implanted prostheses. The relationship between surface roughness and coefficient of friction (COF) under dry and lubricated conditions is studied. Results show that under dry test, friction coefficient is not reduced all the time with a decrease in surface roughness. On the contrary, a threshold of roughness value is observed, and frictional force increases again below this value. This critical value lies between 40 and 100 nm in Sa (roughness). This phenomenon is due to the transfer of friction mechanisms from abrasion to adhesion. Under wet test, COF always decreases with reduction in surface roughness. This result is mainly attributed to the existence of a thin layer of lubricant film that prevents the intimate contact of two articulating surfaces, thus greatly alleviating adhesion friction. Furthermore, surface texturing technology is successful in improving the corresponding tribological performance by decreasing friction force and mitigating surface deterioration. The even-distribution mode of texturing patterns is most suitable for artificial joints. By obtaining the optimal surface roughness and applying texturing technology, the tribological performance of polymer-based bioimplants can be greatly enhanced.

关键词： artificial joints surface roughness friction surface texturing

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Toward Single-Atomic-Layer Lithography on Highly Oriented Pyrolytic Graphite Surfaces Using AFM-Based Electrochemical Etching

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Nanomanufacturing and Metrology 2022年第1期5卷 32-38页

作者： Wei Han Paven Thomas Mathew Srikanth Kolagatla Brian J.Rodriguez fengzhou fang Centre of Micro/Nano Manufacturing Technology(MNMT-Dublin) University College DublinDublin D04 V1W&I reland Shanghai Engineering Research Centre of Ultra-Precision Optical Manufacturing Fudan UniversityShanghai 200433China School of Physics University College DublinDublin D04 V1W&Ireland Conway Institute of Biomolecular and Biomedical Research University College DublinDublin D04 V1W&Ireland State Key Laboratory of Precision Measuring Technology and Instruments Laboratory of Micro/Nano Manufacturing Technology(MNMT)Tianjin UniversityTianjin 300072China

Atomic force microscopy(AFM)-based electrochemical etching of a highly oriented pyrolytic graphite(HOPG)surface is studied toward the single-atomic-layer lithography of intricate patterns.Electrochemical etching is performed in the water meniscus formed between the AFM tip apex and HOPG surface due to a capillary effect under controlled high relative humid-ity(~75%)at otherwise ambient conditions.The conditions to etch nano-holes,nano-lines,and other intricate patterns are investigated.The clectrochemical reactions of HOPG etching should not generatc debris duc to the conversion of graphite to gaseous CO and CO_(2)based on etching reactions.However,debris is observed on the etched HOPG surface,and incom-plete gasification of carbon occurs during the etching process,resulting in the generation of solid intermediates.Moreover,the applied potential is of critical importance for precise etching,and the precision is also significantly influenced by the AFM tip wear.This study shows that the AFM-based electrochemical etching has the potential to remove the material in a single-atomic-layer precision.This result is likely because the etching process is based on anodic dissolution,resulting in the material removal atom by atom.

关键词： Etching Lithography Electrochemical machining Atomic and close-to-atomic scale manufacturing(ACSM)

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