Brittle materials are widely used for producing important components in the industry of optics,optoelectronics,and semiconductors.Ultraprecision machining of brittle materials with high surface quality and surface int...Brittle materials are widely used for producing important components in the industry of optics,optoelectronics,and semiconductors.Ultraprecision machining of brittle materials with high surface quality and surface integrity helps improve the functional performance and lifespan of the components.According to their hardness,brittle materials can be roughly divided into hard-brittle and soft-brittle.Although there have been some literature reviews for ultraprecision machining of hard-brittle materials,up to date,very few review papers are available that focus on the processing of soft-brittle materials.Due to the‘soft’and‘brittle’properties,this group of materials has unique machining characteristics.This paper presents a comprehensive overview of recent advances in ultraprecision machining of soft-brittle materials.Critical aspects of machining mechanisms,such as chip formation,surface topography,and subsurface damage for different machining methods,including diamond turning,micro end milling,ultraprecision grinding,and micro/nano burnishing,are compared in terms of tool-workpiece interaction.The effects of tool geometries on the machining characteristics of soft-brittle materials are systematically analyzed,and dominating factors are sorted out.Problems and challenges in the engineering applications are identified,and solutions/guidelines for future R&D are provided.展开更多
The lightness and high strength-to-weight ratio of the magnesium alloy have attracted more interest in various applications.However,micro/nanostructure generation on their surfaces remains a challenge due to the flamm...The lightness and high strength-to-weight ratio of the magnesium alloy have attracted more interest in various applications.However,micro/nanostructure generation on their surfaces remains a challenge due to the flammability and ignition.Motivated by this,this study proposed a machining process,named the ultraprecision diamond surface texturing process,to machine the micro/nanostructures on magnesium alloy surfaces.Experimental results showed the various microstructures and sawtooth-shaped nanostructures were successfully generated on the AZ31B magnesium alloy surfaces,demonstrating the effectiveness of this proposed machining process.Furthermore,sawtooth-shaped nanostructures had the function of inducing the optical effect and generating different colors on workpiece surfaces.The colorful letter and colorful flower image were clearly viewed on magnesium alloy surfaces.The corresponding cutting force,chip morphology,and tool wear were systematically investigated to understand the machining mechanism of micro/nanostructures on magnesium alloy surfaces.The proposed machining process can further improve the performances of the magnesium alloy and extend its functions to other fields,such as optics.展开更多
In current precision and ultraprecision machining practice,the positioning and control of actuation systems,such as slideways and spindles,are heavily dependent on the use of linear or rotary encoders.However,position...In current precision and ultraprecision machining practice,the positioning and control of actuation systems,such as slideways and spindles,are heavily dependent on the use of linear or rotary encoders.However,positioning control is passive because of the lack of direct monitoring and control of the tool and workpiece positions in the dynamic machining process and also because it is assumed that the machining system is rigid and the cutting dynamics are stable.In ultraprecision machining of freeform surfaces using slow tool servo mode in particular,however,account must be taken of the machining dynamics and dynamic synchronization of the cutting tool and workpiece positioning.The important question also arises as to how ultraprecision machining systems can be designed and developed to work better in this application scenario.In this paper,an innovative dynamics-oriented engineering approach is presented for ultraprecision machining of freeform surfaces using slow tool servo mode.The approach is focused on seamless integration of multibody dynamics,cutting forces,and machining dynamics,while targeting the positioning and control of the tool–workpiece loop in the machining system.The positioning and motion control between the cutting tool and workpiece surface are further studied in the presence of interfacial interactions at the tool tip and workpiece surface.The interfacial cutting physics and dynamics are likely to be at the core of in-process monitoring applicable to ultraprecision machining systems.The approach is illustrated using a virtual machining system developed and supported with simulations and experimental trials.Furthermore,the paper provides further explorations and discussion on implementation perspectives of the approach,in combination with case studies,as well as discussing its fundamental and industrial implications.展开更多
Large-sized potassium dihydrogen phosphate(KDP)crystals are an irreplaceable nonlinear optical component in an inertial confinement fusion project.Restricted by the size,previous studies have been aimed mainly at the ...Large-sized potassium dihydrogen phosphate(KDP)crystals are an irreplaceable nonlinear optical component in an inertial confinement fusion project.Restricted by the size,previous studies have been aimed mainly at the removal principle and surface roughness of small-sized KDP crystals,with less research on flatness.Due to its low surface damage and high machining efficiency,water dissolution ultraprecision continuous polishing(WDUCP)has become a good technique for processing large-sized KDP crystals.In this technique,the trajectory uniformity of water droplets can directly affect the surface quality,such as flatness and roughness.Specifically,uneven trajectory distribution of water droplets on the surface of KDP crystals derived from the mode of motion obviously affects the surface quality.In this study,the material removal mechanism of WDUCP was introduced.A simulation of the trajectory of water droplets on KDP crystals under different eccentricity modes of motion was then performed.Meanwhile,the coefficient of variation(CV)was utilized to evaluate the trajectory uniformity.Furthermore,to verify the reliability of the simulation,some experimental tests were also conducted by employing a large continuous polisher.The results showed that the CV varied from 0.67 to 2.02 under the certain eccentricity mode of motion and varied from 0.48 to 0.65 under the uncertain eccentricity mode of motion.The CV of uncertain eccentricity is always smaller than that of certain eccentricity.Hence,the uniformity of trajectory was better under uncertain eccentricity.Under the mode of motion of uncertain eccentricity,the initial surface texture of the100 mm×100 mm×10 mm KDP crystal did achieve uniform planarization.The surface root mean square roughness was reduced to 2.182 nm,and the flatness was reduced to 22.013μm.Therefore,the feasibility and validity of WDUCP for large-sized KDP crystal were verified.展开更多
The characteristics of several different linear motors have been investigated, and the feed drive system with linear motor instead of screw-nut mechanism has been built for a submicro ultraprecision turning machine. I...The characteristics of several different linear motors have been investigated, and the feed drive system with linear motor instead of screw-nut mechanism has been built for a submicro ultraprecision turning machine. In the control system for the feed drive system arranged as "T", both P-position and PI-speed control loops are used. The feedback variable is obtained from a double frequecy laser interferometor. Experiments show that the feed drive with linear motor is simple in construction, and that its dynamics is better than others. So the machining accuracy of the workpiece machined has been successfully improved.展开更多
Ultraprecision machining of titanium alloy(Ti-6Al-4V)remains challenging due to its low thermal conductivity,pronounced elastic recovery,and tool-workpiece adhesion,all of which degrade surface integrity and accelerat...Ultraprecision machining of titanium alloy(Ti-6Al-4V)remains challenging due to its low thermal conductivity,pronounced elastic recovery,and tool-workpiece adhesion,all of which degrade surface integrity and accelerate tool wear.This study systematically investigates the effect of a weak magnetic field(~0.015 T)on the single-point diamond turning and microgroove machining of Ti-6Al-4V flat surfaces,microgroove arrays,and microstructures.Four machining conditions were designed to decouple the magnetic field effect:no field(nM-nM),field applied only during microgroove cutting(nM-M),field applied only during finish turning(M-nM),and field applied throughout(M-M).Theoretical analyses and experiments have demonstrated that the rotation of the conductive titanium alloy within a magnetic field induces eddy currents,generating Lorentz damping,which suppresses vibrations in Y/Z directions,enhances cutting stability,and improves surface finish.The results showed that magnetic-field assistance significantly reduces both the principal cutting forces and noise levels,and that performance under M-nM conditions surpasses that under nM-M conditions,suggesting that the finishcutting process exerts a stronger influence on the quality of microgroove machining.Microstructures machined under M-M conditions exhibit exceptional dimensional accuracy and uniformity,with groove depths approaching a nominal value of 4μm(reaching~3.98μm under the M-M conditions)and minimal burrs or microcracks forming at boundaries.The findings enhance the understanding of the magnetic field-assisted ultraprecision cutting of titanium alloys,enabling the manufacturing of high-quality micro/nanostructures for applications in aerospace,biomedicine,and optical components.展开更多
In an ultraprecision turning process for small-diameter optical aspheric workpieces,tool-profile errors induce mid-frequency errors in the workpiece profile,limiting further improvements in precision.In this study,an ...In an ultraprecision turning process for small-diameter optical aspheric workpieces,tool-profile errors induce mid-frequency errors in the workpiece profile,limiting further improvements in precision.In this study,an XZB three-axis linkage ultraprecision machining method is proposed,and the effects of tool-center errors are analyzed.To address residual errors in Z-direction profile-error compensation,a workpiece normal-profile-error compensation method is proposed.After XZB three-axis linkage turning and compensation,the workpiece profile error(PV)reaches 0.086μm,surpassing the precision of XZ two-axis machining,and mid-frequency errors are reduced.Compared with Z-direction profile-error compensation,which results in a profile error of 0.092μm,normal-profile-error compensation reduces PV to 0.047μm,considerably improving aspheric accuracy.Experimental results demonstrate that XZB three-axis linkage machining significantly improves the aspheric workpiece profile,enhancing both its accuracy and surface quality.This method reduces mid-frequency errors,and the subsequent application of normal-profile-error compensation further refines the profile,achieving higher overall accuracy.展开更多
Single-point diamond turning(SPDT)is an ultraprecision technique for manufacturing high-precision microlens arrays(MLAs).This method achieves optical surface machining with excellent accuracy,thereby eliminating the n...Single-point diamond turning(SPDT)is an ultraprecision technique for manufacturing high-precision microlens arrays(MLAs).This method achieves optical surface machining with excellent accuracy,thereby eliminating the need for secondary processing techniques.However,the application of SPDT for fabricating large-area MLAs is significantly limited by tool wear,which indirectly affects surface roughness due to the declined accuracy of the cutting edge.Severe tool wear can lead to failure during microstructure machining.In theory,SPDT stitching fabrication through tool replacement enables the management of cutting tool wear,facilitating MLAs production with high-precision and large-area.Nevertheless,maintaining the repositioning accuracy of the new tool relative to the worn tool remains a significant challenge.This study introduces an in-situ optical ranging(ISOR)method to measure and compensate for the tool replacement positioning error between the new and worn tools in accordance with the different feed directions during MLAs production.An in-situ measurement system comprising an optical microscope and a linear variable displacement transducer(LVDT)was developed.The positional relationship between the new and worn tools was determined using the measurement results from the optical microscope and LVDT in their respective directions.MLAs stitching fabrication experiment was conducted using the proposed method and system.The results confirmed the effectiveness and feasibility of the proposed method for the stitching fabrication of MLAs.The measurement and compensation processes were completed within 20 min,achieving an accuracy of 0.1μm.This study provides an effective strategy for manufacturing large-area optical surfaces with high precision and efficiency.展开更多
Wedge-shaped microstructures have the ability to reproduce the excellent adhesive properties of geckos’feet because of their unique anisotropic structure.In particular,the controllability of the wedge-shaped microstr...Wedge-shaped microstructures have the ability to reproduce the excellent adhesive properties of geckos’feet because of their unique anisotropic structure.In particular,the controllability of the wedge-shaped microstructures on adhesion is beneficial to the undisturbed grasp or the capture of space targets.However,the problem currently remains of how to process it efficiently and with high quality.Here a strategy called ultraprecision multistep and layered scribing is proposed for the manufacture of the biomimetic controllable adhesive surface.The results show that the metal master mold prepared based on the manufacturing strategy has not only good surface topography but also high reliability and durability.Furthermore,the controllable adhesive surface of 1.96 cm2,fabricated by the proposed manufacturing strategy,has a normal adhesion of 1.012 N,and the corresponding shear friction and adhesion coefficient are 3.105 N and 4.82,respectively.Additionally,the controllable adhesive surface has been shown to be approximately superhydrophobic and also to possess the properties of controllable adhesion and dynamic adhesion.Also,after 250 adhesion-detachment cycles,the normal adhesion and shear friction only decrease by 5%and 3%,respectively.The research realizes an environmentally friendly and efficient method by which to manufacture a durable metal mold for fabricating a biomimetic controllable adhesive surface,laying a foundation for its effective application in the adherence of space-floating targets.展开更多
Ultraprecision diamond machining and high volume molding for affordable high precision high performance optical elements are becoming a viable process in optical industry for low cost high quality microoptical compone...Ultraprecision diamond machining and high volume molding for affordable high precision high performance optical elements are becoming a viable process in optical industry for low cost high quality microoptical component manufacturing. In this process, first high precision microoptical molds are fabricated using ultraprecision single point diamond machining followed by high volume production methods such as compression or injection molding. In the last two decades, there have been steady improvements in ultraprecision machine design and performance, particularly with the introduction of both slow tool and fast tool servo. Today optical molds, including freeform surfaces and microlens arrays, are routinely diamond machined to final finish without post machining polishing. For consumers, compression mold- ing or injection molding provide efficient and high quality optics at extremely low cost. In this paper, first ultrapreci- sion machine design and machining processes such as slow tool and fast too servo are described then both compression molding and injection molding of polymer optics are discussed. To implement precision optical manufacturing by molding, numerical modeling can be included in the future as a critical part of the manufacturing process to ensure high product quality.展开更多
Deburring of high-precision components to their micrometer features without any damage is very important but of great difficulty as the burr-to-functionality size ratio increases. To this end, this paper proposes a ne...Deburring of high-precision components to their micrometer features without any damage is very important but of great difficulty as the burr-to-functionality size ratio increases. To this end, this paper proposes a new deburring method in which the micro burr should be directly removed based on ultraprecision cutting with the designed monocrystalline diamond tool. To determine the feasibility of the proposed method, this paper applies it for deburring of the precision working edge of the servo valve core. Firstly, the monocrystalline diamond tool is carefully designed by covering a variety of topics like rake angle,clearance angle, edge radius. Then, the finite element(FE) simulation was conducted to characterize the deburring performance during the removal of the micro burr produced by the single abrasive grinding. Finally, an innovative self-designed deburring system was introduced and the deburring process was evaluated in terms of cutting forces, temperatures, tool wear mechanisms and deburring quality of the working edges by experiments. The FE simulation results indicate the suitability of the proposed deburring method. Meanwhile, the experimental findings agree well with simulation results and show that ultraprecision cutting with the specialized monocrystalline diamond tool could be successfully used for deburring of servo valve core edge without any damage. This work can provide technical guidance for similar engineering applications, and thus brings an increase to the machining efficiency for the manufacture of precision components.展开更多
Precision is one of the most important aspects of manufacturing.High precision creates high quality,high performance,exchangeability,reliability,and added value for industrial products.Over the past decades,remarkable...Precision is one of the most important aspects of manufacturing.High precision creates high quality,high performance,exchangeability,reliability,and added value for industrial products.Over the past decades,remarkable advances have been achieved in the area of high-precision manufacturing technologies,where the form accuracy approaches the nanometer level and surface roughness the atomic level.These extremely high precision manufacturing technologies enable the development of high-performance optical elements,semiconductor substrates,biomedical parts,and so on,thereby enhancing the ability of human beings to explore the macroand microscopic mysteries and potentialities of the natural world.In this paper,state-of-the-art high-precision material removal manufacturing technologies,especially ultraprecision cutting,grinding,deterministic form correction polishing,and supersmooth polishing,are reviewed and compared with insights into their principles,methodologies,and applications.The key issues in extreme precision manufacturing that should be considered for future R&D are discussed.展开更多
Microlens arrays are the key component in the next generation of 3D imaging system, for it exhibits some good optical properties such as extremely large field of view angles, low aberration and distortion, high tempor...Microlens arrays are the key component in the next generation of 3D imaging system, for it exhibits some good optical properties such as extremely large field of view angles, low aberration and distortion, high temporal resolution and infinite depth of field. Although many fabrication methods or processes are proposed for manufacturing such precision component, however, those methods still need to be improved. In this review, those fabrication methods are categorized into direct and indirect method and compared in detail. Two main challenges in manufacturing microlens array are identified: how to obtain a microlens array with good uniformity in a large area and how to produce the microlens array on a curved surface? In order to effectively achieve control of the geometry of a microlens,indirect methods involving the use of 3D molds and replication technologies are suggested. Further development of ultraprecision machining technology is needed to reduce the surface fluctuation by considering the dynamics of machine tool in tool path planning. Finally, the challenges and opportunities of manufacturing microlens array in industry and academic research are discussed and several principle conclusions are drawn.展开更多
The burr is one of the common phenomena occurring i n metal cutting operations The mathematical mechanical model of two side dir ection burr formation and transformation is established with plane stress strain th...The burr is one of the common phenomena occurring i n metal cutting operations The mathematical mechanical model of two side dir ection burr formation and transformation is established with plane stress strain theory,based on the orthogonal cutting The main laws of formation and change of the burr are revealed,and it is confirmed by experiment result,which first realizes prediction of the forming and changing of the two side direction burr in metal cutting operation.展开更多
A new tool force model to be presented is based upon process geometry and thecharacteristics of the force system, in which the forces acting on the tool rake face, the cuttingedge rounding and the clearance face have ...A new tool force model to be presented is based upon process geometry and thecharacteristics of the force system, in which the forces acting on the tool rake face, the cuttingedge rounding and the clearance face have been considered, and the size effect is accountable forthe new model. It is desired that the model can be well applicable to conventional diamond turningand the model may be employed as a tool in the design of diamond tools. This approach is quitedifferent from traditional investigations primarily based on empirical studies. As the depth of cutbecomes the same order as the rounded cutting edge radius, sliding along the clearance face due toelastic recovery of workpiece material and plowing due to the rounded cutting edge may becomeimportant in micro-machining, the forces acting on the cutting edge rounding and the clearance facecan not be neglected. For this reason, it is very important to understand the influence of someparameters on tool forces and develop a model of the relationship between them.展开更多
With the development of science and technology, the ultra-precision manufacturing of the brittle and hard materials with superior quality have become a new attractive subject. Brittle materials (such as engineering ce...With the development of science and technology, the ultra-precision manufacturing of the brittle and hard materials with superior quality have become a new attractive subject. Brittle materials (such as engineering ceramics, optical glass, semiconductor and so on) are widely used in electronics, optics, aeronautics and other high technology fields, so there are important theory significance and practical value to systematically study its machining mechanism and technology. Single crystal silicon is one of the typical brittle materials. Single crystal silicon wafer is a basic component of large and ultralarge integrated the circuit, its surface roughness and flatness are the key factor of improving its integration. With the successfully producing of the large diameter single crystal silicon wafer, its manufacturing technology became attractive subject again. This paper carries out computer simulation of nanometer cutting on single crystal silicon. Molecular Dynamics method which is different from continuous mechanics is employed to investigate the features of grinding energy dissipation, grinding force, stress state and grinding temperature, constructs the atom model of tool and work piece, and explains the microscale mechanism of material remove and surface generation of nanometer(subnanometer) manufacturing. This paper also investigates the variation of cutting force, thrust force, specific energy and surface deformation with different tool edge radius, different depth of cut.展开更多
Diamond turning based on a fast tool servo(FTS)is widely used in freeform optics fabrication due to its high accuracy and machining efficiency.As a new trend,recently developed high-frequency and long-stroke FTS units...Diamond turning based on a fast tool servo(FTS)is widely used in freeform optics fabrication due to its high accuracy and machining efficiency.As a new trend,recently developed high-frequency and long-stroke FTS units are independently driven by a separate control system from the machine tool controller.However,the tool path generation strategy for the independently controlled FTS is far from complete.This study aims to establish methods for optimizing tool path for the independent control FTS to reduce form errors in a single step of machining.Different from the conventional integrated FTS control system,where control points are distributed in a spiral pattern,in this study,the tool path for the independent FTS controller is generated by the ring method and the mesh method,respectively.The machined surface profile is predicted by simulation and the parameters for the control point generation are optimized by minimizing the deviation between the predicted and the designed surfaces.To demonstrate the feasibility of the proposed tool path generation strategies,cutting tests of a two-dimensional sinewave and a micro-lens array were conducted and the results were compared.As a result,after tool path optimization,the peak-to-valley form error of the machined surface was reduced from 429 nm to 56 nm for the two-dimensional sinewave by using the ring method,and from 191 nm to 103 nm for the micro-lens array by using the mesh method,respectively.展开更多
Cerium–lanthanum alloys are the main component of nickel–metal hydride batteries,and they are thus an important material in the greenenergy industry.However,these alloys have very strong chemical activity,and their ...Cerium–lanthanum alloys are the main component of nickel–metal hydride batteries,and they are thus an important material in the greenenergy industry.However,these alloys have very strong chemical activity,and their surfaces are easily oxidized,leading to great difficulties in their application.To improve the corrosion resistance of cerium–lanthanum alloys,it is necessary to obtain a nanoscale surface with low roughness.However,these alloys can easily succumb to spontaneous combustion during machining.Currently,to inhibit the occurrence of fire,machining of this alloy in ambient air needs to be conducted at very low cutting speeds while spraying the workpiece with a large amount of cutting fluid.However,this is inefficient,and only a very limited range of parameters can be optimized at low cutting speeds;this restricts the optimization of other cutting parameters.To achieve ultraprecision machining of cerium–lanthanum alloys,in this work,an auxiliary machining device was developed,and its effectiveness was verified.The results show that the developed device can improve the cutting speed and obtain a machined surface with low roughness.The device can also improve the machining efficiency and completely prevent the occurrence of spontaneous combustion.It was found that the formation of a build-up of swarf on the cutting tool is eliminated with high-speed cutting,and the surface roughness(Sa)can reach 5.64 nm within the selected parameters.Finally,the oxidation processes of the cerium–lanthanum alloy and its swarf were studied,and the process of the generation of oxidative products in the swarf was elucidated.The results revealed that most of the intermediate oxidative products in the swarf were Ce^(3+),there were major oxygen vacancies in the swarf,and the final oxidative product was Ce^(4+).展开更多
The fabrication of freeform optical components is increasingly demanded in emerging technologies such as augmented reality,imaging systems,and compact spectrometers.Fast-tool-servo(FTS)diamond turning has become a pro...The fabrication of freeform optical components is increasingly demanded in emerging technologies such as augmented reality,imaging systems,and compact spectrometers.Fast-tool-servo(FTS)diamond turning has become a promising solution for high-speed,high-precision machining of such surfaces.However,achieving nanometric form accuracy remains challenging due to servo-induced dynamic errors,particularly overshoot and control delay.This study proposes a feedforward methodology to predict and compensate for dynamics-induced form errors in long-stroke FTS systems.By capturing FTS position signals and applying normalized cross-correlation(NCC)analysis,a repeatable motion error referred to as the time-shifted following error(TSFE)was identified through time delay compensation of the servo.The three-dimensional map of TSFE was constructed and integrated into the tool path to compensate for the error before machining.Experimental machining test of a dual-sinewave freeform shape achieved peak-to-valley(PV)form error of 0.26μm,which was a 56%reduction compared to without measurement compensation.The repeatability of the three-dimensional map of TSFE showed a standard deviation of 0.007μm on the PV,which confirmed that the TSFE map has enough repeatability to be used as a pre-compensation dataset.Additionally,the FTS system had latent TSFE error regardless the spindle rotation rates.In this study the TSFE map derivation of system indicated approximately 0.5μm PV.These findings establish a fundamental and broadly applicable framework for improving form accuracy in high-speed freeform optics manufacturing using FTS,contributing to the advancement of ultra-precision machining technologies.展开更多
Field-assisted diamond cutting technology is a significant machining method that utilizes external energy fields to enhance the manufacturing performance.However,aimed the emergence of advanced high-performance materi...Field-assisted diamond cutting technology is a significant machining method that utilizes external energy fields to enhance the manufacturing performance.However,aimed the emergence of advanced high-performance materials,traditional single-field-assisted machining struggles to meet stringent precision requirements.Therefore,this study introduces an innovative and unique multi-energy field-assisted ultra-precision machining technology,in-situ laser-magnetic dual-field assisted diamond cutting(LMDFDC),to transcend the limitations of conventional single-field-assisted cutting methods and advance the machinability of challenging materials,notably the multi-principal-element high-entropy alloy(HEA).To elucidate the fundamental science questions of“what occurs,what changes,and what improves”in this work,the phenomenological behaviors of the dual-field coupling interaction are systematically investigated through advanced characterization techniques,spanning macroscopic surface integrity to microscopic atomic arrangement.This comprehensive study encompasses integrated analyses of four machining techniques for HEA workpiece,namely dual-energy field,two single-energy fields,and no-energy field.The research results indicate that the dual-field coupling effect demonstrates a leap in manufacturing performance through thermo-magneto-mechanical multi-physical synergistic interactions,primarily manifested in improved surface quality,reduced subsurface damage,suppressed diamond tool wear,and enhanced material removal stability.The significance of in-situ LMDFDC technology resides in propelling frontier academic developments in multi-physics coupled manufacturing theories while uncovering innovative machining approaches for next-generation high-performance materials.展开更多
文摘Brittle materials are widely used for producing important components in the industry of optics,optoelectronics,and semiconductors.Ultraprecision machining of brittle materials with high surface quality and surface integrity helps improve the functional performance and lifespan of the components.According to their hardness,brittle materials can be roughly divided into hard-brittle and soft-brittle.Although there have been some literature reviews for ultraprecision machining of hard-brittle materials,up to date,very few review papers are available that focus on the processing of soft-brittle materials.Due to the‘soft’and‘brittle’properties,this group of materials has unique machining characteristics.This paper presents a comprehensive overview of recent advances in ultraprecision machining of soft-brittle materials.Critical aspects of machining mechanisms,such as chip formation,surface topography,and subsurface damage for different machining methods,including diamond turning,micro end milling,ultraprecision grinding,and micro/nano burnishing,are compared in terms of tool-workpiece interaction.The effects of tool geometries on the machining characteristics of soft-brittle materials are systematically analyzed,and dominating factors are sorted out.Problems and challenges in the engineering applications are identified,and solutions/guidelines for future R&D are provided.
基金supported by the Special Actions for Developing High-performance Manufacturing of Ministry of Industry and Information Technology(Grant No.:TC200H02J)the Research Grants Council of the Hong Kong Special Ad-ministrative Region,China(Project No.:PolyU 152125/18E)+1 种基金the National Natural Science Foundation of China(Project No.:U19A20104)the Research Committee of The Hong Kong Polytechnic University(Project Code G-RK2V).
文摘The lightness and high strength-to-weight ratio of the magnesium alloy have attracted more interest in various applications.However,micro/nanostructure generation on their surfaces remains a challenge due to the flammability and ignition.Motivated by this,this study proposed a machining process,named the ultraprecision diamond surface texturing process,to machine the micro/nanostructures on magnesium alloy surfaces.Experimental results showed the various microstructures and sawtooth-shaped nanostructures were successfully generated on the AZ31B magnesium alloy surfaces,demonstrating the effectiveness of this proposed machining process.Furthermore,sawtooth-shaped nanostructures had the function of inducing the optical effect and generating different colors on workpiece surfaces.The colorful letter and colorful flower image were clearly viewed on magnesium alloy surfaces.The corresponding cutting force,chip morphology,and tool wear were systematically investigated to understand the machining mechanism of micro/nanostructures on magnesium alloy surfaces.The proposed machining process can further improve the performances of the magnesium alloy and extend its functions to other fields,such as optics.
基金The authors are grateful for Ph.D.Scholarship funding support from Brunel University London and the UKEPSRC.
文摘In current precision and ultraprecision machining practice,the positioning and control of actuation systems,such as slideways and spindles,are heavily dependent on the use of linear or rotary encoders.However,positioning control is passive because of the lack of direct monitoring and control of the tool and workpiece positions in the dynamic machining process and also because it is assumed that the machining system is rigid and the cutting dynamics are stable.In ultraprecision machining of freeform surfaces using slow tool servo mode in particular,however,account must be taken of the machining dynamics and dynamic synchronization of the cutting tool and workpiece positioning.The important question also arises as to how ultraprecision machining systems can be designed and developed to work better in this application scenario.In this paper,an innovative dynamics-oriented engineering approach is presented for ultraprecision machining of freeform surfaces using slow tool servo mode.The approach is focused on seamless integration of multibody dynamics,cutting forces,and machining dynamics,while targeting the positioning and control of the tool–workpiece loop in the machining system.The positioning and motion control between the cutting tool and workpiece surface are further studied in the presence of interfacial interactions at the tool tip and workpiece surface.The interfacial cutting physics and dynamics are likely to be at the core of in-process monitoring applicable to ultraprecision machining systems.The approach is illustrated using a virtual machining system developed and supported with simulations and experimental trials.Furthermore,the paper provides further explorations and discussion on implementation perspectives of the approach,in combination with case studies,as well as discussing its fundamental and industrial implications.
基金funded by the National Natural Science Foundation of China(Grant No.51135002)Science Fund for Creative Research Groups of NSFC(Grant No.51621064)。
文摘Large-sized potassium dihydrogen phosphate(KDP)crystals are an irreplaceable nonlinear optical component in an inertial confinement fusion project.Restricted by the size,previous studies have been aimed mainly at the removal principle and surface roughness of small-sized KDP crystals,with less research on flatness.Due to its low surface damage and high machining efficiency,water dissolution ultraprecision continuous polishing(WDUCP)has become a good technique for processing large-sized KDP crystals.In this technique,the trajectory uniformity of water droplets can directly affect the surface quality,such as flatness and roughness.Specifically,uneven trajectory distribution of water droplets on the surface of KDP crystals derived from the mode of motion obviously affects the surface quality.In this study,the material removal mechanism of WDUCP was introduced.A simulation of the trajectory of water droplets on KDP crystals under different eccentricity modes of motion was then performed.Meanwhile,the coefficient of variation(CV)was utilized to evaluate the trajectory uniformity.Furthermore,to verify the reliability of the simulation,some experimental tests were also conducted by employing a large continuous polisher.The results showed that the CV varied from 0.67 to 2.02 under the certain eccentricity mode of motion and varied from 0.48 to 0.65 under the uncertain eccentricity mode of motion.The CV of uncertain eccentricity is always smaller than that of certain eccentricity.Hence,the uniformity of trajectory was better under uncertain eccentricity.Under the mode of motion of uncertain eccentricity,the initial surface texture of the100 mm×100 mm×10 mm KDP crystal did achieve uniform planarization.The surface root mean square roughness was reduced to 2.182 nm,and the flatness was reduced to 22.013μm.Therefore,the feasibility and validity of WDUCP for large-sized KDP crystal were verified.
文摘The characteristics of several different linear motors have been investigated, and the feed drive system with linear motor instead of screw-nut mechanism has been built for a submicro ultraprecision turning machine. In the control system for the feed drive system arranged as "T", both P-position and PI-speed control loops are used. The feedback variable is obtained from a double frequecy laser interferometor. Experiments show that the feed drive with linear motor is simple in construction, and that its dynamics is better than others. So the machining accuracy of the workpiece machined has been successfully improved.
基金financial supports from Young Scientist Fund of National Natural Science Foundation of China(Project No.52205498/K-ZGFT)the State Key Laboratory in Hong Kong from the Innovation and Technology Commission(ITC)of the Government of the Hong Kong Special Administrative Region(HKSAR),China+2 种基金the General Research Fund(GRF)of the Research Grants Council(RGC)of the Hong Kong Special Administrative Region(HKSAR),China(Project No.PolyU 15220724)the Shenzhen Key Technology Breakthrough Project(No.Z2022N074)Shenzhen Engineering Research Center for Semiconductor-specific Equipment and the Research Committee of The Hong Kong Polytechnic University(Project code:RKWR).
文摘Ultraprecision machining of titanium alloy(Ti-6Al-4V)remains challenging due to its low thermal conductivity,pronounced elastic recovery,and tool-workpiece adhesion,all of which degrade surface integrity and accelerate tool wear.This study systematically investigates the effect of a weak magnetic field(~0.015 T)on the single-point diamond turning and microgroove machining of Ti-6Al-4V flat surfaces,microgroove arrays,and microstructures.Four machining conditions were designed to decouple the magnetic field effect:no field(nM-nM),field applied only during microgroove cutting(nM-M),field applied only during finish turning(M-nM),and field applied throughout(M-M).Theoretical analyses and experiments have demonstrated that the rotation of the conductive titanium alloy within a magnetic field induces eddy currents,generating Lorentz damping,which suppresses vibrations in Y/Z directions,enhances cutting stability,and improves surface finish.The results showed that magnetic-field assistance significantly reduces both the principal cutting forces and noise levels,and that performance under M-nM conditions surpasses that under nM-M conditions,suggesting that the finishcutting process exerts a stronger influence on the quality of microgroove machining.Microstructures machined under M-M conditions exhibit exceptional dimensional accuracy and uniformity,with groove depths approaching a nominal value of 4μm(reaching~3.98μm under the M-M conditions)and minimal burrs or microcracks forming at boundaries.The findings enhance the understanding of the magnetic field-assisted ultraprecision cutting of titanium alloys,enabling the manufacturing of high-quality micro/nanostructures for applications in aerospace,biomedicine,and optical components.
基金supported by the National Natural Science Foundation of China(Grant No.52130503)the Science and Technology Innovation Program of Hunan Province(Grants Nos.2023RC1046 and 2023GK2008)+2 种基金the Hunan Provincial Science and Technology Department(Grant No.2021JC0005)the Postgraduate Scientific Research Innovation Project of Hunan Province(Grant No.QL20220088)the Shenzhen Undertakes Major National Science and Technology Projects(Grant No.CJGJZD20220517142406015).
文摘In an ultraprecision turning process for small-diameter optical aspheric workpieces,tool-profile errors induce mid-frequency errors in the workpiece profile,limiting further improvements in precision.In this study,an XZB three-axis linkage ultraprecision machining method is proposed,and the effects of tool-center errors are analyzed.To address residual errors in Z-direction profile-error compensation,a workpiece normal-profile-error compensation method is proposed.After XZB three-axis linkage turning and compensation,the workpiece profile error(PV)reaches 0.086μm,surpassing the precision of XZ two-axis machining,and mid-frequency errors are reduced.Compared with Z-direction profile-error compensation,which results in a profile error of 0.092μm,normal-profile-error compensation reduces PV to 0.047μm,considerably improving aspheric accuracy.Experimental results demonstrate that XZB three-axis linkage machining significantly improves the aspheric workpiece profile,enhancing both its accuracy and surface quality.This method reduces mid-frequency errors,and the subsequent application of normal-profile-error compensation further refines the profile,achieving higher overall accuracy.
基金The State Key Program of National Natural Science of China(Grant No.52435008).
文摘Single-point diamond turning(SPDT)is an ultraprecision technique for manufacturing high-precision microlens arrays(MLAs).This method achieves optical surface machining with excellent accuracy,thereby eliminating the need for secondary processing techniques.However,the application of SPDT for fabricating large-area MLAs is significantly limited by tool wear,which indirectly affects surface roughness due to the declined accuracy of the cutting edge.Severe tool wear can lead to failure during microstructure machining.In theory,SPDT stitching fabrication through tool replacement enables the management of cutting tool wear,facilitating MLAs production with high-precision and large-area.Nevertheless,maintaining the repositioning accuracy of the new tool relative to the worn tool remains a significant challenge.This study introduces an in-situ optical ranging(ISOR)method to measure and compensate for the tool replacement positioning error between the new and worn tools in accordance with the different feed directions during MLAs production.An in-situ measurement system comprising an optical microscope and a linear variable displacement transducer(LVDT)was developed.The positional relationship between the new and worn tools was determined using the measurement results from the optical microscope and LVDT in their respective directions.MLAs stitching fabrication experiment was conducted using the proposed method and system.The results confirmed the effectiveness and feasibility of the proposed method for the stitching fabrication of MLAs.The measurement and compensation processes were completed within 20 min,achieving an accuracy of 0.1μm.This study provides an effective strategy for manufacturing large-area optical surfaces with high precision and efficiency.
基金supported by the Major Research Plan of the National Natural Science Foundation of China(Grant No.91848202)。
文摘Wedge-shaped microstructures have the ability to reproduce the excellent adhesive properties of geckos’feet because of their unique anisotropic structure.In particular,the controllability of the wedge-shaped microstructures on adhesion is beneficial to the undisturbed grasp or the capture of space targets.However,the problem currently remains of how to process it efficiently and with high quality.Here a strategy called ultraprecision multistep and layered scribing is proposed for the manufacture of the biomimetic controllable adhesive surface.The results show that the metal master mold prepared based on the manufacturing strategy has not only good surface topography but also high reliability and durability.Furthermore,the controllable adhesive surface of 1.96 cm2,fabricated by the proposed manufacturing strategy,has a normal adhesion of 1.012 N,and the corresponding shear friction and adhesion coefficient are 3.105 N and 4.82,respectively.Additionally,the controllable adhesive surface has been shown to be approximately superhydrophobic and also to possess the properties of controllable adhesion and dynamic adhesion.Also,after 250 adhesion-detachment cycles,the normal adhesion and shear friction only decrease by 5%and 3%,respectively.The research realizes an environmentally friendly and efficient method by which to manufacture a durable metal mold for fabricating a biomimetic controllable adhesive surface,laying a foundation for its effective application in the adherence of space-floating targets.
文摘Ultraprecision diamond machining and high volume molding for affordable high precision high performance optical elements are becoming a viable process in optical industry for low cost high quality microoptical component manufacturing. In this process, first high precision microoptical molds are fabricated using ultraprecision single point diamond machining followed by high volume production methods such as compression or injection molding. In the last two decades, there have been steady improvements in ultraprecision machine design and performance, particularly with the introduction of both slow tool and fast tool servo. Today optical molds, including freeform surfaces and microlens arrays, are routinely diamond machined to final finish without post machining polishing. For consumers, compression mold- ing or injection molding provide efficient and high quality optics at extremely low cost. In this paper, first ultrapreci- sion machine design and machining processes such as slow tool and fast too servo are described then both compression molding and injection molding of polymer optics are discussed. To implement precision optical manufacturing by molding, numerical modeling can be included in the future as a critical part of the manufacturing process to ensure high product quality.
基金supported by the National Key R&D Program of China(Grant No.2018YFB2002200)
文摘Deburring of high-precision components to their micrometer features without any damage is very important but of great difficulty as the burr-to-functionality size ratio increases. To this end, this paper proposes a new deburring method in which the micro burr should be directly removed based on ultraprecision cutting with the designed monocrystalline diamond tool. To determine the feasibility of the proposed method, this paper applies it for deburring of the precision working edge of the servo valve core. Firstly, the monocrystalline diamond tool is carefully designed by covering a variety of topics like rake angle,clearance angle, edge radius. Then, the finite element(FE) simulation was conducted to characterize the deburring performance during the removal of the micro burr produced by the single abrasive grinding. Finally, an innovative self-designed deburring system was introduced and the deburring process was evaluated in terms of cutting forces, temperatures, tool wear mechanisms and deburring quality of the working edges by experiments. The FE simulation results indicate the suitability of the proposed deburring method. Meanwhile, the experimental findings agree well with simulation results and show that ultraprecision cutting with the specialized monocrystalline diamond tool could be successfully used for deburring of servo valve core edge without any damage. This work can provide technical guidance for similar engineering applications, and thus brings an increase to the machining efficiency for the manufacture of precision components.
文摘Precision is one of the most important aspects of manufacturing.High precision creates high quality,high performance,exchangeability,reliability,and added value for industrial products.Over the past decades,remarkable advances have been achieved in the area of high-precision manufacturing technologies,where the form accuracy approaches the nanometer level and surface roughness the atomic level.These extremely high precision manufacturing technologies enable the development of high-performance optical elements,semiconductor substrates,biomedical parts,and so on,thereby enhancing the ability of human beings to explore the macroand microscopic mysteries and potentialities of the natural world.In this paper,state-of-the-art high-precision material removal manufacturing technologies,especially ultraprecision cutting,grinding,deterministic form correction polishing,and supersmooth polishing,are reviewed and compared with insights into their principles,methodologies,and applications.The key issues in extreme precision manufacturing that should be considered for future R&D are discussed.
基金Supported by Shenzhen Science,Technology and Innovation Commission of China(Grant No.JCYJ20150630115257902)the Research Grants Council of the Hong Kong Special Administrative Region of China(Grant No.ITS/339/13FX)Research Committee of The Hong Kong Polytechnic University,China (Grant No.RUK0)
文摘Microlens arrays are the key component in the next generation of 3D imaging system, for it exhibits some good optical properties such as extremely large field of view angles, low aberration and distortion, high temporal resolution and infinite depth of field. Although many fabrication methods or processes are proposed for manufacturing such precision component, however, those methods still need to be improved. In this review, those fabrication methods are categorized into direct and indirect method and compared in detail. Two main challenges in manufacturing microlens array are identified: how to obtain a microlens array with good uniformity in a large area and how to produce the microlens array on a curved surface? In order to effectively achieve control of the geometry of a microlens,indirect methods involving the use of 3D molds and replication technologies are suggested. Further development of ultraprecision machining technology is needed to reduce the surface fluctuation by considering the dynamics of machine tool in tool path planning. Finally, the challenges and opportunities of manufacturing microlens array in industry and academic research are discussed and several principle conclusions are drawn.
基金This project is supported by National Natural Science Foundation of China(No.59775071).
文摘The burr is one of the common phenomena occurring i n metal cutting operations The mathematical mechanical model of two side dir ection burr formation and transformation is established with plane stress strain theory,based on the orthogonal cutting The main laws of formation and change of the burr are revealed,and it is confirmed by experiment result,which first realizes prediction of the forming and changing of the two side direction burr in metal cutting operation.
基金This project is supported by National Natural Science Foundation of China (No.50175022)National Aerospace Support Foundation of China(No.0223HIT07).
文摘A new tool force model to be presented is based upon process geometry and thecharacteristics of the force system, in which the forces acting on the tool rake face, the cuttingedge rounding and the clearance face have been considered, and the size effect is accountable forthe new model. It is desired that the model can be well applicable to conventional diamond turningand the model may be employed as a tool in the design of diamond tools. This approach is quitedifferent from traditional investigations primarily based on empirical studies. As the depth of cutbecomes the same order as the rounded cutting edge radius, sliding along the clearance face due toelastic recovery of workpiece material and plowing due to the rounded cutting edge may becomeimportant in micro-machining, the forces acting on the cutting edge rounding and the clearance facecan not be neglected. For this reason, it is very important to understand the influence of someparameters on tool forces and develop a model of the relationship between them.
文摘With the development of science and technology, the ultra-precision manufacturing of the brittle and hard materials with superior quality have become a new attractive subject. Brittle materials (such as engineering ceramics, optical glass, semiconductor and so on) are widely used in electronics, optics, aeronautics and other high technology fields, so there are important theory significance and practical value to systematically study its machining mechanism and technology. Single crystal silicon is one of the typical brittle materials. Single crystal silicon wafer is a basic component of large and ultralarge integrated the circuit, its surface roughness and flatness are the key factor of improving its integration. With the successfully producing of the large diameter single crystal silicon wafer, its manufacturing technology became attractive subject again. This paper carries out computer simulation of nanometer cutting on single crystal silicon. Molecular Dynamics method which is different from continuous mechanics is employed to investigate the features of grinding energy dissipation, grinding force, stress state and grinding temperature, constructs the atom model of tool and work piece, and explains the microscale mechanism of material remove and surface generation of nanometer(subnanometer) manufacturing. This paper also investigates the variation of cutting force, thrust force, specific energy and surface deformation with different tool edge radius, different depth of cut.
基金supported by Japan Society for the Promotion of Science,Grant-in-Aid for Scientific Research(B),Project Number 21H01230.
文摘Diamond turning based on a fast tool servo(FTS)is widely used in freeform optics fabrication due to its high accuracy and machining efficiency.As a new trend,recently developed high-frequency and long-stroke FTS units are independently driven by a separate control system from the machine tool controller.However,the tool path generation strategy for the independently controlled FTS is far from complete.This study aims to establish methods for optimizing tool path for the independent control FTS to reduce form errors in a single step of machining.Different from the conventional integrated FTS control system,where control points are distributed in a spiral pattern,in this study,the tool path for the independent FTS controller is generated by the ring method and the mesh method,respectively.The machined surface profile is predicted by simulation and the parameters for the control point generation are optimized by minimizing the deviation between the predicted and the designed surfaces.To demonstrate the feasibility of the proposed tool path generation strategies,cutting tests of a two-dimensional sinewave and a micro-lens array were conducted and the results were compared.As a result,after tool path optimization,the peak-to-valley form error of the machined surface was reduced from 429 nm to 56 nm for the two-dimensional sinewave by using the ring method,and from 191 nm to 103 nm for the micro-lens array by using the mesh method,respectively.
基金This study was supported by the Science Challenge Project(Grant No.TZ2018006-0201-01)the National Natural Science Foundation of China(Grant Nos.51605327 and 52035009).
文摘Cerium–lanthanum alloys are the main component of nickel–metal hydride batteries,and they are thus an important material in the greenenergy industry.However,these alloys have very strong chemical activity,and their surfaces are easily oxidized,leading to great difficulties in their application.To improve the corrosion resistance of cerium–lanthanum alloys,it is necessary to obtain a nanoscale surface with low roughness.However,these alloys can easily succumb to spontaneous combustion during machining.Currently,to inhibit the occurrence of fire,machining of this alloy in ambient air needs to be conducted at very low cutting speeds while spraying the workpiece with a large amount of cutting fluid.However,this is inefficient,and only a very limited range of parameters can be optimized at low cutting speeds;this restricts the optimization of other cutting parameters.To achieve ultraprecision machining of cerium–lanthanum alloys,in this work,an auxiliary machining device was developed,and its effectiveness was verified.The results show that the developed device can improve the cutting speed and obtain a machined surface with low roughness.The device can also improve the machining efficiency and completely prevent the occurrence of spontaneous combustion.It was found that the formation of a build-up of swarf on the cutting tool is eliminated with high-speed cutting,and the surface roughness(Sa)can reach 5.64 nm within the selected parameters.Finally,the oxidation processes of the cerium–lanthanum alloy and its swarf were studied,and the process of the generation of oxidative products in the swarf was elucidated.The results revealed that most of the intermediate oxidative products in the swarf were Ce^(3+),there were major oxygen vacancies in the swarf,and the final oxidative product was Ce^(4+).
基金Japan Society for the Promotion of Science London,25H00709,Jiwang Yan.
文摘The fabrication of freeform optical components is increasingly demanded in emerging technologies such as augmented reality,imaging systems,and compact spectrometers.Fast-tool-servo(FTS)diamond turning has become a promising solution for high-speed,high-precision machining of such surfaces.However,achieving nanometric form accuracy remains challenging due to servo-induced dynamic errors,particularly overshoot and control delay.This study proposes a feedforward methodology to predict and compensate for dynamics-induced form errors in long-stroke FTS systems.By capturing FTS position signals and applying normalized cross-correlation(NCC)analysis,a repeatable motion error referred to as the time-shifted following error(TSFE)was identified through time delay compensation of the servo.The three-dimensional map of TSFE was constructed and integrated into the tool path to compensate for the error before machining.Experimental machining test of a dual-sinewave freeform shape achieved peak-to-valley(PV)form error of 0.26μm,which was a 56%reduction compared to without measurement compensation.The repeatability of the three-dimensional map of TSFE showed a standard deviation of 0.007μm on the PV,which confirmed that the TSFE map has enough repeatability to be used as a pre-compensation dataset.Additionally,the FTS system had latent TSFE error regardless the spindle rotation rates.In this study the TSFE map derivation of system indicated approximately 0.5μm PV.These findings establish a fundamental and broadly applicable framework for improving form accuracy in high-speed freeform optics manufacturing using FTS,contributing to the advancement of ultra-precision machining technologies.
基金partially supported by the General Research Funds from the Research Grants Council of the Hong Kong Special Administrative Region(HKSAR),China(Project Nos.:PolyU 15221322 and PolyU 15206824)Mainland-Hong Kong Joint Funding Scheme(MHKJFS)from Innovation and Technology Commission(ITC)of the Government of HKSAR(Project No.:MHP/051/22)+2 种基金The Special Funding for Jiangsu Province Innovation Support Program under Grant(BZ2023058)The authors would also like to express their sincere gratitude to the support from the State Key Laboratories in Hong Kong from the ITC of the Government of HKSARthe Research and Innovation Office of The Hong Kong Polytechnic University.
文摘Field-assisted diamond cutting technology is a significant machining method that utilizes external energy fields to enhance the manufacturing performance.However,aimed the emergence of advanced high-performance materials,traditional single-field-assisted machining struggles to meet stringent precision requirements.Therefore,this study introduces an innovative and unique multi-energy field-assisted ultra-precision machining technology,in-situ laser-magnetic dual-field assisted diamond cutting(LMDFDC),to transcend the limitations of conventional single-field-assisted cutting methods and advance the machinability of challenging materials,notably the multi-principal-element high-entropy alloy(HEA).To elucidate the fundamental science questions of“what occurs,what changes,and what improves”in this work,the phenomenological behaviors of the dual-field coupling interaction are systematically investigated through advanced characterization techniques,spanning macroscopic surface integrity to microscopic atomic arrangement.This comprehensive study encompasses integrated analyses of four machining techniques for HEA workpiece,namely dual-energy field,two single-energy fields,and no-energy field.The research results indicate that the dual-field coupling effect demonstrates a leap in manufacturing performance through thermo-magneto-mechanical multi-physical synergistic interactions,primarily manifested in improved surface quality,reduced subsurface damage,suppressed diamond tool wear,and enhanced material removal stability.The significance of in-situ LMDFDC technology resides in propelling frontier academic developments in multi-physics coupled manufacturing theories while uncovering innovative machining approaches for next-generation high-performance materials.
