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Machine learning interatomic potentials (MLIPs) have greatly enhanced molecular dynamics (MD) simulations, achieving near-first-principles accuracy in thermal conductivity studies. In this work, we reveal that this accuracy, observed in BAs and diamond at sub-Debye temperatures, stems from an accidental error cancelation: classical statistics overestimates specific heat while underestimating phonon lifetimes, balancing out in thermal conductivity predictions. However, this balance is disrupted when isotopes are introduced, leading MLIP-based MD to significantly underpredict thermal conductivity compared to experiments and quantum statistics-based Boltzmann transport equation. This discrepancy arises not from classical statistics affecting phonon–isotope scattering rates but from its impact on the interplay between phonon–isotope and phonon–phonon scattering in the normal scattering-dominated BAs and diamond. This work underscores the limitations of MLIP-based MD for thermal conductivity studies at sub-Debye temperatures. [ABSTRACT FROM AUTHOR]

Diamond cutting with a controllable depth of cut at the subnanometric scale is desired for next-generation electronics and optics. However, due to the limits of positioning accuracy of the current machine tools, diamond cutting at subnanometric scale depths remains in realm of molecular dynamic (MD) simulations instead of engineering realization. Cutting force feedback and control is regarded as a potential method to improve the positioning accuracy of machine tools. In this study, an ultra-precision force feedback loop with the resolution down to submillinewton is employed and integrated on an ultra-precision machine tool to enable the capability of cutting at subnanometric scale depth. By this way, the relationship between the cutting force and such small depth of cut needs to be well studied. MD simulations are conducted in this study to analyze the mechanism of material removal and influence of the crystallographic effect on the actual cutting depth and force caused by varied cutting directions at subnanometric to nanometric scale depth in diamond turning. Then, the crystallographic effect of silicon with the depth of cut from subnanometric to nanometric scale is compensated experimentally for accurate cutting at such an extremely small scale. Controllable diamond cutting of structured surfaces with actual depths and amplitudes ranging from several angstroms to a few nanometers on silicon is successfully realized. [Display omitted] • A force feedback loop is integrated on an ultra-precision machine tool to enable the cutting with subnanometric scale depth. • The crystallographic effect of silicon is compensated for accurate cutting with subnanometric to nanometric scale depth. • Structured surfaces with subnanometric to nanometric scale height features on silicon are successfully realized. [ABSTRACT FROM AUTHOR]

Polycrystalline ZnS is a typical infrared optical material. It is widely used in advanced optical systems due to its excellent optical properties. The machining accuracy of polycrystalline ZnS optical elements must satisfy the requirements of high-performance system development. However, the soft and brittle nature of the material poses a challenge for high-quality and efficient machining. In recent years, in situ laser-assisted diamond cutting has been proven to be an effective method for ultra-precision cutting of brittle materials. In this study, the mechanism of in situ laser-assisted cutting on ultra-precision cutting machinability enhancement of ZnS was investigated. Firstly, the physical properties of ZnS were characterized by high-temperature nanoindentation experiments. The result revealed an increase in ductile machinability of ZnS due to plastic deformation and a decrease in microhardness and Young's modulus at high temperatures. It provided a fundamental theory for the ductile–brittle transition of ZnS. Subsequently, a series of diamond-cutting experiments were carried out to study the removal mechanism of ZnS during in situ laser-assisted cutting. It was found that the mass damage initiation depth groove generated by in situ laser-assisted cutting increased by 57.99% compared to the groove generated by ordinary cutting. It was found that micron-sized pits were suppressed under in situ laser-assisted cutting. The main damage form of HIP-ZnS was changed from flake spalling and pits to radial cleavage cracks. Additionally, the laser can suppress the removal mode difference of different grain crystallographic and ensure the ductile region processing. Finally, planning cutting experiments were carried out to verify that a smooth and uniform surface with Sa of 3.607 nm was achieved at a laser power of 20 W, which was 73.58% better than normal cutting. The main components of roughness were grain boundary steps and submicron pit. This study provides a promising method for ultra-precision cutting of ZnS. [ABSTRACT FROM AUTHOR]

A sequential technique that combines wire electrical discharge machining (wire-EDM) and abrasive grinding on dedicated equipment improves the edge quality of boron-doped polycrystalline diamond (BD-PCD) cutting tools. In this study, we focus on material removal mechanisms during BD-PCD machining and surface graphitization caused by wire-EDM thermal damage. Surface topography is used to distinguish ductile- and brittle-regime grinding in tool production. Resin-bonded diamond wheels outperform electroplated diamond wheels in abrasive grinding owing to their self-sharpening capabilities. The experimental results show that BD-PCD tools have higher mechanical properties and performance than standard PCD tools. Maximum edge chipping on BD-PCD surfaces depends on the depth of cut and grinding speed. Microgrinding experiments on BK7 glass reveal that the recommended tool manufacturing approach, which merges wire-EDM and abrasive grinding, results in high-quality surfaces free of microcracks and achieves a surface roughness of 6 nm Sa. Abrasion on the flank face and chipping on the periphery are the main wear patterns on grinding tools. In this study, we improve our understanding of BD-PCD microcutter production, focusing on parameter management for optimal surface quality, edge integrity, and tool performance. We emphasize the necessity of choosing the right grinding wheel to achieve the necessary surface and subsurface quality when making microcutting tools. Raman spectroscopy results are used to explain thermal deterioration when diamond grains turn into graphite at high manufacturing temperatures. We address the challenges of producing high-quality microcutting tools and offer insights into improving BDPCD tool performance and edge quality. [ABSTRACT FROM AUTHOR]

The ultra-precision diamond cutting (UPDC) employs larger cutting parameters in half-finishing process to improve machining efficiency, which introduces microwavy profile to the unmachined surface of finishing process with microscale cutting parameters. The paper makes theoretical and experimental investigations on the microwavy profile effect on cutting process and surface generation in UPDC. The influence of microwavy profile on the surface being machined is considered in diamond cutting process by studying its effect on the instantaneous cutting depth, shear angle, stress, and effective rake angle to build dynamic force model. A new dynamic surface generation model is developed by adding the wavy profile effect and workpiece material properties. The simulated surface profiles in diamond single cutting of different workpiece materials meet well with the experimental ones under different wavy profile patterns. Further studies are conducted to build turning force model and surface profile prediction model for single point diamond turning (SPDT) by adding the diamond-turned microtopography effect on the instantaneous cutting depth. Diamond single cutting experiment and diamond turning experiment are conducted to verify the developed dynamic models, which indicates that the predicted results including cutting force and surface profiles agree well with the experimental results. [ABSTRACT FROM AUTHOR]

Due to the instability of amorphous alloys, the Ni-P alloy coating on the surface of injection mold cores will crystallize after a long period in a high-temperature and high-pressure production environment. The crystallized alloy has higher hardness, poorer ductility, and poorer machinability, making it difficult to repair by single-point diamond turning. This paper presents the results of heat treatment experiments simulating a production environment to obtain the relationship between heat treatment temperature and surface hardness after crystallization. Using the high transmittance of diamond, laser in-situ assisted diamond turning can improve the surface quality and eliminate machining defects, and analyze the influence of process parameters on the surface roughness to determine the optimal machining parameters. The experimental results show that using laser in-situ assisted diamond turning can improve surface quality, extend tool life, and improve accuracy. The final measured face accuracy confirms that the laser-assisted in-situ turned cores are suitable for routine injection molding production. [ABSTRACT FROM AUTHOR]

Freeform micro-structures can exhibit advanced and useful functions of optical components by guiding beam path. Growing interest has been shown in fabricating large-scale 3D freeform micro-structures on hard-to-cut materials as mould for mass production. Currently, ultrasonic vibration-assisted diamond turning is a feasible and efficient technique to fabricate these structures made of steel. However, the tool path linear error increases significantly with the increase in workpiece dimension in fast tool/slow slide servo diamond turning of microstructures with sharp edges. In this research, using Mirrax 40 steel as the mould material and applying a high-frequency ultrasonic tooling system (UTS2) to ease the machining of steel workpiece. To reduce linear error in machining large-scale 3D microstructures, diamond sculpturing instead of diamond turning was applied. This machining technology is called ultrasonic vibration-assisted sculpturing (UVAS). The principle of UVAS, tool path determination, surface generation, tool parameter selection as well as linear error of the tool path and form error induced by ultrasonic vibration kinematics, were comprehensively investigated, in order to fabricate an aspheric microlens array and a freeform microlens array with small theoretical error and reliable slide dynamic response. Furthermore, a large-scale freeform microlens array was fabricated and a measurement method was used to evaluate the machining accuracy. UVAS achieved a form error of less than 0.5 μm and an arithmetic surface roughness Sa of 5 nm for the large-scale freeform microlens array. • Ultrasonic vibration-assisted diamond sculpturing was used to reduce linear error in machining large-scale microstructures. • Form error induced by kinematical overcut in ultrasonic vibration-assisted sculpturing was theoretically clarified. • Tool vibration was eliminated to cut aspheric and freeform microlens arrays by various tool path modification methods. • A method based on finding structural peaks was used to evaluate 3D global form accuracy of large-scale 3D microstructures. [ABSTRACT FROM AUTHOR]

Complex curved surface parts are integral to the mechanical industry, demanding precise machining techniques. Multi-axis slow tool servo turning has emerged as an efficient method due to its high precision and quality. However, the challenge of severe tool flank interference arises, especially on surfaces with large undulation changes. Conventional methods, such as increasing tool clearance angles or adding extra tool axes, detrimentally affect machining precision and stability. To address this, a non-interference toolpath planning method is proposed for complex surfaces with large undulation changes. The approach begins with establishing geometric models of the single-point diamond turning tool and typical complex surfaces, followed by analyzing the mechanism and evolution of tool flank interference. By considering geometric parameters and vector relationships, the practical tool clearance angles are calculated. And then a criterion for subregion division is introduced and the non-cutting stroke is designed, accounting for the maximal acceleration of machine tool axis. Multi-pass toolpaths are generated to navigate different subregions while avoiding interference by transforming spindle rotation direction. Furthermore, a method is proposed to optimize toolpath stitching in practical machining regions, ensuring continuous and smooth transitions while maintaining machining precision and surface quality. Experimental validation, conducted on a hyperbolic paraboloid surface with large undulation changes, demonstrates a significant reduction in surface roughness (Sa) from 380.503 nm to 75.664 nm—a reduction of 80.115 %. The proposed method not only enhances machining precision and surface quality but also extends tool life and improves working conditions. This research offers vital guidance for non-interference toolpath planning in engineering practice. • A non-interference toolpath planning method with the tool clearance angle is presented. • The non-interference strategy is developed by spindle forward and reverse rotation. • An algorithm of non-cutting stroke design in the interference region is presented. • The non-cutting stroke is optimized smoothly based on the cut-in and cut-out direction. [ABSTRACT FROM AUTHOR]

Zirconia ceramic (ZrO2) has been widely utilized in industrial areas for its excellent physical and mechanical properties. It is essential to study the grinding effect and the parameters optimization, to achieve high efficiency and precision grinding. The response surface experiments of ZrO2 grinding are designed, where the grinding wheel speed, workpiece speed, and grinding depth are selected as the three grinding parameters. The experiment is carried out on a surface grinding machine with a diamond grinding wheel. The four response surface quadratic regression models are built for the grinding force, the surface roughness, the surface breakage rate, and the subsurface damage depth. Combined with the four regression models and the maximum undeformed chip thickness model, the effect of grinding parameters on the grinding results is comprehensively assessed. For the integrated minimum of the machining time and the four grinding results, the multi-objective optimization is carried out on the grinding parameters. The correctness of the optimization model is verified by experiment. [ABSTRACT FROM AUTHOR]

The study investigated the fabrication and characterization of a controllable wavy patterned mold using an ultra-precision diamond machining system. The design method of cutting tool path for controllable wavy pattern on a cylindrical surface, considering the tool radius, was discussed. The target was designed as periodic sine wave and random amplitude wave to develop components for next-generation displays. The effectiveness of the designed tool path was confirmed by comparing the machined surface profiles. The compensated tool path was able to reduce the machined shape error by approximately 50%. The optical characteristics of the machined pattern were analyzed by the luminance distribution of the transmitted laser through the replicated optical film for each machined tool path. When the compensated tool path was applied, a symmetrical distribution line with two spots of higher luminance concentration was observed. Finally, an investigation was conducted on the machinability of controllable randomness for next-generation display components, and their optical characteristics were evaluated. [ABSTRACT FROM AUTHOR]

Micro dome arrays are applied as moulds to injection/press moulding to produce micro lens arrays. Fast tool servo (FTS) based diamond turning is a promising technique for manufacturing such micro dome arrays with high accuracy and machining efficiency. In this study, cutting of micro dome array (MDA) on copper with FTS was performed to evaluate the dynamics behaviour of the tool servo and its effects on surface topography. Results show that local surface speed dramatically affects the servo dynamics behaviour. When the local surface speed is higher than a critical value, overcutting and wavy patterns could be formed on the cut-in area of the domes and exit area, which is caused by the servo response and its limitation. By capturing and analysing the position signal and correlating it with the surface topography of the generated dome surface and considering its limitations, an effective strategy for optimizing micro dome array machining parameters was proposed. MDA cutting tests with optimized cutting conditions achieved a significantly improved form accuracy. This study will guide the optimal use of FTS systems in machining micro structured surfaces. [ABSTRACT FROM AUTHOR]

Germanium and other brittle single crystal materials can be diamond turned with negative rake angle tools, but to maintain surface integrity parameters are typically chosen conservatively. This work describes experiments performed on (100)Ge crystal samples that support a recent scientific finding: increasing the surface speed in diamond turning of germanium improves surface integrity. Materials are machined on a modern ultraprecision diamond turning machine at constant surface speed and constant feed per revolution keeping both the geometric character and the material flow dynamics constant during machining. Forces are measured in the experiments at cutting speeds ranging from 0.2 m/s to 10 m/s. Surface roughness of the machined surfaces was characterized using coherence scanning interferometry and surface analysis. The key findings of the work are (a) force and specific forces decrease by approximately a factor of 2 over the cutting speed range and (b) surface damage substantively decreases with cutting speed. This is correlated to the behavior of the cutting forces during machining and the chip geometry. The findings indicate that higher material removal rates can be obtained in diamond turning of germanium and that this increase in material remove rates also improves surface integrity. [ABSTRACT FROM AUTHOR]

The influence of textured patterns on polycrystalline diamond (PCD) tool inserts during dry turning of Ti-6Al-4V was investigated. Four different texture patterns were created on the rake face of the insert by laser irradiation. The results showed that the textured tools improved the machinability of Ti-6Al-4V. The cutting force was less and the surface finish improved, while tool wear was minimized. The enhancement in machining performance was attributed to shortening of contact length, increased shear angle, better anti-adhesion, debris removal, and lower vibration. The typical serrations on the chip surface were brought down. The machined surface displayed minimal material transfer and feed mark ridges. The diagonal pattern (DP) tool provided the best machining characteristics (an improvement of 34% in cutting force and 37% in surface finish at 150 m/min), when compared to other textured patterns considered. [ABSTRACT FROM AUTHOR]

Single-crystal germanium, as an excellent infrared optical material, has been widely applied in X-ray monochromators, night vision systems, and gamma radiation detectors. However, how to obtain high-quality optical lenses on their surfaces still faces challenges due to their hard and brittle properties. To this end, this paper proposes the in situ laser-assisted diamond turning (ILADT) process, which is the combination of a laser heating technique and a single-point diamond turning process. The in situ laser heating technique is employed to enhance the surface quality of the workpiece material, while the single-point diamond turning process is utilized to fabricate optical lenses. Experimental results showed that optical lenses with high surface quality were successfully machined. The profile error is 0.135 μm, indicating the high machining accuracy. The surface roughness Sa of the aspheric lens is 0.909 nm, indicating the high machining quality achieved by the proposed ILADT process. Therefore, this study provides an effective approach for producing high-quality optical lenses on single-crystal germanium surfaces, which holds great promise for future applications in the manufacturing of optical lenses with exceptional quality. [ABSTRACT FROM AUTHOR]

After single-point diamond turning (SPDT), a considerable number of turning marks are typically generated on tungsten carbide molds surface, which can adversely affect their service performance. To eradicate these marks and achieve a sub-nanometer surface roughness, shear thickening polishing (STP) technology is employed to finish the tungsten carbide surface after SPDT process. Three polishing slurries with different abrasives were employed: 5 wt% SiO 2 slurry with average particle size of 80 nm, 1 wt% polycrystalline diamond slurry with average particle size of 0.5 μm, and 1 wt% monocrystalline diamond slurry with average particle size of 0.5 μm. The influence of these slurries on the polishing performance was comprehensively evaluated, covering parameters including material removal rate (MRR), surface roughness (S z), surface roughness (S a), and surface topography. All experiments and measurements in this study were repeated three times, and the average values were taken as the final results to ensure the accuracy of the experiments. The results indicated that SiO 2 exhibited the lowest polishing efficiency and yielded the poorest surface roughness. Monocrystalline diamond performed better, while polycrystalline diamond not only demonstrated superior efficiency but also achieved sub-nanometer finishing. During the shear thickening polishing process, the solid phase particles in the polishing slurry gradually encapsulate the abrasive particles, forming a "flexible fixed abrasive" which effectively removes the turning marks and reduces the surface roughness (S a) to a sub-nanometer level of 0.9 nm. Through the selection of appropriate polishing angles, the S a was further reduced to 0.8 nm. The materials removal mechanism in STP process was elucidated from two perspectives: the wear mechanism of abrasive and the influence of the impurities. Finally, STP process with selected conditions was applied to finish an curve surface of optical mold, and the surface roughness (S a) reduces from 7.7 nm to 1.6 nm. This study provides a novel approach for the ultraprecesion finishing for optical molds with complex surface. • The surface roughness S a of tungsten carbide is reduced from 4 nm to 0.8 nm within 5 min' shear thickening polishing. • Polycrystalline diamond can balance high removal rate and high surface quality due to its high hardness and smooth edges. • The impurities Cr and Ni get removed in a large amount compared to the WC which explains why pits generate. • It provided a sub-nanometer finishing method for optical molds with complex surface. [ABSTRACT FROM AUTHOR]

Fresnel optical films can be efficiently produced in large quantities by manufacturing molds on roller machine tools, using Roll-to-Roll manufacturing technology, and copying the microstructure on the roller mold surface to PET films. The accuracy of the mold determines the quality of the optical films. This paper analyzes the manufacturing principle and processing process of a rotating-tool diamond turning roller mold on roller machine tools. Considering turning efficiency and freedom, two tandem rotating axes were added to the traditional three-axis roller machine tool to form a five-axis roller machine tool. The tandem rotating axis adjusts the tool angle so that the cutting edge directly cuts the Fresnel working surface, increasing the processing efficiency and accuracy. In order to improve manufacturing accuracy, this paper uses spinor theory to establish an error model for machine tools. It uses the Fourier amplitude sensitivity test (FAST) to find the five geometric errors. Finally, an error compensation iterative algorithm is proposed, which quickly and accurately calculates the error compensation amount. Experiments were conducted to study the chatter phenomenon during turning and analyze multiple influencing factors that cause cutting chatter. The experimental results revealed that except for the impact of the stiffness of the workpiece-tool system on cutting chatter, other factors have relatively little influence. Enhancing stiffness can significantly reduce the generation of cutting vibration marks and improve the surface quality of the workpieces. Finally, the Fresnel microstructure was turned on the roller mold. As a result, with reasonable process parameters on the surface, the cutting chatter phenomenon was improved, and the error compensation effect was significant, which verified the reliability of the error compensation method. • Improved roller machine design, and make it possible to manufacture large Fresnel roller molds. • The screw theory was used to model the error of the machine tool, and an error compensation experiment was conducted. • The chatter problem during the cutting process was analyzed through experiments, and the surface quality of the workpiece can be effectively improved by optimizing process parameters. [ABSTRACT FROM AUTHOR]

The achievable performance of conventional repetitive control (CRC) is constrained by the error amplification at the non-harmonic frequencies, the intrinsic sensitivity to the signal period shift and the limited tracking frequency range under fixed sampling rate. To remedy these undesirable behaviors, a notch-filter-based repetitive control (NF-RC) is proposed based on the spectrum-selection filtering scheme in this paper with application to fast tool servos (FTSs). The loop-shaping property of this NF-RC can be flexibly designed by the cascade of a series of parameterized IIR notch filters without the aforementioned limitations of the CRC, so as to provide a unified formula for various RCs and even resonant control schemes. A general realization along with several simplified versions of the IIR notch filter is derived for the digital implementation of the NF-RC. Comparative trajectory tracking experiments on a self-developed FTS have validated the superiorities of the proposed NF-RC in terms of the performance improvement for periodic reference tracking, the robustness against the signal period variations and the trackable frequency range under fixed sampling rate. Taking advantage of an excellent comprehensive performances of the NF-RC scheme, the radial sinusoidal surface and the water-drop surface were successfully produced with high form precision and excellent surface quality after the FTS-based diamond turning. • A novel notch-filter-based repetitive control (RC) scheme is proposed. • This RC scheme can suppress the nonperiodic errors amplification. • This RC scheme can maintain the robustness against the signal frequency fluctuation. • This RC scheme can track any harmonic references under a fixed sampling rate. • This RC scheme provides a unified design framework for various existing RCs. • Two high-accuracy micro-structured surfaces are fabricated with this RC scheme. [ABSTRACT FROM AUTHOR]

SiC p /Al composites are suitable for satisfying the lightweight requirements of terahertz wave-reflecting components. In this paper, diamond-turned surfaces of 60 % high volume fraction SiC p /Al composites are characterized in terms of surface roughness and terahertz reflectivity. The finished surfaces of SiC p /Al composites are obtained using single-point diamond turning with different process parameters, and surface roughness measurements as well as SEM and EDS analyses are conducted on the surfaces. The theoretical relationship between surface roughness and terahertz reflectivity is analyzed, and terahertz reflectivity testing experiments are conducted and validated. The surface roughness evaluation system and prediction model for SiC p /Al composites with a volume fraction of 60 % are established, and the errors between the experimental results and the predicted results are verified within 10 % by random experiments. Finally, the turning process parameters are optimized using a genetic algorithm, and the optimized turning process parameters are obtained as the spindle speed of 750 r/min, the feeding speed of 1 mm/min and the turning depth of 6 μm. • Spindle speed and feeding speed have a significant impact on surface roughness. • The relationship between roughness and reflectivity was analyzed and experimented. • Roughness prediction model is established, and the model error is verified. • A genetic algorithm is adopted to optimize the turning process parameters. [ABSTRACT FROM AUTHOR]

Additive manufacturing processes have progressed in years past from not only being prototyping methods to also being end-product manufacturing methods. However, there are many challenges hindering higher industrial adoption rates of additive manufacturing such as low surface quality of the manufactured parts. Post-process surface treatment methods can play a key role in addressing this challenge. In this work, three mechanical methods were applied to selective laser-sintered polyamide 12 (PA12) parts with the aim of improving the surface quality. The effects of the methods regarding the surface integrity characteristics were evaluated. The results show improved surface roughness across all three methods: from initial Ra of 7.09 μm to 0.055 μm Ra, 0.28 μm Ra and 0.45 μm Ra by grinding, diamond turning and milling on the surfaces oriented upwards during fabrication respectively. Across the three methods, surface hardness was slightly reduced: with a maximum reduction of 2.5% by diamond turning. [ABSTRACT FROM AUTHOR]

Limited research work has been performed to investigate the effect of biological structures and their position (rake surface, flank surface) on cutting tools in enhancing cutting performances. Therefore in current work, effect of change in position of different conventional structures (micro-dimples, micro-grooves) and bio-inspired micro-crescent geometrical structures on machining characteristics of hard-to-cut martensitic AISI 420 steel has been investigated. The structures were generated on a carbide tool using laser machining. The dry turning operation was conducted at constant feed (fz) = 0.14 mm/rev, speed (vc) = 315 m/min, depth (ap) = 0.20 mm. From the obtained responses, it is noticed that the bio-inspired flank surface and rake surface crescent structured tool outperformed other structured and conventional tools. It happened because structures on rake and flank surface of tool helped in enhancing machining performance by breaking contact between interface of the chip–tool, acting as an entrapper of wear debris particles and improving heat transfer between tool–workpiece interfaces. The bio-inspired structured tool also showed minimum tensile residual stress of 315.6 and 390.2 MPa in feed and cutting direction on the machined surface. The results indicate a reduction of 56.44, 28.91, 19.04 and 19.02% in the flank wear, feed force, tangential force and average surface roughness using crescent-shaped rake and flank-faced tool relative to the conventional tool. The research results are very important for expanding the applications of bio-inspired structured tools in various machining operations. [ABSTRACT FROM AUTHOR]

AISI 420 is primarily used for optic molds manufactured through ultraprecision machining with single-crystal diamond tools. Tool wear rapidly occurs due to the diffusion of diamond and iron atoms when cutting ferrous metals with diamond tools. In the machining of optic molds, the diamond tool is uniformly replaced, regardless of the tool status after use for some time due to the difficulty in predicting tool life. This practice results in the wastage of expensive single-crystal diamond tools and reduces productivity. This study addressed the aforementioned issue by developing a tool-life model through theoretical analysis of the effective contact ratio between the tool and the workpiece and a cutting experiment with high-frequency ultrasonic vibration. In addition, the effectiveness of ultrasonic vibration cutting on the suppression of diamond tool wear was demonstrated by measuring tool wear after the cutting experiments. [ABSTRACT FROM AUTHOR]

Morphable polishing tools are capable of finishing diamond turned surfaces with roughness in the nanometre range. The material removal rate of morphable tools polishing is challenging to calculate due to the labyrinth and dimple textures. This paper introduces a multi-scale theoretical model for predicting the material removal rate of morphable polishing tools. The model includes the polishing velocity, polishing pressure, material removal by an abrasive, and number of effective abrasives. First, polishing velocity is obtained by tool kinematics analysis. Second, polishing pressure is obtained based on image processing. Theoretical polishing pressure is calculated by polishing pressure equations. Morphable tool texture images are binarized and conducted with Boolean product of the theoretical polishing pressure images to get the morphable tool polishing pressure. The morphable tool polishing pressure and 12-image averaged pressure are conducted with Boolean product of the polishing velocity to obtain the instant and average material removal rate. Then, the polishing pressure and material removal rate model are validated through pressure measurement and polishing tests, respectively. It is found that the polishing spot is ellipse shape with long axis (10.6 mm) and short axis (9.6 mm). The material removal rate for smooth tools along the short axis is almost constant while it steadily increased along the negative long axis. For labyrinth tools, the material removal rate along the short axis and the long axis is a trapezoidal shape and scalene triangular shape. For dimple tools, the material removal rate along the long axis and the short axis are similar to isosceles triangular shape. The model results agree well with the experimental data and quantify how morphable tool texture influences the polishing pressure component and influences the material removal rate, which makes the polishing process more predictive. The image processing–based method can be further applied to obtain polishing pressure and material removal rate of different complicated polishing tools. [ABSTRACT FROM AUTHOR]

Context—Rapidly solidified aluminium alloy (RSA 443) is increasingly used in the manufacturing of optical mold inserts because of its fine nanostructure, relatively low cost, excellent thermal properties, and high hardness. However, RSA 443 is challenging for single-point diamond machining because the high silicon content mitigates against good surface finishes. Objectives—The objectives were to investigate multiple different ways to optimize the process parameters for optimal surface roughness on diamond-turned aluminium alloy RSA 443. The response surface equation was used as input to three different artificial intelligence tools, namely genetic algorithm (GA), particle swarm optimization (PSO), and differential evolution (DE), which were then compared. Results—The surface roughness machinability of RSA443 in single-point diamond turning was primarily determined by cutting speed, and secondly, cutting feed rate, with cutting depth being less important. The optimal conditions for the best surface finish Ra = 14.02 nm were found to be at the maximum rotational speed of 3000 rpm, cutting feed rate of 4.84 mm/min, and depth of cut of 14.52 µm with optimizing error of 3.2%. Regarding optimization techniques, the genetic algorithm performed best, then differential evolution, and finally particle swarm optimization. Originality—The study determines optimal diamond machining parameters for RSA 443, and identifies the superiority of GA above PSO and DE as optimization methods. The principles have the potential to be applied to other materials (e.g., in the RSA family) and machining processes (e.g., turning, milling). [ABSTRACT FROM AUTHOR]

Laser-processing technology has been widely used in the ultra-precision machining of diamond materials. It has the advantages of high precision and high efficiency, especially in the field of super-hard materials and high-precision parts manufacturing. This paper explains the fundamental principles of diamond laser processing, introduces the interaction mechanisms between various types of lasers and diamond materials, focuses on analyzing the current development status of various modes of laser processing of diamond, briefly discusses the relevant applications in diamond cutting, micro-hole forming, and micro-groove machining, etc., and finally discusses the issues, challenges, and potential future advancements of laser technology in the field of diamond processing at this point. [ABSTRACT FROM AUTHOR]

Die-sinking micro-electrical discharge machining (micro-EDM) is a potential method used to fabricate intricate structures without complex electrode motion planning and compensation. However, machining efficiency and poor discharge states are still bottlenecks. This study conducted a comparative investigation into the impact of ultrasonic vibration on die-sinking micro-EDM of polycrystalline diamond (PCD) and pure titanium (TA2). By adjusting discharge parameters, this study systematically evaluated the influence of ultrasonic vibration on these two materials based on discharge waveforms, motion trajectories, effective discharge counts and groove profiles. At an open-circuit voltage of 100 V, ultrasonic vibration promotes die-sinking micro-EDM of PCD. However, when the open-circuit voltage increases to 200 V, ultrasonic vibration exhibits inhibitory effects in general. Conversely, for TA2, ultrasonic vibration shows a promoting effect at both voltages, indicating the differences of ultrasonic vibration-assisted die-sinking micro-EDM on PCD and TA2. For PCD, ultrasonic cavitation improves the discharge gap environment, accelerating the removal of discharge debris. For TA2, due to its poor thermal conductivity, ultrasonic cavitation acts to break the arc, accelerating heat transfer. These research findings provide guidance for ultrasonic vibration-assisted die-sinking micro-EDM in industrial applications. [ABSTRACT FROM AUTHOR]

The ultraprecision machining of the mold surface is important because the performance of optical components produced using optical injection is related to the surface roughness and shape precision of the mold core. To process hard-to-cut mold core materials such as stainless steel, electroless nickel-phosphorus (NiP) plating is applied to the surface of the substrate, and ultraprecision processing is performed on the plating surface using diamond turning (DT) and magnetorheological finishing (MRF). Although MRF processing can remove tool marks caused by diamond turning and improve shape accuracy, it suffers from poor processability for NiP. In this paper, an ultraprecision processing method with a heat treatment process was presented to improve the MRF processability of electroless NiP. The plating was heat-treated under each condition and subjected to DT processing followed by MRF. The surface roughness and reflectance were measured and evaluated after processing. As a result, the surface roughness of NiP subjected to a 1-h heat treatment at 450 °C significantly decreased from Ra 7.0 nm to Ra 1.5 nm when compared to the specimen that did not undergo any heat treatment. An improvement in surface roughness confirmed that reflectance improved by more than 9% and 18%, respectively, compared to that for the diamond-turned and non-heat-treated specimen. These results confirmed that the MRF performance was improved through the NiP heat treatment process and contributed to quality improvements in ultraprecision injection optical parts. Furthermore, this technology can be applicable to various fields that used NiP plating, including the manufacturing of metal reflectors in the visible and ultraviolet regions. [ABSTRACT FROM AUTHOR]

A novel hybrid electromagnetic-piezoelectric actuated tri-axial fast tool servo (FTS) with the hybrid serial-parallel structure is presented to satisfy the requirements of the large-stroke planar motion and the high-bandwidth vertical motion for the ultraprecision diamond turning of the complicated optical surfaces. To further improve the high-frequency spatial vibration capability, a compact three-dimensional elliptical vibration generator (3D EVG) actuated by four parallel-arranged piezoelectric actuators (PEAs) is integrated into the tri-axial FTS. The structural parameters of the proposed tri-axial FTS system are optimally designed by modeling its mechanical and electromagnetic components, and the measured mechanical performance of the resulting prototype exhibits a good agreement with the designed objective. Finally, hierarchical micro/nano-structured surfaces are fabricated by using the developed tri-axial FTS to demonstrate its comprehensively machining capacity. • A novel hybrid electromagnetic-piezoelectric actuated tri-axial FTS is proposed. • A 3D EVG actuated by four PEAs is developed and integrated into the tri-axial FTS. • The electromagnetic and mechanical components of the tri-axial FTS are modeled. • The system parameters are optimally determined by the optimization models. • Two types of hierarchically micro-structures are fabricated with the tri-axial FTS. [ABSTRACT FROM AUTHOR]

In this study, sol–gel derived spray coatings of highly hydrophobic nature consisting of polystyrene (PS) and SiO2 nanoparticles were developed on polished stainless steel 321 (SS) and textured 6061 aluminium (Al) alloy substrates. The micro-structures on the Al surface were created through ultraprecision machining, known as single-point diamond turning (SPDT) machining. The polished SS and micro-structured Al were coated with PS/SiO2 using a spray coating technique by maintaining a pressure of 4–5 kPa, and positioning the nozzle 20–30 cm away from the substrates. The textured surface of Al was characterised using coherent correlational interferometry (CCI). The PS modified SiO2 nanoparticles and their coatings were characterised using Fourier-Transform Infrared Spectroscopy (FTIR) and field-emission scanning electron microscopy (FESEM). The resulting coating exhibited a micro-nano hierarchical roughness due to the presence of SiO2 nanoparticles and their fine size clusters. The polished SS surface showed static water contact angles of 93.3° and 143.5° before and after coating, respectively. Similarly, the polished and coated structured Al surface exhibited water contact angles of 85.6° and 144.3° before and after coatings. Such coatings can exhibit a great potential particularly in the field of self-cleaning technologies. [ABSTRACT FROM AUTHOR]

The core optics in the deep-space high-energy physics ray detection system are an ultra-precision aspherical surface, which would generate surface errors introduced by the ultra-precision single point diamond turning (SPDT), leaving the millimeter-level length and micron-level height periodic mid-spatial frequency (MSF) errors dissatisfying the expected optical performance. Hence, a corrective technique is urgent to effectively remove MSF errors from optical surfaces, enhancing the compliance control of the tool to adapt to curvature-varying optical surfaces to obtain a stable Gaussian-like removal function. This study explored the sponge figuring processing (SFP) removal mechanism, which verified the robustness and removal efficiency of the tool influence function for the planar and various curvatures of the Ni–P surface. To comprehensively investigate the removal function of SFP, based on the sponge-figuring process removal mechanism with three removal regimes, the relative velocity model and contact pressure model are established and verified for validity by pre-experiment. To obtain a stable and effective removal function, L16 orthogonal experiments and analysis of variance (ANOVA) methods were conducted on flat specimen surfaces on a 3-axis ultra-precision figuring tester machine utilizing a sponge head with in-situ correction of high slurry absorption and retention capacity as the figuring tool. To determine the curvature surface impact on the robustness of the tool influence function (TIF), matching experiments of spatial wavelength and full width at half maximum (FWHM) were executed. As a result, the removal function is mainly impacted by the offset, accounting for 40%, and the error was 8% in the predicted value of the volume removal rate under the optimal parameter conditions. From the perspective of optical performance, the significant peak of 1D-power spectral density (PSD) was suppressed in the mid-frequency band, partially converted into high-frequency band errors, and the mid-frequency surface ripple error was effectively enhanced from 2.4 to 1.8 nm, following multiple iterative figuring, for the variable curvature surface. [ABSTRACT FROM AUTHOR]

Poly(methyl methacrylate) (PMMA), with a glass transition temperature (Tg) over 100 °C, shows good mechanical and optical properties and has broad applications after being machined with single-point diamond turning (SPDT) at room temperature. Because of the high Tg, current efforts mostly focus on optimizing machining parameters to improve workpiece precision without considering the modification of material properties. Cryogenic cooling has been proven to be an effective method in assisting ultra-precision machining for certain types of metals, alloys, and polymers, but has never been used for PMMA before. In this work, cryogenic cooling was attempted during the SPDT of PMMA workpieces to improve surface quality. The machinability and surface properties of cryogenically cooled PMMA were investigated based on the mechanical properties at corresponding temperatures. Nanoindentation tests show that, when temperature is changed from 25 °C to 0 °C, the hardness and Young's modulus are increased by 37% and 22%, respectively. At these two temperature points, optimal parameters including spindle speed, feed rate and cut depth were obtained using Taguchi methods to obtain workpieces with high surface quality. The surface quality was evaluated based on the total height of the profile (Pt) and the arithmetic mean deviation (Ra). The measurement results show that the values of Pt and Ra of the workpiece machined at 0 °C are 124 nm and 6 nm, respectively, while the corresponding values of that machined at 25 °C are 291 nm and 11 nm. The test data show that cryogenic machining is useful for improving the form accuracy and reducing the surface roughness of PMMA. Moreover, the relationship between temperature, material properties and machinability weas established with dynamic mechanical analysis (DMA) data and a theoretical model. This can explain the origin of the better surface quality of the cryogenic material. The basis of this is that temperature affects the viscoelasticity of the polymer and the corresponding mechanical properties due to relaxation. Then, the material property changes will affect surface profile formation during machining. The experimental results and theoretical analysis show that cryogenically cooled PMMA has good machinability and improved surface quality when using SPDT compared to that at ambient temperature. [ABSTRACT FROM AUTHOR]

The heterogeneous mechanical properties of individual phases in SiCp/Al result in significant varying size effect (SE) existed in its deformation process. And modulating the varying SE is crucial for improving the machined surface finish of SiCp/Al in mechanical machining. In this study, we elucidate the mechanisms governing the varying SE in conventional cutting and ultrasonic elliptical vibration-assisted cutting (UEVC) of SiCp/Al using diamond tools by theoretical analysis, numerical simulations and experiments. Specifically, the impact of cutting tool-workpiece contact states in UEVC on the fundamental cutting behavior of SiCp/Al, in terms of microscopic deformation modes and their correlations with machining force variation, machined surface morphology and chip profile, is evaluated. Subsequently, ultrasonic elliptical vibration-assisted diamond turning of SiCp/Al is performed to achieve a surface roughness of 20 nm accompanied with significantly suppressed tool wear. Finally, the compensation effect on the varying SE in SiCp/Al cutting by ultrasonic elliptical vibration of cutting tool is discovered, which leads to decreased brittle fracture and improved surface integrity. The research findings provide a theoretical support for understanding the machining mechanisms of UEVC of SiCp/Al, as well as proposing new perspectives for improving the machinability of SiCp/Al composite accompanied by suppressed varying SE. • Machining mechanisms of SiCp/Al in ultrasonic elliptical vibration-assisted diamond cutting are elucidated. • Origination of varying size effect in diamond cutting of SiCp/Al coupled with tool-particle position is revealed. • The compensation on varying size effect in ultrasonic elliptical vibration-assisted cutting of SiCp/Al is discovered. • A surface roughness of 20 nm of SiCp/Al accompanied with significantly suppressed tool wear is achieved. [ABSTRACT FROM AUTHOR]

Diamond turning of microstructured surfaces based on slow slide servo or fast tool servo technologies suffers from either low machining efficiency or low surface accuracy, due to the highly mixed low-frequency and high-frequency tool trajectory. This work proposes a new parallel tool servo (PTS) turning technology, in which the original tool path is filtered according to an optimal cut-off frequency and then decomposed into independent trajectories separately for a slow slide and a fast stage in parallel. This approach is experimentally validated and compared with existing single-mode servo technologies, with significantly enhanced cutting performance, thus offering a novel perspective for ultra-precision machining. [ABSTRACT FROM AUTHOR]

A predictive digital twin (DT)-driven dynamic error control approach is presented for accuracy control in high-frequency slow-tool-servo ultraprecision diamond turning processes. An explainable artificial intelligence-enabled real-time DT of the total dynamic error (inside and outside the servo loop) was established using in-line acceleration input data near the tool. A feedforward controller was used to mitigate the total dynamic errors before they came into effect. The machining trials using this approach showed that significant improvement in machining accuracy (87%, surface form accuracy; 95%, phase accuracy with precisions of 0.06 µm and 0.05°), and efficiency (8 times the state-of-the-art) were successfully achieved. [ABSTRACT FROM AUTHOR]

Evaluating surface frequency components in the fabrication process is critical for controlling the machined surface quality. The presence of anisotropic ripples on diamond-turned surfaces makes this challenging. A multiscale frequency evaluation method, referred to as Surface Intrinsic Mode Decomposition (SIMD), is proposed for evaluating on-machine surface measurement (OMSM) data. It decomposes continuous surface probing profiles, incorporating both temporal and spatial frequency information. In comparison to the conventional power spectral density (PSD) analysis method, the approach enriches frequency details over a wider range, which contributes to a more comprehensive understanding of surface quality and helps to identify mid-spatial frequency (MSF) errors. [ABSTRACT FROM AUTHOR]

CubeSats, known for their compact size and cost effectiveness, have gained significant popularity. However, their limited size imposes restrictions on the optical aperture and, consequently, the Ground Resolution Distance in Earth Observation missions. To overcome this limitation, the concept of deployable optical payloads with segmented primary mirrors which can unfold like petals has emerged, enabling larger synthetic apertures and enhanced spatial resolution. This study explores the potential benefits of leveraging Additive Manufacturing (AM) and Topology Optimization (TO) in the realm of ultra-precision machining, specifically single-point diamond machining. The goal is to reduce fixture weight while improving stiffness to minimize deformations caused by rotational and cutting forces which compromise optical performance. Through Finite Element Analysis, this research compares conventionally machined fixtures with those produced using AM and TO techniques. The results reveal that concept designs created via TO can achieve a remarkable 68% reduction in weight. This reduction makes the assembly, including the machining fixture and 12 U deployable segments, manageable by a single operator without the need for specialized lifting equipment. Moreover, these innovative designs lead to substantial reductions of up to 86% and 51% in deformation induced by rotational and cutting forces, respectively. [ABSTRACT FROM AUTHOR]

To build a long-wave infrared catadioptric optical system for deep space low-temperature target detection with a lightweight and wide field of view, this work conducted a study that encompasses a local cooling optical system, topology optimization-based metal mirror design, and additive manufacturing. First, a compact catadioptric optical system with local cooling was designed. This system features a 55 mm aperture, a 110 mm focal length, and a 4-degree by 4-degree field of view. Secondly, we applied the principles of topology optimization to design the primary mirror assembly, the secondary mirror assembly, and the connecting baffle. The third and fourth modes achieved a resonance frequency of 1213.7 Hz. Then, we manufactured the mirror assemblies using additive manufacturing and single-point diamond turning, followed by the centering assembly method to complete the optical assembly. Lastly, we conducted performance testing on the system, with the test results revealing that the modulation transfer function (MTF) curves of the optical system reached the diffraction limit across the entire field of view. Remarkably, the system's weight was reduced to a mere 96.04 g. The use of additive manufacturing proves to be an effective means of enhancing optical system performance. [ABSTRACT FROM AUTHOR]

Tungsten carbide-cobalt (WC–Co), as a typical cemented carbide, is widely used in the manufacturing field. However, creating high-quality microstructure arrays on its surfaces remains challenging due to its extraordinary hardness. To solve this problem, this study proposes an in-situ laser-assisted ultraprecision cutting (LAUC) process to machine different microstructure arrays on the WC-Co surfaces. Experimental results show two kinds of microstructure arrays, namely bi-sinusoidal microstructure array and micro-lens array, are successfully created on the WC-Co surfaces. The average error of feature sizes is less than 2%, showing the high cutting accuracy of the in-situ LAUC process. The average surface roughness of microstructure arrays is below 6 nm, showing the high cutting quality of the in-situ LAUC process. Furthermore, a comparison experiment with the traditional ultraprecision diamond turning process shows the proposed in-situ LAUC process improves the machinability of the WC-Co and decreases the tool wear, further demonstrating its superiority. Therefore, this work provides a new and effective method of creating microstructure arrays on WC-Co surfaces, which greatly enhances the machining quality and extends tool life. [ABSTRACT FROM AUTHOR]

This study delves into the intricacies of ultraprecision machining, particularly in the context of machining optical freeform surfaces using Diamond Turning Machines (DTMs). It underscores the dynamic relationship between toolpath generation, hydrostatic bearing in DTMs, and the machining process. Central to this research is the innovative introduction of Metal Matrix Composites (MMCs) to replace the traditional materials used in designing linear bearings. This strategic substitution aims to dynamically enhance both the accuracy and the quality of the machined optical freeform surfaces. The study employs simulation-based analysis using ADAMS to investigate the interfacial cutting forces at the tooltip and workpiece surface and their impacts on the machining process. Through simulations of STS mode ultraprecision machining, the interfacial cutting forces and their relationship with changes in surface curvatures are examined. The results demonstrate that the use of MMC material leads to a significant reduction in toolpath pressure, highlighting the potential benefits of employing lightweight materials in improving the dynamic performance of the system. Additionally, the analysis of slideway joints reveals the direct influence of interfacial cutting forces on the linear slideways, emphasising the importance of understanding and controlling these forces for achieving higher-precision positioning and motion control. The comparative analysis between steel and MMC materials provides valuable insights into the effects of material properties on the system's dynamic performance. These findings contribute to the existing body of knowledge and suggest a potential shift towards more advanced precision forms, possibly extending to pico-engineering in future systems. Ultimately, this research establishes a new standard in the field, emphasising the importance of system dynamics and interfacial forces in the evolution of precision manufacturing technologies. [ABSTRACT FROM AUTHOR]

The high hardness, brittleness, and thermal resistance of fused silica glasses extremely challenge the mass production of complex‐shaped fused silica optics. This paper reports a new process chain for rapidly replicating complex‐shaped fused silica optics from complex molds at ambient temperature. The process chain mainly consists of the ultraprecision diamond turning of the complex‐shaped molds, the rapid shape replication through the silica precursor photopolymerization, and the transparent complex‐shaped optics derivation from the debinding and sintering. The directional shrinkages and surface texture evolutions in the process are comprehensively characterized for the replicated fused silica optics. After the shrinkage compensation, transparent fused silica optics with the spherical, microlens array, and hierarchical freeform surfaces are precisely replicated, exhibiting micrometric form accuracy, nanometric surface roughness, and high imaging quality. The proposed process chain provides a revolutionary approach for the mass production of precise complex‐shaped fused silica optics with fundamentally improved production efficiency and complex shape formation capability. [ABSTRACT FROM AUTHOR]

Cube corner retroreflector is an optical element with high reflectivity, widely used to improve safety in low-light environments. High-precision and surface finish die cores are used to mass-produce high-quality retroreflectors. There are periodic micro-morphologies on the die core surface machined by diamond fly-cutting, which weaken the reflection characteristics of optical elements. The finite element method theoretically revealed the relationship between optical defects and surface topography, and the fly-cutting experiment was carried out to verify the analysis. At the same time, an efficient machining method to eliminate the diffraction phenomenon is proposed. According to the machining results, the error source of this method is analyzed and calibrated. This research provides a new idea for obtaining the optical plane of retroreflectors with high efficiency and accuracy. [ABSTRACT FROM AUTHOR]

Surfaces with nanometric texture, machined by ultra-precision diamond milling (UPDM), have wide applications for their functionalities. Surface texture characterisation is crucial for their quality evaluation and it would vary in the measurement data processing under various scales, which is termed scale effects. However, the scale effects have not been comprehensively studied. In this work, we focus on the scale effects on surface texture characterisation of UPDM. Firstly, a series of experiments were conducted at different material removal rates to produce surfaces with nanometric texture. Secondly, a discrete wavelet transform (DWT)-based method was employed for surface filtering and surface texture parameters (Sa , Sq , and Sz) were evaluated according to ISO standards. Thirdly, power spectral density (PSD) analysis and surface filtering comparison were performed to realize a scale observation. Furthermore, the effects of the filtering scale, the sampling scale, and the subarea scale on surface texture characterisation were investigated. Finally, the results showed that surface topographies were governed by various machining factors which resulted in multi-scale topographical components. The PSD analysis enabled discrimination of the multi-scale topographical components to the underlying machining factors. The DWT-based method achieved a relatively small deviation (<4%) for surface filtering as compared to the zero-order Gaussian regression filter. The filtering scale affected the filtered topographical components and it visualised and differentiated those components with the machining mechanisms. The sampling scale determined the filtered components to yield an impact on the characterisation results and Sz was more sensitive to this effect than Sa and Sq. The subarea scale influenced the probability distributions and statistical values of surface texture parameters within its contained components and it indicated that the increased material removal rate resulted in a deterioration of surface uniformity. • Surfaces with nanometric texture were processed by ultra-precision diamond milling. • Discrete wavelet transform was conducted for surface filtering at multiple scales. • Surface texture parameters were characterized according to the ISO standards. • The scale effects on surface texture characterisation were investigated. [ABSTRACT FROM AUTHOR]

During the milling of a curved surface, the shape of the curved surface changes continuously along the milling path, and the direction of the angle between the axis of the milling tool and the normal vector of the machined surface also changes. In turn, these changes greatly affect the quality of the machined surface. Therefore, to improve the surface quality of machined workpieces, the milling tool inclination angle should be optimized. In the present study, a three-dimensional model of the milling tool path and the workpiece surface was created. The three-dimensional surface model of the workpiece at each machining moment was iteratively built based on the Z-map method. From the macroscopic perspective, the influences of different milling tool inclination angles on surface roughness were analyzed. The difference in surface roughness generated by different inclination angles under the same feed rate and pitch was obtained. When cutting with the top of the milling tool, the roughness was larger compared to other inclination angles, and there was a roughness deviation of about 8% when other inclination angles were selected. Moreover, from the microscopic perspective, the material removal rate from a single feed cycle and the optimal inclination angle range for milling stability were explored. An optimal inclination range of 15–30% was obtained, considering both the total material removal volume and unit-angle material removal volume. Finally, a spherical machining verification experiment was conducted on an ultra-precision machining tool, and the experimental findings agreed well with the simulation results, demonstrating the reliability of the proposed model. The theoretical model of this study can provide a basis for optimal cutting tool inclination angle selection during complex surface milling. • A surface model of the workpiece was built based on the Z-map method. • The influences of milling tool inclination angles on surface roughness were analyzed. • The material removal rate from a single feed cycle was explored. • The optimal inclination angle range for milling stability was explored. [ABSTRACT FROM AUTHOR]

The product's surface quality and service performance depend on the surface integrity features formed by the machining process. Surface integrity consists of many features including surface topography and others. In this work, 3D (areal) surface topography features, particularly height variations, were investigated on the polycrystalline diamond (PCD) turning of alumina. Variations of the areal unevenness and height distribution parameters, namely arithmetic mean deviation (Sa), maximum peak height (Sz), skewness (Ssk) and kurtosis (Sku), with respect to turning parameters such as spindle speed (1000, 2000 & 3000 rpm), feed rate (0.05, 0.075 & 0.1 mm/rev) and depth of cut (1, 3 & 5 μ m) were studied. The Taguchi technique was carried out in this study based on the L9 standard orthogonal array for optimizing the turning parameters for the generation of better topography features. The error analysis was done with the experimental results and the error variations were noticed to be less than 10%. Based on the experimental results, the best surface figure combination of Sa 0.67 μ m, Sz 3.18 μ m, Ssk 0.0039 and Sku 3.06 was found at the employment of spindle speed of 1500 rpm, feed rate of 0.1 mm/rev, and depth of cut of 1 μ m. The distribution of peaks and valleys formed over the PCD-turned alumina surfaces may influence the different functional properties such as fatigue, friction, wear, etc. Besides, the results were examined through means of responses and analysis of variance (ANOVA). The test results also reported that the depth of cut outperforms other hard turning parameters over the surface topography features of the turned alumina ceramics. At a lower depth of cut, the cutting tool is involved in the shearing action which causes the stable material removal of alumina ceramics through an appreciable chip formation. [ABSTRACT FROM AUTHOR]

As the applications for freeform optical surfaces continue to grow, the need for high-precision machining methods is becoming more and more of a necessity. Different toolpath strategies for the ultra-high precision turning of freeform surfaces can have a significant impact on the quality of the machined surfaces. This paper presents a novel toolpath planning method for ultra-precision slow tool servo diamond turning based on the curvature of freeform surfaces. The method analyzes the differential geometric properties of freeform surfaces by reconstructing NURBS freeform surfaces. A mathematical model is constructed based on the parameters of different positions of the freeform surface, toolpath parameters, and tool residual height. Appropriate toolpath parameters can be calculated to generate the optical freeform ultra-precision slow tool servo diamond turning toolpath. Compared with the toolpaths generated by the traditional Archimedes spiral method, the ultra-precision slow tool servo diamond turning toolpath planning method proposed in this paper can generate more uniform toolpaths on the freeform surfaces and keep the residual tool height within a small range. [ABSTRACT FROM AUTHOR]