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Fast tool servo (FTS) in ultra-precision diamond turning is an efficient technique for high-precision fabrication of freeform optics. However, the currently adopted constant scheme for control point sampling takes no account of the shape variation of the desired surface, which might lose some micro features and result in low form accuracy and non-uniform surface quality. Facing this issue, this manuscript proposes a novel adaptive control points sampling strategy, which improves the form accuracy and keeps as many as the micro surface features. In the optimization method, the sampling stepovers between two adjacent control points are actively adjusted to adapt to the surface profile variation. By adopting this method, the control point sampling induced interpolation error is constrained within the desired tolerance and eliminates the lack/over-definition of control points in the machining area. The feasibility of the proposed optimization method is demonstrated by both theoretical simulations and fabrication experiments of sinusoid freeform surfaces. Compared with the constant sampling method, both the theoretical predicted and experimental measured form error of the proposed method is remarkably reduced by about 35 % with the same amount of control points. This technique provides a new route to allocating control points in FTS diamond turning to achieve high form accuracy and machining efficiency in the fabrication of freeform optics.

This paper describes a method for measuring and compensating the roundness error of a larger mandrel manufactured by an ultra-precision diamond-turning lathe aimed to obtain a calibration cylinder with a roundness of less than 0.1 μm. The diamond-turning machine has a cross-stacked hydrostatic guideway, produces a cutting depth and feed movement direction, and a dual-spindle system that is firmly connected to the bed. Due to the good repeatability of aerostatic spindles, only in situ rather than online real-time measurements are required. To this end, three high-precision capacitance displacement sensors were utilized to detect the cross-section of the workpiece and the time domain via the three-point error separation technique to separate the roundness error from the rotation motion error. The slow tool servo (STS) cutting technique was employed to compensate for the roundness error, which did not require extra axes, only the excellent dynamic response of the feed axis; hence, the servo control parameters could be suitably adjusted. The experimental results reveal that the low-order harmonic error, often caused by aerostatic spindles, is almost removed completely. For this particular lathe, the experiments indicate that about 60% of the rotational error motion is compensated, and the roundness error is reduced to less than 0.1 μm, which is evaluated by the least-squares circle method. [ABSTRACT FROM AUTHOR]

A freeform imaging telescope (FIT) can achieve a large field of view, high resolution, light weight, and small volume at the same time. Single-point diamond turning (SPDT) is usually used to fabricate FITs, which is made entirely of aluminum alloy. Compared with a traditional telescope, whose reflector is made of glass and whose structure is aluminum, the coefficient of thermal expansion (CTE) of the structure and reflector of which is non-conforming, the CTE of the structure and reflector in an all-aluminum FIT is identical. Therefore, it was expected to theoretically have athermalization properties. In this paper, an all-aluminum off-axis three-mirror FIT was verified. The opto-mechanical–thermal coupling analysis of the FIT at −20 °C was carried out, including data processing and coordinate transformation. The reflector node deformation data of the global coordinates obtained from the finite-element analysis were converted into XY polynomial coefficients of the local coordinate system in ZEMAX. The results showed that the modulation transfer function (MTF) of the FIT at −20 °C~+40 °C still reached the diffraction limit. Moreover, the MTF of the FIT at −20 °C was 0.291 through a thermal environmental test, which was almost the same as the MTF at 22 °C. These results showed that the all-aluminum FIT could achieve athermalization properties. [ABSTRACT FROM AUTHOR]

Ultra-precision cutting (UPC) is an advanced machining process capable of fabricating components with a surface finish and dimensional accuracy in the nanometer range. The cutting tool edge should possess ultra-sharpness and controlled waviness to bring off a higher degree of finish and accuracy. It also should have high hardness, toughness, thermal resistance and chemical inertness. As the cutting-edge radius is in order of nm, the edge characterization is always arduous. Profound knowledge regarding the wear patterns of the UPC tools is indispensable as it will affect the machining quality to a great extent. Hence, to employ a cutting tool for UPC operations, one should know the different variants of UPC and their characteristics, different tool materials and their properties, geometries and how it affects machining accuracy, various edge preparation method and characterization techniques and their limitations, associated measurement errors, tool wear patterns and processes to control the wear. These diverse areas have to be brought under a single roof to systematically choose the material, geometry, and fabrication method for UPC tools. This article provides a comprehensive review of the research related to cutting tools of UPC to understand and evaluate the current trends in the development of UPC tools. [ABSTRACT FROM AUTHOR]

Featured Application: The outcome of the study provides an efficient machining way to fabricate optical microstructure mold made of difficult-to-machine materials which could be used for mass production of optical functional components. Ultrasonic vibration-assisted cutting (UVAC) has been regarded as a promising technology to machine difficult-to-machine materials. It allows for a sub-micrometer form accuracy and surface roughness in the nanometer range. In this paper, high-frequency vibration-assisted sculpturing is used to efficiently fabricate quadrilateral microlens array with sharp edges, instead of using slow-slide-servo diamond turning with vibration. The machining principle of diamond sculpturing, the cutting dynamics of ultrasonic vibration, and the tool edge on the theoretical form error between the designed structure and the machined structure were investigated for this technique. Then, the quadrilateral microlens array was machined by means of conventional sculpturing (CS) and high-frequency ultrasonic vibration-assisted sculpturing (HFUVAS), respectively, followed by a study of the cutting performances including form accuracy, the surface morphology of the machined structure, and the tool wear. Results showed that conventional sculpturing fabricated microlens array with poor form accuracy and surface finish due to couple effect of material adhesion and tool wear, while the high-frequency ultrasonic vibration-assisted sculpturing achieved optical application level with sub-micrometer form accuracy and surface roughness of nanometer due to reduction of material adhesion and tool wear resulted from high-frequency intermittent cutting. [ABSTRACT FROM AUTHOR]

Monocrystalline silicon is an important material for processing electronic and photovoltaic devices. The fixed diamond wire sawing technology is the first key technology for monocrystalline silicon wafer processing. A systematic study of the relationship between the fracture strength, stress and breakage rate is the basis for thinning silicon wafers. The external vibration excitation of sawing machine and diamond wire lead to the transverse vibration and longitudinal vibration for silicon wafers. The transverse vibration is the main reason of wafer breakage. In this paper, a mathematical model for calculating breakage ratio of silicon wafer is established. The maximum stress and breakage ratio for as-sawn silicon wafers are studied. It is found that the maximum amplitude of the silicon wafers with the size of 156 mm × 156 mm × 0.2 mm was 160 μm during the diamond wire sawing process. The amplitude, maximum stress and breakage rate of the wafers increased with the increase of the cutting depth. The smaller the silicon wafer thickness, the larger of silicon wafer breakage ratio. In the sawing stage, the breakage ratio of the 156 mm × 156 mm section with a thickness of 0.15 mm of silicon wafers is 6%. [ABSTRACT FROM AUTHOR]

Microsatellites have a great attraction to researchers due to their high reliability, resource utilization, low cost, and compact size. As the core component of the optical payload, the mirror directly affects the system package size. Therefore, the structural design of mirrors is critical in the compact internal space of microsatellites. This study proposes a closed-back mirror with composite surfaces based on additive manufacturing (AM). Compared with the open-back mirror, it provides excellent optomechanical performance. In addition, AM significantly reduces the intricate mechanical parts' manufacturing difficulty. Finally, the roughness was better than 2 nm. The surface shape of the AM aluminum mirror reached RMS 1/10λ (λ = 632.8 nm) with the aid of ultra-precision machining technologies such as single-point diamond turning (SPDT), surface modification, and polishing, and the maximum deviation of the surface shape was about RMS 1/42λ (λ = 632.8 nm) after the thermal cycle test, which verified the optical grade application of AM. [ABSTRACT FROM AUTHOR]

High-power impulse magnetron-sputtering thick metal/carbon–nitride-doped metal-matrix multilayer nano-composite coating can be applied to cutting-tool holder components to improve cutting insert's life. One of the challenges of such an add-on solution is the poor adhesion between the thick coating and the hard alloy substrate, such as WC-Co shim. This work presents a study on WC-Co substrate surface preparation methods for HiPIMS coating and its adhesion improvement. Three mechanical surface pretreatment methods were investigated: machining (grinding), diamond polishing, and grit blasting. White-light interferometry was used for substrate surface texture measurement before and after pretreatment. It was demonstrated that, compared to machining and diamond polishing, grit blasting can significantly improve the interface adhesion between the ~200 µm-thick Cu:CuCNx coating and WC-Co shim. Grit blasting was also found to be beneficial for improving the cutting insert's life in the external turning process. In turning tests, the coating lifetime for grit-blasted shim was more than 90 min, whereas the coating lifetimes for machined shim (conventional shim) and diamond-polished shim were ~85 min and ~70 min, respectively. Further, by comparing the HiPIMS gradient chromium pre-layer between the coating and substrate for the different shims, the study also explained that the quasi-isotropic surface texture of grit-blasted shim is more advantageous for coating–substrate interface adhesion. [ABSTRACT FROM AUTHOR]

On the demand of low-cost, lightweight, miniaturized, and integrated optical systems, precision lenslet arrays are widely used. Diamond turning is often used to fabricate lenslet arrays directly or molds that are used to mold lenslet arrays. In this paper, mainly by real-time monitoring position following error for slow tool servo, different fabrication parameters are quantitatively studied and optimized for actual fabrication, then by actual fabrication validation, uniform and high-fidelity surface topography across the actual whole lenslet array is achieved. The evaluated fabrication parameters include sampling strategy, inverse time feed, arc-length, etc. The study provides a quick, effective, and detailed reference for both convex and concave lenslet array cutting parameter selection. At the end, a smooth zonal machining strategy toolpath is demonstrated for fabricating concave lenslet arrays. [ABSTRACT FROM AUTHOR]

Metal and especially aluminum mirrors have wide applications in the optical industry due to their desirable properties, hence requiring very high polished surfaces. One of the methods of preparing aluminum mirrors is single-point diamond turning. In this research, the manufacturing process of 6061-grade aluminum mirrors has been studied using diamond turning and consequent polishing process in order to reach surfaces with acceptable optical properties. In the first part, the effective range of turning parameters was determined. The results showed that the feed values less than 5 µm/rev, the cutting-edge radius between 0.2 and 0.8 mm, and the rotational speed of 2250 rpm have a greater effect on the surface roughness. In the second part of the research, initially, the turning process was performed with effective parameters and then the polishing process was applied as the final finishing process. Surface finish is evaluated by surface roughness and surface interferometry parameters. The results showed that the smaller surface roughness after the diamond tool turning process led to higher optical properties after the final polishing process. The lowest PV value equal to 0.293 µm was obtained by diamond turning with 3 µm/rev and a cutting-edge radius of 0.8 mm. [ABSTRACT FROM AUTHOR]

Featured Application: The findings of this paper can be used to guide the opto-mechanical system design of lightweight metal elliptic mirrors with a high steepness. In the field of using aerospace for detection and imaging, due to the small space volume and moment of inertia, the demand for ultra-compact high steepness mirrors is increasingly urgent. It is a technical challenge to ensure a high steepness and light weight at the same time. Since the bending stiffness of the mirror is positively correlated with the thickness of the mirror, the accurate selection of an initial mirror thickness can improve the iterative efficiency of its lightweight design and ensure high steepness. In this paper, a flat plate equivalent modeling and performance estimation method for the initial structure of a high steepness elliptical mirror is proposed, and it is appropriate to quickly evaluate whether the mirror thickness meets the requirements of self-weight deformation. This method can realize the fast modeling and performance evaluation of high steepness mirrors. In order to realize the compact layout of aerospace payloads, the design and manufacture of high-steepness lightweight aluminum alloy mirrors is a key technology to be explored. For high-steepness mirrors, the traditional method is to establish the initial thickness that satisfies the bending stiffness through finite element optimization iteration, which cannot achieve fast modeling and performance estimation. In this paper, firstly, the equivalent modeling method of the mirror with high steepness is proposed to achieve the equivalent of the elliptic mirror with a diameter of 410 × 310 mm and F# less than 0.7. Based on the mathematical model, topology shape optimization was used to build a highly lightweight mirror structure that could be quickly assembled, and the equivalent area–mass density of the mirror is less than 34 kg/mm2. Next, the rationality of design feasibility was verified by simulation analysis. Finally, by using single point diamond turning combined with post polishing process, the high-precision manufacturing of conventional aluminum alloy mirror was realized. The results show that the mirror shape accuracy is 1/10 λ (λ = 632.8 nm), and the surface roughness Ra is 3.342 nm. This research provides strong theoretical support and application prospects for the low-cost and rapid manufacturing of high-steepness lightweight aluminum alloy mirrors. [ABSTRACT FROM AUTHOR]

The single-point diamond turning is widely used as an ultra-precision fabricating method of freeform optics. However, the remounting error of the workpiece and the misalignment error of the cutting tool will reduce the manufacturing accuracy. As a result, an alignment method is needed to specify the actual position of the remounted workpiece. Monoscopic deflectometry is a high-precision, low-cost and high-dynamic range measurement method for specular surfaces. The structural simplicity and flexibility make it suitable for the in-situ measurement and monitoring. A method of workpiece positioning is proposed based on monoscopic deflectometry. A mathematical model is constructed assisted with reverse ray tracing and workpiece rotation around the main spindle. The geometrical pose and location of the workpiece are solved by minimizing the re-projection error of ray tracing. This method effectively decouples different degrees of freedom of the workpiece, and the remounting error can be suppressed accordingly. Experimental result shows that the positioning accuracy is comparable with that of a coordinate measuring machine. • A positioning based on the monoscopic deflectometry is proposed which solves the problems of repeated clamping in SPDT. • A method to obtain different positions of the workpiece by rotating, and solving the coupling problem is proposed. • The accuracy of the proposed method of positioning is comparable to coordinate measuring machine (CMM). [ABSTRACT FROM AUTHOR]

On the basis of modeling of stresses, we analyzed the technological conditions guaranteeing the required cutting properties of grinding wheels in the operations of rough and finishing grinding performed in the course of their dressing by turning with diamond tools. We performed the theoretical analysis of force interactions between diamond crystals and abrasive grains and established stresses formed in the "abrasive grain–diamond crystal" contact system. The models of equivalent stresses were created according to the theory of maximum normal stresses. We also considered the theoretical aspects of simulation of the stresses in the "abrasive grain–diamond crystal" impact system with regard for the contact strength of the material of grains. [ABSTRACT FROM AUTHOR]

The biodegradable magnesium (Mg) alloys have been acknowledged amongst the top potential biomedical materials for developing different orthopedic devices. Indeed, the processed Mg alloys' surface integrity shows a substantial contribution to the resulting biomedical applications' performance. In this paper, the effect of various influential process parameters of an ultra-precision diamond turning (UPDT), such as rotational frequency of spindle, tool overhanging (TOH), feed rate (FR), and depth-of-cut (DOC) on the chip formation, shearing mechanism, and surface finish of the biodegradable Mg AZ31 alloy have been studied. The resulting chips' analysis of the different processing parameters has been studied to investigate the involved shearing mechanism. Besides, a relationship between the resulting surface topography and the consequences of UPDT-parameters on skewness ( sk ) and kurtosis ( ku ) was studied. The statistical analysis highlighted that the FR and TOH significantly influenced the surface roughness of the Mg AZ31 alloys at a 95% confidence level. Therefore, being statistically dominating, the morphology of the formed chip has also been influenced by FR and TOH's parametric levels. The UPDT-processed Mg-alloy possessed a nano-finished surface that acted as hydrophobic and could prevent the surface from corrosion. In the light of experimental findings, the UPDT-processed Mg-alloy can be used for orthopedic screws and plates applications. [ABSTRACT FROM AUTHOR]

In reciprocating diamond wire sawing of quartz glass, the reversing and acceleration and deceleration will cause the position change of diamond wire, resulting in the discontinuous wire sawing in the reversing stage, so as to leave residual material on the processing surface and form wire marks. Also, the cutting load will cause diamond wire deformation as bow shape, and affect the machining accuracy. In this paper, the evaluation of DWS machining performance of quartz glass focus on the sawing time, cutting force and vibration, wire tension, machining surface flatness and roughness, surface morphology and wire state. The theoretical analysis of wire mark was carried out, and the simplified wire bow model of quartz glass sawing was established. The existence of wire mark and wire bow were verified by detecting the 3D contour of the slice. In addition, a diamond wire electrical discharge sawing (DWEDS) was performed to find the differences to DWS in the above indicators. Experiments were presented in jet cooling and bath cooling conditions. It was found that the cutting force, vibration, and wire tension of DWEDS are more stable than that of DWS. The DWEDS has been proved helpful to improve machining performance of quartz glass from surface roughness, sawing time, processing state, and wire bow control as it reduces the macro cutting force acting on the diamond wire although the discharge effect is weak. The SEM of slice surface and diamond wire showed no significant difference between DWEDS and DWS. Also, the influence of feed speed and cooling methods on machining performance was investigated. [ABSTRACT FROM AUTHOR]

Ultra-precision direct diamond shaping (DDS) is an attractive method for manufacturing highly accurate and complex features. DDS employs 4 of the 5-axes in an Ultra-Precision Machine (UPM) with a conventional diamond tool to machine features on a workpiece mounted on a rotary axis. It has been proven to be effective and flexible in manufacturing intricate features, from microfluidics to Fresnel lenses. However, a significant technical hurdle in the practical implementation of DDS is the complexity of its non-conventional tool path generation. Current practices in generating DDS tool paths rely on programming and significant mathematical manipulation. This is not only time consuming but also requires the user to overcome a steep learning curve. Moreover, conventional Computer-Aided Machining (CAM) software does not support DDS tool paths, but instead supports tool path generation for common machining processes like milling and turning. This paper discusses the use of a special-purpose post processor to bridge the compatibility gap between CAM and DDS tool path generation. The mathematics and logic of converting CAM milling tool paths to DDS would be discussed. Finally, the post processor was experimentally verified using a case study. [ABSTRACT FROM AUTHOR]

High-precision machined surfaces are usually processed by high-precision or even ultra-precision machine tools; however, the processing costs are high, which are not conducive to widespread applications. This study attempts to improve machined surface accuracy on an ordinary milling machine by diamond fly cutting using an in-process measurement and control method. In order to achieve high-precision compensation, an experimental control system was constructed. To verify the effectiveness of the control system, experiments of suppressing machine tool errors, disturbance errors, and application to curved surface machining were carried out. At a low feed rate, the peak-to-valley height, Rz, of the machined surface was reduced from 0.4 to 0.2 μm by compensating for machine tool errors after horizontal cutting. Disturbance errors can be effectively suppressed, especially errors in the direction in which the tool escapes. For the application of curved surface machining, the accuracy was obviously improved in the range ± 1 mm at the top of the arc surface after arc machining. Thus, the possibility of high-precision machining for ordinary milling machines was confirmed in this study. [ABSTRACT FROM AUTHOR]

Titanium alloys have great potential in ultra-precision situations due to the excellent properties, such as high corrosion resistance, high specific-strength and high biocompatibility. However, the application of titanium alloys in ultra-precision field is limited by the poor machinability. There are difficulties in obtaining the optical surface. In this study, the possibility for obtaining optically graded surfaces of titanium alloys by ultra-precision polishing was investigated. Before the ultra-precision polishing, ultra-precision turning with a single point diamond tool was used to get all sample surfaces. But, titanium alloy is difficult to obtain good surface quality by ultra-precision diamond turning. The samples results confirmed that most of the surface roughness values are higher than 30 nm. In order to explore the polishing process, a large number of ultra-precision polishing experiments were conducted. In addition, the effects of different ultra-precision polishing parameters on the surface profiles of titanium alloy Ti6Al4V were investigated in depth. The results show that the average values of surface roughness of titanium alloy parts with ultra-precision turning can be further reduced by 70% or so by ultra-precision polishing. Using a reasonable combination of high spindle speed and large cutting depth, the value of surface roughness can even be lower than 2 nm. [ABSTRACT FROM AUTHOR]

The NiP coating has excellent wear and corrosion resistance, and electroless nickel-phosphorus coating is one of the best measures for surface modification of metal optical devices. The NiP layer could be processed by single-point diamond turning (SPDT). However, the periodic marks on the surface of the NiP coating processed by SPDT will lead to diffraction and stray light, which will reduce the reflectivity and image quality of the mirror. This paper studied smoothing polishing based on chemical mechanical polishing to remove turning periodic marks efficiently. Firstly, we studied the chemical corrosion and mechanical removal mechanism of smoothing polishing of the NiP coating through theoretical analysis. Then, the influencing factors of processing the quality of smoothing polishing are analyzed, and the optimal machining parameters and polishing slurry formula are formulated. Finally, through the developed process, the surface roughness of Root Mean Square (RMS) 0.223 nm is realized on the NiP coating, and an ultra-smooth surface that can meet the service accuracy of a hard X-ray mirror is obtained. Our research simplifies the high-precision machining process of the NiP coating and improves the machining efficiency. Therefore, it can be used as a new high-precision manufacturing NiP coating method. [ABSTRACT FROM AUTHOR]

Replication of micro/nano-scale optical components onto non-planar substrates is considered technically challenging and excessively expensive via existing manufacturing approaches. A low-cost, large-volume and high-precision fabrication approach is thus highly desirable. In this paper, a novel precision compression molding approach that enables large-volume and high-resolution replication of micro/nano-scale optical features from planar to non-planar substrates is proposed. A micro-lens array is demonstrated to be transferred from a planar master mold to a non-planar substrate. In such process, a micro-lens array mold is initially fabricated by single-point diamond turning on a planar mold surface and then replicated by micro-injection molding. After that, the optical structures are transferred from micro-injected polymeric samples to a nickel foil by electro-plating, which is employed as a critical transition medium. To obtain sufficient flexibility with considerable strength, the thickness of the electro-plating mold is controlled to be around 75 μm, which is further integrated with precision molding tools to replicate micro/nano-scale optical features onto cylindrical substrates. Geometrical profile and surface roughness of the fabricated optical components in each processing step are characterized experimentally. The results indicate that the replication of the micro-lens array successfully demonstrates the process to transfer micro-optical components from planar surfaces to non-planar thermo-plastic polymeric substrates with high fidelity and optical-level surface quality. Compared with conventional precision compression molding, this novel proposed method in this research could achieve much higher flexibility and comparable fidelity with low cost on transferring optical structures from planar to non-planar surfaces. The application of this method might be widely extended to numerous replication methods, such as precision glass molding, roll-to-roll and roll-to-plane imprinting. • A new flexible-mold based molding method for micro-optical elements on planar and non-planar substrates is proposed. • The micro-structures on planar surfaces can be precisely transferred onto a flexible metallic mold. • The geometrical accuracy and surface roughness of the molded sample is obtained. • Unlike the conventional polymer-based flexible mold, this method can be widely used in elevated temperature (up to 1,000℃). [ABSTRACT FROM AUTHOR]

The rapid development of optical instruments has necessitated the efficient manufacturing of a wide variety of optics with high form accuracy and ultra-smooth texture. Single-point diamond turning (SPDT) has the advantage of high efficiency in form generation because it can directly produce optical surfaces with sub-micrometer form accuracy. However, the inevitable residual turning marks affect the performance of the optical surface by causing diffraction and generating stray light. Thus, there is great interest in developing economical and efficient post-treatment methods for diamond-turned surfaces with wide applicability and superior form-preserving capability. In this study, an active fluid jet (AFJ) polishing technology for removing diamond turning marks was developed and investigated. A turning mark removal (TMR) simulation model in the AFJ polishing was developed based on the material removal characteristics and fluid–structure interaction (FSI) analysis. Spot polishing tests were carried out through orthogonal experiments to study the effect of the polishing parameters on the material removal rate of the turning marks and verify the proposed model. Accordingly, the optimal combination of parameters was obtained. To evaluate the form-preserving ability of the method, a spiral polishing test was conducted, whose results showed that the value of material removal that is suitable for eliminating the turning marks without destroying the surface form can be determined by from the changes in the surface profiles and microtopography. Hence, a form-preserving process can be realized by adjusting the dwell time and tool path in the AFJ polishing process. Finally, the practicality of the AFJ polishing method was demonstrated on an aluminum surface. The experimental and theoretical results prove that AFJ polishing technology can enable form-preserving post-treatment of diamond-turned surfaces. • A simulation model is established to describe the removal of turning marks. • The machining parameters are investigated to achieve efficient form-preserved AFJ polishing. • Form-preserving AFJ polishing is applied to remove turning marks of optical components. [ABSTRACT FROM AUTHOR]

In this paper, industrial robots are used for complex-shaped stone grinding due to their high flexibility and multiple degrees of freedom. However, when using industrial robots to grind complex-shaped stone, due to the large variation of curvature of the model, traditional overall surface grinding machining methods often use small-diameter diamond tools for machining, and the same process parameters are used throughout the process, without considering the relationship between the influence of the change of curvature characteristics of complex surfaces on machining time and surface roughness. This paper cites the complex-shaped stone as the research object and gives the surface machining complexity calculation method based on the complex-shaped stone surface curvature characteristics. On this basis, the variation rules of machining time and surface roughness with respect to spindle speed, feed rate, cutting width, cutting depth and surface machining complexity are analyzed, and the optimal grinding parameters under different machining complexity are determined by the weighted summation method. Finally, the proposed surface complexity-based stone grinding optimization method is compared with the conventional surface integral grinding method, and the experimental results showed that the machining time is shortened by 16.4% and the surface roughness is reduced by 3.58% by using the zonal machining method based on the machining complexity. [ABSTRACT FROM AUTHOR]

The processing of high-entropy alloys (HEAs) via laser metal deposition (LMD) is well known. However, it is still difficult to avoid chemical intermixing of the elements between the coating and the substrate. Therefore, the produced coatings do not have the same chemical composition as the HEA feedstock material. Single-layer CrFeCoNi and AlCrFeCoNi HEA coatings were deposited using high-speed laser metal deposition (HS-LMD). Elemental mapping confirmed a good agreement with the chemical composition of the powder feedstock material, and revealed that chemical intermixing was confined to the immediate substrate interface. The coatings are characterized by a homogeneous structure with good substrate bonding. The machining of these coatings via turning is possible. Subsequent diamond smoothing results in a strong decrease in the surface roughness. This study presents a complete manufacturing chain for the production of high-quality HS-LMD HEA coatings. [ABSTRACT FROM AUTHOR]

The cooling method of silicon material sawing in solar energy industry is jet cooling and flood cooling. In this paper, a machining method of diamond wire electrical discharge sawing (DWEDS) under environmentally improved bath cooling was proposed. Its advantages were compared to jet cooling by carrying a series of sawing tests. It was found that DWEDS under bath cooling obtained better machining accuracy and better surface quality than that under jet cooling. Also, the machining accuracy and cutting efficiency in DWEDS were better than those in diamond wire sawing (DWS). The same conclusions were proved by scanning electron microscope observation of the wafer surface. In addition, the wire tension in DWEDS sawing was found more stable than that in DWS. Finally, the wire wear was as another indicator to evaluate the cooling effect. No significant difference in wire wear between bath cooling and jet cooling was found. However, the wire wear of DWEDS under the same cooling method is higher than that of DWS, which means the discharge effect is helpful to the wire self-sharpening from another point of view. [ABSTRACT FROM AUTHOR]

Chalcogenide glass (ChG) is widely studied due to its wide infrared transmission window, low refractive index temperature coefficient, and low dispersion coefficient. Precision glass molding (PGM) and single-point diamond turning (SPDT) are representative high-efficiency and high-precision methods for ChG processing. However, the high softening degree of ChG under high-temperature conditions leads to abnormal gas release and severe mold adhesion which deteriorate surface quality. Although SPDT typically facilitates high-precision machining, it has limited efficacy in long-term, large-area, large-depth processing; this limitation causes severe tool wear due to the high hardness and brittleness of ChG material. A new process combining the advantages of PGM and SPDT technology is proposed to fabricate aspheric lenses on ChG (IRG202) by ultra-precision and high-efficiency machining. The pre-molding of ChG by PGM reduces cutting loss during aspheric lens machining by SPDT. The machined aspheric lenses have the high quality with a form error of PV 103.5 nm and surface roughness Ra of 8.3 nm. The processing efficiency of each single lens is increased by almost 8 times over the traditional method. The proposed ChG aspheric lens fabrication process maintains high precision even under mass production conditions. [ABSTRACT FROM AUTHOR]

The increasing demand for machining non-rotational optical surfaces requires capable and flexible cutting tool path generation methods for ultra-precision diamond turning. Furthermore, the recent interest in on-machine metrology and corrective machining requires efficient as well as accurate algorithms capable to handle point cloud based surface data. In the present work, a new computation method for the tool path generation is proposed that focuses on three-axes corrective machining. It is based on the principle of defining the surface to be machined by a point cloud of given density, since surface measurement data is usually available as point cloud. Numeric approximation techniques are used to compute the surface normal vectors and calculate the resulting positions of the cutting tool path preserving a uniform radial axis motion for face turning. Investigations are performed in order to quantify the error between the calculated tool path and the exact analytical solution. The error dependencies are analyzed regarding the local surface slope and numerical parameters. Error values below 1 nm are achieved. In addition, form deviation results prove the method's capability for corrective diamond turn machining. [ABSTRACT FROM AUTHOR]

To realize a multi-channel integrated filter on a single substrate, a new preparation method is proposed in this paper, which was to adjust the thickness of the space layer based on the Fabry–Pérot interferometer theory. Optical thickness adjustment is achieved by integrating multispectral channels on a single substrate that is fabricated combined with coating, nanoimprinting, and single point diamond turning. A multi-channel filter is integrated on a mold and machined once, and three kinds of multi-channel array filter molds are fabricated utilizing fast tool servo turning. The accuracy of each channel is analyzed for the machine accuracy of the mold, which affords the key to this method. Although there exists a slight oscillation error on the surface of each channel, the maximum error is less than 4 nm and the ratio of error and differentials designed is less than 7%. The results indicate that the processing method of the multi-channel filter mold is feasible. As far as this technology is concerned, it provides technical support for mass manufacturing of large-scale multi-channel array filters. [ABSTRACT FROM AUTHOR]

A new element is proposed for producing an azimuthally polarized beam with a vortex phase dependence. The element is formed by two conical surfaces in such a way that the optical element resembles a mountain with a crater on top, like a volcano (volcanic cone is volcone). The element in the form of a refractive bi-conic axicon is fabricated by diamond turning, in which an internal conical cavity is made. Polarization conversion in this optical element occurs on the inner surface due to the refraction of beams at the Brewster angle. The outer surface is used to collimate the converted beam, which significantly distinguishes the proposed element from previously proposed approaches. The paper describes a method for calculating the path of beams through a refractive bi-conic axicon, taking into account phase and polarization conversions. In the case of incident circularly polarized radiation, azimuthally polarized ring-shape beam radiation is generated at the output. The proposed element is experimentally made of polymethyl methacrylate on a CNC milling machine. The experiment demonstrates the effectiveness of the proposed element. [ABSTRACT FROM AUTHOR]

The freeform surface quality is limited by the measurement, and form error cannot be convergent via compensation machining. This paper proposed a surface matching measurement strategy based on the least squares principle and iterative precision adjustment to precisely obtain surface form error after manufacturing by single point diamond turning. Through the coordinate transformation of translation and rotation, the measured surface was aligned with theoretical surface at the same coordinate system. The corresponding simulation was carried out to verify the performance of the proposed method, and the simulation results indicated that this method can achieve accurate alignment in a sub-nanometer range. Finally, with XY polynomial freeform surface as the ideal surface, compensation experiments were undertaken. The form error of freeform converged continuously after compensation machining for three times, during which the form accuracy of PV and RMS were down to 335 nm and 34 nm respectively from 1.4 um and 173 nm. The results showed that capability of the proposed compensation method was verified and the form accuracy could be improved effectively. [ABSTRACT FROM AUTHOR]

In this paper, a high-precision, low-cost, batch processing nanoimprint method is proposed to process a spherical microlens array (MLA). The nanoimprint mold with high surface precision and low surface roughness was fabricated by single-point diamond turning. The anti-sticking treatment of the mold was carried out by perfluorooctyl phosphoric acid (PFOPA) liquid deposition. Through the orthogonal experiment of hot embossing with the treated mold and subsequent inductively coupled plasma (ICP) etching, the microstructure of MLA was transferred to the silicon substrate, with a root mean square error of 17.7 nm and a roughness of 12.1 nm Sa. The average fitted radius of the microlens array units is 406.145 µm, which is 1.54% different from the design radius. [ABSTRACT FROM AUTHOR]

• Optimization of process parameters utilizing response surface methodology. • The optimized processing efficiency achieved 1.56 cm/h, with a roughness of 0.76 µm. • Successful machining of 4-inch diamond substrates. Microsecond-pulsed fiber laser was employed for the surface planarization processing of large-scale freestanding polycrystalline diamond. The effects of process parameters, including rotational processing speed, pulse duration, duty cycle, and line spacing, on the processing outcomes were investigated using statistical approach, specifically, response surface methodology (RSM). As for surface roughness (R), the influence of pulse width was more important than duty cycle and line spacing, while rotational processing speed hardly presented significant influence; however, for material removal rate (S), the impact of line spacing is most pronounced. The laser processing of diamond led to a graphitization, while the observed sputtering of small particles at the laser focus identified as the primary cause for high removal rates. The developed high-energy laser planarization system demonstrated capability in processing of large 4-inch diamond wafers, presenting an effective technology for achieving both higher-quality surfaces and elevated removal rates simultaneously in comparison to mechanical grinding methods. [ABSTRACT FROM AUTHOR]

[Display omitted] • Over smoothing of filtering is identified as one of the major sources of on-machine compensation in fabrication of structured surface. • A novel on-machine profile error evaluation and compensation strategy based on anisotropic diffusion filter is proposed. • The proposed method controlled the form error of high aspect ratio structured surface at the scale of submicron. Structured surfaces with high aspect ratio are promising in optical components, healthcare devices, and microelectronics. A preferable method to create precise structured surfaces is using single point diamond turning with on-machine surface measurement (OMSM). However, fabricating these surfaces often pose challenges due to steep gradients and discontinuous slopes, leading to significant form errors in machining. We propose an innovative solution by employing partial differential equation (PDE) filtration in a closed loop compensation process to enhance form accuracy and surface roughness compared to traditional methods. We tackle the problem of over-smoothing induced profile error encountered with traditional Gaussian filters. The proposed compensation strategy adapts to surface curvature and reduces instrument noise during on-machine measurements. Experimental of fabricating a segment spherical artefact, demonstrate improved precision. After adopting the proposed method, the form error is reduced from 1.2 µm to 0.5 µm and vibration ripples are mitigated, and a better surface finish is achieved. [ABSTRACT FROM AUTHOR]

• Mesh-free and finite element methods are compared in nano-scale cutting simulation. • Influence of tool-tip wear on the nano-scale cutting mechanism is revealed. • The significance of tip radius enlargement in AFM-based nano-scratching is investigated. • The thickness of plastically deformed layer of scratched nano-grooves are analysed. This study explores the modelling methodology using mesh-free smoothed particle hydrodynamics (SPH) and finite element modelling (FE) techniques to simulate the AFM-based nano-scratching processes for advancing precision engineering in nanotechnology. Tip wear in nano machining substantially increases the tip radius, thereby influencing the material removal mechanism and subsequently affecting the quality of machined nanostructures. In this context, this study examines the effects of rake angle (the inclination of the main cutting edge to the plane perpendicular to the scratched surface), tip radius and scratching depth on cutting forces, groove dimensions, and deformed thickness. This was achieved by implementing an in-house SPH method based particle code employing a Lagrangian algorithm, and an FE model incorporating the dynamic explicit algorithm implemented (in ABAQUS) to carry out nano-scratching simulations. The investigation revealed that the cutting mechanism transitioned to ploughing when the scratching depth decreased to 30% of the tip radius for OFHC-Cu workpiece material machined with a diamond tip. The dominance of normal forces over cutting forces during scratching indicated the side flow of material in the vicinity of the tip radius under intense contact pressure. The ploughing mechanism exhibited more sensitivity at a higher negative rake angle of 60°. Increased scratching depth and tip radius led to more significant material deformation owing to the induction of higher cutting forces, with the maximum deformation thickness 3.6 times the tip radius. The simulated results demonstrated favourable concordance with the experimental data. [ABSTRACT FROM AUTHOR]

The size selectivity and exploitation patterns of two T0 (diamond mesh) codends were tested and compared with T90 (diamond mesh turned by 90°) codends in demersal trawl fishery targeting white croaker (Pennahia argentata) of the northern South China Sea. The four experimental codends involved two mesh sizes, 30 and 35 mm, respectively. The size selectivity of the T0 codend with mesh size of 30 mm, T0_30, was used as a starting point to compare with the rest codends. The results showed that compared with the T0_30 codend increasing the mesh size to 35 mm or applying the T90 codends would result in significantly larger L50 values, and the retention risk (probability) of undersized white croaker with length < 8.5 cm would significantly reduce. These codends, however, had no effect on improving the size selectivity of undersized white croaker with the length ranging between 10 and 15 cm. The results of our study will have relevant implications for fishing gears management and future direction of codend selectivity research. • Four codends with different mesh shapes and mesh sizes were tested to improve the size selectivity and exploitation pattern for white croaker (Pennahia argentata). • Increasing the mesh size of diamond-mesh codend from 30 to 35 mm or/and applying the T90 codends would obtain significantly larger L50 values, and the retention probability of undersized white croaker would significantly reduce for fish with length <8.5 cm. • The experimental codends had no effect on improving the size selectivity of juvenile white croaker with the length ranging between 10 and 15 cm. [ABSTRACT FROM AUTHOR]

Diamond has attracted extensive attention from many scholars because of its unique properties. However, there are still bottlenecks in how to achieve high efficiency polishing and global flattening of diamond which restrict its application. The aim of this study is to obtain a globally homogeneous flattened diamond surface in macro dimension by introducing a compound motion of the polished workpiece. It is shown that ultra-smooth diamond surface machining with global flattening can be realized by UV-assisted low-speed dynamic friction polishing technique, and the typical roughness is 0.175 nm as measured by 3D optical surface profiler. These experimental results demonstrate that the catalytic phase transition process of UV light is the underlying mechanism to realize the diamond surface polishing under low rotational speed conditions. Additionally, the composite motion of the diamond sample with the metal disk brings large enhancement to the effect of polishing global flattening on the sample surface. The theoretical and experimental studies in this paper provide novel ideas for achieving efficient and polished global flattening of diamond. [Display omitted] • Our team previously proposed a diamond polishing technique, which was optimized and improved according to 3DM-DFP in this paper. • Ultrasmooth diamond surfaces with surface roughness Rq=0.218 nm and Ra=0.173 nm were obtained. • The comprehensive polishing mechanism is discussed, and the theory of diamond diffusion removal is expanded. • The kinematic analysis of the composite motion process was carried out, and the optimal motion parameters were theoretically obtained. [ABSTRACT FROM AUTHOR]

The contact process between the chip and the rake face is directly affected by the temperature of the rake face, and then tool wear and machining quality is indirectly influenced by it. In this study, a temperature prediction model for the rake face of modified diamond tools during dry turning of the 6061 aluminum alloy was established based on the moving heat source method. The shear heat source, rake face chip friction heat source, cutting edge-workpiece ploughing effect heat source, cutting edge workpiece roll burnishing heat source, and flank face workpiece elastic recovery heat source were considered by this model during the dry diamond turning, simultaneously considering the non-uniformity of heat source intensity and heat distribution ratio, as well as the influence of ion implantation on the temperature of the tool rake face. The experimental results indicate that this model successfully predicts the temperature of the modified tool rake face, and it is found that an increase in dose will promote a decrease in the temperature of the rake face. Theoretical analysis reveals that modified cutting tools have the characteristic of reducing the temperature of the rake face, revealing the essence of the influence of "modification" on the temperature of the rake face from the perspective of the cutting mechanism, and providing a theoretical basis for optimizing modification parameters. [Display omitted] • A temperature prediction model of modified tools during dry diamond turning is established. • The ion implantation is considered in the model. • Doses effectively decrease the rake face temperature during dry diamond turning. • Experimental results agree well with predicted results with an average error of 14 %. [ABSTRACT FROM AUTHOR]

Diamond turning is an effective technology for processing metal mirrors used in photoelectric communications, radar, and other fields. In diamond turning, the precipitated phase is an essential factor that influences the surface quality of the metal mirrors. However, in previous studies, the precipitation phase has typically been handled as a random variable in a surface morphology model to evaluate its influence on the surface roughness, instead of determining the formation mechanism and proposing suppression solutions. In this study, a new phenomenon is observed in the diamond turning of metal mirrors, that is, the micro diamond tool can reduce the protrusion of the precipitated phase under a small feed rate and improve the surface quality. Investigating the turning process using diamond tools with varying tool nose radii at small feed rates (<1 μm/r), the underlying transformation mechanism of the precipitation phase is determined with the advanced material characterization technologies. The growth of the precipitated phase with an increase in the tool nose radius is explained using the energy gradient theory. The results showed that the increased material strain on the machined surface decreased the activation energy of solute diffusion in the material, causing solute accumulation and precipitate phase growth. With a further increase of tool nose radius to around 1000 μm, the β'' phase breaks and rotates. The representative volume element method shows that when undergoing severe plastic deformation, dislocations and grain boundaries quickly aggregate and slide on the precipitated phase, which will lead to the fracture and rotation of β'' phase. These findings provide a theoretical basis for the development of highly smooth mirrors. [Display omitted] • The mechanism of precipitation phase change on the surface of workpiece is discussed. • With the increase in tool nose radius, the volume of the precipitated phase increases. • As the tool nose radius further enlarges, the precipitated phase is torn and evenly distributed. • Reducing the plastic deformation can lessen the protrusion of the precipitated phase. [ABSTRACT FROM AUTHOR]

With the widespread application of binderless tungsten carbide (WC) moulds, optical finish with ideal surface integrity is in great demand. Although Pre-heat laser assisted turning (Pre-LAT) is a potential method to achieve optical surface on hard and brittle materials, there is less investigation on the surface integrity, which needs to be studied for better understanding of Pre-LAT mechanism. In this article, the critical depth of no observed surface crack on binderless WC was experimentally studied with the laser pre-heat assistance. The subsurface damage is analyzed in detail, and the material removal mechanism during Pre-LAT is subsequently revealed. [ABSTRACT FROM AUTHOR]

The resulting surface integrity of (100)Ge subjected to off-axis single point diamond turning was investigated. Feedrate was varied using 9 and 20 μm/rev at 10 μm nominal depth of cut. Surface topography was measured with coherence scanning interferometry and atomic force microscopy. The resulting near surface lattice disorder was investigated with channeling Rutherford Backscattering Spectrometry and Raman Spectroscopy. Measured near surface lattice disorder was quantified in terms of equivalent amorphous layer thickness and minimum channeling yield. A comparison of the resulting surface integrity was made with surfaces created by chemomechanical polishing and magnetorheological finishing. [ABSTRACT FROM AUTHOR]