Editorial

3 pages, 166 KiB

Open AccessEditorial

Editorial for the Special Issue on “Frontiers of Ultra-Precision Machining”

by Jiang Guo, Chunjin Wang and Chenwei Kang

Micromachines 2022, 13(2), 220; https://doi.org/10.3390/mi13020220 - 29 Jan 2022

Cited by 2 | Viewed by 1781

Ultra-precision machining is a multi-disciplinary research area that is an important branch of manufacturing technology [...] Full article

(This article belongs to the Special Issue Frontiers in Ultra-Precision Machining)

Research

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19 pages, 11364 KiB

Open AccessArticle

Multi-Physics Coupling Modeling and Experimental Investigation of Vibration-Assisted Blisk Channel ECM

by Juchen Zhang, Shasha Song, Junsheng Zhang, Weijie Chang, Haidong Yang, Huohong Tang and Shunhua Chen

Micromachines 2022, 13(1), 50; https://doi.org/10.3390/mi13010050 - 29 Dec 2021

Cited by 9 | Viewed by 1679

Abstract

Due to its advantages of good surface quality and not being affected by material hardness, electrochemical machining (ECM) is suitable for the machining of blisk, which is known for its hard-to-machine materials and complex shapes. However, because of the unstable processing and low [...] Read more.

Due to its advantages of good surface quality and not being affected by material hardness, electrochemical machining (ECM) is suitable for the machining of blisk, which is known for its hard-to-machine materials and complex shapes. However, because of the unstable processing and low machining quality, conventional linear feeding blisk ECM has difficulty in obtaining a complex structure. To settle this problem, the vibration-assisted ECM method is introduced to machine blisk channels in this paper. To analyze the influence of vibration on the process of ECM, a two-phase flow field model is established based on the RANS k-ε turbulence model, which is suitable for narrow flow field and high flow velocity. The model is coupled with the electric field, the flow field, and the temperature field to form a multi-physics field coupling model. In addition, dynamic simulation is carried out on account of the multi-physics field coupling model and comparative experiments are conducted using the self-developed ECM machine tool. While a shortcut appeared in the contrast experiment, machining with vibration-assisted channel ECM achieved fine machining stability and surface quality. The workpiece obtained by vibration-assisted channel ECM has three narrow and straight channels, with a width of less than 3 mm, an aspect ratio of more than 8, and an average surface roughness Ra in the hub of 0.327 μm. Compared with experimental data, the maximum relative errors of simulation are only 1.05% in channel width and 8.11% in machining current, which indicates that the multi-physics field coupling model is close to machining reality. Full article

(This article belongs to the Special Issue Frontiers in Ultra-Precision Machining)

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9 pages, 3419 KiB

Open AccessArticle

Single-Wedge Lift-Out for Atom Probe Tomography Al/Ni Multilayers Specimen Preparation Based on Dual-Beam-FIB

by Yi Qiao, Yalong Zhao, Zheng Zhang, Binbin Liu, Fusheng Li, Huan Tong, Jintong Wu, Zhanqi Zhou, Zongwei Xu and Yue Zhang

Micromachines 2022, 13(1), 35; https://doi.org/10.3390/mi13010035 - 27 Dec 2021

Cited by 1 | Viewed by 2420

Abstract

Atomic probe tomography (APT) samples with Al/Ni multilayer structure were successfully prepared by using a focused ion beam (FIB), combining with a field emission scanning electron microscope, with a new single-wedge lift-out method and a reduced amorphous damage layer of Ga ions implantation. [...] Read more.

Atomic probe tomography (APT) samples with Al/Ni multilayer structure were successfully prepared by using a focused ion beam (FIB), combining with a field emission scanning electron microscope, with a new single-wedge lift-out method and a reduced amorphous damage layer of Ga ions implantation. The optimum vertex angle and preparation parameters of APT sample were discussed. The double interdiffusion relationship of the multilayer films was successfully observed by the local electrode APT, which laid a foundation for further study of the interface composition and crystal structure of the two-phase composites. Full article

(This article belongs to the Special Issue Frontiers in Ultra-Precision Machining)

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13 pages, 3310 KiB

Open AccessArticle

Piezoelectric Hysteresis Modeling of Hybrid Driven Three-Dimensional Elliptical Vibration Aided Cutting System Based on an Improved Flower Pollination Algorithm

by Xifeng Fu, Hong Gong, Mingming Lu, Jiakang Zhou, Jieqiong Lin, Yongsheng Du and Ruiqi Zhou

Micromachines 2021, 12(12), 1532; https://doi.org/10.3390/mi12121532 - 09 Dec 2021

Cited by 1 | Viewed by 1913

Abstract

Three-dimensional elliptical vibration assisted cutting technology has been widely used in the past few years. The piezoelectric stack drive structure is an important part of the three-dimensional elliptical vibration aided cutting system. Its piezoelectric hysteresis characteristics affects the final output of the elliptical [...] Read more.

Three-dimensional elliptical vibration assisted cutting technology has been widely used in the past few years. The piezoelectric stack drive structure is an important part of the three-dimensional elliptical vibration aided cutting system. Its piezoelectric hysteresis characteristics affects the final output of the elliptical trajectory. Aiming at this problem, a piezoelectric hysteresis modeling method based on a generalized Bouc–Wen model is presented in this paper. An improved flower pollination algorithm (IFPASO) was used to identify Bouc–Wen model parameters. Standard test result shows that IFPASO has better algorithm performance. The model identification effect experiment proved that the Bouc–Wen model obtained by IFPASO identification, the highest modeling accuracy of the three axial subsystems, can reach 98.86%. Therefore, the model can describe the piezoelectric hysteresis characteristics of the three axial subsystems of the 3D-EVC system effectively and has higher modeling accuracy and fitting accuracy. Full article

(This article belongs to the Special Issue Frontiers in Ultra-Precision Machining)

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14 pages, 4518 KiB

Open AccessArticle

Characterization of Surface Topography Variation in the Ultra-Precision Tool Servo-Based Diamond Cutting of 3D Microstructured Surfaces

by Wei Yuan and Chi-Fai Cheung

Micromachines 2021, 12(12), 1448; https://doi.org/10.3390/mi12121448 - 26 Nov 2021

Cited by 4 | Viewed by 1430

Abstract

Previous models of the relative tool-work vibration are not generalized to represent the surface generation mechanism in the ultra-precision tool servo-based diamond cutting (UTSDC) of three-dimensional (3D) microstructured surfaces. This is due to the fact that the tool-work vibration in UTSDC is no [...] Read more.

Previous models of the relative tool-work vibration are not generalized to represent the surface generation mechanism in the ultra-precision tool servo-based diamond cutting (UTSDC) of three-dimensional (3D) microstructured surfaces. This is due to the fact that the tool-work vibration in UTSDC is no longer a steady harmonic vibration with a constant amplitude but is influenced by the tool motion along the thrust direction. In this paper, dynamic modeling of the cutting system is presented for the characterization of surface topography variation in UTSDC of a microlens array considering the tool-work vibration as an underdamped vibration. The natural frequency and damping ratio of the cutting system are determined by the data-dependent systems (DDS) method. Based on the analysis of the surface profile and cutting force signals, it is found that the tool-work vibration is significantly enhanced in the cut-in process when the cutting speed increases. The simulation results show that the proposed dynamic model can well-determine root-mean-squares

RMS

values of the surface primary profile and the dynamic force acting on the force sensor. The dynamic model provides insight into the formation of the surface topography variation in UTSDC of 3D microstructured surfaces, and the model might be applied in self-optimized machining systems in the future. Full article

(This article belongs to the Special Issue Frontiers in Ultra-Precision Machining)

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13 pages, 5387 KiB

Open AccessArticle

Research on Self-Aligning Flanges Based on Piezoelectric Actuators Applied to Precision Grinding Machines

by Xuepeng Huang, Zhenzhong Wang, Bingyi Shen and Pengli Lei

Micromachines 2021, 12(11), 1393; https://doi.org/10.3390/mi12111393 - 13 Nov 2021

Cited by 2 | Viewed by 1645

Abstract

Laser fusion research requires a large number of high-precision large-diameter aspherical components. To improve the grinding efficiency in the component production process, the manual operation time during the grinding process needs to be reduced. The grinding process requires the installation of the dressed [...] Read more.

Laser fusion research requires a large number of high-precision large-diameter aspherical components. To improve the grinding efficiency in the component production process, the manual operation time during the grinding process needs to be reduced. The grinding process requires the installation of the dressed grinding wheel onto the grinding machine spindle, and the off-line dressing results in installation errors during the loading and unloading process, which requires more time for manual alignment. To achieve self-aligning, the circumferential contour of the grinding wheel was first restored by the reversal method, then noise reduction and circle fitting were performed to obtain the eccentricity value and eccentricity position between the flange and the spindle, and finally, the flange was adjusted finely by three piezoelectric actuators installed inside the flange to reduce the eccentricity. Three repetitive experiments were conducted to verify that the self-aligning flange can reduce the eccentricity value by retracting the piezoelectric actuators so that the proper alignment between the flange and the spindle could meet the requirements; the average eccentricity value of the three experiments decreased by 74%, which greatly improved the efficiency of the grinding wheel alignment. Full article

(This article belongs to the Special Issue Frontiers in Ultra-Precision Machining)

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14 pages, 6034 KiB

Open AccessArticle

Study on the Algorithm of Three-Dimensional Surface Residual Material Height of Nano-ZrO₂ Ceramics under Ultra-Precision Grinding

by Yanyan Yan, Zhaoqing Zhang, Junli Liu, Haozhe Yan and Xiaoxu Wang

Micromachines 2021, 12(11), 1363; https://doi.org/10.3390/mi12111363 - 04 Nov 2021

Cited by 5 | Viewed by 1558

Abstract

A large number of studies have shown that the height of a residual material is the key factor affecting the surface quality of ultra-precision grinding. However, the grinding process contains several random factors, such as the randomness of grinding particle size and the [...] Read more.

A large number of studies have shown that the height of a residual material is the key factor affecting the surface quality of ultra-precision grinding. However, the grinding process contains several random factors, such as the randomness of grinding particle size and the random distribution of grinding particles, which cause the complexity of the material removal process. In this study, taking the Nano-ZrO₂ as an example, the removal process of surface materials in ultra-precision grinding of hard and brittle materials was analyzed by probability. A new calculation method for the height of surface residual materials in ultra-precision grinding of Nano-ZrO₂ was proposed, and the prediction model of the three-dimensional roughness S_a and S_q were established by using this calculation method. The simulation and experimental results show that this calculation method can obtain the more accurate surface residual material height value which accords with the characteristics of three-dimensional roughness sampling, which provides a theoretical reference for the analysis of the material removal process and the surface quality evaluation of ultra-precision grinding of hard and brittle materials. Full article

(This article belongs to the Special Issue Frontiers in Ultra-Precision Machining)

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12 pages, 6112 KiB

Open AccessArticle

Study on the Electrorheological Ultra-Precision Polishing Process with an Annular Integrated Electrode

by Cheng Fan, Yigang Chen, Yucheng Xue and Lei Zhang

Micromachines 2021, 12(10), 1235; https://doi.org/10.3390/mi12101235 - 12 Oct 2021

Cited by 7 | Viewed by 1525

Abstract

Electrorheological (ER) polishing, as a new ultra-precision super-effect polishing method, provides little damage to the workpiece surface and is suitable for polishing all kinds of small and complex curved surface workpieces. In this paper, an ER polishing tool with an annular integrated electrode [...] Read more.

Electrorheological (ER) polishing, as a new ultra-precision super-effect polishing method, provides little damage to the workpiece surface and is suitable for polishing all kinds of small and complex curved surface workpieces. In this paper, an ER polishing tool with an annular integrated electrode is developed. The orthogonal experiments are carried out on the six influencing factors of ER polishing which include the applied voltage, the abrasive particle size, the abrasive concentration, the polishing gap, the polishing time and the tool spindle speed. The influence order of these six factors on the ER polishing is obtained. On this basis, the effect of a single process parameter of ER polishing on surface roughness is studied experimentally. Full article

(This article belongs to the Special Issue Frontiers in Ultra-Precision Machining)

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12 pages, 3984 KiB

Open AccessArticle

Influence of Lubricant Environment on Machined Surface Quality in Single-Point Diamond Turning of Ferrous Metal

by Menghua Zhou, Jianpeng Wang and Guoqing Zhang

Micromachines 2021, 12(9), 1110; https://doi.org/10.3390/mi12091110 - 15 Sep 2021

Cited by 5 | Viewed by 1911

Abstract

In the field of single-point diamond turning (SPDT), machining ferrous metal is an important research topic with promising application. For SPDT of ferrous metal, the influence of lubricant on the workpiece surface morphology remains to be studied. In this study, three lubricant machining [...] Read more.

In the field of single-point diamond turning (SPDT), machining ferrous metal is an important research topic with promising application. For SPDT of ferrous metal, the influence of lubricant on the workpiece surface morphology remains to be studied. In this study, three lubricant machining environments were selected to carry out specific control experiments. The machined surface morphology and cutting force in different lubricant machining environments were analyzed. The experiment results showed that the lubricant environment will have significant impacts on the quality of the machined surface morphology of ferrous metal. In the environment of minimum quantity lubrication machining (MQLM-oil), better machined surface quality can be obtained than that in ordinary dry machining (ODM) and high-pressure gas machining (HGM). Furthermore, the cutting force captured in the ODM and HGM environment increased with the increase of the cutting depth, while the cutting force in the MQLM-oil environment remained almost unchanged. That indicates MQLM-oil can suppress the formation of hard particles to improve the machining quality. Full article

(This article belongs to the Special Issue Frontiers in Ultra-Precision Machining)

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18 pages, 6776 KiB

Open AccessArticle

Influence of Different Tool Electrode Materials on Electrochemical Discharge Machining Performances

by Islam Md. Rashedul, Yan Zhang, Kebing Zhou, Guoqian Wang, Tianpeng Xi and Lei Ji

Micromachines 2021, 12(9), 1077; https://doi.org/10.3390/mi12091077 - 07 Sep 2021

Cited by 15 | Viewed by 2939

Abstract

Electrochemical discharge machining (ECDM) is an emerging method for developing micro-channels in conductive or non-conductive materials. In order to machine the materials, it uses a combination of chemical and thermal energy. The tool electrode’s arrangement is crucial for channeling these energies from the [...] Read more.

Electrochemical discharge machining (ECDM) is an emerging method for developing micro-channels in conductive or non-conductive materials. In order to machine the materials, it uses a combination of chemical and thermal energy. The tool electrode’s arrangement is crucial for channeling these energies from the tool electrode to the work material. As a consequence, tool electrode optimization and analysis are crucial for efficiently utilizing energies during ECDM and ensuring machining accuracy. The main motive of this study is to experimentally investigate the influence of different electrode materials, namely titanium alloy (TC4), stainless steel (SS304), brass, and copper–tungsten (CuW) alloys (W70Cu30, W80Cu20, W90Cu10), on electrodes’ electrical properties, and to select an appropriate electrode in the ECDM process. The material removal rate (MRR), electrode wear ratio (EWR), overcut (OC), and surface defects are the measurements considered. The electrical conductivity and thermal conductivity of electrodes have been identified as analytical issues for optimal machining efficiency. Moreover, electrical conductivity has been shown to influence the MRR, whereas thermal conductivity has a greater impact on the EWR, as characterized by TC4, SS304, brass, and W80Cu20 electrodes. After that, comparison experiments with three CuW electrodes (W70Cu30, W80Cu20, and W90Cu10) are carried out, with the W70Cu30 electrode appearing to be the best in terms of the ECDM process. After reviewing the research outcomes, it was determined that the W70Cu30 electrode fits best in the ECDM process, with a 70 μg/s MRR, 8.1% EWR, and 0.05 mm OC. Therefore, the W70Cu30 electrode is discovered to have the best operational efficiency and productivity with performance measures in ECDM out of the six electrodes. Full article

(This article belongs to the Special Issue Frontiers in Ultra-Precision Machining)

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14 pages, 3207 KiB

Open AccessArticle

Molecular Dynamic Investigation of the Anisotropic Response of Aluminum Surface by Ions Beam Sputtering

by Chunyang Du, Yifan Dai, Chaoliang Guan and Hao Hu

Micromachines 2021, 12(7), 848; https://doi.org/10.3390/mi12070848 - 20 Jul 2021

Cited by 2 | Viewed by 1848

Abstract

Aluminum optics are widely used in modern optical systems because of their high specific stiffness and high reflectance. With the applied optical frequency band moving to visible, traditional processing technology cannot meet the processing precision. Ion beam sputtering (IBS) provides a highly deterministic [...] Read more.

Aluminum optics are widely used in modern optical systems because of their high specific stiffness and high reflectance. With the applied optical frequency band moving to visible, traditional processing technology cannot meet the processing precision. Ion beam sputtering (IBS) provides a highly deterministic technology for high-precision aluminum optics fabrication. However, the surface quality is deteriorated after IBS. The interaction between the bombard atoms and the surface morphology evolution mechanism are not clear, and systematic research is needed. Thus, in this paper, the IBS process for single crystal aluminum with different crystallographic orientations are studied by the molecular dynamics method. The ion beam sputter process is firstly demonstrated. Then, the variation of sputter yield of the three crystal faces is analyzed. The sputter yield difference of different crystal surfaces causes the appearance of the relief structure. Then, the gravel structure generates on the single crystal surfaces and dominates the morphology evolution. The state of the atom diffusion of the specific crystal surfaces will determine the form of the gravel structure. Furthermore, the form and distribution of subsurface damage and stress distribution of three different crystal surfaces are analyzed. Although there are great differences in defect distribution, no stress concentration was found in three workpieces, which verifies that the ion beam sputter is a stress-free machining method. The process of IBS and the mechanism of morphology evolution of aluminum are revealed. The regularity and mechanism will provide a guidance for the application of IBS in aluminum optics manufacture fields. Full article

(This article belongs to the Special Issue Frontiers in Ultra-Precision Machining)

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13 pages, 5540 KiB

Open AccessArticle

Simulation Analysis of Cluster Effect of High-Shear Low-Pressure Grinding with Flexible Abrasive Tools

by Chengjin Tian, Jinguo Han, Yebing Tian, Bing Liu, Zhiqiang Gu and Xintao Hu

Micromachines 2021, 12(7), 827; https://doi.org/10.3390/mi12070827 - 15 Jul 2021

Cited by 9 | Viewed by 2244

Abstract

Based on the clustering effect of shear-thickening fluids (STFs), a high-shear low-pressure flexible grinding wheel has been developed. In order to explore the material removal mechanism, the coupled Eulerian—Lagrangian (CEL) method is adopted to simulate the novel grinding process. The simulation results show [...] Read more.

Based on the clustering effect of shear-thickening fluids (STFs), a high-shear low-pressure flexible grinding wheel has been developed. In order to explore the material removal mechanism, the coupled Eulerian—Lagrangian (CEL) method is adopted to simulate the novel grinding process. The simulation results show that particle clustering effects do occur at the tangential and bottom positions of the micro-convex peak when it instantaneously strikes the workpiece surface. The particle clusters drive the harder abrasive particles to resist the strong interactions of micro-convex peaks. The micro-convex peaks are removed due to the cutting effect of the harder abrasive particles. Compared with traditional grinding, the ratio of tangential force to normal force for the high-shear low-pressure flexible grinding wheel is improved. The various trends in force ratio are consistent with the experimental results, which verifies the effectiveness of high-shear low-pressure grinding. Full article

(This article belongs to the Special Issue Frontiers in Ultra-Precision Machining)

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15 pages, 8446 KiB

Open AccessArticle

An Investigation of the Cutting Strategy for the Machining of Polar Microstructures Used in Ultra-Precision Machining Optical Precision Measurement

by Chen-Yang Zhao, Chi Fai Cheung and Wen-Peng Fu

Micromachines 2021, 12(7), 755; https://doi.org/10.3390/mi12070755 - 27 Jun 2021

Cited by 6 | Viewed by 2050

Abstract

In this paper, an investigation of cutting strategy is presented for the optimization of machining parameters in the ultra-precision machining of polar microstructures, which are used for optical precision measurement. The critical machining parameters affecting the surface generation and surface quality in the [...] Read more.

In this paper, an investigation of cutting strategy is presented for the optimization of machining parameters in the ultra-precision machining of polar microstructures, which are used for optical precision measurement. The critical machining parameters affecting the surface generation and surface quality in the machining of polar microstructures are studied. Hence, the critical ranges of machining parameters have been determined through a series of cutting simulations, as well as cutting experiments. First of all, the influence of field of view (FOV) is investigated. After that, theoretical modeling of polar microstructures is built to generate the simulated surface topography of polar microstructures. A feature point detection algorithm is built for image processing of polar microstructures. Hence, an experimental investigation of the influence of cutting tool geometry, depth of cut, and groove spacing of polar microstructures was conducted. There are transition points from which the patterns of surface generation of polar microstructures vary with the machining parameters. The optimization of machining parameters and determination of the optimized cutting strategy are undertaken in the ultra-precision machining of polar microstructures. Full article

(This article belongs to the Special Issue Frontiers in Ultra-Precision Machining)

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12 pages, 3931 KiB

Open AccessArticle

High-Accuracy Surface Topography Manufacturing for Continuous Phase Plates Using an Atmospheric Pressure Plasma Jet

by Huiliang Jin, Caixue Tang, Haibo Li, Yuanhang Zhang and Yaguo Li

Micromachines 2021, 12(6), 683; https://doi.org/10.3390/mi12060683 - 10 Jun 2021

Cited by 2 | Viewed by 1762

Abstract

The continuous phase plate (CPP) is the vital diffractive optical element involved in laser beam shaping and smoothing in high-power laser systems. The high gradients, small spatial periods, and complex features make it difficult to achieve high accuracy when manufacturing such systems. A [...] Read more.

The continuous phase plate (CPP) is the vital diffractive optical element involved in laser beam shaping and smoothing in high-power laser systems. The high gradients, small spatial periods, and complex features make it difficult to achieve high accuracy when manufacturing such systems. A high-accuracy and high-efficiency surface topography manufacturing method for CPP is presented in this paper. The atmospheric pressure plasma jet (APPJ) system is presented and the removal characteristics are studied to obtain the optimal processing parameters. An optimized iterative algorithm based on the dwell point matrix and a fast Fourier transform (FFT) is proposed to improve the accuracy and efficiency in the dwell time calculation process. A 120 mm × 120 mm CPP surface topography with a 1326.2 nm peak-to-valley (PV) value is fabricated with four iteration steps after approximately 1.6 h of plasma processing. The residual figure error between the prescribed surface topography and plasma-processed surface topography is 28.08 nm root mean square (RMS). The far-field distribution characteristic of the plasma-fabricated surface is analyzed, for which the energy radius deviation is 11 μm at 90% encircled energy. The experimental results demonstrates the potential of the APPJ approach for the manufacturing of complex surface topographies. Full article

(This article belongs to the Special Issue Frontiers in Ultra-Precision Machining)

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18 pages, 9000 KiB

Open AccessArticle

An Elementary Approximation of Dwell Time Algorithm for Ultra-Precision Computer-Controlled Optical Surfacing

by Yajun Wang, Yunfei Zhang, Renke Kang and Fang Ji

Micromachines 2021, 12(5), 471; https://doi.org/10.3390/mi12050471 - 21 Apr 2021

Cited by 4 | Viewed by 1755

Abstract

The dwell time algorithm is one of the key technologies that determines the accuracy of a workpiece in the field of ultra-precision computer-controlled optical surfacing. Existing algorithms mainly consider meticulous mathematics theory and high convergence rates, making the computation process more uneven, and [...] Read more.

The dwell time algorithm is one of the key technologies that determines the accuracy of a workpiece in the field of ultra-precision computer-controlled optical surfacing. Existing algorithms mainly consider meticulous mathematics theory and high convergence rates, making the computation process more uneven, and the flatness cannot be further improved. In this paper, a reasonable elementary approximation algorithm of dwell time is proposed on the basis of the theoretical requirement of a removal function in the subaperture polishing and single-peak rotational symmetry character of its practical distribution. Then, the algorithm is well discussed with theoretical analysis and numerical simulation in cases of one-dimension and two-dimensions. In contrast to conventional dwell time algorithms, this proposed algorithm transforms superposition and coupling features of the deconvolution problem into an elementary approximation issue of function value. Compared with the conventional methods, it has obvious advantages for improving calculation efficiency and flatness, and is of great significance for the efficient computation of large-aperture optical polishing. The flatness of φ150 mm and φ100 mm workpieces have achieved PVr₁₅₀ = 0.028 λ and PVcr₁₀₀ = 0.014 λ respectively. Full article

(This article belongs to the Special Issue Frontiers in Ultra-Precision Machining)

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14 pages, 5599 KiB

Open AccessArticle

A New Method for Precision Measurement of Wall-Thickness of Thin-Walled Spherical Shell Parts

by Jiang Guo, Yongbo Xu, Bo Pan, Juntao Zhang, Renke Kang, Wen Huang and Dongxing Du

Micromachines 2021, 12(5), 467; https://doi.org/10.3390/mi12050467 - 21 Apr 2021

Cited by 7 | Viewed by 2220

Abstract

Thin-walled parts are widely used in shock wave and detonation physics experiments, which require high surface accuracy and equal thickness. In order to obtain the wall thickness of thin-walled spherical shell parts accurately, a new measurement method is proposed. The trajectories, including meridian [...] Read more.

Thin-walled parts are widely used in shock wave and detonation physics experiments, which require high surface accuracy and equal thickness. In order to obtain the wall thickness of thin-walled spherical shell parts accurately, a new measurement method is proposed. The trajectories, including meridian and concentric trajectories, are employed to measure the thickness of thin-walled spherical shell parts. The measurement data of the inner and outer surfaces are unified in the same coordinate system, and the thickness is obtained based on a reconstruction model. The meridian and concentric circles’ trajectories are used for measuring a spherical shell with an outer diameter of Φ210.6 mm and an inner diameter of Φ206.4 mm. Without the data in the top area, the surface errors of the outer and inner surfaces are about 5 μm and 6 μm, respectively, and the wall-thickness error is about 8 μm with the meridian trajectory. Full article

(This article belongs to the Special Issue Frontiers in Ultra-Precision Machining)

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14 pages, 6985 KiB

Open AccessArticle

The Influence of Crystal Orientation on Subsurface Damage of Mono-Crystalline Silicon by Bound-Abrasive Grinding

by Wei Yang and Yaguo Li

Micromachines 2021, 12(4), 365; https://doi.org/10.3390/mi12040365 - 28 Mar 2021

Cited by 5 | Viewed by 2763

Abstract

Subsurface damage (SSD) produced in a grinding process will affect the performance and operational duration of single-crystal silicon. In order to reduce the subsurface damage depth generated during the grinding process by adjusting the process parameters (added), experiments were designed to investigate the [...] Read more.

Subsurface damage (SSD) produced in a grinding process will affect the performance and operational duration of single-crystal silicon. In order to reduce the subsurface damage depth generated during the grinding process by adjusting the process parameters (added), experiments were designed to investigate the influence of machining factors on SSD. This included crystal orientation, diamond grit size in the grinding wheel, peripheral speed of the grinding wheel, and feeding with the intention to optimize the parameters affecting SSD. Compared with isotropic materials such as glass, we considered the impact of grinding along different crystal directions <100> and <110> on subsurface damage depth (added). The Magnetorheological Finishing (MRF) spot technique was used to detect the depth of SSD. The results showed that the depth of SSD in silicon increased with the size of diamond grit. SSD can be reduced by either increasing the peripheral speed of the grinding wheel or decreasing the feeding rate of the grinding wheel in the <100> crystal orientation, if the same size of diamond grit was employed. In addition, we proposed a modified model around surface roughness and subsurface crack depth, which considered plastic and brittle deformation mechanisms and material properties of different crystal orientations. When the surface roughness (R_Z) exceeded the brittle-plastic transition’s critical value R_ZC (R_ZC<100> > 1.5 μm, R_ZC<110> > 0.8 μm), cracks appeared on the subsurface. The experimental results were consistent with the predicted model, which could be used to predict the subsurface cracks by measuring the surface roughness. However, the model only gives the approximate range of subsurface defects, such as dislocations. The morphology and precise depth of plastic deformation subsurface defects, such as dislocations generated in the fine grinding stage, needed to be inspected by transmission electron microscopy (TEM), which were further studied. Full article

(This article belongs to the Special Issue Frontiers in Ultra-Precision Machining)

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14 pages, 9035 KiB

Open AccessArticle

Rapid and Non-Destructive Repair of Fused Silica with Cluster Damage by Magnetorheological Removing Method

by Mingjie Deng, Ci Song, Feng Shi, Yaofei Zhang, Ye Tian and Wanli Zhang

Micromachines 2021, 12(3), 274; https://doi.org/10.3390/mi12030274 - 06 Mar 2021

Cited by 3 | Viewed by 1459

Abstract

The damage repair of fused silica based on the CO₂ laser repair technique has been successfully applied in high-power laser systems in the controllable nuclear fusion field. However, this kind of repairing technique mainly focuses on large-scale laser damage with sizes larger [...] Read more.

The damage repair of fused silica based on the CO₂ laser repair technique has been successfully applied in high-power laser systems in the controllable nuclear fusion field. However, this kind of repairing technique mainly focuses on large-scale laser damage with sizes larger than 200 μm, but ignores the influence of cluster small-scale damage with sizes smaller than 50 μm. In order to inhibit the growth of small-scale damage and further improve the effect of fused silica damage repair, this paper carried out a study on the repair of fused silica damage using the magnetorheological (MR) removing method. The feasibility of fused silica damage repairing was verified, and the evolution law of the number, morphology, and the surface roughness of small-scale damage were all analyzed. The results showed that the MR removing method was non-destructive compared to traditional repairing technologies. It not only effectively improved the whole damage repairing rate to more than 90%, but it also restored the optical properties and surface roughness of the damaged components in the repairing process. Based on the study of the MR removing repair law, a combined repairing process of 4 μm MR removal and 700 nm computer controlled optical surfacing (CCOS) removal is proposed. A typical fused silica element was experimentally repaired to verify the process parameters. The repairing rate of small-scale damage was up to 90.4%, and the surface roughness was restored to the level before repairing. The experimental results validate the effectiveness and feasibility of the combined repairing process. This work provides an effective method for the small-scale damage repairing of fused silica components. Full article

(This article belongs to the Special Issue Frontiers in Ultra-Precision Machining)

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