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15 pages, 11240 KiB

Open AccessArticle

Optimization of the Morphology of the Removal Function for Rotating Abrasive Water Jet Polishing

by Guipeng Tie, Zhiqiang Zhang, Bo Wang, Ci Song, Feng Shi, Wanli Zhang and Hailun Si

Micromachines 2023, 14(10), 1931; https://doi.org/10.3390/mi14101931 - 14 Oct 2023

Cited by 3 | Viewed by 1306

Abstract

Abrasive water jet polishing has significant advantages in the manufacturing of complex optical components (such as high-slope optical component cavities) that require high-precision manufacturing. This is due to its processing process, in which the polishing tool does not make direct contact with the [...] Read more.

Abrasive water jet polishing has significant advantages in the manufacturing of complex optical components (such as high-slope optical component cavities) that require high-precision manufacturing. This is due to its processing process, in which the polishing tool does not make direct contact with the surface of the workpiece, and instead maintains a considerable distance. However, the removal functions of most existing abrasive water-jet polishing technologies do not possess strict symmetry, which significantly impacts the ability to correct surface figure errors. Therefore, this study implements rotating abrasive water-jet polishing based on traditional abrasive water jet processing to optimize the removal function, which turns it into a Gaussian form; thus, obtaining a type of removal function more suitable for CCOS polishing. This paper derives an empirical formula between the distance s’ from the peak removal point of the removal function to the stagnation point and the nozzle tilt angle α, based on geometric relationships and experimental results, analyzes the relationship between material removal efficiency, nozzle tilt angle, and standoff distance. Finally, this paper verifies through experiments the validity of this empirical formula under different process parameters. Therefore, this study obtains the process conditions that allow rotating abrasive water-jet polishing technology to achieve a stable Gaussian form removal function, and the appropriate process parameters to be selected in conjunction with polishing efficiency; thereby, effectively improving the removal function’s corrective ability and manufacturing efficiency. It provides theoretical support for the processing capability and process parameter selection of abrasive water-jet polishing technology, solves the problem of limited shaping capability of existing abrasive water jet tools, and significantly improves the manufacturing capability of high-end optical components. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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14 pages, 4550 KiB

Open AccessArticle

Experimental Study on the Preparation of Ultra-Fine Brass Tube Electrodes by Ultrasonic Vibration

by Hanlin Yu, Yugang Zhao, Zhihao Li, Chuang Zhao, Shuo Meng, Yu Tang, Xiajunyu Zhang and Guangxin Liu

Micromachines 2023, 14(6), 1234; https://doi.org/10.3390/mi14061234 - 12 Jun 2023

Viewed by 1425

Abstract

In order to automatically process ultra-fine copper tube electrodes, this study proposes a new method of ultrasonic vibration processing of ultra-fine copper tube, analyzes its processing principle, designs a new set of experimental processing equipment and completes the processing of 1.206 mm inner [...] Read more.

In order to automatically process ultra-fine copper tube electrodes, this study proposes a new method of ultrasonic vibration processing of ultra-fine copper tube, analyzes its processing principle, designs a new set of experimental processing equipment and completes the processing of 1.206 mm inner diameter, 1.276 mm outer diameter with core brass tube. Not only can the copper tube be completed with core decoring, the surface of the processed brass tube electrode also has good integrity. The effect of each machining parameter on the surface roughness of the electrode after machining was investigated by a single-factor experiment and the optimal machining effect was achieved under the conditions of machining gap 0.1 mm, ultrasonic amplitude 0.186 mm, table feed speed 6 mm/min, tube rotation speed 1000 r/min and reciprocating machining two times. The surface roughness was reduced from 1.21 μm before machining to 0.11 μm, and the residual pits, scratches and oxide layer on the surface were completely removed, which greatly improved the surface quality of the brass tube electrode and prolonged its service life. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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10 pages, 19678 KiB

Open AccessArticle

Micro-Shaping of Pure Aluminum in Long-Duration Wire Electrochemical Micromachining Using Bipolar Nanosecond Pulses

by Xiaolei Bi, Meng Jia and Lingchao Meng

Micromachines 2023, 14(5), 1046; https://doi.org/10.3390/mi14051046 - 13 May 2023

Viewed by 1340

Abstract

With the increasing application of three-dimensional pure aluminum microstructures in micro-electromechanical systems (MEMS) and for fabricating terahertz components, high-quality micro-shaping of pure aluminum has gradually attracted attention. Recently, high-quality three-dimensional microstructures of pure aluminum with a short machining path have been obtained through [...] Read more.

With the increasing application of three-dimensional pure aluminum microstructures in micro-electromechanical systems (MEMS) and for fabricating terahertz components, high-quality micro-shaping of pure aluminum has gradually attracted attention. Recently, high-quality three-dimensional microstructures of pure aluminum with a short machining path have been obtained through wire electrochemical micromachining (WECMM), owing to its sub-micrometer-scale machining precision. However, machining accuracy and stability decrease owing to the adhesion of insoluble products on the surface of the wire electrode in long-duration WECMM, which limits the application of pure aluminum microstructures with a long machining path. In this study, the bipolar nanosecond pulses are used to improve the machining accuracy and stability in long-duration WECMM of pure aluminum. A negative voltage of −0.5 V was considered appropriate based on experimental results. Compared with the traditional WECMM using unipolar pulses, the machining accuracy of the machined micro-slit and the duration of stable machining were significantly improved in long-duration WECMM using bipolar nanosecond pulses. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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16 pages, 6579 KiB

Open AccessArticle

Polishing Characteristics of Cemented Carbide Using Cubic Boron Nitride Magnetic Abrasive Powders

by Pengfei Chen, Yuewu Gao, Yugang Zhao, Guoyong Zhao, Guixiang Zhang, Haiyun Zhang and Zhuang Song

Micromachines 2022, 13(12), 2167; https://doi.org/10.3390/mi13122167 - 8 Dec 2022

Cited by 3 | Viewed by 1646

Abstract

This paper describes the application of bonded magnetic abrasive powders (MAPs) in the magnetic abrasive finishing (MAF) process. In order to improve the poor finishing performance and short service life of MAPs in polishing super-hard materials, a double-stage atomization technique was used to [...] Read more.

This paper describes the application of bonded magnetic abrasive powders (MAPs) in the magnetic abrasive finishing (MAF) process. In order to improve the poor finishing performance and short service life of MAPs in polishing super-hard materials, a double-stage atomization technique was used to successfully manufacture MAPs with a CBN as an abrasive phase. The prepared results show that CBN abrasives with their original structure were deeply and densely embedded on the surface of spherical MAPs. Based on the MAF process, a five-level and four-factor central composite design experiment was carried out to verify the developed MAPs polishing performance on the finishing of cemented carbide parts (864 Hv). Working gap, rotational speed, feed rate of a workpiece, and mesh number of MAP were considered as influence factors. The analysis data was used to understand different interactions of significant parameters. A regression model for predicting the change of surface roughness was obtained, and the optimal parameter combination was figured out through a solution of a quadratic equation in Design-Expert software. According to MAF results, the strong cutting ability of atomized CBN MAPs improved the surface roughness of cemented carbide by over 80% at the optimum parameters. The strong cutting ability of atomized CBN MAPs can produce good surface quality on the hard materials. The findings of this research can promote a large-scale application of MAF technology in the surface polishing of hard materials. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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20 pages, 9648 KiB

Open AccessArticle

Radial Error Motion Measurement and Its Uncertainty Estimation of Ultra Precision Axes of Rotation with Nanometer Level Precision

by Xingbao Liu, Xiaoting Rui, Liang Mi, Qiang Tang, Heng Chen and Yangqiu Xia

Micromachines 2022, 13(12), 2121; https://doi.org/10.3390/mi13122121 - 30 Nov 2022

Cited by 1 | Viewed by 2710

Abstract

The radial error is the key performance indicator of ultra-precision axis. In order to measure and evaluate the radial error of ultra-precision axis with nanometer accuracy, a measurement system with an accuracy of nanometer based on capacitive displacement probes and standard spheres is [...] Read more.

The radial error is the key performance indicator of ultra-precision axis. In order to measure and evaluate the radial error of ultra-precision axis with nanometer accuracy, a measurement system with an accuracy of nanometer based on capacitive displacement probes and standard spheres is developed. The nonlinearity error of capacitive displacement probes, misalignment error of the probes, eccentric error of standard spheres, error caused by environment temperature change, environment vibration and error separation methods are analyzed and the effects of the above factors are obtained; Multiple measurement examples carried out with the measurement system this paaper constructed indicate the repeatability of the measurement system reaches 10.5 nm and the roundness error of artifact separated is less than 4.03 nm. In order to evaluate the measurement dispersion of the ultra-precision axis radial error, the major uncertainty components and the complete process of the comprehensive evaluation of the measurement uncertainty are proposed. The combined uncertainty of radial error motion measurement of the ultra-precision axis with Donaldson reversal is 31.64 nm (k = 2). Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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19 pages, 7539 KiB

Open AccessArticle

Study on the Thermohydrodynamic Friction Characteristics of Surface-Textured Valve Plate of Axial Piston Pumps

by Zhaoqiang Wang, Lingtao Sun, Bo Han, Xiaoqiang Wang and Zhiwei Ge

Micromachines 2022, 13(11), 1891; https://doi.org/10.3390/mi13111891 - 2 Nov 2022

Cited by 5 | Viewed by 1653

Abstract

The purpose of this paper is to study the oil film and friction characteristics of valve plates with a micro-textured surface and to explore the influence of textures of different shapes and sizes on the valve plates. Firstly, on the basis of thermohydrodynamic [...] Read more.

The purpose of this paper is to study the oil film and friction characteristics of valve plates with a micro-textured surface and to explore the influence of textures of different shapes and sizes on the valve plates. Firstly, on the basis of thermohydrodynamic theory, this paper established the lubrication model of the oil film on the valve plate pair of swashplate axial piston pumps, according to the Reynolds equation. Secondly, the micro-texture was added to the mathematical model of the valve plate pair’s oil film. A combination of the energy equation, oil-film-thickness equation, elastic deformation equation, viscosity–pressure and viscosity–temperature equation, the finite difference method, as well as the relaxation iteration method, was used to solve the problem, and the textured and non-textured valve plate surfaces were simulated. The nephogram of the oil-film-thickness distribution, elastic deformation distribution, oil-film-pressure distribution and oil-film-temperature distribution were generated. Then, the control variable method was used to change the cylinder rotational speed, tilt angle, oil viscosity, initial oil film thickness and other parameters to analyze their effects on oil film characteristics. In addition, the friction characteristics of non-textured surfaces, square textured surfaces, triangular textured surfaces and circular textured surfaces were compared and analyzed. It was found that the textured surface of valve plates can obviously improve friction efficiency under the same operating conditions. The square texture, especially, is the preferable shape, rather than the triangular texture and the circular texture, and the friction performance is at its best when the texture depths are between 20

μ m

and 50

μ m

. The results provide a theoretical basis for the design and improvement of the valve plate. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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12 pages, 3278 KiB

Open AccessArticle

Tangential Ultrasonic-Vibration Assisted Forming Grinding Gear: An Experimental Study

by Wenbo Bie, Bo Zhao, Guofu Gao, Fan Chen and Jiangwei Jin

Micromachines 2022, 13(11), 1826; https://doi.org/10.3390/mi13111826 - 26 Oct 2022

Cited by 2 | Viewed by 1885

Abstract

This study used a forming grinding wheel to machine an involute spur gear with ultrasonic vibration applied to the gear in order to improve the gear processing technology and enhance the gear processing effect. Conventional grinding and ultrasonic vibration-assisted forming grinding gear (TUVA-FGG) [...] Read more.

This study used a forming grinding wheel to machine an involute spur gear with ultrasonic vibration applied to the gear in order to improve the gear processing technology and enhance the gear processing effect. Conventional grinding and ultrasonic vibration-assisted forming grinding gear (TUVA-FGG) tests were carried out. The effects of grinding parameters, such as spindle speed, feed rate, radial grinding depth, and ultrasonic amplitude, on grinding force, grinding temperature, residual stress, surface roughness, and surface morphology were analyzed. The TUVA-FGG significantly improved processing efficiency. With the increase in spindle speed, the maximum reductions in the normal and tangential grinding forces, grinding temperature, and surface roughness reached 33.6, 24.5, 23.9, and 21.6%, respectively. With the increase in feed rate, the respective maximum reductions were 21.4, 19.7, 20.3, and 16.1%. With the increase in radial grinding depth, these values attained 24.6, 20.3, 21.5, and 17.6%, respectively. Finally, with the increase in ultrasonic amplitude, these reductions reached 21.4, 19.7, 21.5, and 19.4%. The maximum residual compressive stress grew by 30.3, 27.5, 30.9, and 27.5% with the increase of wheel rotation speed, feed speed, radial grinding depth, and ultrasonic amplitude, respectively. TUVA-FGG changed the conventional continuous cutting mechanism between the abrasive grain and workpiece into intermittent cutting, reducing grinding forces, grinding temperature, and surface roughness. Moreover, it increased residual compressive stress and improved the micromorphology of the tooth surface, thus enhancing gear machining efficiency. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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20 pages, 11685 KiB

Open AccessArticle

Experimental Investigation on Part Quality and Dust Emission during Minimum Quantity Lubricated (MQL) Edge Finishing of Granite

by Haithem Bahri, Victor Songmene and Jules Kouam

Micromachines 2022, 13(10), 1714; https://doi.org/10.3390/mi13101714 - 11 Oct 2022

Cited by 1 | Viewed by 1724

Abstract

Edge-finishing of granites by grinding is a process frequently used in the granite processing industry to generate the final desired shape and edge quality of products. However, this process releases significant amounts of fine and ultrafine particles (FPs and UFPs) containing crystalline silica. [...] Read more.

Edge-finishing of granites by grinding is a process frequently used in the granite processing industry to generate the final desired shape and edge quality of products. However, this process releases significant amounts of fine and ultrafine particles (FPs and UFPs) containing crystalline silica. When inhaled, this dust can cause silicosis disease and threaten the health and safety of workers. The purpose of this study is to optimize the process by decreasing the concentrations of dust generated while also maintaining the required surface finish. Experimental tests were planned and performed on granite samples using a full factorial design. Two cutting tool edge shapes were studied (chamfer and concave) using G150 and G600 grit size tools, at various spindle speeds (1500, 2500, 3500 rpm), feed rates (500, 1000, 1500 mm/min) and lubrication flow rates (20, 40, 60 mL/min). The findings show that the particle emissions as well as the surface finish depend on the tool shape, its grit size, and the machining and lubrication parameters used. Higher MQL flow rates led to better finished surface quality and lower concentrations of fine dust. Polishing with flood lubrication reduces the maximum number concentration of FPs corresponding to particles smaller than 1 µm diameter by about 85% as compared to dry polishing and produced the best surface finish. Polishing with lubrication in MQL mode at 60 mL/min led to the production of part with Ra-value comparable with that obtained in flood lubrication condition. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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15 pages, 5595 KiB

Open AccessArticle

Research on Continuous Error Compensation of a Sub-Arc-Second Macro/Micro Dual-Drive Rotary System

by Manzhi Yang, Linyue Li, Chuanwei Zhang, Yumei Huang, Hongzhang Wu and Bin Feng

Micromachines 2022, 13(10), 1662; https://doi.org/10.3390/mi13101662 - 2 Oct 2022

Cited by 4 | Viewed by 1477

Abstract

In this paper, a sub-arc-second macro/micro dual-drive rotary system is designed, and the continuous compensation of the system error and its experimental research are completed. First, the macro-drive system is driven by a direct-drive motor, and the micro-drive system uses a piezoelectric ceramic [...] Read more.

In this paper, a sub-arc-second macro/micro dual-drive rotary system is designed, and the continuous compensation of the system error and its experimental research are completed. First, the macro-drive system is driven by a direct-drive motor, and the micro-drive system uses a piezoelectric ceramic to drive the micro-drive rotary mechanism; the system uses a micro-drive system to compensate the motion error of the macro-drive system, and uses circular grating to feedback the displacement of the macro/micro total output turntable to form a macro/micro dual-drive closed-loop control system. Second, based on the establishment of the system error model, the design of the system’s continuous error compensation scheme is completed. Finally, the positioning accuracy testing of the system, direct error compensation of the macro-drive, manual error compensation of the macro-drive, error compensation performance of the micro-drive part and macro/micro compensation of the system are carried out in the study. The results show that the repeated positioning error and the positioning error of the system are reduced by 78.8% and 95.2%, respectively, after macro/micro compensation. The correctness and effectiveness of the designed system design, error compensation and control method are verified through performance tests, and its positioning accuracy is verified to the sub-arc-second (0.1 arcsecond) level. The research in this paper has important reference value for the development of ultra-precision macro/micro dual-drive technology. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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16 pages, 2630 KiB

Open AccessArticle

Prediction of Surface Roughness in Gas-Solid Two-Phase Abrasive Flow Machining Based on Multivariate Linear Equation

by Wenhua Wang, Wei Yuan, Jie Yu, Qianjian Guo, Shutong Chen, Xianhai Yang and Jianchen Cong

Micromachines 2022, 13(10), 1649; https://doi.org/10.3390/mi13101649 - 30 Sep 2022

Cited by 2 | Viewed by 1432

Abstract

The main purpose of this study is to explore a surface roughness prediction model of Gas-Solid Two-Phase Abrasive Flow Machining. In order to achieve the above purpose, an orthogonal experiment was carried out. Q235 steel as processing material and white corundum with different [...] Read more.

The main purpose of this study is to explore a surface roughness prediction model of Gas-Solid Two-Phase Abrasive Flow Machining. In order to achieve the above purpose, an orthogonal experiment was carried out. Q235 steel as processing material and white corundum with different particle sizes as abrasive particles were used in the experiment. Shape and spindle speed were the main reference factors. The range method and factor trend graph are used to comprehensively analyze the experimental results of different processing stages of the detection point, and the optimal parameter combination of A₃B₂C₁D₂ was obtained. According to the experimental results, a multiple linear regression equation was established to predict the surface roughness, and the experimental results were solved and significantly analyzed by software to obtain a highly reliable prediction model. Through experiments, modeling and verification, it is known that the maximum error between the obtained model and the actual value is 0.339 μm and the average error is 0.00844 μm, which can better predict the surface roughness of the gas-solid two-phase flow abrasive pool. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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16 pages, 4867 KiB

Open AccessArticle

Design and Performance Research of a Precision Micro-Drive Reduction System without Additional Motion

by Manzhi Yang, Xiaodong Zhang, Chuanwei Zhang, Hongzhang Wu and Yizhi Yang

Micromachines 2022, 13(10), 1636; https://doi.org/10.3390/mi13101636 - 29 Sep 2022

Cited by 5 | Viewed by 1693

Abstract

A micro-drive system is a key part of macro-micro-drive technology and precision positioning technology in which a micro-drive reduction system can provide more precise motion and suitable small space motion. Therefore, it is necessary to study precision micro-drive reduction systems. In this paper, [...] Read more.

A micro-drive system is a key part of macro-micro-drive technology and precision positioning technology in which a micro-drive reduction system can provide more precise motion and suitable small space motion. Therefore, it is necessary to study precision micro-drive reduction systems. In this paper, based on the design of a micro-drive reduction mechanism without force and displacement in non-motion direction, a precision micro-drive reduction system driven by a piezoelectric ceramic actuator (PZT) was designed, and the strength, dynamic and motion performance of the system was analyzed. First, based on the principle of a flexure hinge lever and the principle of balanced additional force, a type of precision micro-drive reduction mechanism with an adjustable reduction ratio was designed. Second, the strength performance of the system was analyzed by finite element analysis, and the dynamic performance of the system was analyzed by finite element analysis and experiments. Finally, the kinematic performance of the system was analyzed by theoretical analysis, the finite element method and experiment, and the motion linear equation was calculated based on the linear fitting equations of three methods. The study results showed that the system had good strength and dynamic performances, and the system’s motion had the advantages of high precision and good linearity. This research has certain reference value for the design and performance research of micro-drive mechanisms. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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21 pages, 5644 KiB

Open AccessArticle

Output-Only Time-Varying Modal Parameter Identification Method Based on the TARMAX Model for the Milling of a Thin-Walled Workpiece

by Junjin Ma, Xinhong Yan, Yunfei Li, Haoming Li, Yujie Li and Xiaoyan Pang

Micromachines 2022, 13(10), 1581; https://doi.org/10.3390/mi13101581 - 22 Sep 2022

Viewed by 1662

Abstract

The process parameters chosen for high-performance machining in the milling of a thin-walled workpiece are determined by a stability prediction model, which needs accurate modal parameters of the machining system. However, the in-process modal parameters are different from the offline modal parameters and [...] Read more.

The process parameters chosen for high-performance machining in the milling of a thin-walled workpiece are determined by a stability prediction model, which needs accurate modal parameters of the machining system. However, the in-process modal parameters are different from the offline modal parameters and are difficult to precisely obtain due to material removal. To address this problem, an accurate time-dependent autoregressive moving average with an exogenous input (TARMAX) method is proposed for the identification of the modal parameters in the milling of a thin-walled workpiece. In this process, a TARMAX model considering external force excitation is constructed to characterize the actual condition in the milling of a thin-walled workpiece. Then, recursive method and sliding window recursive method are used to identify TARMAX model parameters under time-varying cutting conditions. Subsequently, a three-degree of freedom (3-DOF) time-varying structure numerical model under theoretical milling forces and white-noise excitation is established, and the computational results show that the predicted natural frequencies using the proposed method are in close agreement with the simulated values. Finally, several experiments are designed and carried out to validate the effectiveness of the proposed method. The experimental results show that the predicted accuracy of the proposed method using actual cutting forces is 95.68%. Good agreement has been drawn in the numerical simulation and machining experiments. Our further research objectives will focus on the prediction of the damping ratios, modal stiffness, and modal mass. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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14 pages, 5642 KiB

Open AccessArticle

Experimental Studies on Fabricating Lenslet Array with Slow Tool Servo

by Wenjun Kang, Masafumi Seigo, Huapan Xiao, Daodang Wang and Rongguang Liang

Micromachines 2022, 13(10), 1564; https://doi.org/10.3390/mi13101564 - 21 Sep 2022

Cited by 2 | Viewed by 1648

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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11 pages, 3501 KiB

Open AccessArticle

The Precision Analysis of Cutting Edge Preparation on CBN Cutting Inserts Using Rotary Ultrasonic Machining

by Marcel Kuruc, Tomáš Vopát, Jana Moravčíková and Ján Milde

Micromachines 2022, 13(10), 1562; https://doi.org/10.3390/mi13101562 - 21 Sep 2022

Cited by 6 | Viewed by 2042

Abstract

This paper is focused on the issue of preparing the cutting edge microgeometry of cutting inserts made of cubic boron nitride (CBN). The aim of this research was to investigate the possibilities of rotary ultrasonic machining (RUM) for preparing asymmetric cutting edge microgeometries [...] Read more.

This paper is focused on the issue of preparing the cutting edge microgeometry of cutting inserts made of cubic boron nitride (CBN). The aim of this research was to investigate the possibilities of rotary ultrasonic machining (RUM) for preparing asymmetric cutting edge microgeometries of various shapes (chamfers, circular, and elliptical rounding and their combinations) on a CBN cutting tool. In this article, a new type of advanced cutting edge preparation method is presented. CBN is relatively resistant to the most often used (abrasive) methods of cutting-edge preparation, due to its very high hardness (which is a prerequisite property for machining difficult-to-cut materials). Such hard materials could be processed using advanced manufacturing methods, and rotary ultrasonic machining (RUM) is one such method. Experiments have shown that RUM can be used for machining CBN. However, high hardness is not the only challenge here. For cutting edge preparation, it is necessary to achieve an adequate accuracy of size and dimensions. The presented paper analyzes the suitability of the RUM process for processing CBN inserts. The results of the experiment showed that this method can be used for preparing asymmetric cutting edge microgeometries with various shapes. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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15 pages, 3954 KiB

Open AccessArticle

Geometric Error Analysis and Compensation in Spherical Generating Grinding of Hemispherical Shell Resonators

by Yu Wang, Chaoliang Guan, Yifan Dai and Shuai Xue

Micromachines 2022, 13(9), 1535; https://doi.org/10.3390/mi13091535 - 16 Sep 2022

Viewed by 2010

Abstract

The geometric accuracy of a hemispherical shell resonator (HSR) affects the assembly accuracy and final performance of a hemispherical resonant gyroscope in many ways. During the precision grinding of a resonator, the tool-setting error and wear error affect the form and positional accuracy [...] Read more.

The geometric accuracy of a hemispherical shell resonator (HSR) affects the assembly accuracy and final performance of a hemispherical resonant gyroscope in many ways. During the precision grinding of a resonator, the tool-setting error and wear error affect the form and positional accuracy of the inner and outer spherical surfaces. In this study, a compensation method for generating grinding of the HSR is proposed to address this problem. The geometric errors of the inner and outer spherical surfaces are systemically analyzed and a geometric model of the tool setting and wheel wear is established for generating grinding of the HSR. According to this model, a mapping relationship between the wheel pose and size, form, and positional error of the HSR was proposed. Experiments regarding machining, on-machine measurements, and error compensation were performed using the mapping relationship. The results demonstrate that the proposed method can reduce the radius error of the inner and outer spherical surfaces from 10 μm to 1 μm, sphericity from 5 μm to 1.5 μm, and concentricity from 15 μm to 3 μm following grinding. The form and positional errors are simultaneously improved, verifying the effectiveness of the proposed method. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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25 pages, 5809 KiB

Open AccessArticle

Influence of Machining Conditions on Micro-Geometric Accuracy Elements of Complex Helical Surfaces Generated by Thread Whirling

by Vasile Merticaru, Gheorghe Nagîț, Oana Dodun, Eugen Merticaru, Marius Ionuț Rîpanu, Andrei Marius Mihalache and Laurențiu Slătineanu

Micromachines 2022, 13(9), 1520; https://doi.org/10.3390/mi13091520 - 14 Sep 2022

Cited by 3 | Viewed by 2354

Abstract

Complex surfaces such as helical ones are commonly used in machinery. Such surfaces can be obtained by various machining processes, one of these processes being thread whirling. The influence of machining conditions needs to be better understood to develop a more precise prediction [...] Read more.

Complex surfaces such as helical ones are commonly used in machinery. Such surfaces can be obtained by various machining processes, one of these processes being thread whirling. The influence of machining conditions needs to be better understood to develop a more precise prediction of the specific resulting errors involved in thread whirling. This paper firstly presents the theoretical conditions which generate micro-deviations on whirled surfaces. A theoretical model which considers the geometrical parameters describing the whirling head and cutters and the process’s whole kinematics was developed. The threaded surface was described as a complex compound surface resulting from intersecting successive ruled helical surfaces corresponding to the cutting edges of the set of cutters from the whirling head. Numerical simulation results were exemplified and validation experiments were both designed and performed. Empirical mathematical models were established to highlight the influence of the input factors such as thread pitch and external diameter, the ratio between the diameter of cutters’ top edge disposal and the thread’s external diameter, the rotary speed of the whirling head, and the rotary speed of the workpiece on some accuracy elements and roughness parameters of the threaded surface. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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19 pages, 4945 KiB

Open AccessArticle

Prediction and Optimization of Surface Roughness for Laser-Assisted Machining SiC Ceramics Based on Improved Support Vector Regression

by Chen Cao, Yugang Zhao, Zhuang Song, Di Dai, Qian Liu, Xiajunyu Zhang, Jianbing Meng, Yuewu Gao, Haiyun Zhang and Guangxin Liu

Micromachines 2022, 13(9), 1448; https://doi.org/10.3390/mi13091448 - 1 Sep 2022

Cited by 11 | Viewed by 1892

Abstract

In this paper, the surface roughness of SiC ceramics was investigated in laser-assisted machining (LAM) processes; machine learning was used to predict surface roughness and to optimize the process parameters, and therefore, to ultimately improve the surface quality of a workpiece and obtain [...] Read more.

In this paper, the surface roughness of SiC ceramics was investigated in laser-assisted machining (LAM) processes; machine learning was used to predict surface roughness and to optimize the process parameters, and therefore, to ultimately improve the surface quality of a workpiece and obtain excellent serviceability. First, single-factor turning experiments were carried out on SiC ceramics using LAM according to the material removal mechanism to investigate the variation trend of the effects of different laser powers, rotational speeds, feed rates, and cutting depths on surface roughness. Then, laser power, rotational speed, feed rate and cutting depth were selected as the four factors, and the surface roughness was used as the target value for the orthogonal experiments. The results of the single-factor experiments and the orthogonal experiments were combined to construct a prediction model based on the combination of the grey wolf optimization (GWO) algorithm and support vector regression (SVR). The coefficient of determination (R²) of the optimized prediction model reached 0.98676 with an average relative error of less than 2.624%. Finally, the GWO algorithm was used to optimize the global parameters of the prediction model again, and the optimal combination of process parameters was determined and verified by experiments. The actual minimum surface roughness (Ra) value was 0.418 μm, and the relative error was less than 1.91% as compared with the predicted value of the model. Therefore, the prediction model based on GWO-SVR can achieve accurate prediction of the surface roughness of SiC ceramics in LAM and can obtain the optimum surface roughness using parameter optimization. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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25 pages, 15308 KiB

Open AccessArticle

A Method of Restraining the Adverse Effects of Grinding Marks on Small Aperture Aspheric Mirrors

by Jiahui Bao, Xiaoqiang Peng, Hao Hu and Tao Lai

Micromachines 2022, 13(9), 1421; https://doi.org/10.3390/mi13091421 - 28 Aug 2022

Cited by 2 | Viewed by 1532

Abstract

The grinding method is used as the preliminary processing procedure for small aperture aspheric mirrors. Regular grinding marks produced in the grinding process significantly affect the mid-spatial frequency error; however, because of their small radius of surface curvatures and high steepness, they are [...] Read more.

The grinding method is used as the preliminary processing procedure for small aperture aspheric mirrors. Regular grinding marks produced in the grinding process significantly affect the mid-spatial frequency error; however, because of their small radius of surface curvatures and high steepness, they are difficult to polish using traditional methods. Therefore, in this study, the ultra-precision grinding and polishing process of fused quartz material was investigated, and the influence of grinding marks was analyzed, which achieved the purpose of restraining the grinding marks in the grinding process. The generation mechanisms of horizontal and vertical grinding marks were analyzed by means of simulation and experiment, and the relationship between different grinding process parameters and surface quality was explored. A magnetorheological finishing (MRF) spot method was used to explore the effects of grinding marks on subsurface damage (SSD). The elastic adaptive polishing method was used to polish an aspheric lens with high steepness and small caliber. Based on the principle of an elastic adaptive polishing mathematical model, the grinding marks were suppressed, and the mid-spatial frequency error of the lens was reduced by optimizing the polishing path and composition of the polishing fluid. The final roughness reached 10 nm Ra. In this paper, the source of wear marks and their influence on the mid-spatial frequency error of small aperture aspheric mirrors are analyzed, and the grinding marks were suppressed by elastic adaptive polishing. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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16 pages, 4932 KiB

Open AccessArticle

Fabrication of Ultra-Fine and Ultra-Long Copper Tube Electrodes by Ultrasonic High-Frequency Percussion

by Xiajunyu Zhang, Yugang Zhao, Hanlin Yu, Zhihao Li, Chuang Zhao, Guangxin Liu, Chen Cao, Qian Liu, Zhilong Zheng and Dandan Zhao

Micromachines 2022, 13(9), 1405; https://doi.org/10.3390/mi13091405 - 27 Aug 2022

Viewed by 1549

Abstract

In this study, a new method of ultrasonic high-frequency percussion (UH-FP) is proposed. Ultra-fine and ultra-long copper tube electrodes cannot be fabricated by traditional processing methods, and the copper tube electrodes fabricated by UH-FP can be used in the process of rotary EDM [...] Read more.

In this study, a new method of ultrasonic high-frequency percussion (UH-FP) is proposed. Ultra-fine and ultra-long copper tube electrodes cannot be fabricated by traditional processing methods, and the copper tube electrodes fabricated by UH-FP can be used in the process of rotary EDM for microfine holes. The UH-FP setup has been established based on an ultrasonic device, a workpiece chucking and rotation device, and a workpiece reciprocating motion device. In this work, by studying the principle of ultrasonic processing, the processing principle and mechanism of ultra-fine and ultra-long copper tube electrode preparation by ultrasonic high-frequency percussion is proposed. The effects of processing parameters (i.e., rotational speed, feed rate, working gap, percussion amplitude) on surface roughness are evaluated quantitatively. Experimental results show that the proposed method could complete the core leach of the core-containing copper tube electrodes after drawing, while improving surface quality. Some surface defects such as cracks, scratches and folds were completed removed, further improving the mechanical performance of processed parts. The surface roughness (Ra) of 0.091 μm was obtained from the initial 0.46 μm under the optimal processing parameters of 800 rpm tube rotational speed, 200 mm/min platform feed speed, 0.13 mm machining gap, 0.15 mm percussion amplitude, and 32 min machining time. The method shows potential for manufacturing copper tube electrodes for a wide range of industrial applications. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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15 pages, 6018 KiB

Open AccessArticle

Study on the Micro Removal Process of Inner Surface of Cobalt Chromium Alloy Cardiovascular Stent Tubes

by Zhuang Song, Yugang Zhao, Zhihao Li, Chen Cao, Guangxin Liu, Qian Liu, Xiajunyu Zhang, Di Dai, Zhilong Zheng, Chuang Zhao and Hanlin Yu

Micromachines 2022, 13(9), 1374; https://doi.org/10.3390/mi13091374 - 23 Aug 2022

Cited by 2 | Viewed by 1970

Abstract

Due to the special manufacturing process of cobalt–chromium alloy cardiovascular stent tubes, there are serious surface defects in their inner walls, which affects the therapeutic effect after implantation. At the same time, the traditional processing technology cannot finish the inner wall of a [...] Read more.

Due to the special manufacturing process of cobalt–chromium alloy cardiovascular stent tubes, there are serious surface defects in their inner walls, which affects the therapeutic effect after implantation. At the same time, the traditional processing technology cannot finish the inner wall of a cardiovascular stent tube. In light of the above problems, magnetic abrasive finishing (MAF) equipment for the inner wall of an ultra-fine and ultra-long cardiovascular stent tube is proposed, and MAF technology is used to improve the surface quality of its inner wall. High-performance spherical magnetic abrasive powders are used to finish the inner wall of a cobalt–chromium alloy cardiovascular stent tube with an inner diameter of 1.6 mm and an outer diameter of 1.8 mm. The effects of finishing time, tube rotational speed, feed speed of the magnetic pole, MAPs filling quantity, and MAP abrasive size on the surface roughness and material removal thickness of cobalt–chromium alloy cardiovascular stent tube are investigated. The results show that the surface roughness of the inner wall of the cobalt–chromium alloy cardiovascular stent decreases from 0.485 μm to 0.101 μm, and the material removal thickness of the defect layer is 4.3 μm. MAF technology is used to solve the problem of the poor surface quality of the inner walls of ultra-fine and ultra-long cobalt–chromium alloy cardiovascular stent tubes. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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17 pages, 5653 KiB

Open AccessArticle

Parametric Studies on Finishing of AZ31B Magnesium Alloy with Al₂O₃ Magnetic Abrasives Prepared by Combining Plasma Molten Metal Powder with Sprayed Abrasive Powder

by Zhihao Li, Yugang Zhao, Guangxin Liu, Chen Cao, Qian Liu, Dandan Zhao, Xiajunyu Zhang, Chuang Zhao and Hanlin Yu

Micromachines 2022, 13(9), 1369; https://doi.org/10.3390/mi13091369 - 23 Aug 2022

Cited by 3 | Viewed by 1854

Abstract

High-performance iron-based Al₂O₃ magnetic abrasive powder (MAP) prepared by combining plasma molten metal powder with sprayed abrasive powder is used for magnetic abrasive finishing (MAF) of AZ31B magnesium alloy to remove surface defects such as creases, cracks, scratches, and pits [...] Read more.

High-performance iron-based Al₂O₃ magnetic abrasive powder (MAP) prepared by combining plasma molten metal powder with sprayed abrasive powder is used for magnetic abrasive finishing (MAF) of AZ31B magnesium alloy to remove surface defects such as creases, cracks, scratches, and pits generated during the manufacturing process of the workpiece, and to reduce surface roughness and improve its wear and corrosion resistance. In order to solve the problem of magnetic abrasive powder splash in the MAF process, the force analysis of the MAP in the processing area is conducted, and a composite magnetic pole processing device was designed and simulated to compare the effects of both devices on MAF, confirming the feasibility of composite magnetic pole grinding. Then, experiments have been designed using Response Surface Methodology (RSM) to investigate the effect of four factors-magnetic pole rotation speed, grinding gap, magnetic pole feed rate, magnetic abrasive filling quantity-on surface roughness and the interactions between them. The minimum surface roughness value that can be obtained is used as the index for parameter optimization, and the optimized parameters are used for experiments, and the results show that the established surface roughness model has good predictive ability. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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13 pages, 10911 KiB

Open AccessArticle

A High Efficiency and Precision Smoothing Polishing Method for NiP Coating of Metal Mirror

by Chao Xu, Xiaoqiang Peng, Junfeng Liu, Hao Hu, Tao Lai, Qilin Yang and Yupeng Xiong

Micromachines 2022, 13(8), 1171; https://doi.org/10.3390/mi13081171 - 25 Jul 2022

Cited by 11 | Viewed by 2723

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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8 pages, 2623 KiB

Open AccessArticle

Figuring Method of High Convergence Ratio for Pulsed Ion Beams Based on Frequency-Domain Parameter Control

by Lingbo Xie, Ye Tian, Feng Shi, Gang Zhou, Shuangpeng Guo, Zhe Zhu, Ci Song and Guipeng Tie

Micromachines 2022, 13(8), 1159; https://doi.org/10.3390/mi13081159 - 22 Jul 2022

Cited by 2 | Viewed by 1583

Abstract

The continuous phase plate (CPP) provides excellent beam smoothing and shaping impacts in the inertial confinement fusion application. However, due to the features of its dispersion, its surface gradient is frequently too large (>2 μm/cm) to process. When machining a large gradient surface [...] Read more.

The continuous phase plate (CPP) provides excellent beam smoothing and shaping impacts in the inertial confinement fusion application. However, due to the features of its dispersion, its surface gradient is frequently too large (>2 μm/cm) to process. When machining a large gradient surface with continuous ion beam figuring (IBF), the acceleration of the machine motion axis cannot fulfill the appropriate requirements, and the machining efficiency is further influenced by the unavoidable extra removal layer. The pulsed ion beam (PIB) discretizes the ion beam by incorporating frequency-domain parameters, resulting in a pulsed beam with a controlled pulse width and frequency and avoiding the extra removal layer. This research evaluates the processing convergence ability of IBF and PIB for the large gradient surface using simulation and experiment. The findings reveal that PIB offers obvious advantages under the same beam diameter. Compared with the convergence ratio (γ = 2.02) and residuals (RMS = 184.36 nm) of IBF, the residuals (RMS = 27.48 nm) of PIB are smaller, and the convergence ratio (γ = 8.47) is higher. This work demonstrates that PIB has better residual convergence in large gradient surface processing. It is expected to realize ion beam machining with a higher convergence ratio. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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18 pages, 6041 KiB

Open AccessArticle

Ultra-Precision Cutting and Characterization of Reflective Convex Spherical Blazed Grating Elements

by Huang Li, Xiaoqiang Peng, Chaoliang Guan and Hao Hu

Micromachines 2022, 13(7), 1115; https://doi.org/10.3390/mi13071115 - 15 Jul 2022

Cited by 8 | Viewed by 1959

Abstract

In this work, based on the diffraction principle of reflective blazed grating, the structure size of the convex spherical blazed grating unit is determined, the machining accuracy of the convex spherical blazed grating is formulated, the effects of tool nose radius and Poisson [...] Read more.

In this work, based on the diffraction principle of reflective blazed grating, the structure size of the convex spherical blazed grating unit is determined, the machining accuracy of the convex spherical blazed grating is formulated, the effects of tool nose radius and Poisson burr on the diffraction efficiency of the convex spherical blazed grating are analyzed, and the performances of cutting convex gratings with microcrystalline aluminum RSA6061 and RSA6061+ chemically plated NiP for two workpiece materials are compared. A convex spherical blazed grating with a radius of curvature R = 41.104 mm, substrate diameter 14 mm, grating density 53.97 line/mm, and blaze angle of roughly 3.8° is turned by a four-axis ultra-precision machining system by adjustment of the cutting tool, workpiece material, and cutting parameters, as well as modification of the layouts of the blazed grating on the convex sphere. The results of the testing of convex spherical blazed grating elements in both layouts show that the size error of the grating period is close for both layouts, the size error of grating height is smaller in the equal-along-arc layout, the blaze angle error in the equal-along-projection layout is only 0.74%, and the average roughness of the blazed surface is less than 5 nm to meet the processing quality requirements of the reflective convex spherical blazed grating. The greater the blaze angle accuracy of the blazed grating, the higher its diffraction efficiency, so the grating element with an equal-along-projection layout has a higher diffraction efficiency than the grating element with an equal-along-arc layout. RSA6061+ chemically plated NiP material is superior to RSA6061 material in Poisson burr height and blazed surface roughness, which is more suitable for Offner-type imaging spectrometers in the spectral range 0.95–2.5 μm (SWIR). Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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8 pages, 2821 KiB

Open AccessArticle

Simulation Analysis and Performance Test of a Compressible Piezoelectric Pump Fluid Cavity

by Xia Liu, Tongyu Wang, Hu Wang, Jun Hou, Jinlong Liu, Jiaying Lin, Shenfang Li, Zhicong Wang, Xiaochao Tian and Zhigang Yang

Micromachines 2022, 13(7), 1100; https://doi.org/10.3390/mi13071100 - 13 Jul 2022

Cited by 2 | Viewed by 1630

Abstract

The large load loss of piezoelectricity pumps leads to fluid energy in the fluid chamber during fluid transportation. In this paper, the output performance of a piezoelectricity pump is improved by changing the structure parameters of the fluid chamber to reduce the fluid [...] Read more.

The large load loss of piezoelectricity pumps leads to fluid energy in the fluid chamber during fluid transportation. In this paper, the output performance of a piezoelectricity pump is improved by changing the structure parameters of the fluid chamber to reduce the fluid load. The mechanism of fluid flow energy loss in the body cavity of hydraulic pumps is simulated and analyzed, and the influence of the dimensions of the inlet and outlet valves and the height of the cavity on fluid energy loss is obtained. The flow rate and pressure of inlet and outlet valves with different cavity heights and different driving frequencies are obtained. The results show that the flow rate and output pressure of the hydraulic pump are optimized when the cavity height is 3 mm, and the inlet and outlet valve diameters are 2.5 mm. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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10 pages, 2873 KiB

Open AccessArticle

Nonlinear Effects of Pulsed Ion Beam in Ultra-High Resolution Material Removal

by Lingbo Xie, Ye Tian, Feng Shi, Ci Song, Guipeng Tie, Gang Zhou, Jianda Shao and Shijie Liu

Micromachines 2022, 13(7), 1097; https://doi.org/10.3390/mi13071097 - 12 Jul 2022

Cited by 3 | Viewed by 1657

Abstract

Ion beam sputtering is widely utilized in the area of ultra-high precision fabrication, coating, and discovering the microworld. A pulsed ion beam (PIB) can achieve higher material removal resolution while maintaining traditional ion beam removal performance and macro removal efficiency. In this paper, [...] Read more.

Ion beam sputtering is widely utilized in the area of ultra-high precision fabrication, coating, and discovering the microworld. A pulsed ion beam (PIB) can achieve higher material removal resolution while maintaining traditional ion beam removal performance and macro removal efficiency. In this paper, a 0.01 s pulse width beam is used to sputter atom layer deposition (ALD) coated samples. The nano-scale phenomenon is observed by high-resolution TEM. The results show that when the cumulative sputtering time is less than 1.7 s, the sputtering removal of solid by ion beam is accompanied by a nonlinear effect. Furthermore, the shortest time (0.05 s) and lowest thickness (0.35 nm) necessary to remove a uniform layer of material were established. The definition of its nonlinear effect under a very small removal amount guides industrial ultra-high precision machining. It reveals that PIB not only has high removal resolution on nanoscale, but can also realize high volume removal efficiency and large processing diameter at the same time. These features make PIB promising in the manufacturing of high power/energy laser optics, lithography objective lens, MEMS, and other ultra-high precision elements. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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25 pages, 7628 KiB

Open AccessArticle

A New Nonlinear Spatial Compliance Model Method for Flexure Leaf Springs with Large Width-to-Length Ratio under Large Deformation

by Yin Zhang, Jianwei Wu, Jiansheng Pan, Zhenzhuo Yan and Jiubin Tan

Micromachines 2022, 13(7), 1090; https://doi.org/10.3390/mi13071090 - 9 Jul 2022

Cited by 2 | Viewed by 1716

Abstract

Flexure leaf spring (FLS) with large deformation is the basic unit of compliant mechanisms with large stroke. The stiffness along the non-working directions of FLSs with large width-to-length ratio (w/L) is high. The motion stability of the compliant mechanism [...] Read more.

Flexure leaf spring (FLS) with large deformation is the basic unit of compliant mechanisms with large stroke. The stiffness along the non-working directions of FLSs with large width-to-length ratio (w/L) is high. The motion stability of the compliant mechanism based on this type of FLS is high. When this type of FLS is loaded along the width direction, the shear deformation needs to be characterized. Nevertheless, currently available compliance modeling methods for FLS are established based on Euler–Bernoulli beam model and cannot be used to characterize shear models. Therefore, these methods are not applicable in this case. In this paper, a new six-DOF compliance model for FLSs with large w/L is established under large deformation. The shear deformation along the width direction model is characterized based on the Timoshenko beam theory. The new constraint model and differential equations are established to obtain a high-precision compliance model expression for this type of FLS. The effects of structural parameters on the compliance of the FLS are analyzed. Finally, the accuracy of the model is verified both experimentally and by finite element simulation. The relative error between theoretical result and experiment result is less than 5%. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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21 pages, 6774 KiB

Open AccessArticle

Two-Step Glass Molding Process for Forming Glass Edges with Obtuse Angles for Mobile Displays

by Jeongyeon Park, Sungho Chang, Dongwon Lee, Hyeonhwa Lee, Bongchul Kang and Jongsu Kim

Micromachines 2022, 13(7), 1032; https://doi.org/10.3390/mi13071032 - 29 Jun 2022

Cited by 1 | Viewed by 2349

Abstract

The domain of edge displays with 2.5D or 3D curved designs has been expanded to improve user convenience. The currently available 3D cover glass offers a limited curvature radius of at least 5 mm and a curvature less than 88°, due to limitations [...] Read more.

The domain of edge displays with 2.5D or 3D curved designs has been expanded to improve user convenience. The currently available 3D cover glass offers a limited curvature radius of at least 5 mm and a curvature less than 88°, due to limitations in the undercuts and formability of parts. The development of a full 3D cover, applicable to next-generation displays, requires cover glass molding technology with a curvature exceeding 90°. Here, a mold design and molding process, which addresses the current limitations by dividing the existing glass molding press (GMP) process into two stages, is proposed. The bending geometry of the glass prepared on the basis of the proposed mold design plan during single-step compression forming and two-step compression forming was predicted using commercial analysis software. A molding product with a curvature radius of 2.5 mm and an angle of curvature of 138.9° was produced when process conditions with bending by up to 180° with no damage were applied during actual forming experiments. Further research on annealing and cooling processes of GMP is expected to enable the design and process implementation to manufacture curved glass with a single curvature of at least 90° and multiple curvatures. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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19 pages, 14518 KiB

Open AccessArticle

Analysis of Tool Wear and Roughness of Graphite Surfaces Machined Using MCD and NCD-Coated Ball Endmills

by Hyeonhwa Lee, Jinsoo Kim, Jeongyeon Park and Jongsu Kim

Micromachines 2022, 13(5), 766; https://doi.org/10.3390/mi13050766 - 13 May 2022

Cited by 2 | Viewed by 2172

Abstract

The high-purity G5 graphite material is widely used for glass moulding and provides high hardness and brittleness because it is sintered to fine particles unlike other graphite materials. Hence, tool cutting of a G5 workpiece is performed by local fracture instead of plastic [...] Read more.

The high-purity G5 graphite material is widely used for glass moulding and provides high hardness and brittleness because it is sintered to fine particles unlike other graphite materials. Hence, tool cutting of a G5 workpiece is performed by local fracture instead of plastic deformation of the machined surface. Although a diamond-coated tool with outstanding hardness is used to machine very hard graphite, the tool shows variability regarding the service life and machining performance depending on the grain size, even in the same machining environment. We investigated the wear and change trend of machined surface roughness considering microcrystalline diamond (MCD) and nanocrystalline diamond (NCD)-coated tools, which are generally used to machine graphite materials, and analysed their relation with coating. For rough machining, the MCD-coated tool, for which the delamination of coating occurred later, showed less wear and improved machined surface roughness. For precision machining, the NCD tool showed less tool wear rate relative to the cutting length, leading to a small difference in the machined surface roughness between the two tools. We conclude that if rough and precision machining processes are performed using the same cutting tool, the MCD-coated tool is advantageous in terms of service life, while the difference in roughness of the final machined surface between the tools is negligible. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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14 pages, 4587 KiB

Open AccessArticle

Research on Compound PID Control Strategy Based on Input Feedforward and Dynamic Compensation Applied in Noncircular Turning

by Yong Zhang, Yue Huang and Yu Wang

Micromachines 2022, 13(2), 341; https://doi.org/10.3390/mi13020341 - 21 Feb 2022

Cited by 5 | Viewed by 2342

Abstract

The fast tool servo (FTS) control strategy is the control core of high-speed noncircular turning. This method should ensure high-speed and precision positioning and have the corresponding anti-interference ability in the micro-stroke motion with dynamic changes of tool feed and load. Most of [...] Read more.

The fast tool servo (FTS) control strategy is the control core of high-speed noncircular turning. This method should ensure high-speed and precision positioning and have the corresponding anti-interference ability in the micro-stroke motion with dynamic changes of tool feed and load. Most of the previous FTS control studies used the repetitive control and speed feedforward control strategy, which achieved promising results under ideal machining conditions. However, this strategy showed some defects in the real-world complex and changeable working conditions such as time-varying cutting force, intermittent cutting and fluctuating machine spindle speed. This paper proposed and implemented a compound proportional integral derivative control strategy based on input feedforward and dynamic compensation in noncircular turning. This technique successfully met the motion requirements of the high responsiveness of micro-stroke in noncircular turning and overcame disturbances from complex time variations of the cutting force, intermittent cutting case of the product and fluctuations of machine spindle speed. According to the findings, the machining tracking error was less than ±2 µm. Experimental results demonstrated the excellent tracking performance and machining effect of this control strategy. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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7 pages, 5836 KiB

Open AccessArticle

Application of Flow Field Analysis in Ion Beam Figuring for Ultra-Smooth Machining of Monocrystalline Silicon Mirror

by Zhe Wang, Lingqi Wu, Yuanyuan Fang, Aihuan Dun, Jiaoling Zhao, Xueke Xu and Xiaolei Zhu

Micromachines 2022, 13(2), 318; https://doi.org/10.3390/mi13020318 - 18 Feb 2022

Cited by 7 | Viewed by 1804

Abstract

X-ray free-electron lasers are large modern scientific devices that play an important role in fields such as frontier physics and biomedicine. In this study, a light source is connected to an experimental station through beam lines, which requires numerous ultra-smooth and high-precision X-ray [...] Read more.

X-ray free-electron lasers are large modern scientific devices that play an important role in fields such as frontier physics and biomedicine. In this study, a light source is connected to an experimental station through beam lines, which requires numerous ultra-smooth and high-precision X-ray mirrors. Monocrystalline silicon is an ideal substrate material where ion-beam figuring is required. However, the ultra-smooth surface is damaged after the ion-beam figuring. Through an analysis of the machined surface, it is found that in the process of vacuum pumping, the impurities in the cavity adhere to the machined surface and increase the roughness after processing. Therefore, an optimized vacuum-pumping scheme is proposed. The experiment demonstrates that the original value of the processed surface roughness remains unchanged. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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15 pages, 3942 KiB

Open AccessArticle

Comprehensive Design Method of a High-Frequency-Response Fast Tool Servo System Based on a Full-Frequency Error Control Algorithm

by Zelong Li, Chaoliang Guan, Yifan Dai, Shuai Xue and Lianmin Yin

Micromachines 2021, 12(11), 1354; https://doi.org/10.3390/mi12111354 - 31 Oct 2021

Cited by 6 | Viewed by 1773

Abstract

With the development of optoelectronic information technology, high-performance optical systems require an increasingly higher surface accuracy of optical mirrors. The fast tool servo (FTS) based on the piezoelectric actuator is widely used in the compensation machining of high-precision optical mirrors. However, with the [...] Read more.

With the development of optoelectronic information technology, high-performance optical systems require an increasingly higher surface accuracy of optical mirrors. The fast tool servo (FTS) based on the piezoelectric actuator is widely used in the compensation machining of high-precision optical mirrors. However, with the low natural frequency of mechanical structures, hysteresis of the piezoelectric actuators, and phase delay of the control systems, conventional FTS systems face problems such as a low working frequency and a large tracking error. This study presents a method for the design of a high-performance FTS system. First, a flexure hinge servo turret with a high natural frequency was designed through multi-objective optimization and finite element simulations. Subsequently, a composite control algorithm was proposed, targeting the problems of hysteresis and phase delay. The modified Prandtl–Ishlinskii inverse hysteresis model was used to overcome the hysteresis effect and a zero-phase error tracker was designed to reduce the phase error. The experimental results reveal that the tracking error of the designed FTS system was <10% in the full frequency range (0–1000 Hz). Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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15 pages, 2338 KiB

Open AccessReview

Recent Advances In Silicon Carbide Chemical Mechanical Polishing Technologies

by Chi-Hsiang Hsieh, Che-Yuan Chang, Yi-Kai Hsiao, Chao-Chang A. Chen, Chang-Ching Tu and Hao-Chung Kuo

Micromachines 2022, 13(10), 1752; https://doi.org/10.3390/mi13101752 - 16 Oct 2022

Cited by 30 | Viewed by 9755

Abstract

Chemical mechanical polishing (CMP) is a well-known technology that can produce surfaces with outstanding global planarization without subsurface damage. A good CMP process for Silicon Carbide (SiC) requires a balanced interaction between SiC surface oxidation and the oxide layer removal. The oxidants in [...] Read more.

Chemical mechanical polishing (CMP) is a well-known technology that can produce surfaces with outstanding global planarization without subsurface damage. A good CMP process for Silicon Carbide (SiC) requires a balanced interaction between SiC surface oxidation and the oxide layer removal. The oxidants in the CMP slurry control the surface oxidation efficiency, while the polishing mechanical force comes from the abrasive particles in the CMP slurry and the pad asperity, which is attributed to the unique pad structure and diamond conditioning. To date, to obtain a high-quality as-CMP SiC wafer, the material removal rate (MRR) of SiC is only a few micrometers per hour, which leads to significantly high operation costs. In comparison, conventional Si CMP has the MRR of a few micrometers per minute. To increase the MRR, improving the oxidation efficiency of SiC is essential. The higher oxidation efficiency enables the higher mechanical forces, leading to a higher MRR with better surface quality. However, the disparity on the Si-face and C-face surfaces of 4H- or 6H-SiC wafers greatly increases the CMP design complexity. On the other hand, integrating hybrid energies into the CMP system has proven to be an effective approach to enhance oxidation efficiency. In this review paper, the SiC wafering steps and their purposes are discussed. A comparison among the three configurations of SiC CMP currently used in the industry is made. Moreover, recent advances in CMP and hybrid CMP technologies, such as Tribo-CMP, electro-CMP (ECMP), Fenton-ECMP, ultrasonic-ECMP, photocatalytic CMP (PCMP), sulfate-PCMP, gas-PCMP and Fenton-PCMP are reviewed, with emphasis on their oxidation behaviors and polishing performance. Finally, we raise the importance of post-CMP cleaning and make a summary of the various SiC CMP technologies discussed in this work. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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20 pages, 5310 KiB

Open AccessReview

Progress in the Preparation and Characterization of Convex Blazed Gratings for Hyper-Spectral Imaging Spectrometer: A Review

by Huang Li, Xiaoqiang Peng, Chaoliang Guan and Hao Hu

Micromachines 2022, 13(10), 1689; https://doi.org/10.3390/mi13101689 - 7 Oct 2022

Cited by 9 | Viewed by 3755

Abstract

Convex blazed gratings, which can effectively broaden the spectral range and improve spectral resolution, have gradually evolved into a crucial optical component for lightweight and compact imaging spectroscopy instruments. Their design, processing, and testing involve multidisciplinary interdisciplinary scientific issues, and they continue to [...] Read more.

Convex blazed gratings, which can effectively broaden the spectral range and improve spectral resolution, have gradually evolved into a crucial optical component for lightweight and compact imaging spectroscopy instruments. Their design, processing, and testing involve multidisciplinary interdisciplinary scientific issues, and they continue to be a major area of research in imaging optics applications. This paper summarizes the effects of various grating groove shapes and structural parameters on the spectral range and diffraction efficiency of convex blazed gratings, after providing a brief introduction to the typical functions and applications of convex blazed gratings. Firstly, the latest progress in typical processing methods for convex blazed gratings is reviewed. It focuses on the current fabrication processes and reviews their capabilities in creating convex blazed gratings from three main types of technologies, namely ultra-precision machining, high-energy density beam processing, and chemically assisted fabrication processes. Secondly, the adaptability of the manufacturing process for convex blazed gratings on different scales is summarized, analyzing the adaptation of current procedures to various grating fabrication scales and their bottlenecks. Finally, the characterization methods and future feasible characterization methods for convex blazed gratings are reviewed. The development trend of efficient and precise preparation of convex blazed gratings is pointed out. Full article

(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology)

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