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Editorial

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2 pages, 159 KiB

Open AccessEditorial

Editorial for the Special Issue on Ultra Precision Technologies for Micromachining, Volume II

by Yukui Cai, Xichun Luo, Jining Sun and Wenlong Chang

Micromachines 2022, 13(11), 1975; https://doi.org/10.3390/mi13111975 - 15 Nov 2022

Viewed by 1101

Abstract

With the increasing demand for ultra-high-precision products and micro-products in fields such as aerospace, national defense, military, transportation, and people’s livelihoods, it has become an important development trend in the field of machining to realize ultra-high-precision machining and miniaturization with a higher level [...] Read more.

With the increasing demand for ultra-high-precision products and micro-products in fields such as aerospace, national defense, military, transportation, and people’s livelihoods, it has become an important development trend in the field of machining to realize ultra-high-precision machining and miniaturization with a higher level and higher quality [...] Full article

(This article belongs to the Special Issue Ultra Precision Technologies for Micromachining, Volume II)

Research

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16 pages, 4443 KiB

Open AccessArticle

Determination of the Efficiency of Hot Nano-Grinding of Mono-Crystalline Fcc Metals Using Molecular Dynamics Method

by Nikolaos E. Karkalos and Angelos P. Markopoulos

Micromachines 2022, 13(3), 415; https://doi.org/10.3390/mi13030415 - 06 Mar 2022

Cited by 5 | Viewed by 2055

Abstract

Abrasive processes are essential to the manufacturing field, due to their capability of rendering high-quality surfaces with minimum effect on workpiece integrity. As it is especially difficult to perform sufficient experimental work, numerical studies can be successfully employed to evaluate techniques for the [...] Read more.

Abrasive processes are essential to the manufacturing field, due to their capability of rendering high-quality surfaces with minimum effect on workpiece integrity. As it is especially difficult to perform sufficient experimental work, numerical studies can be successfully employed to evaluate techniques for the improvement of the efficiency of nanometric abrasive processes. In the present study, for the first time, cases of nanogrinding on workpieces of three different fcc metals, namely, copper, nickel, and aluminum are investigated under different preheating temperatures, in order to determine the efficiency of the hot nano-grinding technique. For the simulations, a molecular dynamics model for peripheral nanogrinding is developed including multiple abrasive grains and realistic grain trajectory and grinding forces, and chip characteristics and subsurface alterations are evaluated. The results indicate that using elevated preheating temperatures is beneficial for nanogrinding, as forces can be considerably reduced and material removal can be facilitated, especially for temperatures over 40% of the material melting temperature (T_m). However, the detrimental effect on workpiece integrity is also evident at higher preheating temperatures, due to the high temperature on the whole workpiece, posing limitations to the applicability of the hot nano-grinding technique. Based on the findings of this study, preheating temperatures in the range of 0.4–0.55 T_m are recommended. Full article

(This article belongs to the Special Issue Ultra Precision Technologies for Micromachining, Volume II)

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13 pages, 7457 KiB

Open AccessArticle

Optimal Controller Design for Ultra-Precision Fast-Actuation Cutting Systems

by Fei Ding, Xichun Luo, Duo Li, Zheng Qiao and Bo Wang

Micromachines 2022, 13(1), 33; https://doi.org/10.3390/mi13010033 - 27 Dec 2021

Cited by 3 | Viewed by 2006

Abstract

Fast-actuation cutting systems are in high demand for machining of freeform optical parts. Design of such motion systems requires good balance between structural hardware and controller design. However, the controller tuning process is mostly based on human experience, and it is not feasible [...] Read more.

Fast-actuation cutting systems are in high demand for machining of freeform optical parts. Design of such motion systems requires good balance between structural hardware and controller design. However, the controller tuning process is mostly based on human experience, and it is not feasible to predict positioning performance during the design stage. In this paper, a deterministic controller design approach is adopted to preclude the uncertainty associated with controller tuning, which results in a control law minimizing positioning errors based on plant and disturbance models. Then, the influences of mechanical parameters such as mass, damping, and stiffness are revealed within the closed-loop framework. The positioning error was reduced from 1.19 nm RMS to 0.68 nm RMS with the new controller. Under the measured disturbance conditions, the optimal bearing stiffness and damping coefficient are

1.1 \times 10^{5} N / m

and

237.7 N / (m \cdot s^{- 1})

, respectively. We also found that greater moving inertia helps to reduce all disturbances at high frequencies, in agreement with the positioning experiments. A quantitative understanding of how plant structural parameters affect positioning stability is thus shown in this paper. This is helpful for the understanding of how to reduce error sources from the design point of view. Full article

(This article belongs to the Special Issue Ultra Precision Technologies for Micromachining, Volume II)

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16 pages, 41640 KiB

Open AccessArticle

Positioning Performance of a Sub-Arc-Second Micro-Drive Rotary System

by Manzhi Yang, Zhenyang Lv, Chuanwei Zhang, Yizhi Yang, Gang Jing, Wei Guo, Zhengxiong Lu, Yumei Huang, Kaiyang Wei, Linyue Li, Bin Feng and Hongyu Ge

Micromachines 2021, 12(9), 1063; https://doi.org/10.3390/mi12091063 - 31 Aug 2021

Cited by 5 | Viewed by 2080

Abstract

In the macro/micro dual-drive rotary system, the micro-drive system compensates for the position error of the macro-drive system. To realize the sub-arc-second (i.e., level of 1″–0.1″) positioning of the macro/micro dual-drive rotary system, it is necessary to study the positioning performance of the [...] Read more.

In the macro/micro dual-drive rotary system, the micro-drive system compensates for the position error of the macro-drive system. To realize the sub-arc-second (i.e., level of 1″–0.1″) positioning of the macro/micro dual-drive rotary system, it is necessary to study the positioning performance of the sub-arc-second micro-drive rotary system. In this paper, we designed a sub-arc-second micro-drive rotary system consisting of a PZT (piezoelectric actuator) and a micro rotary mechanism, and used simulation and experimental methods to study the positioning performance of the system. First, the micro-drive rotary system was developed to provide ultra-precise rotary motion. In this system, the PZT has ultrahigh resolution at a level of 0.1 nanometers in linear motion; a micro rotating mechanism was designed according to the composite motion principle of the flexible hinge, which could transform the linear motion of piezoelectric ceramics into rotating motion accurately. Second, the drive performance was analyzed based on the drive performance experiment. Third, kinematics, simulation, and experiments were carried out to analyze the transformation performance of the system. Finally, the positioning performance equation of the system was established based on the two performance equations, and the maximum rotary displacements and positioning error of the system were calculated. The study results showed that the system can provide precision motion at the sub-arc-second and good linearity of motion. This study has a certain reference value in ultra-precision positioning and micromachining for research on rotary motion systems at the sub-arc-second level. Full article

(This article belongs to the Special Issue Ultra Precision Technologies for Micromachining, Volume II)

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12 pages, 15361 KiB

Open AccessArticle

Investigation on the Exit Burr Formation in Micro Milling

by Zhongwei Chen, Xian Wu, Kai Zeng, Jianyun Shen, Feng Jiang, Zhongyuan Liu and Wenjun Luo

Micromachines 2021, 12(8), 952; https://doi.org/10.3390/mi12080952 - 12 Aug 2021

Cited by 8 | Viewed by 2689

Abstract

The burr on micro part has harmful effect on the dimensional accuracy and service performance. The original control of exit burr formation during micro milling is desirable and advisable. In this paper, the formation mechanism of exit burr was studied based on the [...] Read more.

The burr on micro part has harmful effect on the dimensional accuracy and service performance. The original control of exit burr formation during micro milling is desirable and advisable. In this paper, the formation mechanism of exit burr was studied based on the varying cutting direction during micro milling. Three exit burr control strategies were concluded, the material properties embrittlement, the support stiffness increasing and machining parameter optimizing operations. Then, micro milling experiments were carried out to investigate the exit burr morphology and size. It was found that the exit burr formation was attributed to the change of material flowing path at the exit surface, which was caused by the negative shear deformation zone that was induced by the discontinuous shape features. Different exit burr morphologies were classified; the triangle exit burr type was caused by the varying exit burr growing direction along the exit surface. The optimal machining parameters in micro milling to obtain a small exit burr were suggested. Full article

(This article belongs to the Special Issue Ultra Precision Technologies for Micromachining, Volume II)

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10 pages, 3817 KiB

Open AccessArticle

Kuhn–Munkres Algorithm-Based Matching Method and Automatic Device for Tiny Magnetic Steel Pair

by Zheng Xu, Guo-zhao Yuan, Xiao-dong Wang, Xian-shuai Quan, Tong-qun Ren and Jun-shan Liu

Micromachines 2021, 12(3), 316; https://doi.org/10.3390/mi12030316 - 18 Mar 2021

Cited by 4 | Viewed by 1908

Abstract

The tiny magnetic steel pair (TMSP), composed by two tiny magnetic steel blocks (TMSBs), is critical for some precision instruments. Incorrect matching of TMSP may result in insufficient instrument performance. Herein, the matching method of TMSP based on the Kuhn–Munkres algorithm is proposed. [...] Read more.

The tiny magnetic steel pair (TMSP), composed by two tiny magnetic steel blocks (TMSBs), is critical for some precision instruments. Incorrect matching of TMSP may result in insufficient instrument performance. Herein, the matching method of TMSP based on the Kuhn–Munkres algorithm is proposed. Further, an automatic TMSP matching device is developed. Especially, an ingenious clamp for multiple constraints of TMSB is presented and a visual/magnetism/force hybrid control strategy is realized for the safe and efficient manipulation of TMSBs in a magnetic environment. Moreover, with the TMSBs of a pendulum accelerometer, the matching experiments are conducted to validate the comprehensive performance. The result of the numerical experiment shows that the Kuhn–Munkres algorithm-based method is stable and efficient. The results of measurement and TMSP matching experiments show that the device has good repeatability (<1 mT) and practicability. The proposed matching method has great application prospect in various matching and microassembly of TMSPs. Full article

(This article belongs to the Special Issue Ultra Precision Technologies for Micromachining, Volume II)

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25 pages, 19129 KiB

Open AccessArticle

Effect of KDP-Crystal Material Properties on Surface Morphology in Ultra-Precision Fly Cutting

by Dongju Chen, Shupei Li and Jinwei Fan

Micromachines 2020, 11(9), 802; https://doi.org/10.3390/mi11090802 - 25 Aug 2020

Cited by 5 | Viewed by 3018

Abstract

To study the effect of material properties on the surface morphology of potassium dihydrogen phosphate (KDP) crystals, an ultra-precision fly cutting machine tool with a single-point diamond tool was used to perform a cutting experiment on (100) crystal plane of the KDP crystal. [...] Read more.

To study the effect of material properties on the surface morphology of potassium dihydrogen phosphate (KDP) crystals, an ultra-precision fly cutting machine tool with a single-point diamond tool was used to perform a cutting experiment on (100) crystal plane of the KDP crystal. The elastic modulus, shear modulus, hardness, and dislocation of KDP crystals are taken into the cutting force model by introducing the strain gradient plasticity theory. Since the size effect and dynamic response will affect the surface roughness during ultra-precision machining, the surface roughness of workpieces in ultra-precision fly cutting is hard to predict. Based on the previously established strain gradient plasticity theoretical model, cutting force model, and the dynamic characteristics of the ultra-precision fly cutting system, a surface morphology prediction model under the influence of KDP crystal material properties was established. Finally, the accuracy of the surface morphology prediction model was verified by ultra-precision fly cutting experiments, and identified the frequency range of the characteristic signal caused by the anisotropy of the KDP crystal from the frequency, thereby verifying the KDP crystal material properties has a significant effect on the surface of the machined workpiece roughness. Full article

(This article belongs to the Special Issue Ultra Precision Technologies for Micromachining, Volume II)

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Review

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32 pages, 10694 KiB

Open AccessReview

Scanning Probe Lithography: State-of-the-Art and Future Perspectives

by Pengfei Fan, Jian Gao, Hui Mao, Yanquan Geng, Yongda Yan, Yuzhang Wang, Saurav Goel and Xichun Luo

Micromachines 2022, 13(2), 228; https://doi.org/10.3390/mi13020228 - 29 Jan 2022

Cited by 22 | Viewed by 5755

Abstract

High-throughput and high-accuracy nanofabrication methods are required for the ever-increasing demand for nanoelectronics, high-density data storage devices, nanophotonics, quantum computing, molecular circuitry, and scaffolds in bioengineering used for cell proliferation applications. The scanning probe lithography (SPL) nanofabrication technique is a critical nanofabrication method [...] Read more.

High-throughput and high-accuracy nanofabrication methods are required for the ever-increasing demand for nanoelectronics, high-density data storage devices, nanophotonics, quantum computing, molecular circuitry, and scaffolds in bioengineering used for cell proliferation applications. The scanning probe lithography (SPL) nanofabrication technique is a critical nanofabrication method with great potential to evolve into a disruptive atomic-scale fabrication technology to meet these demands. Through this timely review, we aspire to provide an overview of the SPL fabrication mechanism and the state-the-art research in this area, and detail the applications and characteristics of this technique, including the effects of thermal aspects and chemical aspects, and the influence of electric and magnetic fields in governing the mechanics of the functionalized tip interacting with the substrate during SPL. Alongside this, the review also sheds light on comparing various fabrication capabilities, throughput, and attainable resolution. Finally, the paper alludes to the fact that a majority of the reported literature suggests that SPL has yet to achieve its full commercial potential and is currently largely a laboratory-based nanofabrication technique used for prototyping of nanostructures and nanodevices. Full article

(This article belongs to the Special Issue Ultra Precision Technologies for Micromachining, Volume II)

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