Ultraprecision Machining Technology—Manufacture and Metrology of Structured and Freeform Surfaces for Functional Applications

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "D:Materials and Processing".

Deadline for manuscript submissions: closed (30 September 2017) | Viewed by 32016

Special Issue Editors


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State Key Laboratory of Ultra-Precision Machining Technology, Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
Interests: precision engineering; ultra-precision machining technology; precision metrology
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Partner State Key Laboratory of Ultraprecision Machining Technology, Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong
Interests: advanced materials processing; ultraprecision machining; manufacturing strategy
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Structured and freeform surfaces with functional characteristics have been widely used in many mission-critical applications, such as advanced optics, aerospace, automotive, telecommunications, biomedical, and micro-fluidics. These surfaces have non-rotational symmetry with sub-micrometre form accuracy and nanometric surface finishing. Due to their geometrical complexity and high precision requirements, this leads to numerous research challenges in different fields including ultraprecision machining technologies, cutting mechanics, surface generation mechanisms, novel machine design, accurate control of the machining process through modelling and simulation of ultraprecision machining processes, error compensation, freeform measurement and on-machine metrology. This Special Issue aims to provide a good collection of the latest research results and findings in design, ultraprecision machining and measurement of structured and freeform surfaces and their functional characteristics. This Special Issue will also contain selected papers from the Asian Society for Precision Engineering and Nanotechnology (ASPEN)/American Society for Precision Engineering (ASPE) Spring Topical Meeting 2017 on Manufacture and Metrology of Structured and Freeform Surfaces for Functional Applications (http://www.aspen-aspe2017-topical.com/index.php) which will be held from 14–17 March 2017, in Hong Kong, China.

Prof. Dr. Benny C.F. Cheung
Prof. Dr. W.B. Lee
Guest Editors

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Keywords

  • Structured surfaces

  • Freeform surfaces

  • Ultraprecision machining

  • Machine design

  • Precision manufacturing

  • Cutting mechanics

  • Surface generation mechanisms

  • Measurement and characterization of structured and freeform surfaces

  • Precision metrology

  • Modelling and simulation

  • Advanced manufacturing technology

Published Papers (7 papers)

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Research

10 pages, 4362 KiB  
Article
Fiducial-Aided Robust Positioning of Optical Freeform Surfaces
by Shixiang Wang, Chi Fai Cheung, Mingjun Ren and Mingyu Liu
Micromachines 2018, 9(2), 52; https://doi.org/10.3390/mi9020052 - 30 Jan 2018
Cited by 5 | Viewed by 3682
Abstract
Form characterization of a machined optical freeform surface demands accurate alignment of the sampled measured data points on the machined surface, and they are compared with the designed geometry of the surface through positioning. In this paper, a fiducial-aided robust positioning method (FAPM) [...] Read more.
Form characterization of a machined optical freeform surface demands accurate alignment of the sampled measured data points on the machined surface, and they are compared with the designed geometry of the surface through positioning. In this paper, a fiducial-aided robust positioning method (FAPM) is developed which attempts to evaluate freeform surfaces with high efficiency and precision. The FAPM method makes use of fiducials as reference datum to form a fiducial-aided computer-aided design (FA-CAD) of the freeform surface which not only establishes an inherent surface feature, but also links the different coordinate systems among design coordinate frame, machine tool, and measurement instrument. To verify the capability of the proposed method, a series of experiments were conducted. Compared with the traditional freeform measurement method (e.g., least squares method), the results indicate that the robustness and accuracy of the measurement is significantly enhanced by the FAPM. Full article
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17 pages, 4838 KiB  
Article
A Study of Mechanics in Brittle–Ductile Cutting Mode Transition
by Gaobo Xiao, Mingjun Ren and Suet To
Micromachines 2018, 9(2), 49; https://doi.org/10.3390/mi9020049 - 29 Jan 2018
Cited by 24 | Viewed by 5433
Abstract
This paper presents an investigation of the mechanism of the brittle–ductile cutting mode transition from the perspective of the mechanics. A mechanistic model is proposed to analyze the relationship between undeformed chip thickness, deformation, and stress levels in the elastic stage of the [...] Read more.
This paper presents an investigation of the mechanism of the brittle–ductile cutting mode transition from the perspective of the mechanics. A mechanistic model is proposed to analyze the relationship between undeformed chip thickness, deformation, and stress levels in the elastic stage of the periodic chip formation process, regarding whether brittle or ductile mode deformation is to follow the elastic stage. It is revealed that, the distance of tool advancement required to induce the same level of compressive stress decreases with undeformed chip thickness, and thereby the tensile stress below and behind the tool decreases with undeformed chip thickness. As a result, the tensile stress becomes lower than the critical tensile stress for brittle fracture when the undeformed chip thickness becomes sufficiently small, enabling the brittle–ductile cutting mode transition. The finite element method is employed to verify the analysis of the mechanics on a typical brittle material 6H silicon carbide, and confirmed that the distance of the tool advancement required to induce the same level of compressive stress becomes smaller when the undeformed chip thickness decreases, and consequently smaller tensile stress is induced below and behind the tool. The critical undeformed chip thicknesses for brittle–ductile cutting mode transition are estimated according to the proposed mechanics, and are verified by plunge cutting experiments in a few crystal directions. This study should contribute to better understanding of the mechanism of brittle–ductile cutting mode transition and the ultra-precision machining of brittle materials. Full article
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6742 KiB  
Article
Modeling and Simulation of a Machining Process Chain for the Precision Manufacture of Polar Microstructure
by Chenyang Zhao, Chi Fai Cheung and Mingyu Liu
Micromachines 2017, 8(12), 345; https://doi.org/10.3390/mi8120345 - 27 Nov 2017
Cited by 13 | Viewed by 4478
Abstract
This paper presents a functional microstructured surface, named Polar Microstructure. Polar microstructure is a three dimensional (3D) structured surface possessing a pattern of distribution of latitude and longitude micro-topographies with geometrical characteristics, which is similar to that in the Earth’s north or south [...] Read more.
This paper presents a functional microstructured surface, named Polar Microstructure. Polar microstructure is a three dimensional (3D) structured surface possessing a pattern of distribution of latitude and longitude micro-topographies with geometrical characteristics, which is similar to that in the Earth’s north or south pole. The spacing of its small surface features can achieve form accuracy at the micrometer level. Polar microstructure has great potential for applications in precision measurement of angle displacement based on the characteristics of its surface features. This paper presents the development of a machining process chain system that integrates single point diamond turning (SPDT) and diamond broaching together to fabricate polar microstructure. A framework of a machining process chain system is presented which is composed of input module, design module, simulation module, output module, and metrology module. After that, modeling of the machining process chain composed of SPDT and diamond broaching is built up. The model takes into consideration the initial surface topography of the workpiece. Simulations have been conducted to obtain the optimal machining parameters in each machining process. A series of experiments was conducted for the ultra-precision machining of various types of polar microstructures. The machining results show that the machining process chain system is technically feasible and effective in the precision manufacturing of polar microstructure. The experimental results agree well with the simulated results. Full article
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3606 KiB  
Article
Thin-Walled Double Side Freeform Component Milling Process with Paraffin Filling Method
by Jun Zha, Jing Chu, Yipeng Li and Yaolong Chen
Micromachines 2017, 8(11), 332; https://doi.org/10.3390/mi8110332 - 21 Nov 2017
Cited by 6 | Viewed by 3354
Abstract
The machining of thin-walled double side freeform component has many challenges in terms of the geometrical complexity, high-requirement accuracy, and especially low stiffness. This paper surveys the filling method during the milling processes of thin-walled double side freeform component. Firstly, the DEFORM-3D was [...] Read more.
The machining of thin-walled double side freeform component has many challenges in terms of the geometrical complexity, high-requirement accuracy, and especially low stiffness. This paper surveys the filling method during the milling processes of thin-walled double side freeform component. Firstly, the DEFORM-3D was used to analyze and calculate the surface residual stress which provides a theoretical basis for parameters selection of the rough milling process, and the optimal milling parameters were obtained by the Taguchi method. Residual stress measurements have been carried out to verify the simulation results. The results show the difference between simulation and experimental data is less than 15%. Secondly, semi-finishing parameters and finishing process parameters were determined by equal error step length and step distance method. Thirdly, two machining experiments were conducted with and without paraffin filling, and the accuracy was measured by coordinate measurement machine. The results shown that the PV values are 25.16 μm and 20.34 μm for the concave and convex surface, and the corresponding RMS values are 13.75 μm and 11.93 μm in the first milling experiment. The PV values have improved to 8.53 μm and 7.12 μm, and RMS values have improved to 2.45 μm and 3.05 μm by the filled method applied. Full article
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14450 KiB  
Article
Fabrication of Hexagonal Microlens Arrays on Single-Crystal Silicon Using the Tool-Servo Driven Segment Turning Method
by Mao Mukaida and Jiwang Yan
Micromachines 2017, 8(11), 323; https://doi.org/10.3390/mi8110323 - 30 Oct 2017
Cited by 36 | Viewed by 6326
Abstract
Single-crystal silicon microlens arrays are increasingly required in advanced infrared optics. In this study, the authors attempted to fabricate hexagonal microlens arrays, which offer high optical efficiency, on a single-crystal silicon wafer using diamond turning. A tool-servo driven segment turning method was proposed [...] Read more.
Single-crystal silicon microlens arrays are increasingly required in advanced infrared optics. In this study, the authors attempted to fabricate hexagonal microlens arrays, which offer high optical efficiency, on a single-crystal silicon wafer using diamond turning. A tool-servo driven segment turning method was proposed to reduce the dynamic error of the machine tool induced by lenslet edges during lens array cutting. From the results of both cutting experiments and theoretical analysis of the machine tool dynamic error, it was demonstrated that the segment turning method reduced significantly the dynamic errors and led to high form accuracy. As a result, sharp edges among the lenslets were generated precisely and microlens arrays with a form error of ~300 nm peak-to-valley and surface roughness of ~5 nmSa, which meets the requirements of infrared optical systems, were successfully fabricated. The subsurface damage, such as the amorphization of silicon, caused by machining was also reduced. Full article
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2730 KiB  
Article
Investigation of Production Limits in Manufacturing Microstructured Surfaces Using Micro Coining
by Michael Zahner, Lukas Lentz, Felix Steinlein and Marion Merklein
Micromachines 2017, 8(11), 322; https://doi.org/10.3390/mi8110322 - 30 Oct 2017
Cited by 5 | Viewed by 3509
Abstract
The application of microstructured surfaces is one possible method to reduce friction in lubricated contacts between components with relative movement. Due to this, the energy efficiency and the occurring wear during the operating time of the final products could be decreased. To manufacture [...] Read more.
The application of microstructured surfaces is one possible method to reduce friction in lubricated contacts between components with relative movement. Due to this, the energy efficiency and the occurring wear during the operating time of the final products could be decreased. To manufacture structured surfaces economically, a micro coining process was analyzed within this study. This process offers the potential for integration into the established manufacturing processes of different final products, such as tappets used in a valve train. Thus, large-scale production is enabled. To detect the manufacturing limits of the micro coining process, the manufacturing of the coining tools as well as the coining process needs to be investigated. Within this study, the achievable accuracy and the failure of cuboid and cylindrical microstructure elements with selected dimensions were analyzed. For both types of microstructures, the minimal lateral dimensions were detected. Besides the achievable accuracy, correlations between different geometrical dimensions of the micro elements are presented. Additionally, the aspect ratio is detected as the main cause of failure for the micro coining process. In general, the suitability of a coining process for manufacturing microstructured surfaces is proven. Full article
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8399 KiB  
Article
Study on Ti-6Al-4V Alloy Machining Applying the Non-Resonant Three-Dimensional Elliptical Vibration Cutting
by Mingming Lu, Jiakang Zhou, Jieqiong Lin, Yan Gu, Jinguo Han and Dongpo Zhao
Micromachines 2017, 8(10), 306; https://doi.org/10.3390/mi8100306 - 13 Oct 2017
Cited by 30 | Viewed by 4546
Abstract
The poor machinability of Ti-6Al-4V alloy makes it hard to process by conventional processing methods even though it has been widely used in military and civilian enterprise fields. Non-resonant three-dimensional elliptical vibration cutting (3D-EVC) is a novel cutting technique which is a significant [...] Read more.
The poor machinability of Ti-6Al-4V alloy makes it hard to process by conventional processing methods even though it has been widely used in military and civilian enterprise fields. Non-resonant three-dimensional elliptical vibration cutting (3D-EVC) is a novel cutting technique which is a significant development potential for difficult-to-cut materials. However, few studies have been conducted on processing the Ti-6Al-4V alloy using the non-resonant 3D-EVC technique, the effect of surface quality, roughness, topography and freeform surface has not been clearly researched yet. Therefore, the machinability of Ti-6Al-4V alloy using the non-resonant 3D-EVC apparatus is studied in this paper. Firstly, the principle of non-resonant 3D-EVC technique and the model of cutter motion are introduced. Then the tool path is synthesized. The comparison experiments are carried out with traditional continuous cutting (TCC), two-dimension elliptical vibration cutting (2D-EVC), and the non-resonant 3D-EVC method. The experimental results shown that the excellent surface and lower roughness (77.3 nm) could be obtained using the non-resonant 3D-EVC method; the shape and dimension of elliptical cutting mark also relates to the cutting speed and vibration frequency, and the concave/convex spherical surface topography are achieved by non-resonant 3D-EVC in the Ti-6Al-4V alloy. This proved that the non-resonant 3D-EVC technique has the better machinability compared with the TCC and 2D-EVC methods. Full article
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