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Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials
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Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Manufacturing Processes and Systems".

Deadline for manuscript submissions: closed (10 December 2022) | Viewed by 40120

Special Issue Editors

Prof. Dr. Mingjun Chen

E-Mail Website
Guest Editor
1. State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150001, China
2. School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China
Interests: ultra-precision machining technology and process equipment; micro/nano manufacturing technology and application; optical-component surface defect detection and control/repair technology
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Jian Cheng

E-Mail Website
Guest Editor
1. State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150001, China
2. School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China
Interests: precision/ultra-precision processing technology; optical (sub)surface defect detection and integrity evaluation; laser-induced damage mechanism and precision mitigation
Special Issues, Collections and Topics in MDPI journals
Dr. Qi Liu

E-Mail Website
Guest Editor
Centre for Precision Manufacturing, Department of Design, Manufacturing and Engineering Management, University of Strathclyde, Glasgow G1 1XQ, UK
Interests: ultra-precision machining; micro/nano fabrication; advanced manufacturing technology and equipment; surface integrity evaluation; digital twin
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Xichun Luo

E-Mail Website
Guest Editor
Centre for Precision Manufacturing, Department of Design, Manufacturing and Engineering Management, University of Strathclyde, Glasgow G1 1XJ, UK
Interests: ultra-precision machining; hybrid micromachining; nanofabrication; digital manufacturing
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Ultra-precision manufacturing technology is primarily used to generate high quality and functional components usually made from difficult-to-machine materials (e. g., hard-brittle glasses, soft-brittle KDP crystals, or single-crystal silicon). The objective of ultra-precision manufacturing is to generate high-value-added parts with high surface finish, high form accuracy and surface integrity for the optical, electronic, aerospace, biomedical applications, etc. However, with the rapid development of the cutting-edge technology, ultra-precision manufacturing is also facing two important challenges: (i) the surface roughness and geometric features/patterns of the processed components have approached nanometer and submicron scales, respectively, requiring even higher precision machine tool equipment and technology; (ii) Due to the difficult-to-cut attributions  of the workpiece materials (e.g., hardness, brittleness, viscosity, low thermal conductivity), some undesired features (such as micro cracks, grinding marks, subsurface damage, residual stress) are prone to engage into the machined surfaces, causing a negative impact on the application performance and service life. Hence, it is essential to, on the one hand, develop more specific and dedicated ultra-precision manufacturing machine tool and technology; and, on the other hand, gain more insight into the underlying relationship between the manufacturing process and surface integrity as well as the application performance.

Therefore, the objective of this Special Issue is the publication of original research and review articles in the field of ultra-precision manufacturing technology and the machined-surface performance evaluation. Suitable topics include but are not limited to the following:

  • Design of Ultra-precision manufacturing equipment and cutting tools;
  • Development of Ultra-precision manufacturing technologies, such as cutting/milling/grinding/polishing;
  • Micromachining mechanics, applications, and challenges;
  • Nano/ Micro fabrication technologies (i.e., laser, FIB, EDM, AFM) ;
  • Assisted machining technologies such as ultrasonic-assisted machining (UAM), vibration assisted machining (VAM), laser-assisted machining (LAM) etc.;
  • Understanding of the fundamental material manufacturing mechanism and machining processes;
  • Analysis of the machined surface integrity;
  • Performance evaluation of the processed functional components.

Prof. Dr. Mingjun Chen
Prof. Dr. Jian Cheng
Dr. Qi Liu
Prof. Dr. Xichun Luo
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • ultra-precision machining technologies: cutting/milling/grinding/polishing
  • ultra-precision machine equipment design and assembly
  • ultra-precision measurement
  • micro-nano machining
  • laser machining
  • electrical discharge machining
  • ultrasonic assisted machining
  • abrasive jet machining
  • surface generation mechanism
  • surface integrity evaluation
  • functional surface performance evaluation

Published Papers (17 papers)

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Editorial

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3 pages, 160 KiB  
Editorial
Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials
by Qi Liu, Mingjun Chen, Jian Cheng and Xichun Luo
Materials 2023, 16(12), 4322; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16124322 - 11 Jun 2023
Viewed by 1503
Abstract
Ultra-precision manufacturing requires superior components with an impeccable surface finish and accuracy [...] Full article
(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials)

Research

Jump to: Editorial, Review

15 pages, 6068 KiB  
Article
Fractal Analysis on Machined Surface Morphologies of Soft-Brittle KDP Crystals Processed by Micro Ball-End Milling
by Qi Liu, Jian Cheng, Zhirong Liao, Mingyu Liu, Mingjun Chen, Linjie Zhao, Hongqin Lei and Wenyu Ding
Materials 2023, 16(5), 1782; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16051782 - 21 Feb 2023
Cited by 3 | Viewed by 1288
Abstract
The micro-defects on KH2PO4 (KDP) optic surfaces are mainly repaired by the micro-milling technique, while it is very easy to introduce brittle cracks on repaired surfaces, as KDP is soft and brittle. To estimate machined surface morphologies, the conventional method [...] Read more.
The micro-defects on KH2PO4 (KDP) optic surfaces are mainly repaired by the micro-milling technique, while it is very easy to introduce brittle cracks on repaired surfaces, as KDP is soft and brittle. To estimate machined surface morphologies, the conventional method is surface roughness, but it fails to distinguish ductile-regime machining from brittle-regime machining directly. To achieve this objective, it is of great significance to explore new evaluation methods to further characterize machined surface morphologies. In this study, the fractal dimension (FD) was introduced to characterize the surface morphologies of soft-brittle KDP crystals machined by micro bell-end milling. The 3D and 2D fractal dimensions of the machined surfaces and their typical cross-sectional contours have been calculated, respectively, based on Box-counting methods, and were further discussed comprehensively by combining the analysis of surface quality and textures. The 3D FD is identified to have a negative correlation with surface roughness (Sa and Sq), meaning the worse the surface quality the smaller the FD. The circumferential 2D FD could quantitively characterize the anisotropy of micro-milled surfaces, which could not be analyzed by surface roughness. Normally, there is obvious symmetry of 2D FD and anisotropy on the micro ball-end milled surfaces generated by ductile-regime machining. However, once the 2D FD is distributed asymmetrically and the anisotropy becomes weaker, the assessed surface contours would be occupied by brittle cracks and fractures, and corresponding machining processes will be in a brittle regime. This fractal analysis would facilitate the accurate and efficient evaluation of the repaired KDP optics by micro-milling. Full article
(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials)
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17 pages, 3406 KiB  
Article
Structural and Functional Picosecond Laser Modification of the Nimonic 263 Superalloy in Different Environmental Conditions and Optimization of the Irradiation Process
by Boris Rajčić, Tatjana Šibalija, Vladimir Nikolić, Miha Čekada, Jelena Savović, Sanja Petronić and Dubravka Milovanović
Materials 2023, 16(3), 1021; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16031021 - 22 Jan 2023
Cited by 2 | Viewed by 1515
Abstract
In this experimental study, picosecond laser treatment was performed on a nickel-based superalloy Nimonic 263, aiming to investigate the surface effects induced by irradiation in different atmospheric conditions and, concerning changes in surface composition, regarding the possibility for improvement of its functionality. Besides [...] Read more.
In this experimental study, picosecond laser treatment was performed on a nickel-based superalloy Nimonic 263, aiming to investigate the surface effects induced by irradiation in different atmospheric conditions and, concerning changes in surface composition, regarding the possibility for improvement of its functionality. Besides the varying laser parameters, such as a number of pulses and pulse energy, environmental conditions are also varied. All surface modifications were carried out in standard laboratory conditions and a nitrogen- and argon-rich atmosphere. The resulting topography effects depend on the specific laser treatment and could be categorized as increased roughness, crater formation, and formation of the laser-induced periodic surface structures (LIPSS). Changes in the chemical surface composition are distinguished as the potential formation of the protective oxides/nitrides on the sample surface. Numerous characterization techniques analyse the resulting effects on the topography and surface parameters. The multi-response parametric optimization of the picosecond laser process was performed using an advanced statistical method based on Taguchi’s robust parameter design. Finally, the optimal parameter conditions for Nimonic 263 modification are suggested. Full article
(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials)
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12 pages, 3371 KiB  
Article
Investigation of Surface Integrity of Selective Laser Melting Additively Manufactured AlSi10Mg Alloy under Ultrasonic Elliptical Vibration-Assisted Ultra-Precision Cutting
by Rongkai Tan, Xuesen Zhao, Qi Liu, Xianmin Guo, Fengtao Lin, Liquan Yang and Tao Sun
Materials 2022, 15(24), 8910; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15248910 - 13 Dec 2022
Cited by 4 | Viewed by 1283
Abstract
Additive manufacturing technology has been widely used in aviation, aerospace, automobiles and other fields due to the fact that near-net-shaped components with unprecedented geometric freedom can be fabricated. Additively manufactured aluminum alloy has received a lot of attention, due to its excellent material [...] Read more.
Additive manufacturing technology has been widely used in aviation, aerospace, automobiles and other fields due to the fact that near-net-shaped components with unprecedented geometric freedom can be fabricated. Additively manufactured aluminum alloy has received a lot of attention, due to its excellent material properties. However, the finished surface of additively manufactured aluminum alloy with nanoscale surface roughness is quite challenging and rarely addressed. In this paper, a novel machining technology known as ultrasonic elliptical vibration-assisted cutting (UEVC) was adopted to suppress the generation of cracks, improve the surface integrity and reduce tool wear during the ultra-precision machining of selective laser melting (SLM) additively manufactured AlSi10Mg alloy. The experimental results revealed that, in the conventional cutting (CC) process, surface defects, such as particles, pores and grooves, appeared on the machined surface, and the machined surface rapidly deteriorated with the increase in cumulative cutting area. In contrast, an almost flawless machined surface was obtained in the UEVC process, and its roughness value was less than 10 nm. Moreover, the tool wear of the CC tool was remarkably greater than that of the UEVC tool, and the standard flank wear width of the CC tool was more than twice that of the UEVC tool. Therefore, the UEVC technology is considered to be a feasible method for the ultra-precision machining of SLM additively manufactured AlSi10Mg alloy. Full article
(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials)
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17 pages, 6190 KiB  
Article
In-Situ Measurement and Slow-Tool-Servo Compensation Method of Roundness Error of a Precision Mandrel
by Zheng Qiao, Yangong Wu, Wentao Chen, Yuanyuan Jia and Bo Wang
Materials 2022, 15(22), 8037; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15228037 - 14 Nov 2022
Cited by 2 | Viewed by 1546
Abstract
This paper describes a method for measuring and compensating the roundness error of a larger mandrel manufactured by an ultra-precision diamond-turning lathe aimed to obtain a calibration cylinder with a roundness of less than 0.1 μm. The diamond-turning machine has a cross-stacked hydrostatic [...] Read more.
This paper describes a method for measuring and compensating the roundness error of a larger mandrel manufactured by an ultra-precision diamond-turning lathe aimed to obtain a calibration cylinder with a roundness of less than 0.1 μm. The diamond-turning machine has a cross-stacked hydrostatic guideway, produces a cutting depth and feed movement direction, and a dual-spindle system that is firmly connected to the bed. Due to the good repeatability of aerostatic spindles, only in situ rather than online real-time measurements are required. To this end, three high-precision capacitance displacement sensors were utilized to detect the cross-section of the workpiece and the time domain via the three-point error separation technique to separate the roundness error from the rotation motion error. The slow tool servo (STS) cutting technique was employed to compensate for the roundness error, which did not require extra axes, only the excellent dynamic response of the feed axis; hence, the servo control parameters could be suitably adjusted. The experimental results reveal that the low-order harmonic error, often caused by aerostatic spindles, is almost removed completely. For this particular lathe, the experiments indicate that about 60% of the rotational error motion is compensated, and the roundness error is reduced to less than 0.1 μm, which is evaluated by the least-squares circle method. Full article
(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials)
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19 pages, 5922 KiB  
Article
Effect of Pre-Existing Micro-Defects on Cutting Force and Machined Surface Quality Involved in the Ball-End Milling Repairing of Flawed KDP Crystal Surfaces
by Hongqin Lei, Jian Cheng, Dinghuai Yang, Linjie Zhao, Mingjun Chen, Jinghe Wang, Qi Liu, Wenyu Ding and Guang Chen
Materials 2022, 15(21), 7407; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15217407 - 22 Oct 2022
Cited by 7 | Viewed by 1400
Abstract
When serving in extremely high-power laser conditions, KH2PO4 (KDP) surfaces are susceptible to incur laser damage points (also known as defects). Using micro-ball end milling cutters to repair and remove the pre-existing damage points on the flawed KDP crystal surface [...] Read more.
When serving in extremely high-power laser conditions, KH2PO4 (KDP) surfaces are susceptible to incur laser damage points (also known as defects). Using micro-ball end milling cutters to repair and remove the pre-existing damage points on the flawed KDP crystal surface is the most effective method to control the growth of laser damage points on KDP crystal surfaces and prolong their service life. However, there are various forms of micro-defects (such as pits, scratches and brittle fractures) around the laser damage points on KDP crystal surfaces which possess remarkable effects on the micro-milling repair process and consequently deteriorate the repair quality. In this work, combined with nano-indentation experiments, elastic–plastic mechanics and fracture mechanics theory, a constitutive model considering the anisotropic property of KDP crystals and a three-dimensional (3D) finite element model (FEM) were established to simulate the cutting force and surface topography involved in the ball-end milling repairing of flawed KDP crystal surfaces. Besides, the micro-milling experiments were conducted to evaluate the change of cutting force and machined surface quality in the presence of micro-defects with various feed rates. The results show that micro-defects would induce the fluctuation of cutting force and a change of the undeformed cutting thickness (UCT) in the process of repairing the damage points on the crystal surface, which would lead to the brittle–ductile transition (BDT) and affect the machined surface quality. The machined surface quality was found to be deteriorated by the pre-existing micro-defects when the UCT was small (the UCT was less than 375 nm). On the contrary, brittle mode cutting in the local area can be transformed into ductile mode cutting, resulting in an improvement of repaired surface quality that is exhibited by the cutting force and microtopography. This work has great theoretical significance and engineering practical value for the promotion and application of micro-milling repairing technology in the practical manufacturing and operation of KDP optics applied to high-power laser systems. Full article
(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials)
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17 pages, 5175 KiB  
Article
Experimental Investigations and Effect of Nano-Powder-Mixed EDM Variables on Performance Measures of Nitinol SMA
by Rakesh Chaudhari, Yug Shah, Sakshum Khanna, Vivek K. Patel, Jay Vora, Danil Yurievich Pimenov and Khaled Giasin
Materials 2022, 15(20), 7392; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15207392 - 21 Oct 2022
Cited by 9 | Viewed by 1401
Abstract
In the present study, the effect of alumina (Al2O3) nano-powder was investigated for the electrical discharge machining (EDM) of a Nitinol shape memory alloy (SMA). In addition to the nano-powder concentration, other parameters of pulse-on-time (Ton), pulse-off-time [...] Read more.
In the present study, the effect of alumina (Al2O3) nano-powder was investigated for the electrical discharge machining (EDM) of a Nitinol shape memory alloy (SMA). In addition to the nano-powder concentration, other parameters of pulse-on-time (Ton), pulse-off-time (Toff), and current were selected for the performance measures of the material removal rate (MRR), surface roughness (SR), and tool wear rate (TWR) of Nitinol SMA. The significance of the design variables on all the output measures was analyzed through an analysis of variance (ANOVA). The regression model term has significantly impacted the developed model terms for all the selected measures. In the case of individual variables, Al2O3 powder concentration (PC), Toff, and Ton had significantly impacted MRR, TWR, and SR measures, respectively. The influence of EDM variables were studied through main effect plots. The teaching–learning-based optimization (TLBO) technique was implemented to find an optimal parametric setting for attaining the desired levels of all the performance measures. Pursuant to this, the optimal parametric settings of current at 24 A, PC at 4 g/L, Toff at 10 µs, and Ton of 4 µs have shown optimal input parameters of 43.57 mg/min for MRR, 6.478 mg/min for TWR, and 3.73 µm for SR. These results from the TLBO technique were validated by performing the experiments at the optimal parametric settings of the EDM process. By considering the different user and application requirements, 40 Pareto points with unique solutions were generated. Lastly, scanning electron microscopy (SEM) performed the machined surface analysis. The authors consider this to be very beneficial in the nano-powder-mixed EDM process for appropriate manufacturing operations. Full article
(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials)
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18 pages, 2899 KiB  
Article
An Investigation on the Total Thickness Variation Control and Optimization in the Wafer Backside Grinding Process
by Yuanhang Liu, Hongfei Tao, Dewen Zhao and Xinchun Lu
Materials 2022, 15(12), 4230; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15124230 - 15 Jun 2022
Cited by 2 | Viewed by 5588
Abstract
The wafer backside grinding process has been a crucial technology to realize multi-layer stacking and chip performance improvement in the three dimension integrated circuits (3D IC) manufacturing. The total thickness variation (TTV) control is the bottleneck in the advanced process. However, the quantitative [...] Read more.
The wafer backside grinding process has been a crucial technology to realize multi-layer stacking and chip performance improvement in the three dimension integrated circuits (3D IC) manufacturing. The total thickness variation (TTV) control is the bottleneck in the advanced process. However, the quantitative analysis theory model and adjustment strategy for TTV control are not currently available. This paper developed a comprehensive simulation model based on the optimized grinding tool configuration, and several typical TTV shapes were obtained. The relationship between the TTV feature components and the spindle posture was established. The linear superposition effect of TTV feature components and a new formation mechanism of TTV shape were revealed. It illustrated that the couple variation between the two TTV feature components could not be eliminated completely. To achieve the desired wafer thickness uniformity through a concise spindle posture adjustment operation, an effective strategy for TTV control was proposed. The experiments on TTV optimization were carried out, through which the developed model and TTV control strategy were verified to play a significant role in wafer thickness uniformity improvement. This work revealed a new insight into the fine control method to the TTV optimization, and provided a guidance for high-end grinding tool and advanced thinning process development. Full article
(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials)
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13 pages, 3905 KiB  
Article
A Process Parameter Design Method for Improving the Filament Diameter Accuracy of Extrusion 3D Printing
by Kaicheng Yu, Qiang Gao, Lihua Lu and Peng Zhang
Materials 2022, 15(7), 2454; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15072454 - 26 Mar 2022
Cited by 6 | Viewed by 2036
Abstract
Process parameters have a significant impact on the filament diameter of extrusion 3D printing. To precisely control filament diameter, this paper proposes a novel method based on experiments to guide process parameter design. Additionally, an extrusion 3D printing device was developed, by which [...] Read more.
Process parameters have a significant impact on the filament diameter of extrusion 3D printing. To precisely control filament diameter, this paper proposes a novel method based on experiments to guide process parameter design. Additionally, an extrusion 3D printing device was developed, by which the influence of crucial process parameters and rheological properties on the diameter of printed filaments could be investigated experimentally and theoretically. Furthermore, poly (l-lactide-co-ε-caprolactone) (PLCL) was used as a case study to detail the design procedure of the proposed method. The printable range of the process parameters for PLCL was acquired, and a fitting surface for the experimental data was calculated to guide the process parameter design. According to the results of the experiment, by adjusting the process parameters, PLCL filaments with five different diameters of 120, 130, 140, 150, and 160 μm can be fabricated with a 100 μm nozzle. The deviations between the actual filament diameters and the desired diameter are less than 5 μm, which validates the reliability of the proposed method. Full article
(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials)
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20 pages, 8855 KiB  
Article
Experimental Analysis of Ductile Cutting Regime in Face Milling of Sintered Silicon Carbide
by Marvin Groeb, Lorenz Hagelüken, Johann Groeb and Wolfgang Ensinger
Materials 2022, 15(7), 2409; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15072409 - 24 Mar 2022
Cited by 2 | Viewed by 2629
Abstract
In this study, sintered silicon carbide is machined on a high-precision milling machine with a high-speed spindle, closed-loop linear drives and friction-free micro gap hydrostatics. A series of experiments was undertaken varying the relevant process parameters such as feedrate, cutting speed and chip [...] Read more.
In this study, sintered silicon carbide is machined on a high-precision milling machine with a high-speed spindle, closed-loop linear drives and friction-free micro gap hydrostatics. A series of experiments was undertaken varying the relevant process parameters such as feedrate, cutting speed and chip thickness. For this, the milled surfaces are characterized in a process via an acoustic emission sensor. The milled surfaces were analyzed via confocal laser scanning microscopy and the ISO 25178 areal surface quality parameters such as Sa, Sq and Smr are determined. Moreover, scanning electron microscopy was used to qualitatively characterize the surfaces, but also to identify sub-surface damages such as grooves, breakouts and pitting. Raman laser spectroscopy is used to identify possible amorphization and changes to crystal structure. We used grazing incidence XRD to analyze the crystallographic structure and scanning acoustic microscopy to analyze sub-surface damages. A polycrystalline diamond tool was able to produce superior surfaces compared to diamond grinding with an areal surface roughness Sa of below 100 nm in a very competitive time frame. The finished surface exhibits a high gloss and reflectance. It can be seen that chip thickness and cutting speed have a major influence on the resulting surface quality. The undamaged surface in combination with a small median chip thickness is indicative of a ductile cutting regime. Full article
(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials)
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16 pages, 5064 KiB  
Article
The Stability of Spiral-Grooved Air Journal Bearings in Ultrahigh Speeds
by Laiyun Song, Guoqin Yuan, Hongwen Zhang, Yalin Ding and Kai Cheng
Materials 2022, 15(5), 1759; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15051759 - 25 Feb 2022
Cited by 2 | Viewed by 2296
Abstract
The spiral-grooved structure has been proposed for promoting the load capacity and stiffness of hybrid air journal bearings. In this paper, the dynamic characteristics of spiral-grooved hybrid bearings are first calculated. The stability criteria of the bearings are proposed and analyzed with different [...] Read more.
The spiral-grooved structure has been proposed for promoting the load capacity and stiffness of hybrid air journal bearings. In this paper, the dynamic characteristics of spiral-grooved hybrid bearings are first calculated. The stability criteria of the bearings are proposed and analyzed with different groove structure parameters using frequency domain analysis. It is found that the length of the spiral-groove has significant influence on the stability of the spindle system. Finally, the critical speed of the spiral-grooved hybrid bearing and rotor system is analyzed, and an experiment is carried out to validate the proposed model, finding that groove structure can promote the stability of the air bearing systems. Full article
(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials)
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13 pages, 1807 KiB  
Article
Tool Wear and Milling Characteristics for Hybrid Additive Manufacturing Combining Laser Powder Bed Fusion and In Situ High-Speed Milling
by David Sommer, Dominik Pape, Cemal Esen and Ralf Hellmann
Materials 2022, 15(3), 1236; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15031236 - 07 Feb 2022
Cited by 8 | Viewed by 1774
Abstract
We report on milling and tool wear characteristics of hybrid additive manufacturing comprising laser powder bed fusion and in situ high-speed milling, a particular process in which the cutter mills inside the powder bed without any cooling lubricant being applicable. Flank wear is [...] Read more.
We report on milling and tool wear characteristics of hybrid additive manufacturing comprising laser powder bed fusion and in situ high-speed milling, a particular process in which the cutter mills inside the powder bed without any cooling lubricant being applicable. Flank wear is found to be the dominant wear characteristic with its temporal evolution over utilization period revealing the typical s-shaped dependence. The flank wear land width is measured by microscopy and correlated to the achievable surface roughness of milled 3D-printed parts, showing that for flank wear levels up to 100 μm a superior surface roughness below 3 μm is accessible for hybrid additive manufacturing. Further, based on this correlation recommended tool, life scenarios can be deduced. In addition, by optimizing the finishing tool start position and the number of afore-built layers, the milling process is improved with respect to the maximum millable angle for undercut surfaces of 3D-printed parts to 30° for the roughing process and to 40° for the entire machining process including finishing. Full article
(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials)
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20 pages, 8166 KiB  
Article
Non-Linear Dynamic Analysis on Hybrid Air Bearing-Rotor System under Ultra-High Speed Condition
by Laiyun Song, Guoqin Yuan, Hongwen Zhang, Yalin Ding and Kai Cheng
Materials 2022, 15(2), 675; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15020675 - 17 Jan 2022
Cited by 2 | Viewed by 1767
Abstract
The non-linear dynamic behavior of a hybrid air bearing-rotor system is very complicated and requires careful attention when designing to avoid spindle failure, especially under ultra-high speed condition. In this paper, the rotor trajectory of a hybrid air bearing-rotor system is obtained by [...] Read more.
The non-linear dynamic behavior of a hybrid air bearing-rotor system is very complicated and requires careful attention when designing to avoid spindle failure, especially under ultra-high speed condition. In this paper, the rotor trajectory of a hybrid air bearing-rotor system is obtained by solving the unsteady Reynolds equation and motion equations simultaneously. The typical non-linear behavior of hybrid air bearing-rotor systems is illustrated with the analysis of the rotor trajectory, the phase angle, time domain vibration and power spectral density. Furthermore, the influences of the rotor mass, external load, rotating speed and unbalanced mass on the non-linear behavior are investigated. Finally, the effect of structure parameters on the rotor trajectory is studied and the phenomenon under ultra-high speed condition is illustrated, which provides some new guidelines on the ultra-high speed air spindle design. Full article
(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials)
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16 pages, 6610 KiB  
Article
Analytical Compliance Equations of Generalized Elliptical-Arc-Beam Spherical Flexure Hinges for 3D Elliptical Vibration-Assisted Cutting Mechanisms
by Han Wang, Shilei Wu and Zhongxi Shao
Materials 2021, 14(20), 5928; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14205928 - 09 Oct 2021
Cited by 4 | Viewed by 1593
Abstract
Elliptical vibration-assisted cutting technology has been widely applied in complicated functional micro-structured surface texturing. Elliptical-arc-beam spherical flexure hinges have promising applications in the design of 3D elliptical vibration-assisted cutting mechanisms due to their high motion accuracy and large motion ranges. Analytical compliance matrix [...] Read more.
Elliptical vibration-assisted cutting technology has been widely applied in complicated functional micro-structured surface texturing. Elliptical-arc-beam spherical flexure hinges have promising applications in the design of 3D elliptical vibration-assisted cutting mechanisms due to their high motion accuracy and large motion ranges. Analytical compliance matrix formulation of flexure hinges is the basis for achieving high-precision positioning performance of these mechanisms, but few studies focus on this topic. In this paper, analytical compliance equations of spatial elliptic-arc-beam spherical flexure hinges are derived, offering a convenient tool for analysis at early stages of mechanism design. The mechanical model of a generalized flexure hinge is firstly established based on Castigliano’s Second Theorem. By introducing the eccentric angle as the integral variable, the compliance matrix of the elliptical-arc-beam spherical flexure hinge is formulated. Finite element analysis is carried out to verify the accuracy of the derived analytical compliance matrix. The compliance factors calculated by the analytical equations agree well with those solved in the finite element analysis for the maximum error; average relative error and relative standard deviation are 8.25%, 1.83% and 1.78%, respectively. This work lays the foundations for the design and modeling of 3D elliptical vibration-assisted cutting mechanisms based on elliptical-arc-beam spherical flexure hinges. Full article
(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials)
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13 pages, 3857 KiB  
Article
Fabrication of PCD Skiving Cutter by UV Nanosecond Laser
by Jianlei Cui, Xuyang Fang, Xiangyang Dong, Xuesong Mei, Kaida Xu, Zhengjie Fan, Zheng Sun and Wenjun Wang
Materials 2021, 14(14), 4027; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14144027 - 19 Jul 2021
Cited by 5 | Viewed by 2330
Abstract
Polycrystalline diamond (PCD) skiving cutter has dominated research in recent years. However, the traditional methods of fabrication have failed to cut the diamond with high quality. We propose the two-step laser machining process combining roughing machining with orthogonal irradiation and finishing machining with [...] Read more.
Polycrystalline diamond (PCD) skiving cutter has dominated research in recent years. However, the traditional methods of fabrication have failed to cut the diamond with high quality. We propose the two-step laser machining process combining roughing machining with orthogonal irradiation and finishing machining with tangential irradiation. In addition, the processing effect and mechanism of different lasers on the diamond were investigated by a finite element analysis. It’s proved that the ultraviolet nanosecond laser is an excellent machining method for the processing of diamond. Furthermore, the effect of the processing parameters on the contour accuracy (Rt) was studied. The result indicates that the Rt value decreases first and then increases as the increase of the line interval, scanning speed and defocusing amount (no matter positive or negative defocus). Further, Raman spectroscopy was applied to characterize the diamond surface under different cutting methods and the flank face of the tool after processing. Finally, a high-quality PCD skiving cutter was obtained with an Rt of 5.6 µm and no phase transition damage. Full article
(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials)
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Review

Jump to: Editorial, Research

38 pages, 5789 KiB  
Review
An Overview of Laser Metal Deposition for Cladding: Defect Formation Mechanisms, Defect Suppression Methods and Performance Improvements of Laser-Cladded Layers
by Jian Cheng, Yunhao Xing, Enjie Dong, Linjie Zhao, Henan Liu, Tingyu Chang, Mingjun Chen, Jinghe Wang, Junwen Lu and Jun Wan
Materials 2022, 15(16), 5522; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15165522 - 11 Aug 2022
Cited by 16 | Viewed by 3061
Abstract
With the development of society and the economy, there is an increasing demand for surface treatment techniques that can efficiently utilize metal materials to obtain good performances in the fields of mechanical engineering and the aerospace industry. The laser metal deposition (LMD) technique [...] Read more.
With the development of society and the economy, there is an increasing demand for surface treatment techniques that can efficiently utilize metal materials to obtain good performances in the fields of mechanical engineering and the aerospace industry. The laser metal deposition (LMD) technique for cladding has become a research focus in recent years because of its lower dilution rate, small heat-effect zone and good metallurgical bonding between the coating and substrate. This paper reviews the simulation technology for the melt pool’s grain growth mechanism, temperature and stress distribution that are directly related to defect formation in LMD technology. At the same time, the defect suppression method and the performance improvement method of the cladded layer in LMD technology are introduced. Finally, it is pointed out that the active selection of materials according to the required performance, combined with the controllable processing technology, to form the corresponding microstructure, and finally, to actively realize the expected function, is the future development direction of LMD technology. Full article
(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials)
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20 pages, 13114 KiB  
Review
A Review on Surface Finishing Techniques for Difficult-to-Machine Ceramics by Non-Conventional Finishing Processes
by Lida Heng, Jeong Su Kim, Jun Hee Song and Sang Don Mun
Materials 2022, 15(3), 1227; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15031227 - 07 Feb 2022
Cited by 5 | Viewed by 3206
Abstract
Ceramics are advanced engineering materials in which have been broadly used in numerous industries due to their superior mechanical and physical properties. For application, the industries require that the ceramic products have high-quality surface finishes, high dimensional accuracy, and clean surfaces to prevent [...] Read more.
Ceramics are advanced engineering materials in which have been broadly used in numerous industries due to their superior mechanical and physical properties. For application, the industries require that the ceramic products have high-quality surface finishes, high dimensional accuracy, and clean surfaces to prevent and minimize thermal contact, adhesion, friction, and wear. Ceramics have been classified as difficult-to-machine materials owing to their high hardness, and brittleness. Thus, it is extremely difficult to process them with conventional finishing processes. In this review, trends in the development of non-conventional finishing processes for the surface finishing of difficult-to-machine ceramics are discussed and compared to better comprehend the key finishing capabilities and limitations of each process on improvements in terms of surface roughness. In addition, the future direction of non-conventional finishing processes is introduced. This review will be helpful to many researchers and academicians for carrying out additional research related to the surface finishing techniques of ceramics for applications in various fields. Full article
(This article belongs to the Special Issue Ultra-Precision Manufacturing Technology for Difficult-to-Machine Materials)
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