3D Printing of Metals

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Mechanical Engineering".

Deadline for manuscript submissions: closed (30 September 2018) | Viewed by 54953

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Special Issue Editor

Materials Group, Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576, Singapore
Interests: metal additive manufacturing; processing; characterization; lightweight materials; nanocomposites
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Special Issue Information

Dear Colleagues,

3D printing is rapidly emerging as a key manufacturing technique, capable of serving a wide spectrum of applications, ranging from engineering to biomedical sector. Its ability to form both simple and intricate shapes through computer-controlled graphics enables it to create a niche in manufacturing sector. Key challenges remain and a great deal of research is required to develop 3D printing technology for all classes of materials including polymers, metals, ceramics and composites. In view of the growing importance of 3D manufacturing worldwide, this Special Issue is launched aiming to seek original articles to further assist in the development of this promising technology from both scientific and technological perspectives. Targeted reviews including mini-reviews are also welcome as they play a crucial role in educating students and young researchers.

Assoc. Prof. Manoj Gupta
Guest Editor

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Keywords

  • Processing
  • Characterization
  • Properties (physical, mechanical, thermal, chemical properties etc.)
  • Numerical simulation
  • Applications (automotive, aviation, consumer electronics, sports, bio-medical etc.)

Published Papers (10 papers)

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Editorial

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2 pages, 144 KiB  
Editorial
Special Issue: 3D Printing of Metals
by Manoj Gupta
Appl. Sci. 2019, 9(12), 2563; https://doi.org/10.3390/app9122563 - 24 Jun 2019
Cited by 2 | Viewed by 2265
Abstract
Additive manufacturing (AM) has emerged as one of the most enabling new manufacturing technique; the topic has been extensively researched worldwide for almost two decades [...] Full article
(This article belongs to the Special Issue 3D Printing of Metals)

Research

Jump to: Editorial

18 pages, 5123 KiB  
Article
A Thermomechanical Analysis of Conformal Cooling Channels in 3D Printed Plastic Injection Molds
by Suchana Akter Jahan and Hazim El-Mounayri
Appl. Sci. 2018, 8(12), 2567; https://doi.org/10.3390/app8122567 - 11 Dec 2018
Cited by 25 | Viewed by 4609
Abstract
Plastic injection molding is a versatile process, and a major part of the present plastic manufacturing industry. The traditional die design is limited to straight (drilled) cooling channels, which don’t impart optimal thermal (or thermomechanical) performance. With the advent of additive manufacturing technology, [...] Read more.
Plastic injection molding is a versatile process, and a major part of the present plastic manufacturing industry. The traditional die design is limited to straight (drilled) cooling channels, which don’t impart optimal thermal (or thermomechanical) performance. With the advent of additive manufacturing technology, injection molding tools with conformal cooling channels are now possible. However, optimum conformal channels based on thermomechanical performance are not found in the literature. This paper proposes a design methodology to generate optimized design configurations of such channels in plastic injection molds. The design of experiments (DOEs) technique is used to study the effect of the critical design parameters of conformal channels, as well as their cross-section geometries. In addition, designs for the “best” thermomechanical performance are identified. Finally, guidelines for selecting optimum design solutions given the plastic part thickness are provided. Full article
(This article belongs to the Special Issue 3D Printing of Metals)
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15 pages, 6748 KiB  
Article
Superior Mechanical Behavior and Fretting Wear Resistance of 3D-Printed Inconel 625 Superalloy
by Yong Gao and Mingzhuo Zhou
Appl. Sci. 2018, 8(12), 2439; https://doi.org/10.3390/app8122439 - 01 Dec 2018
Cited by 26 | Viewed by 4177
Abstract
Additive manufacturing (AM) nickel-based superalloys have been demonstrated to equate or exceed mechanical properties of cast and wrought counterparts but their tribological potentials have not been fully realized. This study investigates fretting wear behaviors of Inconel 625 against the 42 CrMo4 stainless [...] Read more.
Additive manufacturing (AM) nickel-based superalloys have been demonstrated to equate or exceed mechanical properties of cast and wrought counterparts but their tribological potentials have not been fully realized. This study investigates fretting wear behaviors of Inconel 625 against the 42 CrMo4 stainless steel under flat-on-flat contacts. Inconel 625 is prepared by additive manufacturing (AM) using the electron beam selective melting. Results show that it has a high hardness (335 HV), superior tensile strength (952 MPa) and yield strength (793 MPa). Tribological tests indicate that the AM-Inconel 625 can suppress wear of the surface within a depth of only ~2.4 μm at a contact load of 106 N after 2 × 104 cycles. The excellent wear resistance is attributed to the improved strength and the formation of continuous tribo-layers containing a mixture of Fe2O3, Fe3O4, Cr2O3 and Mn2O3. Full article
(This article belongs to the Special Issue 3D Printing of Metals)
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16 pages, 3402 KiB  
Article
Online Monitoring Based on Temperature Field Features and Prediction Model for Selective Laser Sintering Process
by Zhehan Chen, Xianhui Zong, Jing Shi and Xiaohua Zhang
Appl. Sci. 2018, 8(12), 2383; https://doi.org/10.3390/app8122383 - 25 Nov 2018
Cited by 12 | Viewed by 3036
Abstract
Selective laser sintering (SLS) is an additive manufacturing technology that can work with a variety of metal materials, and has been widely employed in many applications. The establishment of a data correlation model through the analysis of temperature field images is a recognized [...] Read more.
Selective laser sintering (SLS) is an additive manufacturing technology that can work with a variety of metal materials, and has been widely employed in many applications. The establishment of a data correlation model through the analysis of temperature field images is a recognized research method to realize the monitoring and quality control of the SLS process. In this paper, the key features of the temperature field in the process are extracted from three levels, and the mathematical model and data structure of the key features are constructed. Feature extraction, dimensional reduction, and parameter optimization are realized based on principal component analysis (PCA) and support vector machine (SVM), and the prediction model is built and optimized. Finally, the feasibility of the proposed algorithms and model is verified by experiments. Full article
(This article belongs to the Special Issue 3D Printing of Metals)
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16 pages, 6407 KiB  
Article
Design & Manufacture of a High-Performance Bicycle Crank by Additive Manufacturing
by Iain McEwen, David E. Cooper, Jay Warnett, Nadia Kourra, Mark A. Williams and Gregory J. Gibbons
Appl. Sci. 2018, 8(8), 1360; https://doi.org/10.3390/app8081360 - 13 Aug 2018
Cited by 12 | Viewed by 6703
Abstract
A new practical workflow for the laser Powder Bed Fusion (PBF) process, incorporating topological design, mechanical simulation, manufacture, and validation by computed tomography is presented, uniquely applied to a consumer product (crank for a high-performance racing bicycle), an approach that is tangible and [...] Read more.
A new practical workflow for the laser Powder Bed Fusion (PBF) process, incorporating topological design, mechanical simulation, manufacture, and validation by computed tomography is presented, uniquely applied to a consumer product (crank for a high-performance racing bicycle), an approach that is tangible and adoptable by industry. The lightweight crank design was realised using topology optimisation software, developing an optimal design iteratively from a simple primitive within a design space and with the addition of load boundary conditions (obtained from prior biomechanical crank force–angle models) and constraints. Parametric design modification was necessary to meet the Design for Additive Manufacturing (DfAM) considerations for PBF to reduce build time, material usage, and post-processing labour. Static testing proved performance close to current market leaders with the PBF manufactured crank found to be stiffer than the benchmark design (static load deflection of 7.0 ± 0.5 mm c.f. 7.67 mm for a Shimano crank at a competitive mass (155 g vs. 175 g). Dynamic mechanical performance proved inadequate, with failure at 2495 ± 125 cycles; the failure mechanism was consistent in both its form and location. This research is valuable and novel as it demonstrates a complete workflow from design, manufacture, post-treatment, and validation of a highly loaded PBF manufactured consumer component, offering practitioners a validated approach to the application of PBF for components with application outside of the accepted sectors (aerospace, biomedical, autosports, space, and power generation). Full article
(This article belongs to the Special Issue 3D Printing of Metals)
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12 pages, 8108 KiB  
Article
Optimization of AZ91D Process and Corrosion Resistance Using Wire Arc Additive Manufacturing
by Seungkyu Han, Matthew Zielewski, David Martinez Holguin, Monica Michel Parra and Namsoo Kim
Appl. Sci. 2018, 8(8), 1306; https://doi.org/10.3390/app8081306 - 06 Aug 2018
Cited by 29 | Viewed by 5063
Abstract
Progress on Additive Manufacturing (AM) techniques focusing on ceramics and polymers evolves, as metals continue to be a challenging material to manipulate when fabricating products. Current methods, such as Selective Laser Sintering (SLS) and Electron Beam Melting (EBM), face many intrinsic limitations due [...] Read more.
Progress on Additive Manufacturing (AM) techniques focusing on ceramics and polymers evolves, as metals continue to be a challenging material to manipulate when fabricating products. Current methods, such as Selective Laser Sintering (SLS) and Electron Beam Melting (EBM), face many intrinsic limitations due to the nature of their processes. Material selection, elevated cost, and low deposition rates are some of the barriers to consider when one of these methods is to be used for the fabrication of engineering products. The research presented demonstrates the use of a Wire and Arc Additive Manufacturing (WAAM) system for the creation of metallic specimens. This project explored the feasibility of fabricating elements made from magnesium alloys with the potential to be used in biomedical applications. It is known that the elastic modulus of magnesium closely approximates that of natural bone than other metals. Thus, stress shielding phenomena can be reduced. Furthermore, the decomposition of magnesium shows no harm inside the human body since it is an essential element in the body and its decomposition products can be easily excreted through the urine. By alloying magnesium with aluminum and zinc, or rare earths such as yttrium, neodymium, cerium, and dysprosium, the structural integrity of specimens inside the human body can be assured. However, the in vivo corrosion rates of these products can be accelerated by the presence of impurities, voids, or segregation created during the manufacturing process. Fast corrosion rates would produce improper healing, which, in turn, involve subsequent surgical intervention. However, in this study, it has been proven that magnesium alloy AZ91D produced by WAAM has higher corrosion resistance than the cast AZ91D. Due to its structure, which has porosity or cracking only at the surface of the individual printed lines, the central sections present a void-less structure composed by an HCP magnesium matrix and a high density of well dispersed aluminum-zinc rich precipitates. Also, specimens created under different conditions have been analyzed in the macroscale and microscale to determine the parameters that yield the best visual and microstructural results. Full article
(This article belongs to the Special Issue 3D Printing of Metals)
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9 pages, 2733 KiB  
Article
Degradation Classification of 3D Printing Thermoplastics Using Fourier Transform Infrared Spectroscopy and Artificial Neural Networks
by Sung-Uk Zhang
Appl. Sci. 2018, 8(8), 1224; https://doi.org/10.3390/app8081224 - 25 Jul 2018
Cited by 19 | Viewed by 4092
Abstract
Fused deposition modeling (FDM) is the most popular technology among 3D printing technologies because of inexpensive and flexible extrusion systems with thermoplastic materials. However, thermal degradation phenomena of the 3D-printed thermoplastics is an inevitable problem for long-term reliability. In the current study, thermal [...] Read more.
Fused deposition modeling (FDM) is the most popular technology among 3D printing technologies because of inexpensive and flexible extrusion systems with thermoplastic materials. However, thermal degradation phenomena of the 3D-printed thermoplastics is an inevitable problem for long-term reliability. In the current study, thermal degradation of 3D-printed thermoplastics of ABS and PLA was studied. A classification methodology using deep learning strategy was developed so that thermal degradation of the thermoplastics could be classified using FTIR and Artificial Neural Networks (ANNs). Under given data and predefined rules for ANNs, ANN models with nine hidden layers showed the best results in terms of accuracy. To extend this methodology, other thermoplastics, several new datasets for ANNs, and control parameters of ANNs could be further investigated. Full article
(This article belongs to the Special Issue 3D Printing of Metals)
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12 pages, 4281 KiB  
Article
Thermoelectric Cooling-Aided Bead Geometry Regulation in Wire and Arc-Based Additive Manufacturing of Thin-Walled Structures
by Fang Li, Shujun Chen, Junbiao Shi, Yun Zhao and Hongyu Tian
Appl. Sci. 2018, 8(2), 207; https://doi.org/10.3390/app8020207 - 30 Jan 2018
Cited by 84 | Viewed by 8880
Abstract
Wire and arc-based additive manufacturing (WAAM) is a rapidly developing technology which employs a welding arc to melt metal wire for additive manufacturing purposes. During WAAM of thin-walled structures, as the wall height increases, the heat dissipation to the substrate is slowed down [...] Read more.
Wire and arc-based additive manufacturing (WAAM) is a rapidly developing technology which employs a welding arc to melt metal wire for additive manufacturing purposes. During WAAM of thin-walled structures, as the wall height increases, the heat dissipation to the substrate is slowed down gradually and so is the solidification of the molten pool, leading to variation of the bead geometry. Though gradually reducing the heat input via adjusting the process parameters can alleviate this issue, as suggested by previous studies, it relies on experience to a large extent and inevitably sacrifices the deposition rate because the wire feed rate is directly coupled with the heat input. This study introduces for the first time an in-process active cooling system based on thermoelectric cooling technology into WAAM, which aims to eliminate the difference in heat dissipation between upper and lower layers. The case study shows that, with the aid of thermoelectric cooling, the bead width error is reduced by 56.8%, the total fabrication time is reduced by 60.9%, and the average grain size is refined by 25%. The proposed technique provides new insight into bead geometry regulation during WAAM with various benefits in terms of geometric accuracy, productivity, and microstructure. Full article
(This article belongs to the Special Issue 3D Printing of Metals)
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18051 KiB  
Article
Evaluation and Optimization of a Hybrid Manufacturing Process Combining Wire Arc Additive Manufacturing with Milling for the Fabrication of Stiffened Panels
by Fang Li, Shujun Chen, Junbiao Shi, Hongyu Tian and Yun Zhao
Appl. Sci. 2017, 7(12), 1233; https://doi.org/10.3390/app7121233 - 28 Nov 2017
Cited by 62 | Viewed by 8601
Abstract
This paper proposes a hybrid WAAM (wire arc additive manufacturing) and milling process (HWMP), and highlights its application in the fabrication of stiffened panels that have wide applications in aviation, aerospace, and automotive industries, etc. due to their light weight and strong load-bearing [...] Read more.
This paper proposes a hybrid WAAM (wire arc additive manufacturing) and milling process (HWMP), and highlights its application in the fabrication of stiffened panels that have wide applications in aviation, aerospace, and automotive industries, etc. due to their light weight and strong load-bearing capability. In contrast to existing joining or machining methods, HWMP only deposits stiffeners layer-by-layer onto an existing thin plate, followed by minor milling of the irregular surfaces, which provides the possibility to significantly improve material utilization and efficiency without any loss of surface quality. In this paper, the key performances of HWMP in terms of surface quality, material utilization and efficiency are evaluated systematically, which are the results of the comprehensive effects of the deposition parameters (e.g., travel speed, wire-feed rate) and the milling parameters (e.g., spindle speed, tool-feed rate). In order to maximize its performances, the optimization is also performed to find the best combination of the deposition and the milling parameters. The case study shows that HWMP with the optimal process parameters improves the material utilization by 57% and the efficiency by 32% compared against the traditional machining method. Thus, HWMP is believed to be a more environmental friendly and sustainable method for the fabrication of stiffened panels or other similar structures. Full article
(This article belongs to the Special Issue 3D Printing of Metals)
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7258 KiB  
Article
Comparison of Laser-Engraved Hole Properties between Cold-Rolled and Laser Additive Manufactured Stainless Steel Sheets
by Matti Manninen, Marika Hirvimäki, Ville-Pekka Matilainen and Antti Salminen
Appl. Sci. 2017, 7(9), 913; https://doi.org/10.3390/app7090913 - 06 Sep 2017
Cited by 3 | Viewed by 6499
Abstract
Laser drilling and laser engraving are common manufacturing processes that are found in many applications. With the continuous progress of additive manufacturing (3D printing), these processes can now be applied to the materials used in 3D printing. However, there is a lack of [...] Read more.
Laser drilling and laser engraving are common manufacturing processes that are found in many applications. With the continuous progress of additive manufacturing (3D printing), these processes can now be applied to the materials used in 3D printing. However, there is a lack of knowledge about how these new materials behave when processed or machined. In this study, sheets of 316L stainless steel produced by both the traditional cold rolling method and by powder bed fusion (PBF) were laser drilled by a nanosecond pulsed fiber laser. Results were then analyzed to find out whether there are measurable differences in laser processing parts that are produced by either PBF (3D printing) or traditional steel parts. Hole diameters, the widths of burn effects, material removal rates, and hole tapers were measured and compared. Additionally, differences in microstructures of the samples were also analyzed and compared. Results show negligible differences in terms of material processing efficiency. The only significant differences were that the PBF sample had a wider burn effect, and had some defects in the microstructure that were more closely analyzed. The defects were found to be shallow recesses in the material. Some of the defects were deep within the material, at the end and start points of the laser lines, and some were close to the surfaces of the sample. Full article
(This article belongs to the Special Issue 3D Printing of Metals)
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