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Design and Application of Additive Manufacturing: Volume II

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

Deadline for manuscript submissions: 10 July 2024 | Viewed by 15356

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Prof. Dr. Rubén Paz

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Department of Mechanical Engineering, University of Las Palmas de Gran Canaria, 35017 Las Palmas, Spain
Interests: manufacturing processes; additive manufacturing; design optimization; finite element analysis; biomaterials and natural fibre applications; additive manufacturing for tissue engineering applications
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Special Issue Information

Dear Colleagues,

Additive manufacturing (AM) is continuously improving and offering innovative alternatives to conventional manufacturing techniques. The advantages of AM, such as design freedom and low-cost production for short series and prototyping, can be exploited in different sectors by replacing or complementing traditional manufacturing methods. For this to happen, the combination of design, materials and technology must be deeply analysed for every specific application. Despite the continuous progress of AM, there is still a need for further investigation in terms of the design, materials and applications to boost AM implementation in the manufacturing industry as well as other sectors, especially in those where short and personalized series productions could be useful (e.g., medical sector). This Special Issue aims to publish high-level research articles involving design, materials and applications of AM, including innovative design approaches where AM is applied to improve currently used techniques, design and modelling methodologies for specific AM applications, design optimization (also driven by numerical methods such as finite element analysis) for pioneering uses of AM, innovative design and applications of functionally graded additive manufacturing and 4D printing, the combination of design, materials and AM for advanced tissue engineering applications and biosensors, etc. The proposals must focus on the application of AM, including the design methodologies used and the experimental characterizations needed according to the specific materials and requirements of the intended applications.

Prof. Dr. Rubén Paz
Guest Editor

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Keywords

additive manufacturing
innovative applications
design
materials
simulation
optimization

Published Papers (12 papers)

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Research

14 pages, 5434 KiB

Open AccessArticle

An Interactive Web-Based Platform for Support Generation and Optimisation for Metal Laser Powder Bed Fusion

by Antonios Dimopoulos, Giorgos Chryssinas, Dimitra Mavroforaki, Tat-Hean Gan and Panagiotis Chatzakos

Materials 2024, 17(7), 1639; https://doi.org/10.3390/ma17071639 - 03 Apr 2024

Viewed by 563

Abstract

Powder bed fusion—laser beam (PBF-LB), a prevalent and rapidly advancing additive manufacturing (AM) technology nowadays, serves the industry by producing thin, complex, and lightweight components for various sectors, including healthcare, automotive, defence, and aerospace. However, this technology encounters challenges related to the construction of critical parts and the high overall process costs. Equally significant is the role of support structures in metal laser powder bed fusion (PBF-LB/M). The absence of supports can lead to defective and collapsed parts, while the incorrect selection of a support type or the addition of unnecessary supports results in increased material usage and additional post-processing efforts. Therefore, there is a pressing need for advanced software capable of generating appropriate support structures and predicting the thermomechanical behaviour of a part under PBF-LB/M printing conditions. Such software would be beneficial for the industry to avoid printing defects caused by high thermal stresses, minimise material usage, reduce printing time, and ensure high-quality prints. In this study, we introduce a web-based support generation and optimisation platform for PBF-LB/M. Through this platform, among other features, users can import three-dimensional (3D) parts and generate block-type support structures with diamond perforations based on the PySLM library, all within a user-friendly web environment. The first release of the platform (v0.6) is fully interactive and accessible online at no cost. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing: Volume II)

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24 pages, 13388 KiB

Open AccessArticle

Dimensional Characterization and Hybrid Manufacturing of Copper Parts Obtained by Atomic Diffusion Additive Manufacturing, and CNC Machining

by Elena Monzón, Pablo Bordón, Rubén Paz and Mario Monzón

Materials 2024, 17(6), 1437; https://doi.org/10.3390/ma17061437 - 21 Mar 2024

Viewed by 532

Abstract

The combination of Atomic Diffusion Additive Manufacturing (ADAM) and traditional CNC machining allows manufacturers to leverage the advantages of both technologies in the production of functional metal parts. This study presents the methodological development of hybrid manufacturing for solid copper parts, initially produced using ADAM technology and subsequently machined using a 5-axis CNC system. The ADAM technology was dimensionally characterized by adapting and manufacturing the seven types of test artifacts standardized by ISO/ASTM 52902:2019. The results showed that slender geometries suffered warpage and detachment during sintering despite complying with the design guidelines. ADAM technology undersizes cylinders and oversizes circular holes and linear lengths. In terms of roughness, the lowest results were obtained for horizontal flat surfaces, while 15° inclined surfaces exhibited the highest roughness due to the stair-stepping effect. The dimensional deviation results for each type of geometry were used to determine the specific and global oversize factors necessary to compensate for major dimensional defects. This also involved generating appropriate over-thicknesses for subsequent CNC machining. The experimental validation of this process, conducted on a validation part, demonstrated final deviations lower than 0.5% with respect to the desired final part, affirming the feasibility of achieving copper parts with a high degree of dimensional accuracy through the hybridization of ADAM and CNC machining technologies. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing: Volume II)

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25 pages, 3517 KiB

Open AccessArticle

Venturi Injector Optimization for Precise Powder Transport for Directed Energy Deposition Manufacturing Using the Discrete Element Method and Genetic Algorithms

by Joshua García-Montagut, Rubén Paz, Mario Monzón and Begoña González

Materials 2024, 17(4), 911; https://doi.org/10.3390/ma17040911 - 16 Feb 2024

Viewed by 465

Abstract

Additive manufacturing technologies such as directed energy deposition use powder as their raw material, and it must be deposited in a precise and controlled manner. Venturi injectors could be a solution for the highly precise transport of particulate material. They have been studied from different perspectives, but they are always under high-pressure conditions and mostly fed by gravity. In the present study, an optimization of the different dimensional parameters needed for the manufacturing of a Venturi injector in relation to a particle has been carried out to maximize the amount of powder capable of being sucked and transported for a specific flow in a low-pressure system with high precision in transport. For this optimization, simulations of Venturi usage were performed using the discrete element method, generating different variations proposed by a genetic algorithm based on a preliminary design of experiments. Statistical analysis was also performed to determine the most influential design variables on the objective, with these being the suction diameter (D3), the throat diameter (d2), and the nozzle diameter (d1). The optimal dimensional relationships were as follows: a D3 34 times the particle diameter, a d2 26.5 times the particle diameter, a d1 40% the d2, a contraction angle alpha of 18.73°, and an expansion angle beta of 8.28°. With these proportions, an 85% improvement in powder suction compared to the initial attempts was achieved, with a maximum 2% loss of load. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing: Volume II)

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18 pages, 8991 KiB

Open AccessFeature PaperArticle

Effects of Laser Defocusing on Bead Geometry in Coaxial Titanium Wire-Based Laser Metal Deposition

by Remy Mathenia, Aaron Flood, Braden McLain, Todd Sparks and Frank Liou

Materials 2024, 17(4), 889; https://doi.org/10.3390/ma17040889 - 15 Feb 2024

Cited by 1 | Viewed by 564

Abstract

Coaxial wire-based laser metal deposition is a versatile and efficient additive process that can achieve a high deposition rate in the manufacturing of complex structures. In this paper, a three-beam coaxial wire system is studied, with particular attention to the effects of deposition height and laser defocusing on the resulting bead geometry. As the deposition standoff distance changes, so does the workpiece illumination proportion, which describes the ratio of energy going directly into the feedstock wire and into the substrate. Single titanium beads are deposited at varying defocus levels and deposition rates and the bead aspect ratio is measured and analyzed. Over the experimental settings, the defocusing level and deposition rate were found to have a significant effect on the resulting bead aspect ratio. As the defocusing level is increased away from the beam convergence plane, the spot size increases and the deposited track is wider and flatter. Process parameters can be used to tune the deposited material to a desired aspect ratio. In coaxial wire deposition, defocusing provides an adjustment mechanism to the distribution of heat between the wire and substrate and has an important impact on the resulting deposit. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing: Volume II)

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17 pages, 19041 KiB

Open AccessArticle

Assessment of Residual Stresses in Laser Powder Bed Fusion Manufactured IN 625

by Alexandru Paraschiv, Gheorghe Matache and Mihai Vladut

Materials 2024, 17(2), 413; https://doi.org/10.3390/ma17020413 - 14 Jan 2024

Cited by 1 | Viewed by 733

Abstract

Residual stresses pose significant challenges in the powder bed fusion of metals using a laser (PBF-LB/M), impacting both the dimensional accuracy and mechanical properties. This study quantitatively analyzes deformation and residual stresses in additively manufactured Inconel 625. Investigating both as-built and stress-relieved states with varied scanning strategies (90°, 67°, strip, and 90° chessboard) in PBF-LB/M/IN625, distortion is evaluated using the bridge curvature method. Quantitative measurements are obtained through 3D laser surface scanning on pairs of bridge specimens—one measured before and after detachment from the build plate, and the other undergoing stress-relieving heat treatment at 870 °C for 1 h. The findings reveal that, among as-built specimens, the 90° and 90° strip strategies induce the least distortion, followed by the 67° and chessboard 90° strategies. Furthermore, stress-relief treatment significantly reduces residual stress levels. After post-treatment, the deformation in X-axis samples with 90° and 90° strip strategies decreases by 39% and 42%. In contrast, the samples with the 67° and 90° checkerboard strategies exhibit more pronounced reductions of 44% and 63%, respectively. These quantitative results contribute useful insights for optimizing PBF-LB/M/IN625 processes in additive manufacturing. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing: Volume II)

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14 pages, 45524 KiB

Open AccessArticle

Effect of Current Waveforms during Directed Energy Deposition of 4043 Aluminum Alloy on Microstructure, Hardness, and Wear of Alloy

by Kumar Ujjwal, Katipalli Anand Kumar, Mukul Anand, R. K. Singh Raman and Alok Kumar Das

Materials 2023, 16(20), 6716; https://doi.org/10.3390/ma16206716 - 16 Oct 2023

Cited by 1 | Viewed by 1325

Abstract

Wire arc additive manufacturing (WAAM) was employed to fabricate 4043 aluminum alloy walls. To investigate the effects of sinusoidal, triangular, and rectangular waveforms of alternating current (AC) and their transients on the wall geometry, microstructure evolution, hardness, and wear properties were evaluated. The root mean square (RMS) current value was maximum for the rectangular and minimum for the triangular waveform. The section produced by the triangular waveform had the highest height-to-width ratio, indicating that this waveform can be a favorable choice for creating components using WAAM. The optical micrographs of the transverse cross-section of the printed sections revealed the grain structure produced with this waveform to be heterogeneous, having a columnar dendritic structure at the bottom and equiaxed at the top portion. The waveforms also had an impact on the hardness and wear characteristics of all the walls, which were attributed to their cooling rate. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing: Volume II)

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19 pages, 10058 KiB

Open AccessArticle

Case Study of Additively Manufactured Mountain Bike Stem

by Filip Véle, Michal Ackermann, Jakub Macháček and Jiří Šafka

Materials 2023, 16(13), 4717; https://doi.org/10.3390/ma16134717 - 29 Jun 2023

Cited by 1 | Viewed by 1363

Abstract

This article is focused on a case study of the topology optimisation of a bike stem manufactured by selective laser melting (SLM) additive technology. Topology optimisation was used as a design tool to model a part with less material used for transferring specific loads than the conventional method. For topology optimisation, Siemens NX 12 software was used with loads defined from the ISO 4210-5 standard. Post-processing of the topology-optimised shape was performed in Altair Inspire software. For this case study, the aluminium alloy AlSi10Mg was selected. For qualitative evaluation, the mechanical properties of the chosen alloy were measured on the tensile specimens. The design of the new bike stem was evaluated by Ansys FEA software with static loadings defined by ISO 4210-5. The functionality of the additively manufactured bike stem was confirmed by actual experiments defined by ISO 4210-5. The resulting new design of the bike stem passed both static tests and is 7.9% lighter than that of the reference. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing: Volume II)

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25 pages, 40379 KiB

Open AccessArticle

Application of Functionally Graded Shell Lattice as Infill in Additive Manufacturing

by Slawomir Kedziora, Thierry Decker and Elvin Museyibov

Materials 2023, 16(12), 4401; https://doi.org/10.3390/ma16124401 - 15 Jun 2023

Viewed by 1156

Abstract

The significance of lightweight designs has become increasingly paramount due to the growing demand for sustainability. Consequently, this study aims to demonstrate the potential of utilising a functionally graded lattice as an infill structure in designing an additively manufactured bicycle crank arm to achieve construction lightness. The authors seek to determine whether functionally graded lattice structures can be effectively implemented and explore their potential real-world applications. Two aspects determine their realisations: the lack of adequate design and analysis methods and the limitations of existing additive manufacturing technology. To this end, the authors employed a relatively simple crank arm and design exploration methods for structural analysis. This approach facilitated the efficient identification of the optimal solution. A prototype was subsequently developed using fused filament fabrication for metals, enabling the production of a crank arm with the optimised infill. As a result, the authors developed a lightweight and manufacturable crank arm showing a new design and analysis method implementable in similar additively manufactured elements. The percentage increase of a stiffness-to-mass ratio of 109.6% was achieved compared to the initial design. The findings suggest that the functionally graded infill based on the lattice shell improves structural lightness and can be manufactured. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing: Volume II)

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21 pages, 5683 KiB

Open AccessArticle

Tuning Shear Thinning Factors of 3D Bio-Printable Hydrogels Using Short Fiber

by Slesha Tuladhar, Scott Clark and Ahasan Habib

Materials 2023, 16(2), 572; https://doi.org/10.3390/ma16020572 - 06 Jan 2023

Cited by 6 | Viewed by 1879

Abstract

Among various available 3D bioprinting techniques, extrusion-based three-dimensional (3D) bioprinting allows the deposition of cell-laden bioink, ensuring predefined scaffold architecture that may offer living tissue regeneration. With a combination of unique characteristics such as biocompatibility, less cell toxicity, and high water content, natural hydrogels are a great candidate for bioink formulation for the extrusion-based 3D bioprinting process. However, due to its low mechanical integrity, hydrogel faces a common challenge in maintaining structural integrity. To tackle this challenge, the rheological properties, specifically the shear thinning behavior (reduction of viscosity with increasing the applied load/shear rate on hydrogels) of a set of hybrid hydrogels composed of cellulose-derived nanofiber (TEMPO-mediated nano-fibrillated cellulose, TO-NFC), carboxymethyl cellulose (CMC), and commonly used alginate, were explored. A total of 46 compositions were prepared using higher (0.5% and 1.0%) and lower percentages (0.005% and 0.01%) of TO-NFC, 1–4% of CMC, and 1–4% of alginate to analyze the shear thinning factors such as the values of n and K, which were determined for each composition from the flow diagram and co-related with the 3D printability. The ability to tune shear thinning factors with various ratios of a nanofiber can help achieve a 3D bio-printed scaffold with defined scaffold architecture. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing: Volume II)

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11 pages, 2408 KiB

Open AccessArticle

Function Integration in Additive Manufacturing: Design and Realization of an LPBF Built Compressed Air Motor

by Benedikt Adelmann and Ralf Hellmann

Materials 2022, 15(19), 6632; https://doi.org/10.3390/ma15196632 - 24 Sep 2022

Cited by 1 | Viewed by 1212

Abstract

We present a compressed air motor, completely built by laser powder bed fusion. To highlight the fully functional integration by additive manufacturing, the rotor, stator, bearings, turbine, gas inlet and outlet were all built in a single print job. The material used was Inconel 718, and the motor was 44 mm tall and 12 mm in diameter. With the rotation axis of the motor in print in the direction of the laser powder bed fusion process, no build supports are needed, and thus the rotor and stator are fully moveable against each other. Plain bearings were used to position the rotor inseparably inside the stator, with a bearing gap of 0.2 mm, resulting in stable rotation. The idle rotation speed of the motor was measured with a digital laser measuring device as a function of air pressure and inlet size. With linear behavior between the rotation speed and gas pressure of up to 5.5 bar, the motor can be easily controlled. With varying gas inlet sizes, the idle rotation speed of the compressed air motor is also varied. A maximum rotation speed of 90,000 rpm was achieved at 1.5 mm gas inlet size and 3 bar gas pressure. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing: Volume II)

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23 pages, 8237 KiB

Open AccessArticle

Evaluation of the Performance of Atomic Diffusion Additive Manufacturing Electrodes in Electrical Discharge Machining

by Pablo Bordón, Rubén Paz and Mario D. Monzón

Materials 2022, 15(17), 5953; https://doi.org/10.3390/ma15175953 - 28 Aug 2022

Cited by 3 | Viewed by 2081

Abstract

Atomic Diffusion Additive Manufacturing (ADAM) is an innovative Additive Manufacturing process that allows the manufacture of complex parts in metallic material, such as copper among others, which provides new opportunities in Rapid Tooling. This work presents the development of a copper electrode manufactured with ADAM technology for Electrical Discharge Machining (EDM) and its performance compared to a conventional electrolytic copper. Density, electrical conductivity and energy-dispersive X-ray spectroscopy were performed for an initial analysis of both ADAM and electrolytic electrodes. Previously designed EDM experiments and optimizations using genetic algorithms were carried out to establish a comparative framework for both electrodes. Subsequently, the final EDM tests were carried out to evaluate the electrode wear rate, the roughness of the workpiece and the rate of material removal for both electrodes. The EDM results show that ADAM technology enables the manufacturing of functional EDM electrodes with similar material removal rates and rough workpiece finishes to conventional electrodes, but with greater electrode wear, mainly due to internal porosity, voids and other defects observed with field emission scanning electron microscopy. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing: Volume II)

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21 pages, 10162 KiB

Open AccessArticle

On the Morphological Deviation in Additive Manufacturing of Porous Ti6Al4V Scaffold: A Design Consideration

by Seyed Ataollah Naghavi, Haoyu Wang, Swastina Nath Varma, Maryam Tamaddon, Arsalan Marghoub, Rex Galbraith, Jane Galbraith, Mehran Moazen, Jia Hua, Wei Xu and Chaozong Liu

Materials 2022, 15(14), 4729; https://doi.org/10.3390/ma15144729 - 06 Jul 2022

Cited by 8 | Viewed by 2207

Abstract

Additively manufactured Ti scaffolds have been used for bone replacement and orthopaedic applications. In these applications, both morphological and mechanical properties are important for their in vivo performance. Additively manufactured Ti6Al4V triply periodic minimal surface (TPMS) scaffolds with diamond and gyroid structures are known to have high stiffness and high osseointegration properties, respectively. However, morphological deviations between the as-designed and as-built types of these scaffolds have not been studied before. In this study, the morphological and mechanical properties of diamond and gyroid scaffolds at macro and microscales were examined. The results demonstrated that the mean printed strut thickness was greater than the designed target value. For diamond scaffolds, the deviation increased from 7.5 μm (2.5% excess) for vertical struts to 105.4 μm (35.1% excess) for horizontal struts. For the gyroid design, the corresponding deviations were larger, ranging from 12.6 μm (4.2% excess) to 198.6 μm (66.2% excess). The mean printed pore size was less than the designed target value. For diamonds, the deviation of the mean pore size from the designed value increased from 33.1 μm (−3.0% excess) for vertical struts to 92.8 μm (−8.4% excess) for horizontal struts. The corresponding deviation for gyroids was larger, ranging from 23.8 μm (−3.0% excess) to 168.7 μm (−21.1% excess). Compressive Young’s modulus of the bulk sample, gyroid and diamond scaffolds was calculated to be 35.8 GPa, 6.81 GPa and 7.59 GPa, respectively, via the global compression method. The corresponding yield strength of the samples was measured to be 1012, 108 and 134 MPa. Average microhardness and Young’s modulus from α and β phases of Ti6Al4V from scaffold struts were calculated to be 4.1 GPa and 131 GPa, respectively. The extracted morphology and mechanical properties in this study could help understand the deviation between the as-design and as-built matrices, which could help develop a design compensation strategy before the fabrication of the scaffolds. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing: Volume II)

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