Design, Processes and Materials for Additive Manufacturing

A special issue of Journal of Manufacturing and Materials Processing (ISSN 2504-4494).

Deadline for manuscript submissions: closed (31 July 2024) | Viewed by 13958

Special Issue Editor


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Special Issue Information

Dear Colleagues,

Additive manufacturing (AM) has several advantages over traditional manufacturing technologies and has grown very quickly in recent years. However, there are still technological issues preventing the industry from utilizing its full potential, which can be categorized under three pillars, namely design, processes, and materials.

Such challenges include design and redesign for AM aiming to improve manufacturability, productivity, and quality, and the encapsulation of post-processing for AM into the design phase. These can be expanded towards techniques for the utilization of AI towards AM design optimization, as well as design aspects/considerations for multi-material AM and 4D printing.

Regarding process-related AM challenges, there is still a need for methodologies to mitigate the quality issues with AM parts and the optimization of process parameters for the improvement in specific key performance indicators (KPIs) related to quality and productivity, either experimentally or through simulation. Another aspect is connected to strategies and applications for in situ monitoring, defect detection, and process control, especially for metal-based AM, as well as decision support systems for AM process selection. Additionally, there is an exigency of practical and innovative modeling/simulation approaches for AM (nano-, micro-, macro-, multi-scale), as well as digital twins for AM, utilizing a holistic solution approach. Process optimization for improved surface quality and reduced post-processing is another important challenge, which will reduce the costs of AM and further increase its appeal for many industrial applications. Finally, other important topics include innovative AM processes allowing for higher productivity and a minimized need for post-processing and the design and validation of innovative hybrid AM systems.

As far as the materials pillar is concerned, there is still a need to further investigate the impact of process parameters on microstructure and mechanical properties, both experimentally and through simulations, as well as for the development of efficient quality assessment applications of mechanical properties of metal AM components. Additionally, material-related aspects of 4D printing, such as the testing and validation of 4D printing materials and methodologies for 4D printing using conventional AM equipment and materials, should be further investigated. Additional challenges include the development of techniques and methodologies for the utilization of multi-material AM for high-added-value products, as well as new materials for AM, including their testing and validation (metals, polymers, ceramics, composites, cement-based, biomaterials).

The focus and goal of this Special Issue is to address the design-, process-, and material-related challenges of AM, which include, but are not limited to, the aforementioned ones, and to propose improvements in aspects related to those three pillars to avail the wider industrial adoption of AM.

Dr. Panagiotis Stavropoulos
Guest Editor

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Keywords

  • additive manufacturing
  • AM design optimization
  • post-processing for AM
  • process optimization
  • in situ monitoring, defect detection, and process control for metal-based AM
  • material-related aspects of 4D printing
  • utilization of multi-material AM
  • new materials for AM

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Published Papers (10 papers)

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Research

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26 pages, 7709 KiB  
Article
A Machine Learning Approach for Mechanical Component Design Based on Topology Optimization Considering the Restrictions of Additive Manufacturing
by Abid Ullah, Karim Asami, Lukas Holtz, Tim Röver, Kashif Azher, Katharina Bartsch and Claus Emmelmann
J. Manuf. Mater. Process. 2024, 8(5), 220; https://doi.org/10.3390/jmmp8050220 - 1 Oct 2024
Viewed by 753
Abstract
Additive manufacturing (AM) and topology optimization (TO) emerge as vital processes in modern industries, with broad adoption driven by reduced expenses and the desire for lightweight and complex designs. However, iterative topology optimization can be inefficient and time-consuming for individual products with a [...] Read more.
Additive manufacturing (AM) and topology optimization (TO) emerge as vital processes in modern industries, with broad adoption driven by reduced expenses and the desire for lightweight and complex designs. However, iterative topology optimization can be inefficient and time-consuming for individual products with a large set of parameters. To address this shortcoming, machine learning (ML), primarily neural networks, is considered a viable tool to enhance topology optimization and streamline AM processes. In this work, a machine learning (ML) model that generates a parameterized optimized topology is presented, capable of eliminating the conventional iterative steps of TO, which shortens the development cycle and decreases overall development costs. The ML algorithm used, a conditional generative adversarial network (cGAN) known as Pix2Pix-GAN, is adopted to train using a variety of training data pairs consisting of color-coded images and is applied to an example of cantilever optimization, significantly enhancing model accuracy and operational efficiency. The analysis of training data numbers in relation to the model’s accuracy shows that as data volume increases, the accuracy of the model improves. Various ML models are developed and validated in this study; however, some artefacts are still present in the generated designs. Structures that are free from these artefacts achieve 91% reliability successfully. On the other hand, the images generated with artefacts may still serve as suitable design templates with minimal adjustments. Furthermore, this research also assesses compliance with two manufacturing constraints: the limitations on build space and passive elements (voids). Incorporating manufacturing constraints into model design ensures that the generated designs are not only optimized for performance but also feasible for production. By adhering to these constraints, the models can deliver superior performance in future use while maintaining practicality in real-world applications. Full article
(This article belongs to the Special Issue Design, Processes and Materials for Additive Manufacturing)
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22 pages, 7692 KiB  
Article
Holistic Framework for the Implementation and Validation of PBF-LB/M with Risk Management for Individual Products through Predictive Process Stability
by Hajo Groneberg, Sven Oberdiek, Carolin Schulz, Andreas Hofmann, Alexander Schloske and Frank Doepper
J. Manuf. Mater. Process. 2024, 8(4), 158; https://doi.org/10.3390/jmmp8040158 - 25 Jul 2024
Viewed by 807
Abstract
The additive manufacturing technology powder bed fusion of metal with a laser beam (PBF-LB/M) is industrially established for tool-free production of complex and individualized components and products. While the in-processing is based on a layer-by-layer build-up of material, both upstream and downstream process [...] Read more.
The additive manufacturing technology powder bed fusion of metal with a laser beam (PBF-LB/M) is industrially established for tool-free production of complex and individualized components and products. While the in-processing is based on a layer-by-layer build-up of material, both upstream and downstream process steps (pre-processing and post-processing) are necessary for demand-oriented production. However, there are increasing concerns in the industry about the efficient and economical implementation and validation of the PBF-LB/M. Individual products for mass personalization pose a particular challenge, as they are subject to sophisticated risk management, especially in highly regulated sectors such as medical technology. Additive manufacturing using PBF-LB/M is a suitable technology but a complex one to master in this environment. A structured system for holistic decision-making concerning technical and economic feasibility, as well as quality and risk-oriented process management, is currently not available. In the context of this research, a framework is proposed that demonstrates the essential steps for the systematic implementation and validation of PBF-LB/M in two structured phases. The intention is to make process-related key performance indicators such as part accuracy, surface finish, mechanical properties, and production efficiency controllable and ensure reliable product manufacturing. The framework is then visualized and evaluated using a practice-oriented case study environment. Full article
(This article belongs to the Special Issue Design, Processes and Materials for Additive Manufacturing)
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32 pages, 22728 KiB  
Article
Selective Sheet Extrusion: A Novel Manufacturing Process for Large-Format Material Extrusion
by Brian Parrott, Angelica Coronado Preciado and Eric Feron
J. Manuf. Mater. Process. 2024, 8(4), 145; https://doi.org/10.3390/jmmp8040145 - 5 Jul 2024
Viewed by 820
Abstract
The trade-off between resolution and speed represents a significant challenge when extrusion-based additive manufacturing (AM) is used for large-format additive manufacturing (LFAM). This paper presents an analysis of a new material extrusion process, named selective sheet extrusion (SSE), that aims to decouple these [...] Read more.
The trade-off between resolution and speed represents a significant challenge when extrusion-based additive manufacturing (AM) is used for large-format additive manufacturing (LFAM). This paper presents an analysis of a new material extrusion process, named selective sheet extrusion (SSE), that aims to decouple these parameters. Unlike traditional single-nozzle material extrusion processes, SSE utilizes a single, very wide nozzle through which extrusion is controlled by an array of dynamically actuated teeth at the nozzle outlet. This allows the system to deposit a selectively structured sheet of material with each pass, potentially enabling the deposition of an entire layer of a part in a single pass. An analysis of the theoretical performance of the SSE technology, in terms of speed and material efficiency in comparison with single-nozzle extrusion systems, predicted speed increases of 2–3 times for the geometries that were explored. The analysis was then validated through experimental work that indicated a normalized improvement in print speed of between 2.3 and 2.5 times using a proof-of-concept SSE prototype. The SSE concept expands the opportunity frontier of LFAM technologies by enabling enhanced print speeds, while maintaining higher resolutions at scale. This enhancement in speed and/or resolution could have significant benefits, especially in large-scale prints that benefit from enhanced internal resolution. Full article
(This article belongs to the Special Issue Design, Processes and Materials for Additive Manufacturing)
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18 pages, 5960 KiB  
Article
Effect of Lattice Structure on Mechanical Properties of Ti-6Al-4V-Ta Alloy for Improved Antibacterial Properties
by Anel Zhumabekova, Malika Toleubekova, Tri Thanh Pham, Didier Talamona and Asma Perveen
J. Manuf. Mater. Process. 2024, 8(4), 133; https://doi.org/10.3390/jmmp8040133 - 26 Jun 2024
Viewed by 1523
Abstract
This study investigates the effect of a tantalum addition and lattice structure design on the mechanical and antibacterial properties of Ti-6Al-4V alloys. TPMS lattice structures, such as Diamond, Gyroid, and Primitive, were generated by MSLattice 1.0 software and manufactured using laser powder bed [...] Read more.
This study investigates the effect of a tantalum addition and lattice structure design on the mechanical and antibacterial properties of Ti-6Al-4V alloys. TPMS lattice structures, such as Diamond, Gyroid, and Primitive, were generated by MSLattice 1.0 software and manufactured using laser powder bed fusion (LPBF). The results indicate that Gyroid and Primitive structures at a 40% density exhibit superior ultimate compressive strength, which closely emulates bone’s biomechanical properties. To be precise, adding 8% tantalum (Ta) significantly increases the material’s elastic modulus and energy absorption, enhancing the material’s suitability for dynamic load-bearing implants. Nevertheless, the Ta treatment reduces bacterial biofilm formation, especially on Gyroid surfaces, suggesting its potential for infection management. Overall, all findings provide critical insights into the development of advanced implant materials, contributing to the fields of additive manufacturing, materials science, and biomedical engineering and paving the way for improved patient outcomes in orthopedic applications. Full article
(This article belongs to the Special Issue Design, Processes and Materials for Additive Manufacturing)
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16 pages, 13981 KiB  
Article
Electrical Smoothing of the Powder Bed Surface in Laser-Based Powder Bed Fusion of Metals
by Andreas Hofmann, Tim Grotz, Nico Köstler, Alexander Mahr and Frank Döpper
J. Manuf. Mater. Process. 2024, 8(3), 112; https://doi.org/10.3390/jmmp8030112 - 28 May 2024
Cited by 1 | Viewed by 964
Abstract
Achieving a homogeneous and uniform powder bed surface as well as a defined, uniform layer thickness is crucial for achieving reproducible component properties that meet requirements when powder bed fusion of metals with a laser beam. The existing recoating processes cause wear of [...] Read more.
Achieving a homogeneous and uniform powder bed surface as well as a defined, uniform layer thickness is crucial for achieving reproducible component properties that meet requirements when powder bed fusion of metals with a laser beam. The existing recoating processes cause wear of the recoater blade due to protruded, melted obstacles, which affects the powder bed surface quality locally. Impairments to the powder bed surface quality have a negative effect on the resulting component properties such as surface quality and relative density. This can lead either to scrapped components or to additional work steps such as surface reworking. In this work, an electric smoother is presented with which a wear-free and contactless smoothing of the powder bed can be realized. The achievable powder bed surface quality was analyzed using optical profilometry. It was found that the electric smoother can compensate for impairments in the powder bed surface and achieve a reproducible surface quality of the powder bed regardless of the initial extent of the impairments. Consequently, the electric smoother offers a promising opportunity to reduce the scrap rate in PBF-LB/M and to increase component quality. Full article
(This article belongs to the Special Issue Design, Processes and Materials for Additive Manufacturing)
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20 pages, 807 KiB  
Article
Faster Evaluation of Dimensional Machine Performance in Additive Manufacturing by Using COMPAQT Parts
by Laurent Spitaels, Endika Nieto Fuentes, Valentin Dambly, Edouard Rivière-Lorphèvre, Pedro-José Arrazola and François Ducobu
J. Manuf. Mater. Process. 2024, 8(3), 100; https://doi.org/10.3390/jmmp8030100 - 16 May 2024
Viewed by 833
Abstract
Knowing the tolerance interval capabilities (TICs) of a manufacturing process is of prime interest, especially if specifications link the manufacturer to a customer. These TICs can be determined using the machine performance concept of ISO 22514. However, few works have applied this to [...] Read more.
Knowing the tolerance interval capabilities (TICs) of a manufacturing process is of prime interest, especially if specifications link the manufacturer to a customer. These TICs can be determined using the machine performance concept of ISO 22514. However, few works have applied this to Additive Manufacturing printers, while testing most of the printing area as recommended takes a very long time (nearly 1 month is common). This paper, by proposing a novel part design called COMPAQT (Component for Machine Performances Assessment in Quick Time), aims at giving the same level of printing area coverage, while keeping the manufacturing time below 24 h. The method was successfully tested on a material extrusion printer. It allowed the determination of potential and real machine tolerance interval capabilities. Independently of the feature size, those aligned with the X axis achieved lower TICs than those aligned with the Y axis, while the Z axis exhibited the best performance. The measurements specific to one part exhibited a systematic error centered around 0 mm ± 0.050 mm, while those involving two parts reached up to 0.314 mm of deviation. COMPAQT can be used in two applications: evaluating printer tolerance interval capabilities and tracking its long-term performance by incorporating it into batches of other parts. Full article
(This article belongs to the Special Issue Design, Processes and Materials for Additive Manufacturing)
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18 pages, 22575 KiB  
Article
Improving the Mechanical Properties of GlassFibre-Reinforced Laser-Sintered Parts Based on Degree of Crystallinity and Porosity Content Using a Warm Isostatic Pressing (WIP) Process
by Hellen De Coninck, Jae Won Choi, Jeroen Soete, Sebastian Meyers and Brecht Van Hooreweder
J. Manuf. Mater. Process. 2024, 8(2), 64; https://doi.org/10.3390/jmmp8020064 - 25 Mar 2024
Viewed by 1323
Abstract
Additively manufactured fibre-reinforced polymers are gaining traction. After the development and optimisation of a novel fibre-deposition system in a laser sintering (LS) setup, polyamide 12 specimens were produced with and without glass fibres. In this study, the relation between the crystallinity, porosity, and [...] Read more.
Additively manufactured fibre-reinforced polymers are gaining traction. After the development and optimisation of a novel fibre-deposition system in a laser sintering (LS) setup, polyamide 12 specimens were produced with and without glass fibres. In this study, the relation between the crystallinity, porosity, and mechanical properties of LS specimens with and without fibres is investigated. After testing as-built LS specimens, a detrimental effect of the fibres on the specimens’ performance was observed with a decrease in UTS of 6%. The degree of crystallinity remained the same; however, a porosity content of 2.6% was observed in specimens with fibres. These pores can have a negative influence on the bonding between the fibres and the matrix. To investigate the influence of the pores, warm isostatic pressing (WIP) was performed on LS specimens with and without fibres. The WIP process shows a positive influence on the specimens without fibres, resulting in an increase in UTS of 8.5%. The influence of the WIP process on specimens with fibres, however, is much less pronounced, with an increase in UTS of only 2%. Neither the crystallinity nor the porosity are the cause of the less-than-expected increase in UTS in LS specimens with fibres. A number of hypotheses and mitigation strategies are provided. Full article
(This article belongs to the Special Issue Design, Processes and Materials for Additive Manufacturing)
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0 pages, 10373 KiB  
Article
Advances in Additive Friction Extrusion Deposition (AFED): Process and Tool Design
by Max Hossfeld and Arnold Wright
J. Manuf. Mater. Process. 2024, 8(2), 57; https://doi.org/10.3390/jmmp8020057 - 5 Mar 2024
Viewed by 2452
Abstract
Additive friction extrusion deposition (AFED) is a recently developed additive manufacturing technique that promises high deposition rates at low forces. Due to the novelty of the process, the underlying phenomena and their interactions are not fully understood, and in particular, the processing strategy [...] Read more.
Additive friction extrusion deposition (AFED) is a recently developed additive manufacturing technique that promises high deposition rates at low forces. Due to the novelty of the process, the underlying phenomena and their interactions are not fully understood, and in particular, the processing strategy and tool design are still in their infancy. This work contributes to the state-of-the-art of AFED through a comprehensive analysis of its working principles and an experimental program, including a representative sample component. The working principle and process mechanics of AFED are broken down into their individual components. The forces and their origins and effects on the process are described, and measures of process efficiency and theoretical minimum energy consumption are derived. Three geometrical features of the extrusion die were identified as most relevant to the active material flow, process forces, and deposition quality: the topography of the inner and outer circular surfaces and the geometry of its extrusion channels. Based on this, the experimental program investigated seven different tool designs in terms of efficiency, force reduction, and throughput. The experiments using AA 6061-T6 as feedstock show that AFED is capable of both high material throughput (close to 550 mm3/s) and reduced substrate forces, for example, the forces for a run at 100 mm3/s remained continuously below 500 N and for a run at 400 mm3/s below 3500 N. The material flow and microstructure of AFED were assessed from macro-sections. Significant differences were found between the advancing and retracting sides for both process effects and material flow. Banded structures in the microstructure show strong similarities to other solid-state processes. The manufacturing of the sample components demonstrates that AFED is already capable of producing industrial-grade components. In mechanical tests, interlayer bonding defects resulted in more brittle failure behavior in the build direction of the structure, whereas in the horizontal direction, mechanical properties corresponding to a T4 temper were achieved. Full article
(This article belongs to the Special Issue Design, Processes and Materials for Additive Manufacturing)
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17 pages, 5631 KiB  
Article
Characterization of the Dimensional Precision, Physical Bonding, and Tensile Performance of 3D-Printed PLA Parts with Different Printing Temperature
by Rayson Pang, Mun Kou Lai, Khairul Izwan Ismail and Tze Chuen Yap
J. Manuf. Mater. Process. 2024, 8(2), 56; https://doi.org/10.3390/jmmp8020056 - 5 Mar 2024
Cited by 1 | Viewed by 2178
Abstract
In this study, tensile test specimens were fabricated using a material extrusion 3D-printer at various printing temperatures to evaluate the development of physical bonds within the same layer as well as in between previous layers. The tensile test specimens were fabricated using PLA [...] Read more.
In this study, tensile test specimens were fabricated using a material extrusion 3D-printer at various printing temperatures to evaluate the development of physical bonds within the same layer as well as in between previous layers. The tensile test specimens were fabricated using PLA material, with printing temperatures ranging from 180 °C to 260 °C. Experimental investigations were conducted to investigate the dimensional accuracy and physical appearance of the parts across printing temperatures. Uniaxial tensile tests were conducted at a strain rate of 1 mm/min and repeated five times for each variable in accordance with the ASTM D638-14 standard. Results showed that increasing the printing temperatures yielded parts with better tensile properties. An approximate difference of 40% in tensile strength was observed between specimens fabricated under the two most extreme conditions (180 °C and 260 °C). The changes in tensile properties were attributed to bonding mechanisms related to interlayer bonding strength and a reduction in voids within the internal geometry. Analysis of the fracture surface using scanning electron microscopy (SEM) revealed fewer and smaller voids within the internal geometry for parts printed at higher temperature. The percentage area of voids reduced significantly when the printing temperature was increased from 180 °C to 220 °C. The tensile properties continuously improved with the printing temperature, with parts printed at 220 °C exhibiting the highest dimensional accuracy. The findings offer insight into the impact of the printing temperature on both the external physical bonds between printed roads, affecting the physical appearance and dimensional accuracy, and the internal bonds, affecting the tensile properties of the fabricated parts. Full article
(This article belongs to the Special Issue Design, Processes and Materials for Additive Manufacturing)
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Review

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20 pages, 305 KiB  
Review
Computer-Aided Optimisation in Additive Manufacturing Processes: A State of the Art Survey
by Tanja Emilie Henriksen, Tanita Fossli Brustad, Rune Dalmo and Aleksander Pedersen
J. Manuf. Mater. Process. 2024, 8(2), 76; https://doi.org/10.3390/jmmp8020076 - 15 Apr 2024
Viewed by 1360
Abstract
Additive manufacturing (AM) is a field with both industrial and academic significance. Computer-aided optimisation has brought advances to this field over the years, but challenges and areas of improvement still remain. Design to execution inaccuracies, void formation, material anisotropy, and surface quality are [...] Read more.
Additive manufacturing (AM) is a field with both industrial and academic significance. Computer-aided optimisation has brought advances to this field over the years, but challenges and areas of improvement still remain. Design to execution inaccuracies, void formation, material anisotropy, and surface quality are examples of remaining challenges. These challenges can be improved via some of the trending optimisation topics, such as artificial intelligence (AI) and machine learning (ML); STL correction, replacement, or removal; slicing algorithms; and simulations. This paper reviews AM and its history with a special focus on the printing process and how it can be optimised using computer software. The most important new contribution is a survey of the present challenges connected with the prevailing optimisation topics. This can be seen as a foundation for future research. In addition, we suggest how certain challenges can be improved and show how such changes affect the printing process. Full article
(This article belongs to the Special Issue Design, Processes and Materials for Additive Manufacturing)
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