Additive Manufacturing Applications Research Articles

Industry 4.0 and Sustainability: a Study on the Applicability of Additive Manufacturing as a Tool for Minimizing Environmental Impacts on Production Processes

Objective: The present research sought to analyze the applicability of additive manufacturing as a tool for minimizing environmental damage in production processes. Methodology: The research was conducted through an integrative literature review. Academic platforms such as SciELO and Google Academic were consulted, using specific keywords related to the theme. Inclusion criteria were established to select complete articles, in Portuguese and Brazilian languages, directly associated with the research theme, published between 2020 and 2024. Results and data analysis: The revised studies emphasize the growing importance of additive manufacturing (AM) and 3D printing technology in transforming production processes towards more sustainable and efficient practices. MA's ability to produce complex parts accurately and personalized, significantly reducing raw material waste through layer-by-layer manufacturing, stands out as a crucial tool to minimize environmental impacts on production. In addition, the integration of MA in the early stages of product development promotes efficiency in production, although more in-depth studies on its environmental and energy impacts are needed. Conclusion: It is therefore concluded that additive manufacturing is an essential tool for more sustainable and innovative practices in the industry, promoting the conservation of natural resources, the reduction of waste and the creation of adaptable and customized solutions. It is therefore up to companies and society to exploit and develop these technologies in search of a more sustainable and competitive future.

Untapped Opportunities in Additive Manufacturing with Metals: From New and Graded Materials to Post-Processing

Metal additive manufacturing (AM) is an innovative manufacturing method with numerous metallurgical benefits, including fine and hierarchical microstructures and enhanced mechanical properties, thanks to the utilization of a local heat source and the rapid solidification nature of the process. High levels of productivity, together with the ability to produce complex geometries and large components, have added to the versatile applicability of metal AM with applications already implemented in various sectors such as medicine, transportation, and aerospace. To further enhance the potential benefits of AM in the context of small- to medium-scale bulk production, metallurgical complexities should be determined and investigated. Hence, this review paper focuses on three significant metallurgical aspects of metal AM processes: in situ alloying, functionally graded materials, and surface treatments for AM parts. The current text is expected to offer insights for future research works on metal AM to expand its potential applications in various advanced manufacturing sectors.

GENETIC ALGORITHM-BASED OPTIMIZATION OF THE LASER-BEAM PATH IN ADDITIVE MANUFACTURING

This study presents a methodology of genetic-algorithm-based optimization of the laser-beam path for improving laser-based additive manufacturing (AM). A simple thermal model was developed to simulate the effects of laser-induced heat input on the temperature distribution within the substrate during the fabrication of one layer. The optimization approach aims to find solutions with more homogeneous temperature properties that minimize the thermal gradient on the substrate caused by laser-based AM. The laser beam, i.e., the tool-path planning, is formulated as the search for the optimal sequence of cell depositions that minimize the fitness function, which is composed of two components, i.e., the thermal fitness and process fitness. The thermal fitness is expressed as the average thermal gradient, and the process fitness regulates the suitability of the proposed tool path for the implementation of the AM process. Various tool-path generators are proposed to initialize the initial population of tool-path solutions. Genetic-algorithm-based tool-path optimization is proposed, where custom initialization, crossover and mutation operators are developed for application in laser-based AM. Simulation studies demonstrate the effectiveness of the genetic-algorithm-based optimization in finding solutions that minimize the fitness function and therefore provide both thermally and, for the AM process implementation, more suitable laser-beam-path solutions.

High-resolution metal 3D printing via digital light processing

Three-dimensional (3D) printing of complex metallic parts with a micrometer resolution can extend the application of additive manufacturing to various fields wherein the mechanical, thermal, and electrical properties of metals are essential. Digital light processing (DLP) offers high-resolution and scalable 3D printing via vat photopolymerization (VPP). We present a high-precision metal 3D printing method, namely lithography metal additive manufacturing (LMAM) that uses DLP for a photosensitive resin filled with metal powder. The printing process and sintering conditions for a stainless-steel feedstock are discussed. Highly complex and hollow structures with a spatial resolution of 35 μm and surface roughness as low as 1 <Ra < 2 μm can be printed on a decimeter scale without any support structures. The density and tensile strength of the sintered parts are 99.3 % and 93 %, respectively, of those of annealed 316 L steel. The LMAM method is suitable for manufacturing small and highly accurate devices with tailored designs in diverse areas, such as microheat exchangers, biomedical implants, and metamaterials, as well as extends metal 3D printing to chemical engineering for pharmaceutical applications.

Embedding lattice structures into ship hulls for structural optimization and additive manufacturing

Additive manufacturing (AM) has been making inroads into the shipbuilding industry. The maritime sector has recognized the potential benefits of AM in terms of cost savings, design flexibility, and rapid prototyping. Lattice structures, known for their vast applications in AM and associated benefits like lightweight design, energy efficiency, and improved material usage, serve as a focal point in this shifting landscape.This paper presents a pioneering approach to integrating lattice structures into shipbuilding via AM, specifically for supporting ship volumes. The method introduces algorithms to create both conformal and uniform lattice structures for structural optimization. According to the case studies in this work, ship models with lattice structures have superior structural properties compared to conventional support elements.

Application of additive manufacturing in developing smoke and flame detectors for a habitable microgravity environment

Application of additive manufacturing in developing smoke and flame detectors for a habitable microgravity environment

Additive manufacturing of hydrogel-based lunar regolith pastes: A pathway toward in-situ resource utilization and in-space manufacturing

Additive Manufacturing (AM), combined with efficient in-situ resource utilization, has the potential to enable sustained presence on the Moon through in-situ production and replacement of construction blocks, engineered parts, and devices in the lunar terrain. As an initial step toward realizing this vision, this work proposes a new material formulation utilizing lunar regolith simulants (LHS-1), water, and a hydrophilic hydrogel-forming polymer (Pluronic F127) to produce a hydrogel-based lunar regolith paste suitable for material extrusion AM. This formulation enables the use of water as another potential lunar in-situ resource for the first time in the literature, considering the recent confirmation of large quantities of water-ice in the shadowed craters around the lunar poles and the presence of water on the sunlit surface of the Moon. To systematically investigate the viability of the proposed hydrogel-based lunar regolith material feedstock and the application of material extrusion AM, this work introduces a three-stage design of experiment (DOE) framework to achieve two fundamental objectives. First, the viable range of lunar regolith simulant in the hydrogel-based material formulation is identified using a categorical quality evaluation of single and multi-layer material depositions. Second, the material printability window is established in terms of printing speed and extrusion rate for different viable material compositions through hierarchically designed experiments. The observed porosity of the sintered parts decreased with increasing regolith content in the material composition, while the density and compressive strength increased with higher regolith content. For material compositions consisting of 25–40 vol% regolith simulants, the observed porosity of the sintered parts decreased from 6.4 to 2.18 %, their density increased from 0.78 to 0.89 g/cm3, and their average compressive strength ranged between 0.68 and 1.32 MPa. Finally, the printability of the material was demonstrated by producing various prototype hand tools and lab-scale construction blocks with varying geometrical complexities. This work represents a crucial step toward in situ resource utilization and sustainable in-space manufacturing, sets the stage for future investigations, and the introduced DOE driven framework offers a pathway toward systematically identifying the optimal material compositions and the corresponding process parameters to enable high-quality prints.

Micromechanical Dilution of PLA/PETG-Glass/Iron Nanocomposites: A More Efficient Molecular Dynamics Approach.

Polylactic acid (PLA) and poly(ethylene terephthalate glycol) (PETG) are popular thermoplastics used in additive manufacturing applications. The mechanical properties of PLA and PETG can be significantly improved by introducing fillers, such as glass and iron nanoparticles (NPs), into the polymer matrix. Molecular dynamics (MD) simulations with the reactive INTERFACE force field were used to predict the mechanical responses of neat PLA/PETG and PLA-glass/iron and PETG-glass/iron nanocomposites with relatively high loadings of glass/iron NPs. We found that the iron and glass NPs significantly increased the elastic moduli of the PLA matrix, while the PETG matrix exhibited modest increases in elastic moduli. This difference in reinforcement ability may be due to the slightly greater attraction between the glass/iron NP and PLA matrix. The NASA Multiscale Analysis Tool was used to predict the mechanical response across a range of volume percent glass/iron filler by using only the neat and highly loaded MD predictions as input. This provides a faster and more efficient approach than creating multiple MD models per volume percent per polymer/filler combination. To validate the micromechanics predictions, experimental samples incorporating hollow glass microspheres (MS) and carbonyl iron particles (CIP) into PLA/PETG were developed and tested for elastic modulus. The CIP produced a larger reinforcement in elastic modulus than the MS, with similar increases in elastic modulus between PLA/CIP and PETG/CIP at 7.77 vol % CIP. The micromechanics-based mechanical predictions compare excellently with the experimental values, validating the integrated micromechanical/MD simulation-based approach.

Additive Manufacturing for Surgical Planning and Education: A Review

Additive manufacturing has been widely used in various industries, including the healthcare sector. Over the last few decades, AM has been playing an important role in the medical field in different areas, including surgical planning, implants, and educational activities. For surgical applications, AM can help surgeons practice and plan an operation until they are confident with the process. This can help to reduce operational risk and time. In addition, it can help to demonstrate the problem to other colleagues. AM has also been used to produce 3D models to teach students and doctors about human anatomy. This paper aims to comprehensively review the diverse applications of additive manufacturing within the domains of surgical planning and medical education. By focusing on the multifaceted roles played by AM in these critical areas, a contribution to the growing body of knowledge that underscores the transformative potential of this technology in shaping the future of healthcare practices is sought to be made.

INNOVATIVE MATERIAL PROCESSING TECHNIQUES IN PRECISION MANUFACTURING: A REVIEW

Precision manufacturing plays a pivotal role in various industries, demanding high accuracy, efficiency, and quality in the production process. The continual pursuit of innovation in material processing techniques is essential to meet evolving demands and challenges. This review explores the latest advancements and innovations in material processing methods within precision manufacturing. The review encompasses a comprehensive analysis of various innovative material processing techniques, including additive manufacturing, subtractive manufacturing, and hybrid approaches. Additive manufacturing, often referred to as 3D printing, has gained significant attention for its capability to produce complex geometries with high precision. The exploration of novel materials, such as metal alloys, polymers, and composites, expands the applicability of additive manufacturing in diverse industrial sectors. Subtractive manufacturing techniques, such as milling, turning, and grinding, are also undergoing transformative advancements to enhance precision and efficiency. Emerging technologies like abrasive waterjet machining, electrical discharge machining (EDM), and laser machining offer improved accuracy and surface finish while enabling the processing of a wide range of materials, including hard-to-machine alloys and composites. Hybrid manufacturing approaches, combining additive and subtractive techniques, are revolutionizing precision manufacturing by leveraging the strengths of both methods. These hybrid systems enable the production of intricate components with high precision, reduced lead times, and minimized material waste, addressing the challenges of traditional manufacturing processes. Furthermore, the review highlights advancements in process monitoring and control technologies, such as in-process sensing, real-time feedback systems, and adaptive control algorithms, facilitating enhanced quality assurance and productivity in precision manufacturing. The integration of advanced computational tools, simulation techniques, and artificial intelligence further augments the optimization and customization capabilities of material processing techniques, driving efficiency and innovation in precision manufacturing. Overall, this review provides valuable insights into the latest developments and trends in innovative material processing techniques, offering a roadmap for future research directions and applications in precision manufacturing industries.&#x0D; Keywords: Material, Processing, Techniques, Precision, Manufacturing, Review.

Insights into the assessment of spreadability of stainless steel powders in additive manufacturing

This work investigates the link between the single particle and bulk flow properties of stainless steel (SS316L) powders and their spreading behaviour for additive manufacturing (AM) application. Two different batches of SS316L powders, noted to have significantly different spreading behaviour in AM machines, were investigated. The two batches had almost identical particle size, morphology and bulk flow properties as quantified by angle of repose, Hausner ratio, Carr index and basic flow energy; however one of the batches did not consistently flow during Hall and Carney flow tests and also had very poor spreadability when evaluated using an in-house spreading rig. The flow and spreading behaviours of the poorly spreading batch significantly improved and became almost identical to the good batch when tested following drying, either in a vacuum oven or a freeze dryer. Elemental analysis revealed that batches had some small but significant differences in chemical composition. This study revealed the complexity of defining a correlation between powder properties and spreading behaviour, and the importance of considering the environmental conditions.

Microstructure and mechanical properties of Cu-Cr-Zr alloy prepared by electron beam additive manufacturing and laser-MIG hybrid welding

Cu-Cr-Zr alloys are widely used as medium-strength and high-conductivity copper alloys in aerospace, transportation and electronic information fields. The application of additive manufacturing technology is expected to realize the preparation of Cu-Cr-Zr alloy parts with complex structure and superior property. However, the commonly used laser additive manufacturing technology is not applicable to the preparation of copper alloys due to its intrinsic high reflection to laser. In this study, we adopted two technologies, i.e., electron beam additive manufacturing (EBAM) and laser-metal inert gas hybrid welding (laser-MIG), for the preparation of Cu-Cr-Zr alloys. Finite element simulation was employed to simulate the temperature field and residual stress field of the material during solidification. The microstructure, relative density, microhardness, tensile properties and electrical conductivity of the as-fabricated samples were characterized. The results showed that samples with better moldability were obtained by both methods at a line energy density of 600 J/mm. In the top area, both methods exhibit medium-sized equiaxed grains with more precipitated phases, showing the best comprehensive properties. The EBAM method demonstrates superior formability, better relative density and electrical conductivity due to more stable temperature field changes. On the other hand, the laser-MIG method obtains finer grains and higher mechanical properties because of a faster cooling rate, but leads to a decrease in relative density and electrical conductivity. This study presents new experimental data for Cu-Cr-Zr alloys prepared by EBAM and laser-MIG methods, contributing to extend the application of additive manufacturing in the preparation of Cu alloys.

Catalytic Chain Transfer in Crosslinking Photopolymerizations

AbstractPresented here is a detailed account of the development and implementation of macrocyclic cobaloxime complexes as sulfur-free, catalytic chain transfer agents (CTAs) in crosslinking photopolymerizations. Although much of this review is dedicated to understanding the fundamentals of catalytic chain transfer (CCT) in photopolymerizations, its impact on network topology and resultant mechanical properties, future goals of applying this technology to multimaterial 3D printing are also discussed. It is our long-term ambition for catalytic, sulfur-free CTAs to supplant existing consumptive, sulfur-based agents to provide new, unexplored, and not currently possible to fabricate photopolymeric materials with a specific eye towards application in dentistry, additive manufacturing, and responsive materials.1 Introduction2 History of Catalytic Chain Transfer (CCT)3 Understanding Catalyst Purity and Chain Transfer Activity4 Evidencing CCT in a Crosslinking Photopolymerization5 Comparing Cobalt(II)-Catalysts to Other Relevant CTAs6 Performance of Cobalt(II)-Catalysts in Commercial Resins7 Limitations of Approach and Looking Forward

Additively manufactured patient specific implants: A review

Medical applications of additive manufacturing have seen a significant growth in recent years due to availability of advanced medical imaging and design software and wide range of materials. The range of additively manufactured medical implants is growing rapidly and surgeons need to keep themselves updated with state-of-the-art of the technology. This article reviews several articles related to medical implants to help surgeons and researchers to stay up-to-date on recent developments in the domain. Additively manufactured medical implants are reviewed into five categories: orthopedic implants, dental implants, cranioplasty implants, scaffold implants for tissue engineering and other medical implants including chest wall reconstructive implants, anti-migration enhanced tracheal stents, and buccopharyngeal stents. Additive manufacturing process and material for fabrication of each type of implant are highlighted in the study. It has been observed that titanium alloy is a suitable material for cementless arthroplasty. Porosity in the implants supports bone ingrowth, which results in a significant reduction in stress shielding. Additive manufacturing has a very attractive future in medical implant fabrication due to its capability to produce complex and customized implants. The AM provides freedom to researcher to explore the complex design of medical implants for better bone regeneration and improved osseointegration.

Excipients in Pharmaceutical Additive Manufacturing: A Comprehensive Exploration of Polymeric Material Selection for Enhanced 3D Printing.

This review provides a comprehensive overview of additive manufacturing (AM) or 3D-printing (3DP) applications in the pharmaceutical industry, with a particular focus on the critical role of polymer selection. By providing insights into how material properties influence the 3DP process and the quality of the final product, this review aims to contribute to a better understanding of the interplay between polymers and pharmaceutical 3DP. As 3DP technologies are increasingly integrated into pharmaceutical sciences, this review contributes insights into the nuanced process of polymer selection, serving mainly as a foundational guide for researchers and formulators new to the subject seeking to harness the full potential of pharmaceutical 3DP by understanding the physicochemical properties, roles, and functions of used polymers in 3D-printed dosage forms and medical devices.

Wire Based Directed Energy Deposition of JBK-75

Applications and adoption of metal additive manufacturing (AM) are increasing for fabrication of low volume, complex components with novel materials, as well as replacement parts. While the use of powder bed fusion-based processes have been widely used to build complex components with fine feature resolution, there is a volume limitation. Expanding the application of metal AM will rely on other processes that remove this build size constraint. These processes are referred to as Directed Energy Deposition (DED) and can use either powder or wire feedstock. Wire based DED provides the highest deposition rates which shortens the fabrication time making it attractive for fabrication of large parts replacing traditional wrought billets or castings. In this study, an iron-based austenitic superalloy (JBK-75) was deposited using an arc-based, wire-fed (AW)-DED process. The material was metallographically characterized and quasi-static mechanical properties were obtained. The resulting microstructure and mechanical properties are compared with conventional wrought and cast forms of JBK-75 subjected to the same heat treatments. As compared to wrought material, the AW-DED grain size was larger after the heat treatment, although the strengths were similar. Improved homogenization was observed after heat treatment in the AW-DED specimens as compared to the cast specimens.

Efficient bead-on-plate weld model for parameter estimation towards effective wire arc additive manufacturing simulation

AbstractDespite the advances in hardware and software techniques, standard numerical methods fail in providing real-time simulations, especially for complex processes such as additive manufacturing applications. A real-time simulation enables process control through the combination of process monitoring and automated feedback, which increases the flexibility and quality of a process. Typically, before producing a whole additive manufacturing structure, a simplified experiment in the form of a bead-on-plate experiment is performed to get a first insight into the process and to set parameters suitably. In this work, a reduced order model for the transient thermal problem of the bead-on-plate weld simulation is developed, allowing an efficient model calibration and control of the process. The proposed approach applies the proper generalized decomposition (PGD) method, a popular model order reduction technique, to decrease the computational effort of each model evaluation required multiple times in parameter estimation, control, and optimization. The welding torch is modeled by a moving heat source, which leads to difficulties separating space and time, a key ingredient in PGD simulations. A novel approach for separating space and time is applied and extended to 3D problems allowing the derivation of an efficient separated representation of the temperature. The results are verified against a standard finite element model showing excellent agreement. The reduced order model is also leveraged in a Bayesian model parameter estimation setup, speeding up calibrations and ultimately leading to an optimized real-time simulation approach for welding experiment using synthetic as well as real measurement data.

Technological Advances in Mechanical Recycling Innovations and Corresponding Impacts on the Circular Economy of Plastics

The impact of plastic pollution on the world and its inhabitants is yet to be fully measured. Significant quantities of microplastics and nanoplastics have been found in human organs, and many diseases have been traced to their presence. Even human placentas have been found to contain microplastics. This study examines the recycling landscape, advanced reprocessing techniques, and technical challenges in this industry. It points out the top recyclable types of plastics (such as high-density polyethylene, polyethylene terephthalate, and thermoplastic elastomers) by analyzing their different recycling capacities globally. It highlights the most advisable recycling techniques by identifying those most successful, least environmentally damaging, and easiest. Mechanical recycling is arguably the easiest and most common recycling technique. This study examines mechanical reprocessing technologies for construction materials, composite boards, additive manufacturing, and other applications. It also points out prevailing setbacks of these approaches and analyzes different solutions. Promising recycling processes are suggested for further investigation.

Failure of 3D-printed composite continuous carbon fibre hexagonal frames

This study presents an approach to enhancing and expanding the structural performance of composite materials by tailoring their geometry. We explored the potential of continuous carbon fibre composite additive printing to create complaint frames based on hexagonal cell design with the aim to better understand and control their mechanical performance. Our investigation examines the failure behaviour of these frames under remote tensile loading. By experimenting with various geometries and aspect ratios at the frame sites, we gained insight into different failure loads and modes. To predict these results, we developed a computational model based on multiscale homogenisation and the Hashin damage criterion, which showed a high degree of precision compared to our experimental results. The findings validate the effectiveness of our computational model, but also highlight the practical applications of additive manufacturing of composites. This research aims to contribute to the advancement of structural design and material optimisation by engineering of composite materials for specific applications, emphasising the integration of their intrinsic strength and lightweight properties with material efficiency and compliance achieved through geometric design considerations.

Large‐Area, High‐Numerical‐Aperture, Freeform Metasurfaces

AbstractNanophotonic devices are optical platforms capable of unprecedented wavefront control. To push the limits of experimental device performance, scalable design methodologies that combine the simplicity and fabricability of conventional design paradigms with the extended capabilities of freeform optimization are required. A novel gradient‐based design framework for large‐area freeform metasurfaces is introduced in which nonlocal interactions between simply shaped nanostructures, placed on an irregular lattice, are tailored to produce high‐order hybridized modes that support customizable large‐angle scattering profiles. Utilizing this approach, multifunctional super‐dispersive metalenses are designed and experimentally demonstrated. The approach to high‐numerical‐aperture radial metalenses capable of diffraction limited focusing and the generation of donut‐shaped point spread functions is also extended. It is anticipated that these concepts will have utility in super‐resolution microscopy, particle trapping, additive manufacturing, and metrology applications that require ultra‐high numerical apertures.