Additive Manufacturing Applications Research Articles

A facile strategy for tuning the density of surface-grafted biomolecules for melt extrusion-based additive manufacturing applications

AbstractMelt extrusion-based additive manufacturing (ME-AM) is a promising technique to fabricate porous scaffolds for tissue engineering applications. However, most synthetic semicrystalline polymers do not possess the intrinsic biological activity required to control cell fate. Grafting of biomolecules on polymeric surfaces of AM scaffolds enhances the bioactivity of a construct; however, there are limited strategies available to control the surface density. Here, we report a strategy to tune the surface density of bioactive groups by blending a low molecular weight poly(ε-caprolactone)5k (PCL5k) containing orthogonally reactive azide groups with an unfunctionalized high molecular weight PCL75k at different ratios. Stable porous three-dimensional (3D) scaffolds were then fabricated using a high weight percentage (75 wt.%) of the low molecular weight PCL5k. As a proof-of-concept test, we prepared films of three different mass ratios of low and high molecular weight polymers with a thermopress and reacted with an alkynated fluorescent model compound on the surface, yielding a density of 201–561 pmol/cm2. Subsequently, a bone morphogenetic protein 2 (BMP-2)-derived peptide was grafted onto the films comprising different blend compositions, and the effect of peptide surface density on the osteogenic differentiation of human mesenchymal stromal cells (hMSCs) was assessed. After two weeks of culturing in a basic medium, cells expressed higher levels of BMP receptor II (BMPRII) on films with the conjugated peptide. In addition, we found that alkaline phosphatase activity was only significantly enhanced on films containing the highest peptide density (i.e., 561 pmol/cm2), indicating the importance of the surface density. Taken together, these results emphasize that the density of surface peptides on cell differentiation must be considered at the cell-material interface. Moreover, we have presented a viable strategy for ME-AM community that desires to tune the bulk and surface functionality via blending of (modified) polymers. Furthermore, the use of alkyne–azide “click” chemistry enables spatial control over bioconjugation of many tissue-specific moieties, making this approach a versatile strategy for tissue engineering applications. Graphic abstract

Study of Mechanical behavior of 3D printed PLA Material manufactured by Fused Deposition Model Technique

Additive Manufacturing has emerged as a groundbreaking technology. This research investigates the strength-to-weight ratio of PLA material in Fused Deposition Modelling (FDM) 3D printing. Utilizing ASTM standards for specimen preparation, both tensile and compression tests were conducted to determine optimal infill patterns and densities. The study aims to provide insights into maximizing structural integrity while minimizing material usage, offering valuable implications for additive manufacturing applications.

A progressive overview of the mainstream additive manufacturing of ceramic components for industrial advancement

Additive manufacturing (AM), well-known as 3D printing, has revolutionized traditional manufacturing methods, particularly in the production of ceramic components. These techniques offer unique advantages and challenges in ceramic component production. Developing specific ceramic materials with AM improves the finished products' mechanical, thermal, and electrical characteristics. Integrating artificial intelligence and machine learning shows promise in improving process control and design optimization, spurring innovation and opening previously unimaginable possibilities, although problems such as material shrinkage, microstructural control, and surface polish remain crucial research areas. This review article presents a comprehensive overview of the advancements and applications of AM for ceramic pieces in the industrial sector. This study highlights the fundamental principles of AM, focusing on their difficulties and potential in ceramic fabrication. A comprehensive review of AM will deliver an understanding of its ability to alter industrial manufacturing and open the door to a new era of ceramic fabrication and applications.

In-Process Monitoring of Inhomogeneous Material Characteristics Based on Machine Learning for Future Application in Additive Manufacturing

In-Process Monitoring of Inhomogeneous Material Characteristics Based on Machine Learning for Future Application in Additive Manufacturing

(Thermo)mechanical and chemical characteristics of photochemically crosslinked acrylates from bio‐ and fossil‐based origin

AbstractThe acrylates with oligomers and monomers from (partially) bio‐based feedstock become available at (semi‐)industrial scale, which can be processed through photochemical crosslinking for applications in coatings, additive manufacturing, electronics, or inks. Although fossil‐ and bio‐based acrylates may have a similar chemical composition, it requires good understanding of processing and structure–property relationships as minor changes in microstructure may strongly alter the performance. A comparative study on mechanical properties and chemical structure of bio‐ and fossil‐based acrylates with different functionalities and backbone structures reveals higher ductility of bio‐based acrylates, in relation with a more complex organization of the intrinsic molecular structure. The latter is confirmed by mechanical testing and visco‐elastic characteristics (dynamic mechanical analysis) yielding lower stiffness and higher dampening of bio‐based acrylates, in parallel with a lower glass transition temperature (differential scanning calorimetry). The complex molecular arrangements include a nanoscale morphology with ordered structure (X‐ray diffraction), conformational changes (infrared spectroscopy), and a residual high‐molecular weight fraction (size exclusion chromatography). The visco‐elastic calculations indicate only 4% to 5% lower crosslinking density and around 10% higher mean molar mass of the polymer chains segments between chemical crosslinks and trapped chain entanglements, which explain the unique structure and performance of bio‐based acrylates.

Selecting subsets of source data for transfer learning with applications in metal additive manufacturing

Selecting subsets of source data for transfer learning with applications in metal additive manufacturing

Impact of deposition time per layer in large format additive manufacturing with glass fiber reinforced ABS

This paper presents a parametric study of layer adhesion in Large Format Additive Manufacturing (LFAM) applications using glass fiber (GF) reinforced acrylonitrile butadiene styrene (ABS). The study focuses on the deposition time per layer (tL) and includes an innovative approach to monitor temperature variation throughout the printing process using an infrared camera. The paper provides a detailed account of the sample fabrication process and experimental tensile tests. Specifically, this study shows how lower times per layer yield better mechanical properties as material is deposited over hotter layers, resulting in smaller thermal gradients, hence better layer adhesion and reduced warpage.

Materials and Methods for All-Cellulose 3D Printing in Sustainable Additive Manufacturing

Additive manufacturing, commonly referred to as 3D printing, is an exciting and versatile manufacturing technology that has gained traction and interest in both academic and industrial settings. Polymeric materials are essential components in a majority of the feedstocks used across the various 3D printing technologies. As the environmental ramifications of sole or primary reliance on petrochemicals as a resource for industrial polymers continue to manifest themselves on a global scale, a transition to more sustainable bioderived alternatives could offer solutions. In particular, cellulose is promising due to its global abundance, biodegradability, excellent thermal and mechanical properties, and ability to be chemically modified to suit various applications. Traditionally, native cellulose was incorporated in additive manufacturing applications only as a substrate, filler, or reinforcement for other materials because it does not melt or easily dissolve. Now, the exploration of all-cellulose 3D printed materials is invigorated by new liquid processing strategies involving liquid-like slurries, nanocolloids, and advances in direct cellulose solvents that highlight the versatility and desirable properties of this abundant biorenewable photosynthetic feedstock. This review discusses the progress of all-cellulose 3D printing approaches and the associated challenges, with the purpose of promoting future research and development of this important technology for a more sustainable industrial future.

Additive Manufacturing of Sensors: A Comprehensive Review

AbstractThe development and manufacturing of sensors are of great importance to modern engineering, as sensors are essential for detecting environmental changes and for the monitoring of various systems. While conventional manufacturing is the most common method for fabricating sensors, additive manufacturing (commonly known as 3D printing) has gained popularity as an efficient alternative. Although additively manufactured sensors are applicable in many engineering fields, building an entire sensor (including the housing structure and sensing components) by additive manufacturing remains challenging. This work presents a comprehensive analysis of the additive manufacturing processes, materials, and applications for sensors that are either fully or partially produced by additive manufacturing. Key issues in material development and processes that limit the development of fully 3D-printed sensors are highlighted. Additionally, the role of additively manufactured sensors plays in green technology has been explored. This review is expected to provide the researchers with a comprehensive understanding of the processes and materials used to produce sensors for various applications.

An investigation on application of friction stir additive manufacturing (FSAM) for the production of AA6061/TiC-graphene hybrid nanocomposite in the shape of multi-layer cylindrical part

In this research, Friction Stir Additive Manufacturing (FSAM) has been investigated for the production of AA6061/TiC-graphene hybrid nanocomposites. For this purpose, nanocomposites were produced in the shape of three-layer cylindrical parts by Friction Stir Deposition (FSD) of the AA6061 consumable rod with pre-placed reinforcement nanoparticles in it (0.25 wt%). TiC and graphene nanoparticles were chosen as the reinforcements for improving hardness and wear behavior in the additive manufactured parts, respectively. The nanocomposites were deposited with four different rotation speeds, including 1200, 1300, 1400, and 1500 rpm, under a continuous feeding speed of 25 mm/min. Also, a reference sample without any reinforcement was deposited for comparison with the nanocomposites. Appearance characteristics, microstructural specifications, hardness, wear behavior, and corrosion resistance were investigated for evaluation of the manufactured parts. FSAM led to the production of fine-grain nanocomposites (∼15–25 μm) with a relatively uniform distribution of the reinforcement nanoparticles. The addition of reinforcement nanoparticles caused improvements in hardness, wear rate, friction coefficient, and corrosion rate by about 42%, 66%, 15%, and 33%, respectively. In this regard, best-manufactured nanocomposite showed good hardness (71.5 HV), superb wear rate (260 × 10^-5 mg/N.m), low friction coefficient (0.697), and excellent corrosion rate (2.6 mpy). Finally, it was observed that performing FSD by increasing the tool rotation speed at a constant vertical speed resulted in nearly 10% grain growth and 45% dissolution of Mg-rich precipitates in the matrix. These microstructural evolutions decreased hardness (∼24%) and corrosion rate (∼50%), and increased wear rate (∼38%) and friction coefficient (∼16%) in the nanocomposites.

Fluid Ejections in Nature.

From microscopic fungi to colossal whales, fluid ejections are universal and intricate phenomena in biology, serving vital functions such as animal excretion, venom spraying, prey hunting, spore dispersal, and plant guttation. This review delves into the complex fluid physics of ejections across various scales, exploring both muscle-powered active systems and passive mechanisms driven by gravity or osmosis. It introduces a framework using dimensionless numbers to delineate transitions from dripping to jetting and elucidate the governing forces. Highlighting the understudied area of complex fluid ejections, this review not only rationalizes the biophysics involved but also uncovers potential engineering applications in soft robotics, additive manufacturing, and drug delivery. By bridging biomechanics, the physics of living systems, and fluid dynamics, this review offers valuable insights into the diverse world of fluid ejections and paves the way for future bioinspired research across the spectrum of life.

Development of microfluidically reconfigurable antenna using additive manufacturing

This research presents a microfluidically reconfigurable additively manufactured antenna. The proposed configuration demonstrates the applicability of additive manufacturing (AM) for fabricating intricate and lightweight structures. Additionally, it established the feasibility of microfluidic technology for achieving continuous frequency reconfigurability. The proposed antenna utilizes the dielectric fluid for reconfiguration, facilitated by pumping it in and out of microfluidic structures using a syringe pump. The incorporation of dielectric fluid in the channels alters the effective dielectric constant of the substrate and causes perturbations in the electric field distributions around the metallic patch. To validate the proposed idea, a prototype of the microfluidically reconfigurable 3D-printed antenna is designed, fabricated, and tested. The operating frequency is reconfigured from 2.38 to 3.49 GHz with a tuning range of 1.11 GHz, and the radiation pattern remains stable across considered cases. It is observed that measured results are in good agreement with simulated values. The prototype of the antenna design is fabricated using a single machining process, eliminating the need for traditional machining. The proposed antenna’s configuration is advantageous for various applications such as IEEE802.11b/g/n, IEEE802.15.1, and IEEE802.16.

Application of additive manufacturing in biomedical domain: a bibliometric review, thematic evolution and content analysis

Application of additive manufacturing in biomedical domain: a bibliometric review, thematic evolution and content analysis

A facile one step route that introduces functionality to polymer powders for laser sintering

Laser Sintering (LS) is a type of Additive Manufacturing (AM) exploiting laser processing of polymeric particles to produce 3D objects. Because of its ease of processability and thermo-physical properties, polyamide-12 (PA-12) represents ~95% of the polymeric materials used in LS. This constrains the functionality of the items produced, including limited available colours. Moreover, PA-12 objects tend to biofoul in wet environments. Therefore, a key challenge is to develop an inexpensive route to introduce desirable functionality to PA-12. We report a facile, clean, and scalable approach to modification of PA-12, exploiting supercritical carbon dioxide (scCO2) and free radical polymerizations to yield functionalised PA-12 materials. These can be easily printed using commercial apparatus. We demonstrate the potential by creating coloured PA-12 materials and show that the same approach can be utilized to create anti-biofouling objects. Our approach to functionalise materials could open significant new applications for AM.

Recent Developments in the Use of Plasma in Medical Applications

A detailed review of the scientific literature was undertaken to examine the most recent developments in plasma processing in the field of medicine. The first part of the review includes a detailed breakdown of the different types of coatings that can be applied onto medical devices using plasma, with a specific focus on antimicrobial surfaces. The developments in plasma-deposited biocompatibles, drug delivery and adhesive coatings in 2023 are described, and specific applications in additive manufacturing are highlighted. The use of plasma and plasma-activated liquids as standalone therapeutics continues to evolve, and pertinent advances in this field are described. In addition, the combination of plasma medicine with conventional pharmaceutical interventions is reviewed, and key emerging trends are highlighted, including the use of plasma to enhance drug delivery directly into tissue. The potential synergies between plasma medicine and chemotherapeutics for oncology and infection treatment are a growing area, and recent advancements are noted. Finally, the use of plasma to control excess antibiotics and to intentionally degrade such materials in waste streams is described.

Performance evaluation of polymer-filled metal fused filament fabrication tooling for profile extrusion

AbstractThe application of additive manufacturing (AM) for tooling in the mould and die industry brings a disruptive potential in process performance, design flexibility and product enhancements. Maturing of existing AM technologies and emerging technologies such as metal-fused filament fabrication (metal FFF) can further support the applicability of AM tooling in polymer profile extrusion. This study provides a complete characterization of metal FFF 17–4 PH stainless-steel die inserts and evaluates their applicability in a polymer extrusion process chain. The presented experimental assessment pivots on the metrological characterization of the produced inserts and the impact of the insert characteristics on the final extrudates’ product. Considering a conventionally manufactured benchmark insert, produced via subtractive methods (CNC machining and electrical discharge machining), comparable results for AM tools in terms of extrudates’ quality and process repeatability are presented. It was found that despite significant higher average surface parameters for AM insert tools (Sa = 2–9 µm vs. Sa = 0.3–0.9 µm for dies manufactured by machining), a much smaller difference was observed in the resulting quality of polymer extrudates’ product. The roughness generation effect of polymer profile extrusion based on the different dies’ internal surface roughness topography and the effect on extrudates product was evaluated. Three-dimensional average roughness Sa on acrylonitrile butadiene styrene extrudate surfaces obtained from conventionally machined dies was in the range of 0.3 µm. For extrudates obtained from additively manufactured dies, their Sa was in the rage of 0.5 µm (despite the much higher surface roughness of FFF dies compared to machined dies). The results confirm that with suitable extrudates’ product requirement, it is feasible to apply metal FFF as the selected manufacturing method for tooling in polymer profile extrusion.

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.

Compression behavior of nanoparticle powder considering fractal aggregate for additive manufacturing

Compression behavior of nanoparticle powder is still unclear, while it could largely affect its applications in additive manufacturing. Considering the fractal structure of aggregates in nanoparticle powder, from the van der Waal's state equation, the relation between porosity and compression pressure of nanoparticle powder was modeled theoretically, i.e. (P + c)(φ-a)=(1-a)c, here P is pressure, φ is porosity, a and c are parameters defined in main text. The model could capture the compression behavior of nanoparticle powders well. Under the same compression pressure, smaller nanoparticles will lead to larger porosity and thus lower thermal conductivity of nanoparticle packed beds, due to the easier aggregate of smaller nanoparticles. The compression behavior and the thermal conductivity of nanoparticle powders or packed beds are expected to supply information for powder spreading and sintering treatment respectively in additive manufacturing.