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The aim of this work is to provide an overview of the current state of additive manufacturing (AM), commonly known as 3D printing, within superficial brachytherapy (BT). Several comprehensive database searches were performed to find publications linked to AM in superficial BT. Twenty-eight core publications were found, which can be grouped under general categories of clinical cases, physical and dosimetric evaluations, proof-of-concept cases, design process assessments, and economic feasibility studies. Each study demonstrated a success regarding AM implementation and collectively, they provided benefits over traditional applicator fabrication techniques. Publications of AM in superficial BT have increased significantly in the last 5 years. This is likely due to associated efficiency and consistency benefits; though, more evidences are needed to determine the true extent of these benefits.

Objective: Highly porous titanium cups have been recently introduced, with contradictory outcomes. A retrospective consecutive case series involving bilateral metachronous total hip arthroplasties (THA) performed with 2 different cups, i.e., Fixa (F) and Fixa Ti-Por (T) (Adler Ortho, Milan, Italy), and the same stem, was evaluated. T sockets, manufactured using electron beam melting, were supposed to prove superior in terms of clinical results, survival rates, and radiographic parameters in comparison to hydroxyapatite-coated F cups with conventional porosity. Subjects and Methods: Twenty-four bilateral metachronous THAs with an F cup on one side and a T socket on the other side were evaluated. Preoperative and postoperative Harris hip scores (HHS) were collected for every patient. Radiographic signs of loosening were assessed. The radiographic signs of osseointegration (radiolucent lines, superolateral buttress, inferomedial buttress, radial trabeculae, and stress shielding) were evaluated. Results: No intraoperative complications occurred. The mean HHS score was excellent and comparable in both groups. At the mean follow-up of 134 months (F) and 79 months (T), no cup or liner revisions were performed. No radiographic signs of loosening were reported. All of the patients revealed 3 parameters of good bony ingrowth at least. Both groups showed similar radiographic parameters regarding osseointegration, which were stable over the time. Stress shielding was more evident in the T cohort (p =0.07). Conclusion: Highly porous titanium cups produced using an additive manufacturing and electron beam melting technology achieved reliable midterm clinical and radiographic results not inferior to those of second-generation cups.

This paper presents the results of an experimental study to evaluate the possibility of using SLM additive technology to produce structures with specific surface morphological features. Qualitative and quantitative tests were conducted on samples fabricated by 3D printing from titanium (Ti6Al4V)-powder-based material and analysed in direct relation to the possibility of their use in medicine for the construction of femoral stem and models with a specific degree of porosity predicted by process-control in the self-decision-making 3D printing machine. This paper presents the results of the study, limitations of the method, recommendations that should be used in the design of finished products, and design proposals to support the fabrication process of 3D printers. Furthermore, the study contains an evaluation of how the printing direction affects the formation of certain structures on the printed surface. The research can be used in the development of 3D printing standardization, particularly in the consideration of process control and surface control.

The paper outlines the achievements and challenges in the additive manufacturing (AM) application to veterinary practice. The state-of-the-art in AM application to the veterinary surgery is presented, with the focus of AM for patient-specific implants manufacturing. It also provides critical discussion on some of the potential issues design and technology should overcome for wider and more effective implementation of additively manufactured parts in veterinary practices. Most of the discussions in present paper are related to the metallic implants, manufactured in this case using so-called powder bed additive manufacturing (PB-AM) in titanium alloy Ti-6AL-4V, and to the corresponding process of their design, manufacturing and implementation in veterinary surgery. Procedures of the implant design and individualization for veterinary surgery are illustrated basing on the four performed surgery cases with dog patients. Results of the replacement surgery in dogs indicate that individualized additively manufactured metallic implants significantly increase chances for successful recovery process, and AM techniques present a viable alternative to amputation in a large number of veterinary cases. The same time overcoming challenges of implant individualization in veterinary practice significantly contributes to the knowledge directly relevant to the modern medical practice. An experience from veterinary cases where organ-preserving surgery with 3D-printed patient-specific implants is performed provides a unique opportunity for future development of better human implants.

Advances in biomaterials and the need for patient-specific bone scaffolds require modern manufacturing approaches in addition to a design strategy. Hybrid materials such as those with functionally graded properties are highly needed in tissue replacement and repair. However, their constituents, proportions, sizes, configurations and their connection to each other are a challenge to manufacturing. On the other hand, various bone defect sizes and sites require a cost-effective readily adaptive manufacturing technique to provide components (scaffolds) matching with the anatomical shape of the bone defect. Additive manufacturing or three-dimensional (3D) printing is capable of fabricating functional physical components with or without porosity by depositing the materials layer-by-layer using 3D computer models. Therefore, it facilitates the production of advanced bone scaffolds with the feasibility of making changes to the model. This review paper first discusses the development of a computer-aided-design (CAD) approach for the manufacture of bone scaffolds, from the anatomical data acquisition to the final model. It also provides information on the optimization of scaffold’s internal architecture, advanced materials, and process parameters to achieve the best biomimetic performance. Furthermore, the review paper describes the advantages and limitations of 3D printing technologies applied to the production of bone tissue scaffolds.

This paper deals with the design and production of stamping tools and dies for sheet metal components and injection molds for plastic components. Laser-based Powder Bed Fusion (LPBF) is the additive manufacturing method used in this investigation. Solid and topology optimized stamping tools and dies 3D-printed in DIN 1.2709 (maraging steel) by LPBF are approved/certified for stamping of up to 2‑mm thick hot-dip galvanized DP600 (dual-phase steel sheet). The punch in a working station in a progressive die used for stamping of 1‑mm thick hot-dip galvanized DP600 is 3D-printed in DIN 1.2709, both with a honeycomb inner structure and after topology optimization, with successful results. 3D printing results in a significant lead time reduction and improved tool material efficiency. The cost of 3D-printed stamping tools and dies is higher than the cost of those made conventionally. The core (inserts) of an injection mold is 3D-printed in DIN 1.2709, conformal cooling optimized and 3D-printed in Uddeholm AM Corrax, and compared with the same core made conventionally. The cooling and cycle time can be improved, if the injection molding core (inserts) is optimized and 3D-printed in Uddeholm AM Corrax. This paper accounts for the results obtained in the above-mentioned investigations., Dieser Beitrag befasst sich mit dem Deisgn und der Herstellung von Stanzwerkzeugen und Matrizen für Blechkomponenten und Spritzgussformen für Kunststoffkomponenten. Das lasergestützte Pulverbettschmelzen (LPBF) ist das in dieser Untersuchung verwendete additive Fertigungsverfahren. Festkörper und topologieoptimierte Stanzwerkzeuge und Matrizen, die von LPBF aus DIN 1.2709 (martensitaushärtender Stahl) 3D-gedruckt werden, sind für das Stanzen von bis zu 2 mm dickem, feuerverzinktem DP600 (Dualphasen-Stahlblech) zugelassen/zertifiziert. Der Stempel in einer Arbeitsstation in einem Werkzeug zum Stanzen von 1 mm dickem, feuerverzinktem DP600 wird aus DIN 1.2709 3D-gedruckt, sowohl mit einer wabenförmigen Innenstruktur als auch nach einer Topologieoptimierung, mit erfolgreichen Ergebnissen. Der 3D-Druck führt zu einer deutlichen Reduzierung der Vorlaufzeit und einer verbesserten Materialeffizienz des Werkzeugs. Die Kosten für 3D-gedruckte Stanzwerkzeuge und Matrizen sind höher als die Kosten für konventionell hergestellte Werkzeuge. Der Kern (Einsätze) einer Spritzgussform wird aus DIN 1.2709 3D-gedruckt, die konforme Kühlung optimiert und asu Uddeholm AM Corrax 3D-gedruckt und mit dem gleichen, konventionell hergestellten Kern verglichen. Die Kühl- und Zykluszeit kann verbessert werden, wenn der Spritzgießkern (Einlegeteile) aus Uddeholm AM Corrax optimiert und 3D-gedruckt wird. In diesem Beitrag werden die Ergebnisse der oben genannten Untersuchungen dargestellt., The complete paper is written in English.

The published paper related to this presentation is published here: https://doi.org/10.1007/s00170-021-06794-0 To achieve a certain visual quality or acceptable surface appearance in injection-molded components, a higher mold Surface temperature is needed. In order to achieve this, injection molds can be dynamically tempered by integrating an active heating and cooling process inside the mold halves. This heating and cooling of the mold halves becomes more efficient when the temperature change occurs closer to the mold surface. Complex channels that carry cold or hot liquids can be manufactured close to the mold surface by using the layer by layer principle of additive manufacturing. Laser powder bed fusion (L-PBF), as an additive manufacturing process, has special advantages; in particular, so-called hybrid tools can be manufactured. For example, complex tool inserts with conformal cooling channels can be additively built on simple, machined baseplates. This paper outlines the thermal simulation carried out to optimize the injection molding process by use of dynamic conformal cooling. Based on the results of this simulation, a mold with conformal cooling channels was designed and Additively manufactured in maraging steel (1.2709) and then experimentally tested.

Highlights • Investigating 3D printed immobilization devices. • Comparing the 3D printed immobilization devices with traditional ones. • Investigating the technical fabrication details of the articles. • Introducing the scope, testing and results of the studied literatures., Background and purpose Radiotherapy is one of the most effective cancer treatment techniques, however, delivering the optimal radiation dosage is challenging due to movements of the patient during treatment. Immobilisation devices are typically used to minimise motion. This paper reviews published research investigating the use of 3D printing (additive manufacturing) to produce patient-specific immobilisation devices, and compares these to traditional devices. Materials and methods A systematic review was conducted across thirty-eight databases, with results limited to those published between January 2000 and January 2019. A total of eighteen papers suitably detailed the use of 3D printing to manufacture and test immobilisers, and were included in this review. This included ten journal papers, five posters, two conference papers and one thesis. Results 61% of relevant studies featured human subjects, 22% focussed on animal subjects, 11% used phantoms, and one study utilised experimental test methods. Advantages of 3D printed immobilisers reported in literature included improved patient experience and comfort over traditional methods, as well as high levels of accuracy between immobiliser and patient, repeatable setup, and similar beam attenuation properties to thermoformed immobilisers. Disadvantages included the slow 3D printing process and the potential for inaccuracies in the digitisation of patient geometry. Conclusion It was found that a lack of technical knowledge, combined with disparate studies with small patient samples, required further research in order to validate claims supporting the benefits of 3D printing to improve patient comfort or treatment accuracy.

Background: Additive manufacturing (AM) has emerged as a serious planning, strategy, and education tool in cardiovascular medicine. This review describes and illustrates the application, development and associated limitation of additive manufacturing in the field of cardiology by studying research papers on AM in medicine/cardiology. Methods: Relevant research papers till August 2018 were identified through Scopus and examined for strength, benefits, limitation, contribution and future potential of AM. With the help of the existing literature & bibliometric analysis, different applications of AM in cardiology are investigated. Results: AM creates an accurate three-dimensional anatomical model to explain, understand and prepare for complex medical procedures. A prior study of patient’s 3D heart model can help doctors understand the anatomy of the individual patient, which may also be used create training modules for institutions and surgeons for medical training. Conclusion: AM has the potential to be of immense help to the cardiologists and cardiac surgeons for intervention and surgical planning, monitoring and analysis. Additive manufacturing creates a 3D model of the heart of a specific patient in lesser time and cost. This technology is used to create and analyse 3D model before starting actual surgery on the patient. It can improve the treatment outcomes for patients, besides saving their lives. Paper summarised additive manufacturing applications particularly in the area of cardiology, especially manufacturing of a patient-specific artificial heart or its component. Model printed by this technology reduces risk, improves the quality of diagnosis and preoperative planning and also enhanced team communication. In cardiology, patient data of heart varies from patient to patient, so AM technologies efficiently produce 3D models, through converting the predesigned virtual model into a tangible object. Companies explore additive manufacturing for commercial medical applications. Keywords: 3D printing, 3D scanning, Additive manufacturing, Artificial heart, Cardiology

Background and objective The purpose of the present paper is to pave the road to the systematic optimization of complex craniofacial surgical intervention and to validate a design methodology for the virtual surgery and the fabrication of cranium vault custom plates. Recent advances in the field of medical imaging, image processing and additive manufacturing (AM) have led to new insights in several medical applications. The engineered combination of medical actions and 3D processing steps, foster the optimization of the intervention in terms of operative time and number of sessions needed. Complex craniofacial surgical intervention, such as for instance severe hypertelorism accompanied by skull holes, traditionally requires a first surgery to correctly “resize” the patient cranium and a second surgical session to implant a customized 3D printed prosthesis. Between the two surgical interventions, medical imaging needs to be carried out to aid the design the skull plate. Instead, this paper proposes a CAD/AM-based one-in-all design methodology allowing the surgeons to perform, in a single surgical intervention, both skull correction and implantation. Methods A strategy envisaging a virtual/mock surgery on a CAD/AM model of the patient cranium so as to plan the surgery and to design the final shape of the cranium plaque is proposed. The procedure relies on patient imaging, 3D geometry reconstruction of the defective skull, virtual planning and mock surgery to determine the hypothetical anatomic 3D model and, finally, to skull plate design and 3D printing. Results The methodology has been tested on a complex case study. Results demonstrate the feasibility of the proposed approach and a consistent reduction of time and overall cost of the surgery, not to mention the huge benefits on the patient that is subjected to a single surgical operation. Conclusions Despite a number of AM-based methodologies have been proposed for designing cranial implants or to correct orbital hypertelorism, to the best of the authors’ knowledge, the present work is the first to simultaneously treat osteotomy and titanium cranium plaque.

In the last few years, three-dimensional printing, that in bone tissue engineering is consider to be a synonymous of additive manufacturing has made its way into the medical field, not only manufacturing medical appliances, study models or building prosthetics. The demand for bone substitution surgeries is growing every year, due to the increase in pathologies affecting bone structure (both traumatic and not traumatic). Nowadays with the possibility of three-dimensional printers becoming bioprinters, engineered bone tissue is starting to become a reality. The aim of this paper is to give the reader an overview of the work done in the last few years towards the advance of three-dimensional printing methods for engineered bone tissue. This paper is divided into six parts, an introduction, then presentation and discussion of the various printing methods with special focus on additive manufacturing (AM), then of bioprinting technologies, further directions of these technologies are considered and a conclusion is done.

Background Three-dimensional (3D) printing has numerous applications and has gained much interest in the medical world. The constantly improving quality of 3D-printing applications has contributed to their increased use on patients. This paper summarizes the literature on surgical 3D-printing applications used on patients, with a focus on reported clinical and economic outcomes. Methods Three major literature databases were screened for case series (more than three cases described in the same study) and trials of surgical applications of 3D printing in humans. Results 227 surgical papers were analyzed and summarized using an evidence table. The papers described the use of 3D printing for surgical guides, anatomical models, and custom implants. 3D printing is used in multiple surgical domains, such as orthopedics, maxillofacial surgery, cranial surgery, and spinal surgery. In general, the advantages of 3D-printed parts are said to include reduced surgical time, improved medical outcome, and decreased radiation exposure. The costs of printing and additional scans generally increase the overall cost of the procedure. Conclusion 3D printing is well integrated in surgical practice and research. Applications vary from anatomical models mainly intended for surgical planning to surgical guides and implants. Our research suggests that there are several advantages to 3D-printed applications, but that further research is needed to determine whether the increased intervention costs can be balanced with the observable advantages of this new technology. There is a need for a formal cost–effectiveness analysis. Electronic supplementary material The online version of this article (doi:10.1186/s12938-016-0236-4) contains supplementary material, which is available to authorized users.

Introduction: 3D printing has quickly found many applications in medicine. However, as with any new technology the regulatory landscape is struggling to stay abreast. Unclear legislation or lack of legislation has been suggested as being one hindrance for wide-scale adoption.Methods: A scoping review was performed in PubMed, Web of Science, SCOPUS and Westlaw International to identify articles dealing with legal issues in medical 3D printing.Results: Thirty-four articles fulfilling inclusion criteria were identified in medical/technical databases and fifteen in the legal database. The majority of articles dealt with the USA, while the EU was also prominently represented. Some common unresolved legal issues were identified, among them terminological confusion between custom-made and patient-matched devices, lack of specific legislation for patient-matched products, and the undefined legal role of CAD files both from a liability and from an intellectual property standpoint. Data protection was mentioned only in two papers and seems an underexplored topic.Conclusion: In this scoping review, several relevant articles and several common unresolved legal issues were identified including a need for terminological uniformity in medical 3D printing. The results of this work are planned to inform our own deeper legal analysis of these issues in the future.

Funding Information: AP is supported by grants from the Viipuri Tuberculosis Foundation, the South-Karelia Medical Association, the Emil Aaltonen Foundation and the Finnish Medical Foundation. PL is supported by the UKRI Strategic Priorities Fund to the UKRI Research Node on Trustworthy Autonomous Systems Governance and Regulation (EP/V026607/1, 2020–2024) and the Leverhulme Trust ‘Biomodifying technologies: governing converging research in the life sciences’ (grant number 68387). MS is supported by the Academy of Finland (grant numbers 325509 and 352438). RB has received funding from the project “Shaping, Fixing, and Making Markets via IPR: Regulating Sustainable Innovation Ecosystems (SHARE)”, funded by the Academy of Finland (decision number 332819). TM’s research for this contribution was supported by a Novo Nordisk Foundation for a scientifically independent Collaborative Research Programme in Biomedical Innovation Law (grant agreement number NNF17SA0027784). Publisher Copyright: Copyright © 2023 Pettersson, Ballardini, Mimler, Li, Salmi, Minssen, Gibson and Mäkitie. Introduction: 3D printing has quickly found many applications in medicine. However, as with any new technology the regulatory landscape is struggling to stay abreast. Unclear legislation or lack of legislation has been suggested as being one hindrance for wide-scale adoption. Methods: A scoping review was performed in PubMed, Web of Science, SCOPUS and Westlaw International to identify articles dealing with legal issues in medical 3D printing. Results: Thirty-four articles fulfilling inclusion criteria were identified in medical/technical databases and fifteen in the legal database. The majority of articles dealt with the USA, while the EU was also prominently represented. Some common unresolved legal issues were identified, among them terminological confusion between custom-made and patient-matched devices, lack of specific legislation for patient-matched products, and the undefined legal role of CAD files both from a liability and from an intellectual property standpoint. Data protection was mentioned only in two papers and seems an underexplored topic. Conclusions: In this scoping review, several relevant articles and several common unresolved legal issues were identified including a need for terminological uniformity in medical 3D printing. The results of this work are planned to inform our own deeper legal analysis of these issues in the future.

Ovim radom prikazana je mogućnost izrade proteze nadomjeska uha primjenom aditivne proizvodnje. Model nadomjeska uha dobiven je 3D skeniranjem suprotne uške, preslikavanja na suprotnu stranu i modeliranja unutar Geomagic Design programa. Prvotno su tehnologijom očvršćivanja taloženjem (FDM) izrađena dva prototipa od polimliječne kiseline (PLA). Prema drugom prototipu modeliran je kalup te izrađen istom tehnologijom i materijalom. Za potrebe diplomskog rada u kalup je izliven silikon za kalupe i dobiven primjer moguće izrade proteze uha ovim postupkom. This paper presents the possibility of making an ear replacement prosthesis using additive manufacturing. The ear prosthesis model was obtained by 3D scanning of the opposite ear, mapping to the opposite side and modeling within the Geomagic Design program. Initially, two prototypes were made from polylactic acid (PLA) using fused deposition modeling (FDM). According to the second prototype, the mold was modeled and made with the same technology and material. For the purposes of the graduation thesis, silicone for molds was poured into the mold and an example of the possible production of an ear prosthesis using this process was obtained.

Microwave breast hyperthermia is a class of cancer treatment, where breast temperature is elevated by a focused electromagnetic (EM) radiation to impair cancer cells. While the current mainstream in microwave breast hyperthermia is centered on bulky and rigid systems, wearable antennas would offer considerable benefits such as superior conformity to individual patient anatomy and better comfort. In this proposition, this paper presents 3D-printed flexible antenna prototypes for wearable breast hyperthermia applications. Since the dielectric properties are expected to dominate the antenna gain but could be influenced by the solid volume percentage, this work first investigates the relationship between the dielectric properties and solid volume percentage of a 3D-printed flexible filament. From this, it is found that with decrease in the solid volume percentage, the dielectric constant decreases following the classic theory of dielectric mixture. Based on this observation, optimal antennas are designed for substrates in different infill levels by running a 3D full-wave EM simulator and fabricated by 3D printing a polyurethane filament. Temperature elevations in a synthetic breast tissue are measured by a thermometer and are ~ 5.5 °C and ~ 3.2 °C at the 5 mm- and 7 mm-deep locations, respectively. The infill percentage makes little difference in the heating efficacy. Based on these findings, this translational study sheds light on the possibility of wearable breast hyperthermia with the 3D-printed flexible and conformal antennas.

The Biosilicate® glass-ceramic is one of the most promising alternatives to the 45S5 Bioglass® in terms of bioactivity, osteoconductivity, osteoinductivity, non-cytotoxicity, and antibacterial properties, with significant advantages in the manufacturing of specific components of complex shapes for bone tissue application. Unlike in 45S5 glass, the crystallization does not lead to a degradation of bioactivity. In the present paper, we explored the suitability of Biosilicate® for the manufacturing of highly porous scaffolds (porosity of 50–80 vol%) by using modern additive manufacturing technologies, such as direct ink writing (DIW) and digital light processing (DLP). Both techniques could be easily applied to fine powders of Biosilicate® mixed with fugitive binders. Significant densification of the struts, despite the limited powder packing, could be achieved using liquid-assisted sintering, in turn, triggered by the phosphate-enriched residual glass phase, already at 1000 °C. The strength-to-density ratio could be variously tuned (from 1.5 to 9.5 MPa cm3/g), especially with DLP-derived samples, by adjusting both the firing temperature and the scaffold topology.

Background The purpose of this paper is to review the available literature on three-dimensionally printed complete dentures in terms of novel biomaterials, fabrication techniques and workflow, clinical performance and patient satisfaction. Methods The methodology included applying a search strategy, defining inclusion and exclusion criteria, selecting studies and forming tables to summarize the results. Searches of PubMed, Scopus, and Embase databases were performed independently by two reviewers to gather literature published between 2010 and 2020. Results A total of 126 titles were obtained from the electronic database, and the application of exclusion criteria resulted in the identification of 21 articles pertaining to printed technology for complete dentures. Current innovations and developments in digital dentistry have successfully led to the fabrication of removable dental prostheses using CAD/CAM technologies. Milled dentures have been studied more than 3D printed ones in the currently available literature. The limited number of clinical studies, mainly case reports, suggest current indications of 3D printing in denture fabrication process to be custom tray, record bases, trial, interim or immediate dentures but not definitive prostheses fabrication. Limitations include poor esthetics and retention, inability to balance occlusion and low printer resolution. Conclusions Initial studies on digital dentures have shown promising short-term clinical performance, positive patient-related results and reasonable cost-effectiveness. 3D printing has potential to modernize and streamline the denture fabrication techniques, materials and workflows. However, more research is required on the existing and developing materials and printers to allow for advancement and increase its application in removable prosthodontics.

Tema ovog rada primjena je aditivne proizvodnje u medicini. U uvodu se govori općenito o aditivnoj tehnologiji, o njenim prednostima i nedostacima. Zatim je navedeno nekoliko najbitnijih primjera iz korištenja aditivne proizvodnje u medicini. Nakon toga obrađena je tema korištenja aditivne proizvodnje za izradu proteza, u kojoj su navedene glavne prednosti takvih proteza i materijali od kojih one mogu biti izrađene. U praktičnom dijelu biti će dan primjer razvijene proteze noge za odgovarajućeg pacijenta. The topic of this paper is applied additive manufacturing in medicine. In the introduction, there will be some basic information about additive technology, its advantages and disadvantages. Then, some of the most important examples of the use of additive production in medicine will be given. After that, the topic of using additive production for prosthesis production will be discussed, which lists the main advantages of such prostheses and the materials from which they can be made. In the practical part, there will be an example of a developed prosthetic leg for a suitable patient.

The helical spring is one of the most used components in mechanisms but there is little research on the application of 3D printing, also called Additive Manufacturing, to springs. Therefore, the objective of this paper is to derive a model for the stiffness of 3D printed springs. The equation assumes that springs are made of orthotropic material and with a rectangular wire cross-section, that is, die springs. A second version of the equation has also been postulated that accounts for the misalignment of the deposited tracks with respect to the direction of the coils due to the coil pitch. The two models are compared to various springs printed with PLA and ULTEM 9085 and are found to accurately predict the stiffness of real, 3D printed springs. These equations allow the design and manufacturing of helical die springs for applications with few load cycles and that require chemical and radiation resistance, such as in space. The equations are also the first step in the development of models for new kinds of springs, such as linear conical springs or hollow wire die springs. National Research Foundation (NRF) This research was supported by the Singapore Centre for 3D printing (SC3DP), the National Research Foundation, Prime Minister's Office, Singapore under its Medium-Sized Centre funding scheme, and National Additive Manufacturing Innovation Cluster.

International audience; 3D printed sand molds for the casting industry play a vital role in manufacturing intricate parts from a computer model. The possibility of producing fairly significant structural castings using a small job-box 3D sand mold printer is another advantage compared to the direct metal 3D printing processes. It is important to identify the relationship between the process parameters and the properties of the sand mold in order to produce a mold with the required strength, permeability and stiffness; to reduce gas emissions during casting and minimize the mass of combustible materials in the mold. Hence, it is possible to create an excellent casting by improving the design of such molds for liquid alloy filling and solidification. The relationship between the printing parameters and the properties of the mold can be a great tool for foundrymen, primarily to optimize the strength and permeability properties of these molds and therefore to provide exact boundary conditions for the solidification simulation prior to a casting trial. This paper reports on a study of a basic outline to quantify the role of the sand mold printing process parameters, particularly the recoater speed and print resolution, on the mold strength and permeability, and their impacts on the anisotropic behavior of the printed sand molds.

International audience; In this paper, we propose to use new 3D-printed meso-structured materials to build soft robots and we present a modeling pipeline for design assistance and control. These meta-materials can be programmed before printing to target specific mechanical properties, in particular heterogeneous stiffness and anisotropic behaviour. Without changing the external shape, we show that using such meta-material can lead to a dramatic change in the kinematics of the robot. This highlights the importance of modeling. Therefore, to help the design and to control soft robots made of these meso-structured materials, we present a modeling method based on numerical homogenization and Finite Element Method (FEM) that captures the anisotropic deformations. The method is tested on a 3 axis parallel soft robot initially made of silicone. We demonstrate the change in kinematics when the robot is built with meso-structured materials and compare its behavior with modeling results.

Additive manufacturing (AM) is considered the latest technology that creates breakthrough innovations and addresses complex medical problems. This is clearly demonstrated by the promising results obtained in regenerative medicine, diagnosis, implants, artificial tissues and organs. This paper provides a basic understanding of the fundamentals of 3D/4D printing along with bioprinting processes. We are briefly discussing about the main printing systems including stereolithography, inkjet 3D printing, extrusion, laser-assisted printing, selective laser melting and Poly-Jet printing. The basic requirements for the selection of successful inks based on polymers, polymer blends, and composites are described. Furthermore, the on-going transition from 3D to 4D printing is highlighted with emphasis on the newest applications in the medical area. Also, a glimpse into the future possibilities and benefits provided by machine learning in the additive manufacturing field is emphasized. Machine learning can improve printing efficiency by using generative design and testing in the pre-fabrication stage. Finally, important limitations and prospects are identified. Within the next few years, AM is set to become an important component in patient-specific medical technologies.

The cooling system of thermoplastic mold plays a critical role during the production process because it not only affects part quality but also its cycle time. Traditionally, due to the limitations of conventional drilling methods, the cooling system of the thermoforming mold usually consists of simple paralleled straight channels that results in a lack of performance to cool complex shapes. Nowadays thanks to the evolution of additive manufacturing technique (AM) characterized by an increase of shape complexity it is possible to design a complex cooling system conformal to the mold geometry (conformal cooling). However conformal cooling respect to others AM design improvements, as topology optimization, is still under development and specific rules that define how to better design cooling channels still do not exist. In this paper, to enlarge the knowledge about this methodology, the authors simulated the performance of three different conformal geometries (serpentine, rectangular and tank) and compared the results with the traditional geometry in terms of cooling performance. Results highlight how serpentine geometry is able to improve process performance imposing a cooling curve characterized by a higher slope respect to the traditional shape.

The aim of this paper is to review the recent evolution of additive manufacturing (AM) within the medical field of preoperative surgical planning. The discussion begins with an overview of the different techniques, pointing out their advantages and disadvantages as well as an in-depth comparison of different characteristics of the printed parts. Then, the state-of-the-art with respect to preoperative surgical planning is presented. On the one hand, different surgical planning prototypes manufactured by several AM technologies are described. On the other hand, materials used for mimicking different living tissues are explored by focusing on the material properties: elastic modulus, hardness, etc. As a result, doctors can practice before performing surgery and thereby reduce the time needed for the operation. The subject of patient education is also introduced. A thorough review of the process that is required to obtain 3D printed surgical planning prototypes, which is based on different stages, is then carried out. Finally, the ethical issues associated with 3D printing in medicine are discussed, along with its future perspectives. Overall, this is important for improving the outcome of the surgery, since doctors will be able to visualize the affected organs and even to practice surgery before performing it.

Wood-based materials in current additive manufacturing (AM) feedstocks are primarily restricted to the micron scale. Utilizing large-scale wood in existing AM techniques remains a challenge. This paper proposes an AM method&mdash, laser-cut veneer lamination (LcVL)&mdash, for wood-based product fabrication. Inspired by laminated object manufacturing (LOM) and plywood technology, LcVL bonds wood veneers in a layer-upon-layer manner. As demonstrated by printed samples, LcVL was able to retain the advantageous qualities of AM, specifically, the ability to manufacture products with complex geometries which would otherwise be impossible using subtractive manufacturing techniques. Furthermore, LcVL-product structures designed through adjusting internal voids and wood-texture directionality could serve as material templates or matrices for functional wood-based materials. Numerical analyses established relations between the processing resolution of LcVL and proportional veneer thickness (layer height). LcVL could serve as a basis for the further development of large-scale wood usage in AM.

The increase in the number of revision surgeries after a total knee replacement surgery reaches 19%. One of the reasons for the majority of revisions relates to the debris of the ultra-high molecular weight polyethylene that serves to facilitate the sliding between the femoral and tibial components. This paper addresses the biomechanical properties of ULTEMTM 1010 in a totally new knee replacement design, based on one of the commercial models of the Stryker manufacturer. It is designed and produced through additive manufacturing that replaces the tibial component and the polyethylene in such a way as to reduce the pieces that are part of the prosthetic assembly to only two: the femoral and the tibial (the so-called “two-component knee prosthesis”). The cytotoxicity as well as the live/dead tests carried out on a series of biomaterials guarantee the best osteointegration of the studied material. The finite element simulation method guarantees the stability of the material before a load of 2000 N is applied in the bending angles 0 , 30 , 60 , 90 , and 120 . Thus, the non-metallic prosthetic material and approach represent a promising alternative for metal-allergic patients., The live/dead test was exclusively supported by the Andalucia FEDER/ITI 2014-2020 Grant for PI 013/017, as well as the Junta de Andalucia TEP 181 and the CTS 253 PAIDI Spanish research groups.

The implementation of a powder bed selective laser processing (PBSLP) technique for bioactive ceramics, including selective laser sintering and melting (SLM/SLS), a laser powder bed fusion (L-PBF) approach is far more challenging when compared to its metallic and polymeric counterparts for the fabrication of biomedical materials. Direct PBSLP can offer binder-free fabrication of bioactive scaffolds without involving postprocessing techniques. This review explicitly focuses on the PBSLP technique for bioactive ceramics and encompasses a detailed overview of the PBSLP process and the general requirements and properties of the bioactive scaffolds for bone tissue growth. The bioactive ceramics enclosing calcium phosphate (CaP) and calcium silicates (CS) and their respective composite scaffolds processed through PBSLP are also extensively discussed. This review paper also categorizes the bone regeneration strategies of the bioactive scaffolds processed through PBSLP with the various modes of functionalization through the incorporation of drugs, stem cells, and growth factors to ameliorate critical-sized bone defects based on the fracture site length for personalized medicine.

Wide resection is currently considered the mainstay treatment for primary bone tumors. When the tumor is located in anatomically complex segments, 3D-Printed Titanium Custom-Made Prostheses (3DPTCMP) are possible reconstructive solutions. The aim of the present paper is to analyze indications, results and complications of a series of 14 patients who underwent pelvis reconstruction with 3DPTCMP after tumor removal from January 2015 to December 2019. Chondrosarcoma was the main histology, indications were tumors located in the acetabular area without enough residual bone to support a cup with an iliac stem, and tumors located near the sacrum-iliac joint. The margins were wide in 12 cases, and marginal and intralesional in one case each. In three cases, resection also included the sacrum-iliac joint, so a spine stabilization was performed and linked to the pelvic prosthesis, The average MSTS score was 46.3%, the 5-year local recurrence-free survival was 85.7%. Wound dehiscences were the main complication, resolved with multiple debridements, nevertheless, prosthesis removal was necessary in one case. Currently, the 3DPTCMP is an effective resource for reconstruction after resection of tumors located in the pelvis. Further studies are necessary to value long-term results, more strategies are necessary to try to reduce the infection rate and improve osteointegration.

Additive manufacturing (AM) has been revolutionizing the manufacturing industry due to its ability to significantly reduce waste and produce components with intricate shapes. Laser Ultrasonics (LU) is a non-contact and couplant free method to generate and detect ultrasound. LU can accommodate complex component shapes; thus, it has the potential to provide a reliable in-process inspection method for AM components. In recent years the development of Laser Induced Phased Arrays (LIPAs) helped overcome the inherently low signal amplitudes of LU at the non-destructive, thermoelastic regime. In this paper, the Full Matrix Capture data acquisition method is used and a LIPA of 68 elements is synthesized in post processing. The Total Focusing Method imaging algorithm is applied for ultrasonic imaging. The technique is demonstrated on a highly scattering titanium alloy Wire Arc Additive Manufactured (WAAM) component producing high quality ultrasonic images, accurately imaging defects at depths up to 10mm below the inspection surface.

PurposeThe purpose of this paper is to communicate a method to perform simultaneous topology optimization of component and support structures considering typical metal additive manufacturing (AM) restrictions and post-print machining requirements.Design/methodology/approachAn integrated topology optimization is proposed using two density fields: one describing the design and another defining the support layout. Using a simplified AM process model, critical overhang angle restrictions are imposed on the design. Through additional load cases and constraints, sufficient stiffness against subtractive machining loads is enforced. In addition, a way to handle non-design regions in an AM setting is introduced.FindingsThe proposed approach is found to be effective in producing printable optimized geometries with adequate stiffness against machining loads. It is shown that post-machining requirements can affect optimal support structure layout.Research limitations/implicationsThis study uses a simplified AM process model based on geometrical characteristics. A challenge remains to integrate more detailed physical AM process models to have direct control of stress, distortion and overheating.Practical implicationsThe presented method can accelerate and enhance the design of high performance parts for AM. The consideration of post-print aspects is expected to reduce the need for design adjustments after optimization.Originality/valueThe developed method is the first to combine AM printability and machining loads in a single topology optimization process. The formulation is general and can be applied to a wide range of performance and manufacturability requirements.

Summarization: The mechanical properties of Fused Filament Fabrication (FFF) 3D printed specimens of acrylonitrile butadiene styrene (ABS), ABS reinforced with carbon fibers (ABS/CFs) and ABS reinforced with carbon nanotubes (ABS/CNTs) are investigated in this paper using various experimental tests. In particular, the mechanical performance of the fabricated specimens was determined by conducting compression and cyclic compression testing, as well as nanoindentation tests. In addition, the design and the manufacturing of hierarchical honeycomb structures are presented using the materials under study. The 3D printed honeycomb structures were examined by uniaxial compressive tests to review the mechanical behavior of such cellular structures. The compressive performance of the hierarchical honeycomb structures was also evaluated with finite element analysis (FEA) in order to extract the stress-strain response of these structures. The results revealed that the 2nd order hierarchy displayed increased stiffness and strength as compared with the 0th and the 1st hierarchies. Furthermore, the addition of carbon fibers in the ABS matrix improved the stiffness, the strength and the hardness of the FFF printed specimens as well as the compression performance of the honeycomb structures. Presented on: Journal of Composites Science