Final Print Research Articles

An alloy-agnostic machine learning framework for process mapping in laser powder bed fusion

PurposeThis study aims to introduce an image-based method to determine the processing window for a given alloy system using laser powder bed fusion equipment based on achieving the desired melting mode across multiple materials for powder-free specimens. The method uses a convolutional neural network trained to classify different track morphologies across different alloy systems to select appropriate printing settings. This method is intended for the development of new alloy systems, where the powder feedstock may be unavailable, or prohibitively expensive to manufacture.Design/methodology/approachA convolutional neural network is designed from scratch to identify the 4 key melting modes that are observed in laser powder bed fusion additive manufacturing across different alloy systems. To increase the prediction accuracy and generalisation accuracy across different materials, the network is trained using a novel hybrid data set that combines fully unsupervised learning with semi-supervised learning.FindingsThis study demonstrates that our convolutional network with a novel hybrid training approach can be generalised across different materials, and k-fold validation shows that the model retains good accuracy with changing training conditions. The model can predict the processing maps for the different alloys with an accuracy of up to 96% in some cases. It is also shown that powder-free single-track experiments are a useful indicator for predicting the final print quality of a component.Originality/valueThe “invariant information clustering” (IIC) approach is applied to process optimisation for additive manufacturing, and a novel hybrid data set construction approach that accounts for uncertainty in the ground truth data, enables the trained convolutional model to perform across a range of different materials and most importantly, generalise to materials outside of the training data set. Compared to the traditional cross-sectioning approach, this method considers the whole length of the single track when determining the melting mode.

Fabrication of Ruby by 3D printing of transparent salt solutions

A novel method is presented for fabricating 3D-printed Cr3+-doped α-Al2O3 complex structures, known as Ruby, using digital light processing (DLP) 3D printing and sol-gel reactions based on solutions only. The aqueous printing solution comprises aluminum and chromium chloride as the sol-gel precursor and acrylic acid (AA) as the polymerizable component. After photopolymerization, aging, and sintering at 1150°C, structures shrink up to 28±7 %, achieving a final printing resolution of 55.7±0.7 μm, surpassing the nominal printer’s resolution of 200 μm. Characterization includes X-ray diffraction, scanning electron microscopy, UV-Vis, and fluorescence measurements, revealing crystalline Cr:α-Al2O3 composition emitting at 693 nm. The structures exhibit maximum compression stress of 89±3 MPa and microhardness of 340–500 HV, showcasing potential applications in thermal insulation, jewelry, and mechanical uses.

Multi-orientation adaptive slice and path generation based on support constraint and relationship matrix

PurposeThe step effect and support structure generated by the manufacturing process of fused deposition molding parts increase the consumables cost and decrease the printing quality. Multiorientation printing helps improve the surface quality of parts and reduce support, but path interference exists between the printing layer and the layers printed. The purpose of this study is to design printing paths between different submodels to avoid interference when build orientation changed.Design/methodology/approachConsidering support constraint, build orientation sequence is designed for submodels decomposed by model topology. The minimum printing angle between printing layers is analyzed. Initial path through the oriented bounding box is planned and slice interference relationship is then detected according to the projection topology mapping. Based on the relationship matrix of multiorientation slice, feasible path is calculated by directed graph (DG). Final printing path is determined under support constraint and checked by minimum printing angle. The simulation model of the robotic arm is established to verify the accessibility of printing path under the constraint of support and slice.FindingsThe proposed method can reduce support structure, decrease volume error and effectively solve the interference problem of the printing path for multiorientation slice.Originality/valueThe method based on projection topology mapping greatly improves the efficiency of interference detection. A feasible path calculated through DGs ensures the effectiveness of the printing path with the constraint of support and slice.

DESIGN AND PRINTING OF HELICAL GEAR WITH RESIN 3D PRINTING MACHINE

Stereolithography 3D printing (SLA) has evolved into a leading additive manufacturing technology, revolutionizing various industries with its precision and versatility. This paper provides a comprehensive overview of the advances and challenges in SLA 3D printing technology. This overview begins with an overview of the principles of SLA printing, including the photopolymerization process and the role of digital slicing software in creating printable 3D models. Next, recent advances in materials such as photopolymer resins have improved mechanical, biocompatibility, and functional properties, expanding the applications of his SLA printing in areas such as aerospace, healthcare, and consumer products. This section explains. Additionally, this review addresses improvements to hardware components such as light sources, build platforms, and optical systems, resulting in increased print speed, resolution, and reliability. Additionally, the impact of advances in post-processing techniques such as UV curing, rinsing, and surface finishing on the final print quality will be investigated. Key Words: Stereolithography, photopolymerization, 3D printing, hardware, UV curing, rinsing.

Construção e validação de História em Quadrinhos para crianças com leucemia linfoide aguda

Abstract Introduction Cancer has an impact on the lives of children and their families. Comics can be a strategy to strengthen the bond and communication between professional/patient/family. Objective To develop and validate an instructional/educational material, in the format of Comics, aimed at children hospitalized with acute lymphocytic leukemia. Methodology Methodological study developed in nine stages: preparation of the research project; content definition and selection; language adaptation; inclusion of illustrations; construction of a pilot material; validation of the material; layout; final printing and availability. Validation took place with 10 specialists between March and May 2022, using the Health Education Content Validation Instrument. Results 5 Comics were created, with 6 main characters, requiring 63 hours of work. They were divided by themes (gastrointestinal disorders; hemorrhagic cystitis; problems related to self-esteem and self-image; risk of infection and bone pain) that obtained a satisfactory global Content Validity Index between 0.78 and 0.87. Conclusions and implications for practice Comics can be used as an attractive and reliable source of information about the disease, supporting information during hospitalization and preparation for discharge.

Applicability of UV-Curable Binders in High Solid Suspensions for Direct-Ink-Write 3D Printing in Extremely Cold Temperatures.

Leveraging material extrusion 3D printing of high solid suspensions for rapid manufacturing in future space missions requires materials compatible with the unique environments found on the Lunar surface. However, there is currently a lack of selection criteria for materials processable in the harsh environmental conditions on the Moon without significantly altering the 3D printers. Here, we provide valuable insights into the behavior of high solid suspensions at low temperatures to guide informed decision-making for manufacturing in subzero environments. We investigate the effects of direct-ink-write (DIW) printing at -30 °C on the structure-property relationships of UV-curable high solid inks of glass microspheres. We analyze the inks based on extrudability and curability at subzero temperatures to verify extrusion, shape retention, and sufficient solidification, culminating in successful printing at -30 °C. Preferential polymerization among monomers is observed at -30 °C and results in a lower cross-linking density in the final print, with a reduced tensile modulus. However, lower ratios of highly mobile monomers result in the retention of mechanical properties, demonstrating the selection criteria for binder design. Through this work, we highlight the importance of binder formulations used for 3D printing in uncommon environmental conditions that are emerging as tomorrow's manufacturing challenge.

Optimization of nozzle for pre-impregnated continuous fiber reinforced 3D printing

The combination of 3D printing technology and pre-impregnated continuous fiber reinforced composites (PICRC) has led to the birth of PICRC 3D printing technology. In the actual PICRC 3D printing process, it is found that the existing PICRC 3D printing head is easily blocked during the compensation wire feeding process, which greatly reduces the success rate of printing. In this paper, the mechanism of PICFRCF 3D print head clogging is analyzed, and the method to solve the problem is explored, which is to adopt appropriate transition length [Formula: see text], printing speed [Formula: see text] and high temperature section length [Formula: see text] to optimize the printing head. The final printing experiment shows that the optimized printing head effectively solves the problem of printing head blocking, and greatly improves the success rate of PICRCF printing.

Real-Time Imaging of Bonding in 3D-Printed Layers.

In recent times, 3D printing technology has revolutionized our ability to design and produce products, but optimizing the print quality can be challenging. The process of extrusion 3D printing involves pressuring molten material through a thin nozzle and depositing it onto previously extruded material. This method relies on bonding between the consecutive layers to create a strong and visually appealing final product. This is no easy task, as many parameters, such as the nozzle temperature, layer thickness, and printing speed, must be fine-tuned to achieve optimal results. In this study, a method for visualizing the polymer dynamics during extrusion is presented, giving insight into the layer bonding process. Using laser speckle imaging, the plastic flow and fusion can be resolved non-invasively, internally, and with high spatiotemporal resolution. This measurement, which is easy to perform, provides an in-depth understanding of the underlying mechanics influencing the final print quality. This methodology was tested with a range of cooling fan speeds, and the results showed increased polymer motion with lower fan speeds and, thus, explained the poor printing quality when the cooling fan was turned off. These findings show that this methodology allows for optimizing the printing settings and understanding the material behavior. This information can be used for the development and testing of novel printing materials or advanced slicing procedures. With this approach, a deeper understanding of extrusion can be built to take 3D printing to the next level.

Vicissitudes of a Dantean Collection: The 1527 ‘Giuntina delle rime’

ABSTRACT The essay shows how the most comprehensive sixteenth-century printed collection of pre-Petrarchan lyric poetry, printed by the Giunti press in Florence in 1527 and known as the ‘Giuntina delle rime’, was conceived as a Dantean collection. The article argues that the ‘Giuntina’ can be understood in relation to a Florentine context that reacted in opposition to Bembo’s codification, in his seminal dialogue Prose nelle quali si ragiona della volgar lingua (1525), of Petrarch and Boccaccio as supreme models for poetry and prose, and his devaluing Dante. This reaction led to the promotion of Dante’s lyric poetry through a collection printed by the leading Florentine publishing house. The essay presents new evidence to show that the original programme of revaluing Dante that lies behind the collection and its scope seem to have undergone a transformation, which obscured the force of that re-evaluation in the final print of the 1527 anthology.

3D Printing Transparent γ‐Alumina Porous Structures Based on Photopolymerizable Sol–Gel Inks

AbstractA novel method for fabricating transparent porous γ‐alumina 3D structures by printing at high resolution is presented. The process is based on combining digital light processing 3D printing (DLP) and sol–gel reactions, all performed in transparent solutions, resulting in ceramic monolithic porous structures. The aqueous printing solution contains mainly aluminum chloride, propylene oxide (PO), ethanol, and acrylic acid (AA). The printed polymerized structures are aged, followed by supercritical drying (SCD), and sintered at high temperatures. During aging and sintering, the printed objects shrink, thus enabling a final printing resolution far beyond the nominal value of the used printer. The resulting structures are crystalline γ‐Al2O3, with a very high surface area, above 1800 m2 g−1, and optical transmission above 80% at 600 nm. In addition, SCD enables precise control of pores’ dimensions and total surface area, which are essential for applications including thermal insulation and catalyst support and for obtaining heat‐resistant transparent optical devices.

STRUCTURAL DEFECTS AND VARIABLE POROSITY IN 3D-PRINTED CUPS FROM SIX MANUFACTURERS

3D printing is rapidly being adopted by manufacturers to produce orthopaedic implants. There is a risk however of structural defects which may impact mechanical integrity. There are also no established standards to guide the design of bone-facing porous structures, meaning that manufacturers may employ different approaches to this. Characterisation of these variables in final-production implants will help understanding of the impact of these on their clinical performance.We analysed 12 unused, final-production custom-made 3D printed acetabular cups that had been produced by 6 orthopaedic manufacturers. We performed high resolution micro-CT imaging of each cup to characterise the morphometric features of the porous layers: (1) the level of porosity, (2) pore size, (3) thickness of porous struts and (4) the depth of the porous layers. We then examined the internal cup structures to identify the presence of any defects and to characterise: (1) their total number, (2) volume, (3) sphericity, (4) size and (5) location.There was a variability between designs in the level of porosity (34% to 85%), pore size (0.74 to 1.87mm), strut thickness (0.28 to 0.65mm), and porous layer depth (0.57 to 11.51mm). One manufacturer printed different porous structures between the cup body and flanges; another manufacturer printed two differing porous regions within the cup body.5 cups contained a median (range) of 90 (58–101) defects. The median defect volume was 5.17 (1.05–17.33) mm3. The median defect sphericity and size were 0.47 (0.19–0.65) and 0.64 (0.27–8.82) mm respectively. The defects were predominantly located adjacent to screw holes, within flanges and at the transition between the flange and main cup body; these were between 0.17 and 4.66mm from the cup surfaces.There is a wide variability between manufacturers in the porous titanium structures they 3D print. The size, shape and location of the structural defects identified are such that there may be an increased risk of crack initiation from them, potentially leading to a fracture. Regulators, surgeons, and manufacturers should be aware of this variability in final print quality.

Small, sustainable, steps to success as a scholar in Health Professions Education - Micro (macro and meta) matters

Introduction: The aim of this short communication is to examine the journey of scholarship in health professions education (HPE). Methods: We will focus on tangible small steps to start, sustain, and succeed along this journey. Through a proposed innovation in scholarship – micro-scholarship – we will describe how this is similar to and an extension of bite-size or micro-learning, and workplace micro-practice related to just-in-time (JiT) learning settings. Results: We will demonstrate how the small steps for generating and engaging with micro-content can be similarly applied to micro-scholarship. Then, progressive and iterative refinement of output and practice of micro-scholarship can be combined and result in macro-scholarship after cycles of public engagement for final digital or print publication. This stepwise approach creates an accessible, sustainable strategy to achieve success as a scholar in HPE. We will elaborate on micro, macro, and meta matters and celebrate how these small steps encourage and allow broad participation in the creation, critique, and progressive refinement of scholarship. Conclusion: Small, sustainable, steps leads to success as a scholar in Health Professions Education - Micro (macro and meta) matters.

From patient to maker - a workflow including people with cerebral palsy in co-creating assistive devices using 3D printing technologies

Purpose Digital fabrication, like 3D printing, is a new opportunity for rehabilitation professionals to produce customized assistive devices. It allows for empowerment and collaboration in device procurement, but practical implementations are scarcely described. We describe the workflow, discuss feasibility and propose directions for future work. Methods We showcase a process of co-manufacturing a custom spoon handle together with two people with cerebral palsy. Our digital manufacturing process was centered around videoconferencing to remotely control the processes from design to final 3D printing. Device functionality and satisfaction were assessed using standard clinical questionnaires: the Individual Priority Problem Assessment Questionnaire (IPPA) and the Quebec User Satisfaction Assessment with Assistive Technology (QUEST 2.0). Results IPPA was instrumental in assessing user needs and device effectiveness. QUEST revealed where to focus future design efforts. Conclusion Involving people with disabilities in co-creation of assistive devices opens for new opportunities for healthcare providers that should be explored in depth using the described methodology. There may also be therapeutic benefits and we envisage specific actions to take in order to make it clinically viable.

President’s Introduction

President’s Introduction Hilary Levine, PhD, CGP, President of EGPS Dear Reader, I am excited that after a period of transition and renewal, a new and improved GROUP journal has been born. It takes a well-coordinated team of people to publish a quarterly journal, and we are fortunate to have had such a dedicated group of people working on GROUP. Recently, several of those people have retired from their roles. I’d like to thank Jonah Schwartz, Erica Gardner-Schuster, and Brunhild Kring for their many years of service to the journal. Contemporaneously, the Board of the Eastern Group Psychotherapy Society (EGPS) has been examining and amending the ways that we have historically centered the experiences of White professionals in private practice. Our newly revised organizational mission reflects our steadfast commitment to being a more just, equitable, diverse, and inclusive organization. The practice of using groups for healing exists on a much broader scale than what has typically been the focus of EGPS’s programming and training. This bias has influenced not only who we attracted as members but also who was interested in writing for and reading our journal. Over the past several months, we have been reimagining and updating how our journal functions to restore our publication to a quarterly journal that serves a broader community of group practitioners. I am grateful to Christine Schmidt for leading this reimagining process. One result was the creation of a mission statement for the journal that is in alignment with our organizational mission. We have strengthened our vision to reflect the unique offerings our journal can bring to group work in an increasingly diverse field. GROUP is a quarterly journal that publishes articles and reviews on the use of groups in the service of healing. The journal encourages creative thought and dissemination of knowledge about group processes and welcomes multiple theoretical orientations, contexts, purposes, and ideologies. Aspiring to be intentionally antioppressive to all people, GROUP seeks to advance scholarship that exemplifies respect for the historical [End Page 7] and current contexts, needs, values, and strengths of cultures, races, and genders typically under- and misrepresented in postcolonial literature. The journal invites articles that integrate perspectives from social work, psychology, politics, sociology, history, the arts, economics, health care, education, and organizational dynamics. Although the journal focuses primarily on the application and experience of group process and practice, GROUP also publishes relevant research articles. Continuously published since 1976, GROUP is the journal of the Eastern Group Psychotherapy Society, a regional affiliate of the American Group Psychotherapy Association. In addition, a search committee, led by Christine Schmidt and Vinny Dehili, was formed to create a new editorial team. I am delighted to announce that after an expansive search for qualified editors, we welcome Dr. Jessica Jean Baptiste and Dr. Marty Cooper to the helm as coeditors of GROUP. They will be joined by a robust and active editorial team to recruit writers and review articles. As our new team gets up and running, rather than putting out four issues this year, we will instead be producing two double issues, 47.1–2 and 47.3–4. Beginning in 2024, we plan to issue four separate quarterly issues. Another change to GROUP is that we have decided to cease production of print editions and to go entirely digital. Please note that this will be the final print edition of GROUP. As always, we welcome potential authors and encourage consultation with the editors about ideas that could be developed into an article. Submitted material receives blind review by scholars and practitioners in the field who serve on the editorial board, although final decisions rest with the editors. For more information, see page 6 or contact info@egps.org. Thank you for your patience during this transition. I hope you thoroughly enjoy this double issue of GROUP. [End Page 8] Copyright © 2023 Eastern Group Psychotherapy Society

Development of a Prediction System for 3D Printed Part Deformation

The Additive Manufacturing (AM) process is applied in industrial applications. However, quality issues of the printed parts, including part distortion and cracks caused by high temperature and fast cooling, result in high residual stress. The theoretical calculation equation shows elastic behavior which is the linear behavior between strain and stress. However, in practice with the additive manufacturing process, strain and stress have nonlinear behavior. So, the prediction of the deformation of a printed part is inaccurate. The contribution of this research is the creation of an Inherent Strain (IS)-based part deformation prediction method during the Selective Laser Melting (SLM) process. To have the deformation in the design stage, we developed software for calculating the IS value and predicting the deformation. The difference between the calculated results and the experimental results is still there, so, we proposed an algorithm and developed an optimization module for the system to minimize this difference. In the final optimal printing process, the parameters are derived in order for the real printing process to have the required quality of the SLM printed part.

The analysis of defects in custom 3D-printed acetabular cups: A comparative study of commercially available implants from six manufacturers.

Three-dimensional (3D) printing is used to manufacture custom acetabular cups to treat patients with massive acetabular defects. There is a risk of defects occurring in these, often in the form of structural voids. Our aim was to investigate the presence of voids in commercially available cups. We examined 12, final-production titanium custom acetabular cups, that had been 3D-printed by six manufacturers. We measured their mass, then performed micro-computed tomography (micro-CT) imaging to determine their volume and density. The micro-CT data were examined for the presence of voids. In cups that had voids, we computed (1) the number of voids, (2) their volume and the cup volume fraction, (3) their sphericity, (4) size, and (5) their location. The cups had median mass, volume, and density of 208.5 g, 46,471 mm3 , and 4.42 g/cm3 , respectively. Five cups were found to contain a median (range) of 90 (58-101) structural voids. The median void volume and cup volume fractions of cups with voids were 5.17 (1.05-17.33) mm3 and 99.983 (99.972-99.998)%, respectively. The median void sphericity and size were 0.47 (0.19-0.65) and 0.64 (0.27-8.82) mm, respectively. Voids were predominantly located adjacent to screw holes, within flanges, and at the transition between design features; these were between 0.17 and 4.66 mm from the cup surfaces. This is the first study to examine defects within final-production 3D-printed custom cups, providing data for regulators, surgeons, and manufacturers about the variability in final print quality. The size, shape, and location of these voids are such that there may be an increased risk of crack initiation from them.

Improving the 3D Printability of Sugar Glass to Engineer Sacrificial Vascular Templates.

A prominent obstacle in scaling up tissue engineering technologies for human applications is engineering an adequate supply of oxygen and nutrients throughout artificial tissues. Sugar glass has emerged as a promising 3D-printable, sacrificial material that can be used to embed perfusable networks within cell-laden matrices to improve mass transfer. To characterize and optimize a previously published sugar ink, we investigated the effects of sucrose, glucose, and dextran concentration on the glass transition temperature (Tg), printability, and stability of 3D-printed sugar glass constructs. We identified a sucrose ink formulation with a significantly higher Tg (40.0 ± 0.9°C) than the original formulation (sucrose-glucose blend, Tg = 26.2 ± 0.4°C), which demonstrated a pronounced improvement in printability, resistance to bending, and final print stability, all without changing dissolution kinetics and decomposition temperature. This formulation allowed printing of 10-cm-long horizontal cantilever filaments, which can enable the printing of complex vascular segments along the x-, y-, and z-axes without the need for supporting structures. Vascular templates with a single inlet and outlet branching into nine channels were 3D printed using the improved formulation and subsequently used to generate perfusable alginate constructs. The printed lattice showed high fidelity with respect to the input geometry, although with some channel deformation after alginate casting and gelation-likely due to alginate swelling. Compared with avascular controls, no significant acute cytotoxicity was noted when casting pancreatic beta cell-laden alginate constructs around improved ink filaments, whereas a significant decrease in cell viability was observed with the original ink. The improved formulation lends more flexibility to sugar glass 3D printing by facilitating the fabrication of larger, more complex, and more stable sacrificial networks. Rigorous characterization and optimization methods for improving sacrificial inks may facilitate the fabrication of functional cellular constructs for tissue engineering, cellular biology, and other biomedical applications.

Le travail du maître imprimeur : La fabrication de la lithographie d'art en couleur dans la France Fin de siècle

In the final years of the nineteenth century, many avant-garde painters in Paris turned to lithography as a new medium through which to further their chromatic exploration. Lithography attracted artists because it did not require their command of the technical aspects of printmaking; they could draw on the stone or transfer paper and then leave the more complex steps to a professional, such as master printer Auguste Clot. Clot became an invaluable collaborator, performing the various labor-intensive steps required to produce color art lithographs, from preparation to final printing. This study examines the printer’s industrial training, manual labor, and technical expertise in color, the medium’s defining aesthetic and material element. The paper argues that the printer’s artisanal labor and crucial collaboration with artists proved essential for the elevation of original art color lithographs above their commercial counterparts.

Predicting the Strength of EBAM 3D Printed Ti-6Al-4V from Processing Conditions

In this study, a process-to-property linear regression model was developed to predict the yield and ultimate tensile strengths of as printed Ti-6Al-4V from electron beam additive manufacturing (EBAM). A total of 8 printing conditions such as bead width, wire feed rate, deposition speed were utilized to predict the material properties in three different notional parts produced over a period of several months. It was found that as the precision and variety of processing conditions collected during print improved between prints, so did the predictive ability of the model. In the final print, the model predicted the yield and ultimate strengths of 72 specimens with an R2 correlation of 0.8 and 0.6 for the horizontal and vertical test specimens, respectively. Although the current model indirectly accounted for thermal fluctuations, further improvements to the model’s ability to predict material strength are expected with the addition of thermal data captured in subsequent notional parts.

Metal Additive Manufacturing of Plastic Injection Molds with Conformal Cooling Channels.

Conformal cooling channels (CCCs) are widely used in the plastic injection molding process to improve the product quality and operational performance. Tooling that incorporates CCCs can be fabricated through metal additive manufacturing (MAM). The present work focuses on the MAM of a plastic injection mold insert with different CCC types that are circular, serpentine, and tapered channels with/without body-centered cubic (BCC) lattices. The entire manufacturing process of the mold insert is explained from the design step to the final printing step including the computational thermal & mechanical simulations, performance assessments, and multiobjective optimization. Compared to the traditional channels, conformal cooling channels achieved up to 62.9% better cooling performance with a better thermal uniformity on the mold surface. The optimum mold geometry is decided using the multiobjective optimization procedure according to the multiple objectives of cooling time, temperature non-uniformity, and pressure drop in the channel. Direct Metal Laser Sintering (DMLS) method is used for manufacturing the molds and the quality of the printed molds are analyzed with the X-ray Computed Tomography (X-ray CT) technique. The errors between the design and the printed parameters are less than 5% for the circular and tapered channels while the maximum deviation of the strut diameters of the BCC is 0.06 mm.