Dissertations / Theses on the topic '3D multi-material printing'

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 62-64).
This thesis presents the development of MultiFab, a multi-material 3D printing architecture that is high-resolution, scalable, and low-cost. MultiFab enables the 3D printing of parts with materials that interact optically and mechanically. The hardware is low-cost since it is built almost exclusively from off-the-shelf components. The system uses commercial piezoelectric printheads that enable multi-material 3D printing with a resolution of at least 40 [mu]m. This thesis presents the design and fabrication of MiniFab, a 3D printer that implements the MultiFab architecture, and its key subsystems, including novel material feeding and UV LED curing systems. Additionally, results show that the printer is capable of producing multi-material parts for a wide variety of applications..
by Javier Eduardo Ramos-Maltés.
S.M.

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 73-75).
The bounds of the design space for 3D-printed objects continue to rapidly extend as the library of printable materials continues to grow. This thesis explores printed objects uniquely enabled by the addition of a magnetic ink to the existing repertoire of materials for the MultiFab printer, a high-resolution, multi-material inkjet 3D printer. Magnetic nanoparticles, a base ink, and a dispersion method are selected to develop the magnetic ink. The ink is optimized for maximal magnetic content and its magnetic properties are characterized. A 9.7 ± 0.8 wt% magnetite ink with expected stability exceeding 10 days is achieved. Design, characterization, and validation of two small-scale multi-material actuators driven by magnetism is performed. The first actuator is a simple fixed cantilever, while the second is a tilting panel. More advanced structures and actuators are explored and are suggestive of an extremely wide scope for potential future applications. The fields of application shown for 3D-printable magnetic ink in a multi-material context range from biomimicry (e.g. stimuli-responsive surfaces) to optics and aerodynamics.
by Louise E. van den Heuvel.
S.M.

Tese de Doutoramento em Arquitetura, com a especialização em Desenho e Computação apresentada na Faculdade de Arquitetura da Universidade de Lisboa para obtenção do grau de Doutor.
Arquitetos e engenheiros estão sob crescente pressão para melhorar a eficiência e a eficácia do setor da arquitetura, engenharia e construção, de forma a reduzir o impacto ambiental, o uso de materiais e os custos. A eficiência de recursos, baseada numa estratégia de economia circular, considera um uso eficiente da energia, assim como dos recursos naturais e materiais. A integração de tecnologias digitais nos processos de construção permitirá uma maior flexibilidade no projeto e customização, bem como a conceção de formas complexas e novos materiais. Nos últimos anos, o interesse no desenvolvimento de tecnologias de fabricação aditiva na construção cresceu, mas encontram-se limitadas ao projeto e fabrico de componentes físicos compostos por materiais com propriedades homogéneas, garantindo a segurança estrutural, mas negligenciando o uso eficiente de recursos. Para superar tais limitações, um novo sistema de fabricação aditiva foi desenvolvido para construção automatizada, permitindo a produção de materiais compósitos heterogéneos com composição espacial variável, através da replicação de processos naturais. Pretende-se, portanto, desenvolver um sistema que permita desenhar e produzir elementos de construção heterogéneos com maior desempenho. Foi desenvolvida uma ferramenta computacional, em Grasshopper, que permite a geração automática da composição do material e o controlo o equipamento de fabricação. A interface com o utilizador permite criar elementos de construção uni ou multimaterial com gradiente de porosidade ou de material, permitindo conceber o material em resposta a requisitos termomecânicos predefinidos, otimizando o seu desempenho. Um equipamento robotizado, composto por várias bombas de material, foi desenvolvido para produzir os elementos de construção heterogéneos gerados pela ferramenta computacional. A necessidade de novos materiais para viabilizar a fabricação aditiva exigiu a realização de trabalho experimental, no qual foram avaliadas as propriedades mecânicas e térmicas de várias misturas de betão de agregados finos contendo cortiça, fibras, basalto e outros resíduos industriais. Foram utilizadas diferentes percentagens de cortiça, uma matéria-prima leve, natural e sustentável, totalmente biodegradável, renovável e reciclável. As misturas de betão com maiores quantidades de cortiça apresentam menor condutividade térmica quando comparadas com as que possuem menor percentagem ou com as que não contêm cortiça, verificando-se igualmente uma redução significativa no peso do material. A utilização de um sistema de fabricação automática que permita a extrusão aditiva betão leve de composição ajustável para a produção de elementos de construção heterogénea poderá ser uma solução eficiente para reduzir os custos energéticos e proporcionar conforto térmico aos utilizadores dos edifícios.
ABSTRACT: Architects and engineers are under increasing pressure to improve the efficiency and effectiveness of the architecture, engineering and construction (AEC) sector, reducing environmental impacts, material use and costs. Resource efficiency, based on a circular economy strategy, considers an efficient use of energy, natural resources, and materials. The integration of digital technologies into construction processes will allow for a greater flexibility in design and customization, as well the emergence of complex shapes and new materials. In recent years, the interest in developing additive manufacturing (AM) technologies in the AEC has increased, though traditional AM technologies are limited to the design and fabrication of physical components with homogeneous material properties, assuring structural safety but with no efficient use of material resources. To overcome these limitations, an AM system was developed for automated fabrication, enabling the fabrication of heterogeneous composite materials with varying material distribution, simulating nature’s structural behavior. The aim is to design and fabricate functionally graded building components with increased performance. A design system, developed in grasshopper, was designed to generate the material composition variation and control the fabrication equipment. The user interface allows creating single or multi-material building components with pore size or material gradients, permitting to design the material in response to thermo-mechanical requirements, optimizing its performance. A multi-pump robot equipment was developed to produce the generated heterogeneous building components. It was necessary to develop printable materials to enable additive fabrication, so experimental work was carried out to assess the mechanical and thermal properties of fiber cement-based concrete mixtures containing cork, basalt and other residual waste. Different percentages of cork were used, as it is a natural and sustainable lightweight raw material, completely biodegradable, renewable, and recyclable. Results show that concrete mixtures with higher quantities of cork have lower thermal conductivity compared to the ones with less percentage or no cork, as well a significant reduction in material weight. The potential use of an AM system to produce printable functionally graded lightweight concretes can be an efficient solution to reduce energy costs and provide thermal comfort for building users.
N/A

The master thesis deals with design of multi material FDM 3D printer. In the first part, current market situation and possible principles of multi material printing are described. Possible variants of individual construction nodes are described in the next part and then the selected variant is processed into a design solution. The benefit of this thesis is a proposal of solution for the automatic printing head exchange, which is practically not concerned by printer manufacturers.

The work herein is, in part, motivated by the idea of creating optimized, actuating structures using additive manufacturing processes (AM). By developing a consistent, repeatable method for designing and manufacturing multi-material compliant mechanisms, significant performance improvements can be seen in application, such as increased mechanism deflection. There are three distinct categories of research that contribute to this overall motivating idea: 1) investigation of an appropriate multi-material topology optimization process for multi-material jetting, 2) understanding the role that manufacturing constraints play in the fabrication of complex, optimized structures, and 3) investigation of an appropriate process for embedding actuating elements within material jetted parts. PolyJet material jetting is the focus of this dissertation research as it is one of the only AM processes capable of utilizing multiple material phases (e.g., stiff and flexible) within a single build, making it uniquely qualified for manufacturing complex, multi-material compliant mechanisms. However, there are two limitations with the PolyJet process within this context: 1) there is currently a dearth of understanding regarding both single and multi-material manufacturing constraints in the PolyJet process and 2) there is no robust embedding methodology for the in-situ embedding of foreign actuating elements within the PolyJet process. These two gaps (and how they relate to the field of compliant mechanism design) will be discussed in detail in this dissertation. Specific manufacturing constraints investigated include 1) "design for embedding" considerations, 2) removal of support material from printed parts, 3) self-supporting angle of surfaces, 4) post-process survivability of fine features, 5) minimum manufacturable feature size, and 6) material properties of digital materials with relation to feature size. The key manufacturing process and geometric design factors that influence each of these constraints are experimentally determined, as well as the quantitative limitations that each constraint imposes on design.
Ph. D.

This paper studies the two aspects of current problems that plagues the Prusa i3 MK3sprinters in possession of JTH and how to resolve them; to be able to get a reliable printoutputs from engineering grade materials apart from conventional materials like PLAand PETG. The second aspect being the implementation of multi material module 2.0S,hereafter referred to as MMU2s successfully by analyzing and testing the current modi-cations and upgrades currently in the community and suggest any further modications,if required, both in terms of hardware and software which is further discussed in theupcoming sections. At present, there are numerous design upgrades and modicationsover the stock parts in the community which claim to iron out the reliability issues ofthe multi material unit. But, the success rates of these modications and upgrades varywidely. We tend to look at some of these modications which helps in eliminating theissues associated with the unit while getting it to produce results in a consistent and reliablemanner. The engineering grade thermoplastics which the university plan to use werealso taken into account to implement in the printers once the MMU2s setup was testedfor reliability. The objective also to create a successful prole sets by tweaking variousparameters in the slicing software for the aforementioned engineering grade materials sothat a ready-to-print prole is available for the corresponding material. During the course of project work, the reliability of the multi material unit was increasedby upgrading few of the components such as idler barrel and selector. Fine tuningof software parameters led to the error free running of the MMU unit by which extensivetesting was possible. Furthermore, engineering grade thermoplastics was able to betested and implemented on the current setup by making use of these software and hardwarechanges. Finally, extensive testing of the multi material unit was done coupled withengineering grade thermoplastics which yielded successful results and the congurationsettings saved for future use in the university.

In diesem Beitrag werden die magnetischen Eigenschaften von ferromagnetischen Proben, welche mittels des neuen 3D-Multimaterialdruckverfahrens (3DMMD) hergestellt wurden, mit herkömmlichen Magnetkreismaterialien verglichen. Dazu wird zunächst die Technologie des Druckverfahrens sowie das Messprinzip und der Versuchsstand beschrieben. Im Weiteren wird ein Überblick über die Materialentwicklung gegeben und die Messergebnisse diskutiert. Es folgt die Betrachtung relevanter Einflüsse bei der Herstellung von Magnetkreisen sowie der Vergleich der Messergebnisse verschiedener Materialien.
In this paper, the magnetic properties of ferromagnetic samples produced using the new 3D multi-material printing process (3DMMD) are compared with conventional magnetic circuit materials. First the technology of the printing process as well as the measuring principle and the test bench are described. Furthermore, an overview of the material development is given and the measurement results are discussed. This is followed by the consideration of relevant influences in the production of magnetic circuits and the comparison of the measurement results of different materials.

The overall goal of this research work is to enhance the capabilities of large-format, polymer material extrusion, additive manufacturing (AM) systems. Specifically, the aims of this research are to (1) Construct, and develop a robust workflow for, a large-format, robotic, AM system; (2) Develop an algorithm for determining and relaying proper rotation commands for 5 degree of freedom (DoF) multi-axis deposition; and (3) Create a method for printing a removable support material in large-format AM. The development and systems-integration of a large-format, pellet-fed, polymer, material extrusion (ME), AM system that leverages an industrial robotic arm is presented. The robotic arm is used instead of the conventional gantry motion stage due to its multi-axis printing ability, ease of tool changes for multi-material deposition and/or subtraction, and relatively small machine footprint. A novel workflow is presented as a method to control the robotic arm for layer-wise fabrication of parts, and several machine modifications and workflow enhancements are presented to extend the multi-axis manufacturing capabilities of the robot. This workflow utilizes existing AM slicers to simplify the motion path planning for the robotic arm, as well as allowing the workflow to not be restricted to a single robotic deposition system. To enable multi-axis deposition, a method for generating tool orientations and resulting deposition toolpaths from a geometry's STL file was developed for 5-DoF conformal printing and validated via simulation using several different multi-DOF robotic arm platforms. Furthermore, this research proposes a novel method of depositing a secondary sacrificial support material was created for large-format AM to enable the fabrication of complex geometries with overhanging features. This method employs a simple tool change to deposit a secondary, water-soluble polymer at the interfaces between the part and supporting structures. In addition, a means to separate support material into smaller sections to extend the range of geometries able to be manufactured via large-format AM is presented. The resultant method was used to manufacture a geometry that would traditionally be considered unprintable on conventional large-format AM systems.
Master of Science
Additive manufacturing (AM), also known as 3D printing, is a method of manufacturing objects in a layer-by-layer technique. Large-format AM is typically defined as an AM system that can create an object larger than 1 m3. There are only a few manufacturers in the world of these systems, and all currently are built on gantry-based motion stages that only allow movement of the printer in three principal axes (X, Y, Z). The primary goal of this thesis is to construct a large-format AM system that uses a robotic arm to enable printing in any direction or orientation. The use of an industrial robotic arm enables printing in multiple planes, which can be used to print structures without support structures, print onto curved surfaces, and to purt with curved layers which produces a smoother external part surface. The design of the large-format AM system was validated through successful printing of objects as large as 1.0x0.5x1.2 m, simultaneous printing of a sacrificial support material to enable overhanging features, and through completing multi-axis printing. To enable multi-axis printing, an algorithm was developed to determine the proper toolpath location and relative orientation to the part surface. Using a part's STL file as input, the algorithm identifies the normal vector at each movement command, which is then used to calculate the required tool orientation. The tool orientations are then assembled with the movement commands to complete the multi-axis toolpath for the robot to perform. Finally, this research presents a method of using a second printing tool to deposit a secondary, water-soluble material to act as supporting structures for overhanging and bridging part features. While typical 3D printers can generally print sacrificial material for supporting overhangs, large-format printers produce layers up to 25 mm wide, rendering any support material impossible to remove without post-process machining. This limits the range of geometries able to be printed to just those with no steep overhangs, or those where the support material is easily reachable by a tool for removal. The solution presented in this work enables the large scale AM processes to create complex geometries.

Bei dem 3D-Multimaterialdruck handelt es sich um ein Verfahren, mit dem es erstmals möglich ist, mehrere Materialien mit unterschiedlichen Eigenschaften in einem Arbeitsgang zu verdrucken. Um die geometrischen und physikalischen Beschränkungen aufzubrechen, wurde an der Professur Elektrischen Energiewandlungssysteme und Antriebe ein Verfahren entwickelt, mit dem es möglich wird, ganze elektromagnetische Energiewandler in einem Arbeitsgang herzustellen. Gleichzeitig lassen sich völlig neue Bauformen von Maschinen realisieren. Durch den Austausch von konventionellen Isolationsmaterialien durch Keramikisolation, werden die thermischen Eigenschaften von Elektromotoren signifikant verbessert.

A novel paste deposition process was developed to widen the range of possible materials and applications. This experimental process developed an increasingly complex series of additive manufacturing machines, resulting in new combinations of novel materials and deposition paths without sacrificing many of the design freedoms inherit in the craft process. The investigation made use of open-source software together with an approach to programming user originated infill geometries to form structural parts, differing from the somewhat automated processing by 'closed' commercial RP systems. A series of experimental trials were conducted to test a range of candidate materials and machines which might be suitable for the PDM process. The combination of process and materials were trailed and validated using a series of themed case studies including medical, food industry and jewellery. Some of the object created great interest and even, in the case of the jewellery items, won awards. Further evidence of the commercial validity was evidenced through a collaborative partnership resulting in the development of a commercial version of the experimental system called Newton3D. A number of exciting potential future directions having been opened up by this project including silicone fabrics, bio material deposition and inclusive software development for user originated infills and structures.

La present tesi doctoral s’ha centrat en el repte d’aconseguir, mitjançant Fabricació Additiva (FA), models per a assaig quirúrgic, sota la premissa que els equips per fer-los haurien de ser accessibles a l’àmbit hospitalari. L’objectiu és facilitar l’extensió de l’ús dels prototips com a eina de preparació d’operacions quirúrgiques, transformant la pràctica mèdica actual de la mateixa manera que en el seu moment ho van fer tecnologies com les que van facilitar l’ús de radiografies. El motiu d’utilitzar FA, en lloc de tecnologies més tradicionals, és la seva capacitat de materialitzar de forma directa les dades digitals obtingudes de l’anatomia del pacient mitjançant sistemes d’escanejat tridimensional, fent possible l’obtenció de models personalitzats. Els resultats es centren en la generació de nou coneixement sobre com aconseguir equipaments d’impressió 3D multimaterials accessibles que permetin l’obtenció de models mimètics respecte als teixits vius. Per facilitar aquesta buscada extensió de la tecnologia, s’ha focalitzat en les tecnologies de codi obert com la Fabricació per Filament Fos (FFF) i similars basades en líquids catalitzables. La recerca s’alinea dins l’activitat de desenvolupament de la FA al CIM UPC, i en aquest àmbit concret amb la col·laboració amb l’Hospital Sant Joan de Déu de Barcelona (HSJD). El primer bloc de la tesi inclou la descripció de l’estat de l’art, detallant les tecnologies existents i la seva aplicació a l’entorn mèdic. S’han establert per primer cop unes bases de caracterització dels teixits vius -sobretot tous- per donar suport a la selecció de materials que els puguin mimetitzar en un procés de FA, a efectes de millorar l’experiència d’assaig dels cirurgians. El caràcter rígid dels materials majoritàriament usats en impressió 3D els fa poc útils per simular tumors i altres referències anatòmiques. De forma successiva, es tracten paràmetres com la densitat, la viscoelasticitat, la caracterització dels materials tous a la indústria, l’estudi del mòdul elàstic de teixits tous i vasos, la duresa d’aquests, i requeriments com l’esterilització dels models. El segon bloc comença explorant la impressió 3D mitjançant FFF. Es classifiquen les variants del procés des del punt de vista de la multimaterialitat, essencial per fer models d’assaig quirúrgic, diferenciant entre solucions multibroquet i de barreja al capçal. S’ha inclòs l’estudi de materials (filaments i líquids) que serien més útils per mimetitzar teixits tous. Es constata com en els líquids, en comparació amb els filaments, la complexitat del treball en processos de FA és més elevada, i es determinen formes d’imprimir materials molt tous. Per acabar, s’exposen sis casos reals de col·laboració amb l’HJSD, una selecció d’aquells en els que el doctorand ha intervingut en els darrers anys. L’origen es troba en la dificultat de l’abordatge d’operacions de resecció de tumors infantils com el neuroblastoma, i a la iniciativa del Dr. Lucas Krauel. Finalment, el Bloc 3 té per objecte explorar nombrosos conceptes (fins a 8), activitat completada al llarg dels darrers cinc anys amb el suport dels mitjans del CIM UPC i de l’activitat associada a treballs finals d’estudis d’estudiants de la UPC, arribant-se a materialitzar equipaments experimentals per validar-los. La recerca ampla i sistemàtica al respecte fa que s’estigui més a prop de disposar d’una solució d’impressió 3D multimaterial de sobretaula. Es determina que la millor via de progrés és la de disposar d’una pluralitat de capçals independents a fi de capacitar la impressora 3D per integrar diversos conceptes estudiats, materialitzant-se una possible solució. Cloent la tesi, es planteja com seria un equipament d’impressió 3D per a models d’assaig quirúrgic, a fi de servir de base per a futurs desenvolupaments.
La presente tesis doctoral se ha centrado en el reto de conseguir, mediante Fabricación Aditiva (FA), modelos para ensayo quirúrgico, bajo la premisa que los equipos para obtenerlos tendrían que ser accesibles al ámbito hospitalario. El objetivo es facilitar la extensión del uso de modelos como herramienta de preparación de operaciones quirúrgicas, transformando la práctica médica actual de la misma manera que, en su momento, lo hicieron tecnologías como las que facilitaron el uso de radiografías. El motivo de utilizar FA, en lugar de tecnologías más tradicionales, es su capacidad de materializar de forma directa los datos digitales obtenidos de la anatomía del paciente mediante sistemas de escaneado tridimensional, haciendo posible la obtención de modelos personalizados. Los resultados se centran en la generación de nuevo conocimiento para conseguir equipamientos de impresión 3D multimateriales accesibles que permitan la obtención de modelos miméticos respecto a los tejidos vivos. Para facilitar la buscada extensión de la tecnología, se ha focalizado en las tecnologías de código abierto como la Fabricación por Hilo Fundido (FFF) y similares basadas en líquidos catalizables. Esta investigación se alinea dentro de la actividad de desarrollo de la FA en el CIM UPC, y en este ámbito concreto con la colaboración con el Hospital Sant Joan de Déu de Barcelona (HSJD). El primer bloque de la tesis incluye la descripción del estado del arte, detallando las tecnologías existentes y su aplicación al entorno médico. Se han establecido por primera vez unas bases de caracterización de los tejidos vivos – principalmente blandos – para dar apoyo a la selección de materiales que los puedan mimetizar en un proceso de FA, a efectos de mejorar la experiencia de ensayo de los cirujanos. El carácter rígido de los materiales mayoritariamente usados en impresión 3D los hace poco útiles para simular tumores y otras referencias anatómicas. De forma sucesiva, se tratan parámetros como la densidad, la viscoelasticidad, la caracterización de materiales blandos en la industria, el estudio del módulo elástico de tejidos blandos y vasos, la dureza de los mismos, y requerimientos como la esterilización de los modelos. El segundo bloque empieza explorando la impresión 3D mediante FFF. Se clasifican las variantes del proceso desde el punto de vista de la multimaterialidad, esencial para hacer modelos de ensayo quirúrgico, diferenciando entre soluciones multiboquilla y de mezcla en el cabezal. Se ha incluido el estudio de materiales (filamentos y líquidos) que serían más útiles para mimetizar tejidos blandos. Se constata como en los líquidos, en comparación con los filamentos, la complejidad del trabajo en procesos de FA es más elevada, y se determinan formas de imprimir materiales muy blandos. Para acabar, se exponen seis casos reales de colaboración con el HJSD, una selección de aquellos en los que el doctorando ha intervenido en los últimos años. El origen se encuentra en la dificultad del abordaje de operaciones de resección de tumores infantiles como el neuroblastoma, y en la iniciativa del Dr. Lucas Krauel. Finalmente, el Bloque 3 desarrolla numerosos conceptos (hasta 8), actividad completada a lo largo de los últimos cinco años con el apoyo de los medios del CIM UPC y de la actividad asociada a trabajos finales de estudios de estudiantes de la UPC, llegándose a materializar equipamientos experimentales para validarlos. La investigación amplia y sistemática al respecto hace que se esté más cerca de disponer de una solución de impresión 3D multimaterial de sobremesa. Se determina que la mejor vía de progreso es la de disponer de una pluralidad de cabezales independientes, a fin de capacitar la impresora 3D para integrar diversos conceptos estudiados, materializándose una posible solución. Para cerrar la tesis, se plantea cómo sería un equipamiento de impresión 3D para modelos de ensayo quirúrgico, a fin de servir de base para futuros desarrollos.

碩士
國立臺灣科技大學
機械工程系
106
The DLP systems is still in development, but most of the systems use DLP or laser as the light source. Most multi-material machines are top-illuminated and there are few down-lit multi-color multi-material 3D printing. This multi-color multi-material 3D printing system used a mobile device, with a rotating disc that can be assembled with several material slots. This study is to improve the multi-color light-curing 3D printing system and is the same as the original system, which uses a portable device and a rotating disk. The improved machine has the function of printing multi-color and printing Multi-materials, and corrects problems that occurred on the original system. The improved positioning accuracy of the rotating disc can be increased by more than 50%. When printing large objects, it will not directly hit the resin tank; and the problem that the Mobile phone is dragged by the turntable will also be sloved, the Mobile phone platform will keep away before the turntable turns away. When the dial is positioned and then returned to the original position, the mobile phone will not be driven by the rotating disc during printing, which improves the success rate of printing.

This thesis main objective is to integrate 3D printing techniques with a post-processing method in a singular system. The idea is to use an existing 3D printer as the base structure, and then integrate an independent equipment for extrusion and spraying, as well as a laser system resulting in a multi-material 3D printing system with integrated post-production proce-dures. The first task consisted in the substitution and suitability of the entire electronics, followed by the ability to print a viscous material by extrusion and this was tested by defining a range of parameters for which it is possible to obtain the desired design of the 3D printed part. With the preliminary tests accomplished it was verified the need for some adjustments, for example, an inclusion of a heating plate on the printing surface. This equipment gives an extrusion/spray ability to the 3D printer, so that it can be used with different material and/or viscosities. The next step was finding a solution for the coupling of the “add-on” type laser to perform the post-processing as a sintering and / or crosslink source. After installation of all components came the operation test and finishing, such as introduction of laser radiation protection panels, com-pressed air inlets, extruder / spray control source, etc. The last part of this thesis was to assess the functionality of the full system and test the printing parameters: for the extrusion were: first layer height, rotation speed, print speed, den-sity, layer height, software’s nozzle diameter, leaning capacity, double wall support; for the spray: dispensing time, dispenser exit width, dispensing height; and for the laser: manual focus and power.

Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e Tecnologia
Com o desenvolvimento tecnológico, os processos de Fabrico Aditivo têm alcançado uma importância acrescida no mundo da indústria quando comparados com outros processos de fabrico. Tal é devido ao facto de para além de serem capazes de produzir estruturas tridimensionais complexas, que não são obtidas por nenhuma outra tecnologia, também o processo produz uma quantidade mínima, ou mesmo nula, de desperdício. A quantidade de matéria-prima que é utilizada é menor quando comparada com outros processos, o que leva à produção de partes, componentes e dispositivos mais económicos. Estes fatores têm uma elevada importância, de tal forma que se sobrepõem a algumas desvantagens associadas, em alguns casos, como à qualidade do acabamento superficial e à tolerância geométrica. Atualmente, os processos de Fabrico Aditivo têm a oportunidade de criar impacto no mundo da produção, sendo um elemento fulcral da Indústria 4.0De todas as tecnologias associada ao fabrico aditivo, a Modelagem por Deposição Fundida (Fused Deposition Modeling – FDM), comummente designada por Impressão 3D, é a mais fácil de utilizar, e que requere equipamentos mais acessíveis e de fácil aquisição. Esta dissertação centra-se na utilização desta tecnologia na produção de protetores bocais para atletas. O processo atual de produção destes dispositivos não utiliza um design adequado, e a produção personalizada envolve um elevado custo. Através do fabrico por FDM, é possível produzir protetores bocais completamente personalizados, por um custo muito menor e com um mínimo de desperdício. Um dos outros objetivos é a utilização de mono ou multi-materiais poliméricos que possam ser substitutos adequados ao material que atualmente é utilizado na produção de protetores bocais, EVA – copolímero de Acetato- de Vinilo de Etileno.Os materiais que foram objeto de estudo desta dissertação foram o copolímero Acrilonitrilo Butadieno Estireno (ABS), Poliestireno de Elevado Impacto (HIPS), Poli(metil metacrilato) (PMMA) e a Poliuretana Termoplástica (TPU). A variação das propriedades mecânicas com a utilização dos dispositivos foi avaliada através do envelhecimento com uma solução de saliva artificial. As propriedades mecânicas foram avaliadas através de testes de Impacto Transversal e testes de Flexão em Três Pontos (Three Point Bending - 3PB) em provetes impressos em mono e em multi-material (estruturas sandwich), antes e após o processo de envelhecimento em saliva artificial. Os provetes testados foram impressos segundo as normas ASTM D790 e Charpy ISO179.
With the advances in technology, Additive Manufacturing (AM) processes have been gaining an increased importance in the world of industry when compared to other manufacturing processes. This is due to the fact that AM is able to produce parts and components with complex geometries unachievable by other technologies, while generating little or no waste during and after production. When compared to other manufacturing processes, AM uses less raw material, which lowers the production costs. The high importance of these factors overcome the drawbacks that are sometimes associated with the quality of the surface finish and geometry tolerance of printed parts. Nowadays, AM processes have the opportunity to have an impact in the manufacturing world, being a core element of the Industry 4.0.From every available process used in Additive Manufacturing, Fused Deposition Modelling (FDM), commonly known as 3D Printing, is the one which requires the less amount of equipment, and is one of the easiest, if not the easiest to use of all processes, and the equipment needed to produce parts, components or devices through this process are easily available. The main topic of this dissertation is the use of this technology with the aim of producing mouthguards for athletes. The current processes to create mouthguards do not produce devices with the adequate design and customized production has a high cost. The materials used have some hindrances associated with them, and the technologies used in the processing produce a high amount of waste. Through FDM processing, it is possible to obtain completely customized mouthguards with minimal waste. There is also the focus on the comprehension of which material and material combination will suit better this application, in order to have a reliable substitute for the current material employed in the production of mouthguards, which is EVA – copolymer of ethylene-vinyl acetate.The used materials were the copolymer Acrylonitrile-Butadiene-Styrene (ABS), High Impact Polystyrene (HIPS), Poly(methyl methacrylate) (PMMA) and Thermoplastic Polyurethane (TPU). The influence of the use on the mechanical properties was also evaluated through an aging process with an artificial saliva solution. For both mono and sandwich multi-material combinations, before and after the saliva influence, the mechanical properties were evaluated through Transverse Impact Testing and Flexural Testing (Three-Point Bending – 3PB). The tested specimens were printed according to the standards ASTM D790 and Charpy ISO179.

碩士
國立臺北科技大學
化學工程研究所
105
Part III：Development of light-curable resin with low shrinkage and its application in continuous liquid interface production (3D printing) The aim of this research is to develop a light-curable acrylic resin with low cure shrinkage. Herein, the formulas in use were followed by the sol-gel reaction mentioned in the first part. Disscussing the effects of changing double bond density on cure shrinkage, also the influence of thermal and mechanical properties by changing design of oligomer structure and the proportion of acrylate functional group. The result show the shrinkage value after curing is obviously declined by reducing the double bond density of the oligomer, and the lowest one is only 0.97% without filleradded. Moreover, the fluidity of resin presents a low temperature glutinous (51200 cps) and a high temperature flowing (1220 cps), which were respectively suitable for 3D molding technology in “Stereo Lithography Apparatus (SLA)” and “Digital Light Processing (DLP)” system. Then the cured material showed 5% and 10% weight loss temperatures under nitrogen at 347~377℃ and 382~411℃, respectively, and the highest tensile strength reaches 18.02 MPa. To sum up, these results suggest that photo-curable acrylic resin has the advantages of easy preparation, colorlessness, fast curing, high pyrolysis temperature and low cure shrinkage, and it should have a good performance in the high-precision 3D molding technology whether in use directly or as a modified agent for commercially available resin.