Dissertationen zum Thema „Additive and Subtractive Manufacturing“

Additive manufacturing (AM), or 3D printing, is a manufacturing method where components are produced by successively adding material to the product layer by layer, unlike traditional machining where material is subtracted from a workpiece. There are advantages and disadvantages with both methods and it can be a complex problem to determine when one method is preferable to the other. The purpose of this study is to develop a decision support model (DSM) that quickly guides the end user in selecting an appropriate method with regards to production costs. Information is gathered through a literature study and interviews with people working with AM and CNC machining. The model takes into consideration material selection, size, times, quantities, geometric complexity, post-processing and environmental aspects. The DSM was formulated in Microsoft Excel. The difference in costs between each method in relation to quantity and complexity was made and compared to the literature. The AM model is verified with calculations from the Sandvik Additive Manufacturing. The margin of error is low, around two to six percent, when waste material isn’t included in the calculations. Unfortunately, verification of the CNC model hasn’t been performed due to a lack of data, which is therefore recommended as future work. The conclusion of the study is that AM will not replace any existing manufacturing method anytime soon. It is, however, a good complement to the metalworking industry, since small, complex parts with few tolerances benefits from AM. An investigation of existing solutions/services related to the study was also performed with the ambition that the DSM can complement existing solutions. It was found that while there are many services that helps companies with implementing AM through consulting, few provides any software to assist the company. Regarding the question if AM is profitable for certain products, only one software fulfilled that demand, though it didn’t provide any actual costs. The DSM therefore fills a gap among the existing services and software.
Additiv tillverkning (AM), eller 3D-printing, är en tillverkningsmetod där komponenter produceras genom att succesivt addera material till produkten lagervis, till skillnad från skärande bearbetning där material subtraheras från ett arbetsstycke. Det finns fördelar och nackdelar med respektive metod och det kan vara ett komplext problem att avgöra när den ena metoden är att föredra framför den andra. Syftet med denna studie är att utveckla en beslutstödjande modell (DSM) som hjälper användaren välja lämplig metod med avseende på produktionskostnader. Information inhämtas genom en litteraturstudie samt intervjuer med personer som arbetar med AM och skärande bearbetning. Modellen tar hänsyn till material, storlek, tider, geometrisk komplexitet, efterbearbetning och miljöeffekter. Den beslutstödjande modellen skapades i Microsoft Excel. Skillnaden i pris mellan respektive tillverkningsmetod beroende på antal och komplexitet jämfördes mot litteraturstudien. Modellen för AM verifieras med hjälp av kostnadskalkyler från Sandvik Additive Manufacturing. Felmarginalen är förhållandevis låg på cirka två till sex procent när spillmaterial inte tas hänsyn till. Tyvärr har modellen för skärande bearbetning inte verifieras på grund av en brist på data, vilket därför rekommenderas som fortsatt arbete.  Slutsatsen är att AM inte kommer ersätta någon nuvarande tillverkningsmetod. Det är dock ett bra komplement till metallindustrin eftersom små, komplexa komponenter med få toleranskrav gynnas av AM. En undersökning över nuvarande tjänster relaterat till studien genomfördes med ambitionen att utreda om den beslutstödjande modellen kompletterar dessa. Resultatet av undersökningen visar att medan det finns många konsulttjänster som hjälper ett företag implementera AM så är det få som erbjuder någon form av mjukvara. Gällande frågan om AM är lönsam för vissa produkter så var det bara en mjukvara som kunde besvara den, dock utan att visa några kostnader. Den beslutstödjande modellen framtagen i denna studie fyller därmed en funktion bland nuvarande tjänster och mjukvaror.

Syftet: Utvärdera produktionstolerans av objekt som producerats genom additiv framställningsteknik (AF) för användning inom tandvård, samt att jämföra denna teknik med subtraktiv framställningsteknik (SF) genom reverse engineering.Material och metod: Tio exemplar av två olika geometriska objekt framställdes från fem olika AF maskiner och en SF maskin. Objekt A efterliknar ett inlay, medan objekt B återspeglar en modell av en fyrledsbro. Alla objekt delades in i olika mätled; X, Y och Z. Mätningarna utfördes med validerade och kalibrerade instrument. Linjära avstånd mättes med ett digitalt skjutmått och hörnradie samt vinklar mättes med ett digitalt mikroskop.Resultat: Vare sig additiv eller subtraktiv framställning uppvisade en perfekt matchning till CAD-filen med hänsyn till de parametrar som utvärderades i denna studie. Standardavvikelsen gällande linjära mätningar för subtraktiv framställning uppvisade konsekventa resultat i alla led, med undantag för X- och Y-led för objektet A och i Y-led för objekt B. Samtliga additiva tillverkningsgrupper hade en konsekvent standardavvikelse i X- och Y-led, men inte i Z-led. Med avseende på hörnradiemätningar, hade SF gruppen i överlag bättre produktionsnoggrannhet för både objekt A och B medan AM grupperna var mindre noggranna.Konklusion: Med hänsyn till begränsningarna med denna in vitro studie, stödjer resultat hypotesen, med hänsyn till att AF hade en bättre förmåga att återskapa komplexa och små geometrier jämfört med SF. Samtidigt identifierades en bättre reproducerbarhet hos SF gällande enkla geometrier och linjära avstånd. Vidare studier krävs för att bekräfta dessa resultat.
Purpose: To evaluate the production tolerance of objects produced by additive manufacturing systems (AM) for usage in dentistry and to compare with subtractive manufacturing system (SM) through reverse engineering. Materials and methods: Ten specimens of two geometrical objects were produced by five different AM machines and one SM machine. Object A mimics an inlay-shaped object, meanwhile object B reflects a four-unit bridge model. All the objects were divided into different measuring-axis; X, Y and Z. Measurements were performed with validated and calibrated equipment. Linear distances were measured with a digital calliper while corner radius and angle were measured with a digital microscope. Results: None of the additive manufacturing or subtractive manufacturing groups presented a perfect match to the CAD-file regarding all parameters included in present study. Considering linear measurements, the standard deviation for subtractive manufacturing group were consistent in all axis, except for X- and Y-axis in object A and Y-axis for object B. Meanwhile additive manufacturing groups had a consistent standard deviation in X- and Y- axis but not in Z-axis. Regarding corner radius measurements, SM group overall had the best accuracy for both object A and B comparing to AM groups. Conclusion: Within the limitations of this in vitro study, results support the hypothesis, considering AM had preferable capability to re-create complex and small geometry compare to SM. Meanwhile, SM were superior producing simple geometry and linear distances. Further studies are required to confirm these results.

Approved for public release; distribution is unlimited
This study examines additive manufacturing (AM) and describes its potential impact on the Navy’s Supply Chain Management processes. Included in the analysis is the implementation of 3D printing technology and how it could impact the Navy’s future procurement processes, specifically based on a conducted analysis of the automotive aerospace industry. Industry research and development has identified multiple dimensions of AM technology, including material variety, cost saving advantages, and lead-time minimizations for manufacturing products. This project is designed to provide the Navy with a recommendation based on an in-depth industry case-study analysis.

La fabrication additive est en pleine expansion et suscite un intérêt grandissant pour l'industrie, la recherche scientifique et le grand public. Les procédés additifs ont permis des ouvertures pour fabriquer des structures à géométrie complexe par rapport aux fabrications classiques. En revanche, le comportement mécanique des fabrications additives en réponse aux chargements est peu exploré. En particulier la caractérisation mécanique de ces fabrications reste un challenge et se limite souvent à des champs d'investigations pseudo-statiques par des moyens de tests mécaniques classiques tels que des essais de traction. Ce travail de thèse tente donc d'apporter une contribution à la caractérisation mécanique dynamique des fabrications additives sur un champ comparatif avec les fabrications soustractives. Cette contribution repose sur l'utilisation de méthodes modales en réponse à des stimuli « Low Velocity » appliqués au marteau de choc et sur une méthode dynamique « High Velocity » en étudiant le comportement à l’impact de plaques réalisées par procédés additifs (SLM) et soustractifs
Additive manufacturing is rapidly expanding and attracting increasing interest from industry, scientific research and the general public. Additive processes have opened up opportunities for producing structures with complex geometries compared to traditional manufacturing. However, the mechanical behavior of additive fabrications under loading conditions is not extensively explored. In particular, the mechanical characterization of these fabrications remains a challenge and often limits itself to pseudo-static investigation fields through conventional mechanical testing methods such as tensile tests. This doctoral thesis aims to contribute to the dynamic mechanical characterization of additive manufacturing on a comparative scale with subtractive manufacturing. This contribution is based on the use of modal methods in response to 'Low Velocity' stimuli applied by an impact hammer, and on a 'High Velocity' dynamic method studying the impact behavior of plates produced by additive (SLM) and subtractive processes

MOTIVATION In the simplest form, a pencil mark on a page is removed by a traditional rubber eraser. However, the marks are often never fully removed, and the paper thins with each attempt to rub out an old idea. But how does one erase a chair? A pilaster? A room? A building?... More importantly, how does the subtractive act of erasing become an additive one? The historical fabric of a building is important; it is also imperative that it does not remain stagnant. Erasing is an opportunity to design an interior environment that both acknowledges the traces of the pencil marks and the eraser. It is an opportunity to learn from historic design strategies and thoughtfully transition into the present to create a living, breathing palimpsest (Plesch, 2015). PROBLEM Current preservation policies and landmarking tactics arguably contradict preservationists’ claims of promoting environmental, economic, and social growth within communities by exempting historical buildings from complying with codes and regulations which consequently use property that could be more sustainably employed. Historical preservation is largely based in social constructs; therefore, present policies should be reflective of societal changes. At times, the act of preserving often removes these buildings from the possibility of a relevant and functional future by attempting to keep them wedged within historical restraints (Avrami, 2016). METHOD Research of precedent incidents of erasure with applications to concepts involving historical preservation and restoration in the fields interior design and architecture will influence the design approach. These precedent studies will include works by Carlo Scarpa, Peter Zumthor, and David Chipperfield. To supplement these studies, other artistic disciplines and artists, including Robert Rauschenberg, will be researched to holistically comprehend approaches to the concept of erasing. The execution of explorations of erasing different objects and media to better understand the process of erasure will also be imperative. These experimentations will include the strategic erasing of pencil sketches and common objects to investigate how to best represent an object that has been erased. PRELIMINARY RESULTS The approach to erasing the historical fabric of a building is largely dependent on the building itself. This is evident in Scarpa’s attention to the physical and metaphorical joinery of new and existing structures in his design of Palazzo Abatellis, Zumthor’s weaving of old and new brickwork at Kolumba, and Chipperfield’s use of exposed ruins in his design strategy for the Neues Museum (McCarter, 2013; Carrington, 2008; RYKWERT, 2009). The process of erasure within the realm of preservation is a constant and demonstrates how the act of erasing allows opportunities for the existence of something new (Katz, 2006). CONCLUSION Choosing to re-program and systematically erase a section of a historically significant but outdated medical tower as a collective art studio space would introduce the opportunity to design an “erased space “as an environment for post-graduate art students to produce creative work. This space would strengthen the growing bond between a school of the arts and a historic medical school while contributing to the culture of the surrounding neighborhoods and contribute to the rich tradition of art within the city.

The supply chain is changing speedily and on a continuous basis to keep up with the rapid changes in the market, which are summarized as increased competition, changes in traditional customer bases, and changes in customers’ expectations. Thus, companies have to change their way of manufacturing final products in order to customize and expedite the delivery of products to customers. Additive manufacturing, the new production system, effectively and efficiently increases the capability of personalization during the manufacturing process. This consequently increases customer’s satisfaction and company’s profitability. In other words, additive manufacturing has become one of the most important technologies in the manufacturing field. Full implementation of additive manufacturing will change many well-known management practices in the production sector. Theoretical development in the field of additive manufacturing in regards to its impact on supply chain management is rare. There is no fully applied approach in the literature that is focused on managing the supply chain when additive manufacturing is applied. While additive manufacturing is believed to revolutionize and enhance traditional manufacturing, there is no comprehensive toolset developed in the manufacturing field that evaluates the impact of additive manufacturing and determines the best production method that suits the applied supply chain strategy. A significant portion of the existing supply chain methods and frameworks were adopted in this study to examine the implementation of additive manufacturing in supply chain management. The aim of this study is to develop a framework to explain when additive manufacturing “3D printing” impacts supply chain management efficiently. To build the framework, interviews with some companies that already use additive manufacturing in their production system have been carried out. Next, an online survey and two case studies evaluated the framework and validated the results of the final version of the framework. The conceptual framework shows the relationship among supply chain strategies, manufacturing strategy and manufacturing systems. The developed framework shows not only the ability of additive manufacturing to change and re-shape supply chains, but its impact as an alternative manufacturing technique on supply chain strategies. This framework helps managers select more effective production methods based on certain production variables, including product’s type, components’ value, and customization level.
The supply chain is changing speedily and on a continuous basis to keep up with the rapid changes in the market, which are summarized as increased competition, changes in traditional customer bases, and changes in customers’ expectations. Thus, companies have to change their way of manufacturing final products in order to customize and expedite the delivery of products to customers. Additive manufacturing, the new production system, effectively and efficiently increases the capability of personalization during the manufacturing process. This consequently increases customer’s satisfaction and company’s profitability. In other words, additive manufacturing has become one of the most important technologies in the manufacturing field. Full implementation of additive manufacturing will change many well-known management practices in the production sector. Theoretical development in the field of additive manufacturing in regards to its impact on supply chain management is rare. There is no fully applied approach in the literature that is focused on managing the supply chain when additive manufacturing is applied. While additive manufacturing is believed to revolutionize and enhance traditional manufacturing, there is no comprehensive toolset developed in the manufacturing field that evaluates the impact of additive manufacturing and determines the best production method that suits the applied supply chain strategy. A significant portion of the existing supply chain methods and frameworks were adopted in this study to examine the implementation of additive manufacturing in supply chain management. The aim of this study is to develop a framework to explain when additive manufacturing “3D printing” impacts supply chain management efficiently. To build the framework, interviews with some companies that already use additive manufacturing in their production system have been carried out. Next, an online survey and two case studies evaluated the framework and validated the results of the final version of the framework. The conceptual framework shows the relationship among supply chain strategies, manufacturing strategy and manufacturing systems. The developed framework shows not only the ability of additive manufacturing to change and re-shape supply chains, but its impact as an alternative manufacturing technique on supply chain strategies. This framework helps managers select more effective production methods based on certain production variables, including product’s type, components’ value, and customization level.

Aus der Einführung: "Stehen wir am Rande einer bio-nanotechnologischen getriebenen Revolution, die unsere Art zu leben, zu arbeiten und miteinander umzugehen grundlegend verändern wird? Welchem gesellschaftspolitischen, wirtschaftlichen und technologischen Wandel haben wir uns zu stellen? Langfristige Entwicklungszyklen (Kondratieff, Schumpeter) führen zur nachhaltigen Weiterentwicklung der Zivilisation. Mittelfristige Entwicklungen wie die Trends Globalisierung, Urbanisierung, Digitalisierung (Miniaturisierung) und Humanisierung (Individualisierung), die immer stärker unser Umfeld und Handeln beeinflussen führen zu ganzheitlichen, weltumspannenden Grundtendenzen der gesellschaftlichen Weiterentwicklung. Die technologischen "Enabler" Computing, Biotechnology, Artifical Intelligence, Robotik, Nanotechnology, Additive Manufacturing und Design Thinking wirken beschleunigend auf die gesellschaftlichen Entwicklungen ein. Die technologischen Möglichkeiten beschleunigen sowohl gesellschaftspolitische Zyklen und zivilisatorische Anpassungen. Durch rasanten technologischen, wissenschaftlichen Fortschritt, zunehmende Globalisierungswirkungen, beschleunigte Urbanisierung und aber auch politischer Interferenzen sind die Veränderungsparameter eines dynamischen Geschäftsumfelds immer schnellere Transformationen ausgesetzt. Alle diese Richtungen zeigen das unsere gesellschaftliche Entwicklung inzwischen stark durch die Technik getrieben ist. Ob dies auch heißt, dass wir den Punkt der Singularität (Kurzweil) absehbar erreichen ist dennoch noch offen. ..."

This thesis researches the possibility and feasibility of applying additive manufacturing technology in the manufacturing of propellers. The thesis concerns the production at the foundry Oshaug Metall AS. Their products consist of propellers and other large products cast in Nickel-Aluminium Bronze. This report looks at three approaches and applications for additive manufacturing at the foundry. These are additively manufactured pattern, sand mold and end metal parts. The available \emph{State of the Art} systems for the three approaches are listed and the systems suitability is discussed. The systems that meet the stated criteria are selected and further discussion on the advantages and disadvantages of the additive manufacturing approach to the application are carried out for the three respective applications. An experiment was carried out on a scaled propeller blade to measure the geometrical accuracy and surface quality of a 3D-printed pattern. The report is concluded with the conclusion to the stated task and recommendations for further work.

This thesis presents methods to make use of additive manufacturing (AM) or 3D printing (3DP) technology for the fabrication of antenna and electromagnetic (EM) structures. A variety of 3DP techniques based on filament, resin, powder and nano-particle inks are applied for the development and fabrication of antennas. Fully and partially metallised 3D printed EM structures are investigated for operation at mainly microwave frequency bands. First, 3D Sierpinski fractal antennas are fabricated using binder jetting printing technique, which is an AM metal powder bed process. It follows with the introduction of a new concept of sensing liquids using and non-planer electromagnetic band gap (EBG) structure is investigated. Such structure can be fabricated with inexpensive fuse filament fabrication (FFF) in combination with conductive paint. As a third method, inkjet printing technology is used for the fabrication of antennas for origami paper applications. The work investigates the feasibility of fabricating foldable antennas for disposable paper drones using low-cost inkjet printing equipment. It then explores the applicability of inkjet printing on a 3D printing substrate through the fabrication of a circularly polarised patch antenna which combines stereolithography (SLA) and inkjet printing technology, both of which use inexpensive machines. Finally, a variety of AM techniques are applied and compared for the production of a diversity WLAN antenna system for customized wrist-worn application.

The evolution of additive manufacturing (AM) techniques has had such an exponential increase especially in recent years that various and remarkable techniques have been developed for the production of metallic materials. These techniques allow to obtain products with remarkable mechanical characteristics. Therefore, the different AM techniques that employed metallic materials were analysed and their strengths and weaknesses were considered. In particular, investigations were carried out on artefacts made by Direct Metal Laser Sintering (DMLS) technique in two different metal alloys: Inconel-625 and titanium grade 2. In relation to Inconel-625, tomographic analyses were carried out for the detection of ad hoc defects, ultrasound analyses to evaluate anistropy, micrographs and tensile tests to evaluate their mechanical characteristics. The titanium grade 2 products were compared with samples made by the traditional fusion technique to assess their suitability in the dental field. The results show that artefacts made by DMLS technique have overall better features than fusion samples: the defects are less widespread and smaller, the hardness - characteristic of mechanical properties - higher.

Additive Manufacturing is a fast-developing technology that is considered to be a game changer in the manufacturing industry. However, a technological innovation itself has no single objective value for a company. Indeed, it is widely acknowledged that the key aspect of a successful commercialization of a technological innovation is the linkage of the technology and the business model. Based on a qualitative study, which presents how companies have to develop their business model to commercialize AM, we conducted interviews with two Swedish small and medium-sized enterprises, which plan to invest in Additive Manufacturing. These two companies are HGF, a manufacturer of thermoplastic elastomers and rubber products, and Tylö, a manufacturer of heaters, steam generators, saunas, steam showers, and infrared saunas. In our analysis, we decided to analyse the cases successively, according to the nine building blocks of the Business Model Canvas. Firstly, we conducted a within-case analysis to analyse each case isolated from each other, and secondly a cross-case analysis to find possible nexuses, relations or, contrasts. The chapter conclusion provides an overall discussion of the most important findings emerging from the analysis with regard to the required changes within the current business model to capture value from the technology. We could find some disparities for two building blocks (channels and revenue streams). Thus, this implies that there is no universal approach to develop the business model to introduce Additive Manufacturing. Nevertheless, most of the required adjustments show accordance. While three building blocks turned out to remain largely the same (key partnerships, cost structure, and customer segments), four building blocks require important changes (key activities, key resources, value propositions, and customer relationships. The most important implications for those building blocks are presented in the following: Key activities: Upgrade product development Key resources: Establish additional production facilities (3D-printers, etc.) Gather new knowledge about AM Value propositions: Offer customized products Customer relationships: Closer relationship with the (end) customer  Enhance customer co-creation

La tesi se centra en l’ús de nanocomposites conductors elèctricament en la fabricació d’additius. En aquest escenari, dos tipus de nanocomposites estan preparats per utilitzar-los com a matèria primera per a la impressió de nanocomposites conductors elèctricament amb dos tipus diferents de matrius; (1) un polímer termoplàstic i (2) una resina termoestable. Els nanotubs de carboni es van utilitzar com a partícules conductores elèctriques de nanoestructura. Aquestes nanoestructures formen xarxes complexes en una matriu de polímer de manera que el material de la matriu es transforma d’un material aïllant en un material conductor elèctricament. La policaprolactona és un polímer semicristal·lí i es considera material matricial adequat entre la classe de polímers termoplàstics, ja que ofereix unes excel·lents característiques reològiques, de flux i elàstiques. Les cadenes es van imprimir mitjançant una extrusora bio i es va mesurar la conductivitat elèctrica en aquestes cadenes amb l’efecte de la deformació uniaxial. La microstructura canvia sota l’efecte de la deformació uniaxial, provocant una alteració de l’orientació de nanotubs de carboni a la matriu de policaprolactona. Com a conseqüència de la reordenació de nanotubs, les vies conductores es desorganitzen o s’organitzen que poden augmentar o disminuir la conductivitat elèctrica en els nanocomposites. Les radiacions del sincrotró s’utilitzen per sondar aquests canvis en la microestructura. Es van preparar diferents composicions mitjançant nanotubs de carboni i es van estudiar les mostres impreses en termes de conductivitat elèctrica i microestructura mitjançant radiacions de sincrotró. A partir de l’anàlisi, es proposa un model que pugui predir la conductivitat elèctrica sota l’efecte de la deformació uniaxial. En termes de polímers termoestables, s’introdueix un sistema senzill per a la impressió de nanocomposites basats en polímers termoset. En un dels capítols es proporciona un detall complet del sistema d’impressió i de la tinta nanocomposita. Es va preparar tinta de nanocomposites basada en epoxi per contenir nanotubs de carboni com a partícules de farciment amb una petita porció de polímer termoplàstic, policaprolactona. Les mostres impreses estan subjectes al biaix extern que indiquen que són conductores elèctricament. Es van preparar diferents composicions utilitzant resina glicidil bisfenol-A epoxi, trietilenetetramina, policaprolactona, nanotubs de carboni i es destaquen els problemes per obtenir una qualitat d’impressió adequada. Les mostres impreses es van estudiar en termes de conductivitat elèctrica estudiant la conductivitat elèctrica de corrent altern i directe. El sistema material s’explora quant al nivell de reticulació, l’estructura i la morfologia i el comportament tèrmic. Es presenta un model per als nanocomposites mitjançant dades d’impedància obtingudes mitjançant l’espectroscòpia dielèctrica de banda ampla. La impressora s’utilitzarà en un futur per imprimir dispositius funcionals a petita escala, inclosos dispositius d’emmagatzematge d’energia, p. bateries d’estat sòlid, supercondensadors i plaques d’elèctrodes per a aquest tipus de dispositius.
La fabricación aditiva (AM) es un proceso de fabricación de capas sucesivas de material para construir un objeto sólido tridimensional a partir de un modelo digital, a diferencia de las metodologías de fabricación sustractiva. AM ofrece la libertad de diseñar e innovar un producto para que se puedan obtener y revisar piezas complejas si es necesario, en un tiempo reducido en comparación con las tecnologías de fabricación tradicionales. En términos de su utilización total y generalizada, la tecnología tiene aplicaciones limitadas. Por motivos similares, la nanotecnología se considera la fuerza impulsora detrás de una nueva revolución industrial. Tiene la capacidad de incorporar funcionalidades específicas, que se producen debido a la escala nanométrica, a las partes deseadas para dispositivos funcionales como electrodos para dispositivos de almacenamiento de energía. La tesis se centra en el uso de nanocompuestos conductores de electricidad en la fabricación aditiva. En este escenario, dos tipos de nanocompuestos están preparados para usar como materia prima para la impresión de nanocompuestos conductores de electricidad que emplean dos tipos diferentes de material matricial; (1) un polímero termoplástico y (2) una resina termoestable. Los nanotubos de carbono se usaron como partículas de nanoestructura eléctricamente conductoras. Estas nanoestructuras forman redes complejas en una matriz polimérica de manera que el material de la matriz se transforma de un material aislante en un material eléctricamente conductor. La policaprolactona es un polímero semicristalino y se considera un material matriz adecuado entre la clase de polímeros termoplásticos, ya que ofrece excelentes características reológicas, de flujo y elásticas. Los hilos se imprimieron usando una extrusora biológica y se midió la conductividad eléctrica en estos hilos bajo el efecto de la deformación uniaxial. La microestructura cambia bajo el efecto de una deformación uniaxial que conduce a alterar la orientación de los nanotubos de carbono en la matriz de policaprolactona. Como consecuencia de la realineación de los nanotubos, las vías conductoras interrumpen u organizan, lo que puede aumentar o disminuir la conductividad eléctrica en los nanocompuestos. Las radiaciones de sincrotrón se utilizan para sondear tales cambios en la microestructura. Se prepararon diferentes composiciones usando nanotubos de carbono y las muestras impresas se estudiaron en términos de conductividad eléctrica y microestructura usando radiaciones sincrotrónicas. Basado en el análisis, se propone un modelo que puede predecir la conductividad eléctrica bajo el efecto de la deformación uniaxial. En términos de polímeros termoestables, se introduce un sistema simple para la impresión de nanocompuestos termoestables a base de polímeros. El detalle completo del sistema de impresión y la tinta de nanocompuestos se proporciona en uno de los capítulos. La tinta de nanocompuesto a base de epoxi se preparó para contener nanotubos de carbono como partículas de relleno con una pequeña porción de polímero termoplástico, policaprolactona. Las muestras impresas están sujetas al sesgo externo que indica que son eléctricamente conductoras. Se prepararon diferentes composiciones usando resina epoxi de glicidil bisfenol-A, trietilentetramina, policaprolactona, nanotubos de carbono y se resaltan los problemas para adquirir la calidad de impresión adecuada. Las muestras impresas se estudiaron en términos de conductividad eléctrica, estudiando la conductividad eléctrica de corriente alterna y continua. El sistema de materiales se explora en términos del nivel de reticulación, estructura y morfología y comportamiento térmico. Se presenta un modelo para los nanocompuestos utilizando datos de impedancia obtenidos mediante espectroscopía dieléctrica de banda ancha. La impresora se utilizará en el futuro para imprimir dispositivos funcionales a pequeña escala, incluidos dispositivos de almacenamiento de energía.
Additive manufacturing is a process of making successive layers of material to build a three-dimensional solid object from a digital model, as opposed to subtractive manufacturing methodologies. This technology offers the freedom to design and innovation of a product so that complex parts can be obtained and revise if needed, within a small time as compared to traditional manufacturing technologies. In terms of its full utilization and widespread, the technology has limited applications. On similar grounds, nanotechnology is considered as the driving force behind a new industrial revolution. It has the ability to incorporate specific functionalities, occur due to the nanometric scale, to desired parts that offer freedom to design functional devices like electrodes for energy storage devices. The thesis is focusing on the use of electrically conductive nanocomposites into additive manufacturing. In this scenario, two types of nanocomposites are prepared to use as raw material for printing of electrically conductive nanocomposites employing two different types of matrix material; (1) a thermoplastic polymer and (2) a thermoset resin. Carbon nanotubes were used as electrically conductive nanostructure particles. These nanostructures form complex networks into a polymer matrix such that the matrix material transforms from an insulative material into an electrically conductive material. Polycaprolactone is a semicrystalline polymer and it is considered suitable matrix material amongst the class of thermoplastic polymers as it offers excellent rheological, flow and the elastic characteristics. Strands were printed using a bio extruder and electrical conductivity was measured in these strands under the effect of uniaxial deformation. The microstructure changes under the effect of uniaxial deformation leading to alter the orientation of carbon nanotubes in the polycaprolactone matrix. As a consequence of realignment of nanotubes, conductive pathways either disrupt or organize which can increase or decrease an electrical conductivity in the nanocomposites. Synchrotron radiations are used to probe such changes in the microstructure. Two different compositions were prepared using carbon nanotubes and the printed samples are studied in terms of electrical conductivity and microstructure using synchrotron radiations. Based on the analysis, a model is proposed that can predict the orientation of carbon nanotubes under the effect of uniaxial deformation. In terms of thermoset polymers, a simple system is introduced for the printing of thermoset polymer (epoxy) based nanocomposites. Complete detail of the printing system is provided in one of the chapters. Epoxy-based nanocomposite ink was prepared to contain carbon nanotubes as filler particles with a small portion of thermoplastic polymer, polycaprolactone. The printed samples are subject to the external bias which indicate that these are electrically conductive. A complete methodology was provided for the preparation of nanocomposite ink. Different compositions were prepared using glycidyl bisphenol-A epoxy resin, triethylenetetramine, polycaprolactone, carbon nanotubes and issues are highlighted to acquire appropriate print quality. The printed samples were studied in terms of electrical conductivity studying alternating and direct current electrical conductivity. The material system is explored in terms of the level of crosslinking, structure and morphology and thermal behaviour. A model is presented for the nanocomposites using impedance data obtained through broadband dielectric spectroscopy. The printer will be used in future to print small scale functional devices including energy storage devices e.g. solid-state batteries, supercapacitors and electrode plates for such kind of devices.
Universitat Autònoma de Barcelona. Programa de Doctorat en Ciència de Materials

The degradation of natural resources as a result of consumption to support the economic growth of humans society represents one of the greatest sustainability challenges. In order to allow economic growth to continue in a sustainable way, it has to be decoupled from the consumption and destruction of natural resources. This thesis focuses on an innovative manufacturing technology called additive manufacturing (AM) and its potential to become a more efficient and cleaner manufacturing alternative. The thesis also investigates the benefits of accessing the technology through the result-oriented Product-Service Systems (PSS) approach. The outcome of the study is the quantification of raw materials and energy consumption. The scope of study is the application of AM in the scale model kit industry. The methods used are the life cycle inventory study and the system dynamics modeling. The result shows that AM has higher efficiency in terms of raw material usage, however it also has higher energy consumption in comparison to the more traditional manufacturing techniques. The result-oriented PSS approach is shown to be able to reduce the amount of manufacturing equipment needed, thus reducing the energy and raw materials used to produce the equipment, but does not completely decouple economic growth from the consumption of natural resources.

Approved for public release; distribution is unlimited
As the Marine Corps continues to conduct small-unit distributed operations, the strain on its logistics intensifies. The Marine Corps must search for a solution to increase the efficiency and responsiveness of its logistics. One solution is using additive manufacturing, commonly referred to as 3D printing. This thesis answers the question of how additive manufacturing can improve the effectiveness of Marine Corps logistics. In order to answer the question, beneficial process(es), application(s), and level of integration are determined through a comparative analysis of current and future 3D-printing processes, examination of several civilian and military examples, and examination of the impact across current doctrine, organization, training, material, leadership, personnel, and facilities. Several issues should be addressed prior to the Marine Corps fully integrating 3D printers, such as the lack of certification and qualification standards, unreliable end product results, and determining ownership of intellectual property. When these issues are properly mitigated, the Marine Corps should procure printers for the purpose of manufacturing repair parts, tools, and other support aids. Marine Expeditionary Units should be the first units to receive the printers. If the printers are integrated properly, they could assist logisticians in supporting Marines conducting distributed operations throughout the battlefield.

For many engineering applications, vibrations and sound can cause a multitude of issues. Several methods for damping out these vibrations are utilised today such as insulation foam used in walls or heavy granite bases for machinery and optical equipment. More recently, the development of acoustic and elastic metamaterials has shown the possibility to manipulate propagating waves in ways that were not previously possible, such as wave attenuation at an exponential rate. Locally Resonant Metamaterials (LRMs) have been shown to attenuate waves with wavelengths two orders of magnitude greater than the lattice constant of the LRM, making them well suited for low frequency applications. They typically consist of a core, an elastic lining, and a matrix material. Much of the research into LRMs is modelling based, with fewer experimental results to correctly verify different designs. One reason for this is that the manufacture of LRMs can be difficult as they require multiple material properties, and design consistency, particularly as the LRM geometries become more complex. Additive manufacturing (aka 3D printing) promises the ability to make complex shapes reliably and repeatedly. Hence, 3D printing techniques could be used to make LRMs. In this project, a custom built 3D printer is developed, which utilises different deposition techniques to allow it to manufacture an LRM. This facilitates the fabrication of more varied designs of metamaterial, which would have been too impractical otherwise to manufacture. The printer is fully customisable in LabVIEW and utilises a unique 'point-cloud' method to process part geometry. More recently, active applications of LRMs have been explored to achieve behaviours that passive metamaterials cannot. One subset of active metamaterials is the growing field of metamaterial energy harvesting. This is the principle that metamaterials can be used to convert vibrations and sound into another form of usable energy, such as electricity. Two concepts are introduced which use an LRM type design with a magnetic core. By the phenomenon of electromagnetic induction, as a propagating wave induces a periodic displacement on the core, a current is induced in adjacent wires which could potentially be stored for later use in an application.

Additive Manufacturing (AM) is a class of echnologies whereby components are made in an additive, layer-by-layer fashion enabling production of complex parts in which complexity has little or no effect on cost. However typical components roduced using these techniques are basic structural items with no major strength requirement and low geometric tolerances made from a single material. his thesis develops a low-cost Fused Filament abrication (FFF) based AM technique to produce functional parts. This is achieved by through esearching and implementing new materials in ombination and using precise control of infill tool paths for existing materials. Robocasting has previously been shown to be extremely versatile, however is known to offer poorer build quality relative to its ess-versatile counterparts. Research was ndertaken to enable Robocasting to be combined with FFF to enable the print quality and practical benefits of FFF with the material flexibility of Robocasting. This resulted in the manufacture of several multiple-material omponents using the technique to demonstrate its potential. In order to minimise the number of materials required to obtain desired properties, the effect of process parameters such as layer height, infill angle, and infill porosity were investigated. In total over an order of agnitude variation in Young’s modulus and tensile strength were achieved, enabling these properties to be actively controlled within the manufactured components. Finally a novel non-eutectic low melting point alloy was developed to be compatible with the FFF process. Its greater viscosity compared to traditional eutectics resulted in improved print quality and the reliable deposition of electrically conductive track 0.57x0.25mm in cross-section. In addition the material is approximately three orders of magnitude more conductive that typical printable organic inks. A micro-controller was produced using the technique in conjunction with traditional electronics components. This represents the first time a functional electrical circuitry, with sufficient conductivity for the majority of applications and interfacing directly with standard electrical components, has been produced using a very low-cost AM technique such as FFF. The research undertaken builds components with substantially improved functionality relative to traditional AM products, enabling electromechanical components with varying mechanical and electrical properties. It is anticipated that this could substantially reduce the part-count for many engineering assemblies and open up Additive Manufacturing to many new applications.

Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 39-40).
Digital fabrication technologies have been improving their capabilities and competitiveness steadily over the past decade and may be approaching an inflection point in their enterprise adoption. However, several important technological, economic (cost) and business (adoption risk) barriers stand in the way of broader adoption. This research seeks to explore the rich history that has driven the growth of Additive Manufacturing (3D Printing) in the application of manufacturing of a displacement or augmentation of current production level techniques, what business model or characteristics will continue to drive growth and industrial adoption, and the current limitation that must be overcome to unlock broader enterprise adoption. Furthermore, from the viewpoint of growth financing, this paper seeks to answer two critical questions to highlight investment opportunities in the space of Additive Manufacturing; 1) Where is digital fabrication positioned to compete with traditional manufacturing methods over the next five years and what are the key enablers, and 2) As digital fabrication becomes more competitive for different applications, who in the value chain benefits the most.
by Jason Wehrs.
M.B.A.

Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, School of Engineering, System Design and Management Program, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 55-56).
Additive Manufacturing (AM) -commonly known as 3d printing - is experiencing an upward trend as measured by a number of metrics, such as patent filing and number of company entries. The number of companies manufacturing hardware, software and materials serving both consumer and industrial segments of this industry has increased over recent years. This technology has radically changed how companies, designers and consumers in general go about prototyping their ideas. AM has also impacted low-volume manufacturing by allowing the production of small batches of products with all the advantages and flexibility the technology confers. Because the industry is still in its fluid phase, a high level of activity and significant changes are still to come. Employing Diffusion of Innovation theory by E.M. Rogers [1] which proposes the use of five factors or dimensions to assess the diffusion speed: relative advantage, compatibility, complexity, triability and observability; the study followed a two-pronged methodology. First I conducted semi-structured interviews and observational analysis; then, I analyzed technological developments, patent activity and firm entry. This study uncovers that 3d-printing something without observing technical requirements is quite easy. But 3d-printing a product that complies with a set of product requirements and specifications, so that the component can then be used in the context of a larger assembly or specific use, is quite another story. Based on observational data this thesis describes the vicissitudes of designing, selecting the printer, setting up the printer's parameters and ultimately printing a component, and thus demonstrates a perspective of the adoptability of this technology.
by Jose M. Garza.
S.M. in Engineering and Management

Thesis: S.M., Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, September 2013.
"September 2013." Cataloged from PDF version of thesis.
Includes bibliographical references (pages 69-76).
Inherent across all scales in Nature's material systems are multiple design dimensions, the existences of which are products of both evolution and environment. In human manufacturing where design must be preconceived and deliberate, static artifacts with no variation of function across directions, distances or time fail to capture many of these dimensions. Inspired by Nature's ability to generate complex structures and responses to external constraints through adaptation, "4D printing" addresses additive fabrication of artifacts with one or more additional design dimension, such as material variation over distance or direction and response or adaptation over time. This work presents and evaluates a series of enabling explorations into the material, time and information dimensions of additive manufacturing: a variable elasticity rapid prototyping platform and an approach towards Digital Anisotropy, a variable impedance prosthetic socket (VTS) as a case study of interfaces between nature and manufacture, CNSilk as an example of on-demand material generation in freeform tensile fabrication, and Material DNA as an exploration into embedded spatio-temporal content variation.
by Elizabeth Yinling Tsai.
S.M.

Thesis: S.M., Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 90-92).
The thesis presents an Additive Manufacturing Enabling Technology for Optically Transparent Glass. The platform builds on existing manufacturing traditions and introduces new dimensions of novelty across scales by producing unique structures with numerous potential applications in product-, and architectural-design. The platform is comprised of scalable modular elements able to operate at the high temperatures required to process glass from a molten state to an annealed product. The process demonstrated enables the construction of 3D parts as described by Computer Aided Design (CAD) models. Processing parameters such as temperature, flow rate, layer height and feed rate, can be adjusted to tailor the printing process to the desired component; its shape and its properties. The research explores, defines and hard-codes geometric constraints and coiling patterns as well as the integration of various colors into the current controllable process, contributing to a new design and manufacturing space. Performed characterization of the printed material to determine its morphological, mechanical and optical properties, is presented and discussed. Printed parts demonstrated strong adhesion between layers and satisfying optical clarity. The molten glass 3D printer as well as the fabricated objects exhibited, demonstrate the production of parts which are highly repeatable, enable light transmission, and resemble the visual and mechanical performance of glass constructs that are conventionally obtained. Utilizing the optical nature of glass, complex caustic patterns were created by projecting light through the printed objects. The 3D printed glass objects and process described here, aim to contribute new capabilities to the ever-evolving history of a very challenging but limitless material - glass.
by John Klein.
S.M.

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 171-179).
Additive manufacturing (AM), the process of building objects layer by layer from a three dimensional digital model, is gaining significance due to its ability to create unique geometries and/or novel material compositions while spanning a wide range of length scales. However, the viability of using AM for the production of end-use parts hinges on improvements to production speed without making sacrifices to quality. This thesis seeks to understand the rate-limits to extrusion-based AM, commonly referred to as fused deposition modeling (FDM), and to demonstrate this understanding via the design and fabrication of a high-throughput extrusion AM platform. Three subsystems - the pinch wheel extruder, the conduction liquefier, and the open loop series gantry - were identified as rate limiting to conventional FDM systems via module level experimentation and analysis. These limitations motivated the development of three alternate mechanisms -a screw-feed extruder, a laser-heated extruder, and H-frame gantry - which are designed to overcome the limitations of conventional techniques. These mechanisms are combined into a high-throughput desktop-scale prototype, called FastFDM. Using the FastFDM system, test parts are fabricated at twice the material deposition rate of state-of-the-art machines while maintaining comparable accuracy and resolution. The FastFDM approach has promising future applications to the extrusion AM of nanocomposite polymer resins, high-throughput AM of high performance thermoplastics, and adaptation to large-scale extrusion AM systems.
by Jamison Go.
S.M.

The study presents a normative framework for the Additive Manufacturing (AM) implementation process in the UK manufacturing sector. The motivations for the study include the lack of socio-technical studies on the AM implementation process and the need for existing and potential future project managers to have an implementation model to guide their efforts in implementing these relatively new and potentially disruptive technologies. The study has been conducted through case research with the primary data collected through the in-depth semi-structured interviews with AM project managers. Seven case studies were conducted representing AM implementation practice at different stages of the implementation cycle. The first stage involved a pilot study at a post-implementer to identify the main areas of interest for AM implementation research. The second involved a wider study of AM implementers at the post-implementation stage with cross case analysis of implementation practice. The final stage involved an investigation into pre-implementation of AM, applying the proposed framework in three companies yet to fully implement AM as a production method. Contribution towards the existing body of literature was in the form of a normative framework for AM implementation in a variety of industrial sectors. The framework describes the main activities in the implementation process and supports a taxonomy of implementers.

This thesis presents the novel application of microwave technology to the process of additive layer manufacturing (ALM). A particle size sensor, based on microwave cavity perturbation, is described and subsequently demonstrated by the measurement of the complex permeability of a series of Titanium powders. The results are compared with existing theory and finite element simulations of metallic powders. The ability to discern changing particle size distributions is important in ensuring the reliable operation of selective laser melting machines but, to remain industrially relevant, it is vital that the proposed system can be produced at low cost. By way of demonstration, the design and construction of an inexpensive scalar network analyser was completed. A systematic study of surface resistance of a number of metal surfaces, produced by Selective Laser Melting, was undertaken. Using a dielectric resonator with a “lift-off” calibration procedure, the losses of surfaces manufactured in orthogonal orientations and different surface finishes were compared. Surface roughness measurements showed that microwave losses were not monotonically dependent on root-mean-square surface roughness; this was attributed to differing roughness feature size distributions. For microwave characterization of materials over a wide temperature range, it is often desirable to perform cavity perturbation measurements at elevated temperatures. However, it is shown here that heat treatment can permanently modify the surface resistance of a metal surface and potentially lead to inaccurate perturbation results. X-Ray diffraction measurements confirm the source of modification is due to changes in surface stress and the appearance of solution precipitates. The sensitivity of microwave measurements to surface stress also demonstrates the potential for microwave assessment of surfaces produced by ALM. Finally, to stimulate further work in this area, the design of a single mode microwave heating system was discussed and a prototype developed.

In this thesis, we develop a new method for Additive Manufacturing of felt to make three dimensional objects. Felting is a method of intertwining fibers to make a piece of textile. In this work, a 6 DOF UR-5 robotic arm equipped with a 3 DOF tool head to test various approaches to using felting. Due to the novelty of this approach several different control architectures and methodologies are presented. We created felted test samples using a range of processing conditions, and tested them in an Instron machine. Samples were tested parallel to the roving fiber direction and perpendicular to the roving fiber direction. Additionally, two pieces of felt were attached to each other with needling, and these were tested with T-peel tests, pulling both in the direction of the roving fibers and perpendicular to the fibers. We present results for the Young's Modulus and Ultimate Strength of each of these samples. It is anticipated that given the appropriate combination of materials and robotic tooling, this method could be used to make parts for a multitude of applications ranging from custom footwear to advanced composites.
Master of Science
In this paper a new approach to Additive Manufacturing centered on mechanically binding fibers together into a cohesive part is presented. This is accomplished via a robotic system and a process called felting, whereby needles push fibers into each other, entangling them. To validate this approach each system and method was tested individually. We present the results of mechanical tests of a variety of felted samples. Given the results, it is believed that robotic needle felting may be a beneficial method of manufacture for several fields, and it has the potential to easily make customized products.

The inability to monitor the molecular trajectories of whole organs throughout the clinically relevant ischemic interval is a critical problem underlying the organ shortage crisis. Here, we report a novel technique for fabricating manufacturing conformal microfluidic devices for organ interface. 3D conformal printing was leveraged to engineer and fabricate novel organ-conforming microfluidic devices that endow the interface between microfluidic channels and the organ cortex. Large animal studies reveal microfluidic biopsy samples contain rich diagnostic information, including clinically relevant biomarkers of ischemic pathophysiology. Overall, these results suggest microfluidic biopsy via 3D printed organ-conforming microfluidic devices could shift the paradigm for whole organ preservation and assessment, thereby relieving the organ shortage crisis through increased availability and quality of donor organs.
Master of Science

A matrix of variably processed Fe-30at%Ni was deposited with variations in laser travel speeds as well and laser powers. A complete shift in phase stability occurred as a function of varying laser travel speed. At slow travel speeds, the microstructure was dominated by a columnar fcc phase. Intermediate travel speeds yielded a mixed microstructure comprised of both the columnar fcc and a martensite-like bcc phase. At the fastest travel speed, the microstructure was dominated by the bcc phase. This shift in phase stability subsequently affected the magnetic properties, specifically saturation magnetization. Ni-Fe-Mo and Ni-Fe-V permalloys were deposited from an elemental blend of powders as well. Both systems exhibited featureless microstructures dominated by an fcc phase. Magnetic measurements yielded saturation magnetizations on par with conventionally processed permalloys, however coercivities were significantly larger; this difference is attributed to microstructural defects that occur during the additive manufacturing process.

The aim of this master thesis project was to statistically correlate various powder characteristics to the quality of additively manufactured parts. An additional goal of this project was to find a potential second source supplier of powder for GKN Aerospace Sweden in Trollhättan. Five Inconel® alloy 718 powders from four individual powder suppliers have been analyzed in this project regarding powder characteristics such as: morphology, porosity, size distribution, flowability and bulk properties. One powder out of the five, Powder C, is currently used in production at GKN and functions as a reference. The five powders were additively manufactured by the process of laser metal deposition according to a pre-programmed model utilized at GKN Aerospace Sweden in Trollhättan. Five plates were produced per powder and each cut to obtain three area sections to analyze, giving a total of fifteen area sections per powder. The quality of deposited parts was assessed by means of their porosity content, powder efficiency, geometry and microstructure. The final step was to statistically evaluate the results through the analysis methods of Analysis of Variance (ANOVA) and simple linear regression with the software Minitab. The method of ANOVA found a statistical significant difference between the five powders regarding their experimental results. This made it possible to compare the five powders against each other. Statistical correlations by simple linear regression analysis were found between various powder characteristics and quality of deposited part. This led to the conclusion that GKN should consider additions to current powder material specification by powder characteristics such as: particle morphology, powder porosity and flowability measurements by a rheometer. One powder was found to have the potential of becoming a second source supplier to GKN, namely Powder A. Powder A had overall good powder properties such as smooth and spherical particles, high particle density at 99,94% and good flowability. The deposited parts with Powder A also showed the lowest amount of pores compared to Powder C, a total of 78 in all five plates, and sufficient powder efficiency at 81,6%.

Additive manufacturing (AM), also known as 3D-printing is an automated manufacturing process in which the component is built layer upon layer from a predefined 3D computer model. In contrast to conventional manufacturing processes where a vast volume of material is wasted due to machining, AM only uses the material that the component consists of. In addition to material savings, the method has a number of potential benefits. Two of these are (1) a large design freedom which enables the production of complex geometries and (2) a reduced compexity in supply chain as parts can be printed on-demand rather than be kept in stock. This master thesis has been performed at Vattenfall Wind Power and aims to investigate the feasibility to reproduce and/or to refurbish one or two spare parts on a wind turbine by AM and if it can introduce any practical benefits. Components with a high failure rate and/or with an suitible design for AM have been investigated. A rotating union or fluid rotary joint (FRJ) was selected for further analysis. A comprehensive background study has been conducted. A current status of metal AM is described as well as a comparison between conventional and additive processes. Furthermore, current and future applications for AM witihin the wind turbine industry are presented. The mehodology "reverse engineering", main components in a wind power plant including the fluid rotary joint as well as fluid dynamics are also treated in the background study. As a part of the process, a fluid rotary joint with worse historical failure data was disassembled and examined. In order to find other design solutions that contributes to a better and more reliable operation, another better performing fluid roraty joint was investigated. Since detail drawings and material information are missing for the examined units, reverse engineering has been carried out to gather details of the designs. A concept for the first unit has been developed, in which improved design solutions has been introduced and a number of changes have been implemented in order to minimize material consumption and to adapt the design for AM. The concept has been evaluated by the use of numerical methods. Costs and build time have also been estimated for the developed concept. This project has illustated that it is feasable to manufacture spare parts by the use of AM. The developed concept demonstrates several improvements that are not possible to achieve with conventional manufacturing processes. Nevertheless, a number of limitations such as insufficient build volume, costs as well as time cosuming engineering effort and post-proccessing methods are present for AM. These restrictions, in combination with lack of 3D-models, limits the possibility to make use of the technology. However, the future looks bright, if the technology continues to develop and if subcontractors are willing to adapt to AM it will probably have a major breakthrough within the windpower industry.
Additiv tillverkning, "additive manufacturing" (AM) eller 3D-printing är en automatiserad tillverkningsmetod där komponenten byggs lager för lager från en fördefinierad 3D datormodell. Till skillnad från konventionella tillverkningsmetoder där en stor mängd material ofta bearbetas bort, använder AM nästintill endast det material som komponenten består utav. Förutom materialbesparingar, har metoden ett flertal andra potentiella fördelar. Två av dessa är (1) en stor designfrihet vilket möjliggör produktion av komplexa geometrier och (2) en möjlighet till en förenklad logistikkedja eftersom komponenter kan tillverkas vid behov istället för att lagerföras. Detta examensarbete har utförts på Vattenfall Vindkraft och har till syfte att undersöka om det är möjligt att tillverka och/eller reparera en eller två reservdelar genom AM och om det i så fall kan införa några praktiska fördelar. En kartläggning av komponenter med hög felfrekvens och/eller som kan vara lämpade för AM har genomförts. Av dessa har en roterande oljekoppling även kallad roterskarv valts ut för vidare analys. En omfattande bakgrundsstudie har utförts. En nulägesorientering inom området AM för metaller redogörs, här redovisas även en generell jämförelse mellan konventionella och additiva tillverkningsmetoder. Vidare behandlas aktuella och framtida användningsområden för AM inom vindkraftsindustrin. I bakgrundsstudien behandlas också arbetssättet "reverse engineering", huvudkomponenter i ett vindkraftsverk inklusive roterskarven samt flödesdynamik. Under arbetets gång har en roterskarv med sämre driftshistorik undersökts. I syfte att finna andra konstruktionslösningar som bidrar till en säkrare drift har en bättre presenterande enhet från en annan tillverkare granskats. Då viss detaljteknisk data och konstruktionsunderlag saknas för de undersökta enheterna har "reverse engineering" tillämpats. Ett koncept har sedan utvecklats för den första enheten där förbättrade konstruktionslösningar har introducerats samtidigt som en rad konstruktionsförändringar har gjorts i syfte att minimera materialåtgången och samtidigt anpassa enheten för AM. Konceptet har sedan evaluerats med hjälp av numeriska beräkningsmetoder. För det givna konceptet har även kostnad och byggtid uppskattats. Arbetet visar på att det är möjligt att ta fram reservdelar till vindkraftverk med hjälp av AM. Det framtagna konceptet visar på ett flertal förbättringar som inte kan uppnås med konventionella tillverkningsmetoder. Emellertid finns det en rad begränsningar såsom otillräcklig byggvolym, kostnader och tidskrävande ingenjörsmässigt arbete och efterbehandlingsmetoder. Dessa förbehåll i kombination med avsaknad av 3D-modeller begränsar möjligheterna att nyttja tekniken i dagsläget. Framtiden ser dock ljus ut, om tekniken fortsätter att utvecklas samtidigt som underleverantörer är villiga att nyttja denna teknik kan AM få ett stort genombrott i vindkraftsindustrin.

Additive Manufacturing (AM) has demonstrated great potential to advance product design and manufacturing, and has showed higher flexibility than conventional manufacturing techniques for the production of small volume, complex and customised components. In an economy focused on the need to develop customised and hi-tech products, there is increasing interest in establishing AM technologies as a more efficient production approach for high value products such as aerospace and biomedical products. Nevertheless, the use of AM processes, for even small to medium volume production faces a number of issues in the current state of the technology. AM production is normally used for making parts with complex geometry which implicates the assessment of numerous processing options or choices; the wrong choice of process parameters can result in poor surface quality, onerous manufacturing time and energy waste, and thus increased production costs and resources. A few commonly used AM processes require the presence of cellular support structures for the production of overhanging parts. Depending on the object complexity their removal can be impossible or very time (and resources) consuming. Currently, there is a lack of tools to advise the AM operator on the optimal choice of process parameters. This prevents the diffusion of AM as an efficient production process for enterprises, and as affordable access to democratic product development for individual users. Research in literature has focused mainly on the optimisation of single criteria for AM production. An integrated predictive modelling and optimisation technique has not yet been well established for identifying an efficient process set up for complicated products which often involve critical building requirements. For instance, there are no robust methods for the optimal design of complex cellular support structures, and most of the software commercially available today does not provide adequate guidance on how to optimally orientate the part into the machine bed, or which particular combination of cellular structures need to be used as support. The choice of wrong support and orientation can degenerate into structure collapse during an AM process such as Selective Laser Melting (SLM), due to the high thermal stress in the junctions between fillets of different cells. Another issue of AM production is the limited parts’ surface quality typically generated by the discrete deposition and fusion of material. This research has focused on the formation of surface morphology of AM parts. Analysis of SLM parts showed that roughness measured was different from that predicted through a classic model based on pure geometrical consideration on the stair step profile. Experiments also revealed the presence of partially bonded particles on the surface; an explanation of this phenomenon has been proposed. Results have been integrated into a novel mathematical model for the prediction of surface roughness of SLM parts. The model formulated correctly describes the observed trend of the experimental data, and thus provides an accurate prediction of surface roughness. This thesis aims to deliver an effective computational methodology for the multi- objective optimisation of the main building conditions that affect process efficiency of AM production. For this purpose, mathematical models have been formulated for the determination of parts’ surface quality, manufacturing time and energy consumption, and for the design of optimal cellular support structures. All the predictive models have been used to evaluate multiple performance and costs objectives; all the objectives are typically contrasting; and all greatly affected by the part’s build orientation. A multi-objective optimisation technique has been developed to visualise and identify optimal trade-offs between all the contrastive objectives for the most efficient AM production. Hence, this thesis has delivered a decision support system to assist the operator in the "process planning" stage, in order to achieve optimal efficiency and sustainability in AM production through maximum material, time and energy savings.

Ett av teknikens mest växande områden idag är additiv tillverkning med ett stort applikationsområde som bara växer. Additiv tillverkning är när man tillverkar komponenter genom att lägga till material istället för att avlägsna material för att tillverka en komponent. I samband med att tekniken utvecklas har additiv tillverkning blivit mer och mer vanligt inom industrin där dess applikationer kan spara företagen en stor summa pengar. Ett område där additiv tillverkning kan visas användbart är i produktionen på Volvo GTO, Umeå som är Volvos ledande tillverkare av lastbilshyttar. För att undersöka om additiv tillverkning kan sänka tillverkningskostnaden, öka kvalitén på produkten eller minska leveranstiden på fabriken så har utredaren genom att ha möten och diskussioner med anställda på fabriken försökt att hitta case där den additiva tekniken kan appliceras. Sex case hittades och undersöktes. Casen handlade bland annat om munstycken i tätningslinan, vakumformningsmallar till snickeriet och fördelningsbrickor på målerirobotar. Casen utreddes genom undersökning och tester för att se vilken additiv teknik som passade bäst för just det fallet. När alla case hade undersökts klart så skapades det en investeringsprioritering för att skapa en plan för hur fabriken ska fortsätta sin satsning på den additiva tekniken. Ordningen på listan baseras på vad utredaren tyckte var viktigast och genomförbart. Ordningen blev: FFF-skrivare utan låst materialsystem, SLA-skrivare och sist hamnade MJF-skrivare. Det bedömdes även att fabriken kan spara in 423 384 SEK om året redan nu genom att utnyttja andra additiva tekniker än den som redan finns på plats i fabriken.
One of the fastest growing areas in the manufacturing industry today is additive manufacturing with a large application area that is only getting bigger. Additive manufacturing is when material is added instead of removed in order to produce a part. In connection with the technology being developed, additive manufacturing has become more and more common in the industry where its applications can save companies a large amount of money. An area where additive manufacturing can be shown to be useful is in the production at Volvo GTO, Umeå which is Volvo's leading manufacturer of truck cabins. To investigate whether additive manufacturing can reduce the manufacturing cost, increase the quality of the product or reduce the delivery time at the factory, the investigator has researched what possible cases related to additive manufacturing there is by having meetings and discussions with employees at the factory and finding where the additive technology could be applied. Six cases were found that were investigated. The cases included, among other things, nozzles in the sealing line, vacuum forming templates for the carpentry department and paint distributors on painting robots. The cases were investigated by examining and testing to see which additive technology is best suited for that particular case. When all cases had been investigated thoroughly, an investment priority list was created to create a plan for how the factory should continue its investment in the additive technology. The order on the list is based on what the investigator thought was most important and feasible. The sequence became: FFF printer without locked material system, SLA printer and a MJF printer. It was also found that the factory can save 423 384 SEK a year already by utilizing other additive methods than the one already in place in the factory.

Additive manufacturing (AM), sometimes called 3D-printing is a group of manufacturing technologies that build up a product using a layer by layer technique and provides new ways of manufacturing parts and products. The Company in this thesis wants to make AM a tool in their manufacturing toolbox. When introducing this manufacturing method, new processes and methods have to be developed. The purpose of this thesis is to develop a methodology that will help the designers when identifying parts that should be manufactured using AM. The development of this methodology has followed the principles of service design which is a holistic interdisciplinary approach where methods from different disciplines are combined to create benefits to the end user experience. Before the development process, a large background study was performed to gather detailed information within the area of AM. The methodology concept was then developed through five iterative cycles where methods such as interviews, trigger material, questionnaire, case study and stakeholder mapping were used. The thesis resulted in an AM handbook with information regarding the technology and a five step methodology for choosing when and why to use AM as a manufacturing method. Step one is to identify the AM potential in a product which is based on complexity, customization and production volume. Step two is to specify requirements of the products, this can be surface finish, tolerances etc. The third step in the design methodology is part screening, which is the making of the final decision about if the product should be printed and if it can be printed. The fourth step is to choose an AM technology based on the requirements specified in step two by providing information about the technologies’ restrictions and possibilities. Step five in this methodology is the design of AM products and provides simple design guidelines. It has been shown that a dynamic task is best solved through working with dynamic methods, therefore service design approach is a flexible and good fit for this thesis. This design methodology is only a part of the AM-area and needs to be supplemented with other knowledge within the area. The first step after implementing this handbook is to investigate how the organization and business is affected when implementing AM.
Additiv tillverkning (AM), även kallat 3D-printing, är benämningen på en grupp tillverkningstekniker där en produkt byggs lager för lager. Denna masteruppsats har utförts i samarbete med ett svenskt industriföretag som levererar lösningar inom tillverkningsindustrin, i rapporten kallat Företaget. Genom att utveckla nya designprocesser och metoder vill Företaget inkludera AM i sin tillverkningsstrategi. Syftet med detta masterexamensarbete var att utveckla en metodik för hur urval och utveckling av produkter anpassade för AM ska ske. Utvecklingen av metodiken följer principerna för tjänstedesign, vilket innebär ett holistiskt tvärvetenskapligt arbetssätt där metoder från olika discipliner kombineras för att skapa en positiv upplevelse för slutanvändaren. Innan utvecklingsprocessens start gjordes en stor bakgrundsstudie för att införskaffa kunskaper kring AM. Därefter utvecklades en metod genom fem iterativa cykler där metoder som intervjuer, triggermaterial, frågeformulär, fallstudier och stakeholdermapping användes. Masteruppsatsen resulterade i en handbok med information kring teknikerna och en metodik i fem steg för att välja när och varför AM bör användas som tillverkningsmetod. Första steget är att identifiera AM potentialen hos en produkt, vilket baseras på komplexitet, kundanpassning och produktionsvolym. I steg två ska produktkrav specificeras, exempel på sådana krav är ytfinhet och toleranser. Tredje steget i metoden handlar om en produkt-undersökning under vilken ett slutgiltigt beslut fattas angående om produkten kan och bör tillverkas. I fjärde steget sker valet av teknik baserat på de produktkrav som specificerats i steg två, genom att information ges angående teknikens möjligheter och begränsningar. Femte steget i metoden handlar om designen av AM produkter och förser konstruktören med enklare riktlinjer för designen. Utveckling av en metodik kräver ett dynamiskt arbetssätt och principerna inom service design visade sig passa bra för detta projekt. Det visade sig också att den resulterade metodik behöver kompletteras med information i framtiden. Det behövs även fastställas tydliga mål för AM i företaget och vilket syfte implementeringen av denna nya process innebär

Objective: The purpose of this study was to evaluate the accuracy of surgical guides for dental implant placement fabricated by additive and subtractive techniques. Methods: A standardized mandible model (BoneModels, Castellón, Spain) was duplicated and the proposed implant position was performed from a diagnostic wax-up. An implant was placed in the printed model as a reference. Cone beam computed tomography (CBCT) was made with the radiographic surgical guide to design a surgical guide on BlueSky Plan 4 software. The .stl file of the surgical guide was exported and fabricated by two different techniques: additive (3D printing) and subtractive (milling). Fifteen surgical guides per group were used to place implants in the printed models. The angular deviations, differences in depth, coronal and apical deviations were measured using GeoMagic Control X software. Results were analyzed by Wilcoxon-Mann-Whitney (Wilcoxon Rank Sum) test and PERMANOVA (Permutational Multivariate Analysis of Variance). Intraclass correlation was used to analyze the reproducibility. A 0.05 level of significance was used, with Bonferroni multiple adjustment as needed. Results: There were no significant differences in accuracy of implant placement using additive technique vs subtractive techniques. The mean angular deviations between planned and actual position of implant in mesio-distal cross-section were 0.780±0.803 degrees for printed group and 0.772±0.724 degrees for the milled group. The analogous results in bucco-lingual cross-section were 1.601±1.223 degrees in in printed group and 1.767±0.762 degrees in the milled group. The differences in depth (mm) were measured in four aspects including mesial, distal, buccal and lingual. The mean differences in depth in the group that using printed surgical guides were 0.373±0.285 mm, 0.325±0.230 mm, 0.240±0.228 mm, and 0.247±0.168 mm in those 4 aspects, respectively. The mean differences in depth in the group that using milled surgical guides were 0.511±0.326 mm, 0.396±0.316 mm, 0.215±0.230 mm, and 0.230±0.122 mm in those four aspects, respectively. The mean coronal deviation showed 0.32 mm in the printed group and 0.27 mm in the milled group. For the apical deviation, the results of this study showed mean apical deviation 0.84 mm in the printed group and 0.80 mm in the milled group. Conclusions: No statistically significant difference was identified between the position of implant placed using surgical guide fabricated by the additive technique (3D printing) vs surgical guides fabricated by subtractive technique (milling). The 3D-printed surgical guide could be an alternative for guided-implant surgery with the benefits of high accuracy, ease of fabrication and reduction of laboratory time and materials, thereby increasing cost-effectiveness.

Nel presente documento vengono illustrate le potenzialità delle micro strutture reticolari e le relative tecniche di additive manufacturing necessarie per realizzarle. A partire da questo vengono presentate le problematiche relative all'analisi FEM di tali strutture, confrontando i risultati ottenuti dalle simulazioni con dati sperimentali ricavati da articoli scientifici. Tali difficoltà sono legate alla complessità di queste strutture e all'elevato numero di elementi. Infine, viene proposto un approccio di tipo "building block" per risolvere le difficoltà computazionali sopra citate e vengono valutati pro e contro di questa soluzione.

The aim of this work was to identify methods for the production of patient-specific biomedical devices via indirect additive manufacturing (AM) methods. Additive manufacturing has been shown to provide a good solution for the manufacture of patient specific implants, but in a limited range of materials, and at a relatively high cost. This research project considered what are known as “indirect” AM approaches, which typically consider AM in combination with one or more subsequent processes in order to produce a part, with a maxillofacial plate and mandible resection used as a demonstrator application. Three different approaches were considered: (i) using AM to produce moulds for powder pressing of bioceramic green parts for subsequent sintering; (ii) using AM to produce moulds for biopolymer sintering; and (iii) 3D printing of bioceramic powders into green parts for subsequent sintering. Apatite wollastonite glass ceramic (AW) and poly-Lactide-co-glycolide (PLGA) were selected as the bioceramic and biopolymer materials to process. These were characterised before and after processing in order to ensure that the processing route did not affect the material properties. Geometric dimensions, the morphological structure and mechanical properties were studied to establish the accuracy, shrinkage and strength of the fabricated biomaterial implants. The use of AM processes to produce moulds for PLGA sintering, and the 3D printing of bioceramic powders formed the best overall results in terms of the definition and properties of the manufactured parts. Parts produced were accurate to within 5% of the as designed dimensions for both the PLGA sintering and the bioceramic powders 3D printing. The indirect AM methods are considered to be promising processing routes for medical devices.

Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, 2016. In conjunction with the Leaders for Global Operations Program at MIT.
Thesis: S.M. in Engineering Systems, Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2016. In conjunction with the Leaders for Global Operations Program at MIT.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 119-123).
Additive manufacturing (AM) has emerged as an effective and efficient way to digitally manufacture complicated structures. Raytheon Missile Systems seeks to gain limited production capability with metals AM, which can only be achieved with qualified, predictable processes that reduce variation. The project documented in this thesis produced two results needed to qualify AM for use on flight-critical parts: i) creation of a standard qualification process building upon Raytheon's product development knowledge, and ii) selection and identification of key metals AM process factors and their corresponding experimental responses. The project has delivered a qualification test plan and process that will be used next year to drive adoption and integration of Raytheon's metals AM technology. The first phase of the designed experiment on AM process factors was completed by experimenting with coupon orientation, position on the build platform, coupon shape and hot isostatic pressing (HIP) post-treatment for an Al alloy (AlSi10Mg) produced via laser powder bed fusion using 400-watt laser equipment. Only coupon orientation had a statistically significant effect on dimensional accuracy, increasing the variance of y-axis (within the build plane) error by ~50%, although this is considered a small increase. HIP decreased yield and ultimate stresses by ~60% while increasing ultimate strain by ~250%. Vertical orientation of coupons decreased yield and ultimate stresses by ~25% and increased ultimate strain by ~30%. Small coupon area on the build platform, associated with thin rectangle coupons, decreased yield stress and ultimate strain by ~5%. The processes and case study from this thesis represent a general advance in the adoption of metals AM in aerospace manufacturing.
by Andrew James Byron.
M.B.A.
S.M. in Engineering Systems

Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, May, 2020
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, May, 2020
Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 107-108).
Many aerospace companies are turning to additive manufacturing solutions to stream-line current production processes and open opportunities for on-demand producibility. While many OEMs are drawn to the appeal of the benefits that additive manufacturing brings, they are beginning to understand the difficulties in what it takes to realize those benefits. This paper analyzes additive manufacturing from an industry perspective down to a company perspective to develop a deeper understanding of the practical use cases as well as the various challenges a company faces should they choose to enter this market. This study begins with market research on the additive manufacturing and aerospace industry before honing in on a several use-case parts from rotary aircraft. Selection criterion were created and applied to analyze the value that additive manufacturing would bring in comparison to that of conventional methods, ultimately determining its feasibility for additive manufacturing.
This study applied the selection criterion to various parts of differing functions among the aircraft, resulting in a group of candidate parts. An evaluation method was created and applied to provide an objective assessment on the candidate parts. Initial insights show that additive manufacturing favor casted parts with features that can be optimized to increase performance and reduce costs and weight. In addition, aerospace has the best product mix of low volume parts that are advantageous to the economies of scale for additive manufacturing. Additionally, this study analyzes a company's organization and previous additive manufacturing efforts to propose ways to approach future development. Venturing through the various road maps that lead to the final goal of certification and addressing organizational barriers generate momentum for continuous development.
These road maps, selection criterion, and evaluation method can be applied through many applications within the general aerospace industry.
by Brendon W Chiu.
M.B.A.
S.M.
M.B.A. Massachusetts Institute of Technology, Sloan School of Management
S.M. Massachusetts Institute of Technology, Department of Mechanical Engineering

Impedance-based Non-Destructive Evaluation for Additive Manufacturing (INDEAM) is rooted in the field of Structural Health Monitoring (SHM). INDEAM generalizes the structure-to-itself comparisons characteristic of the SHM process through introduction of inter-part comparisons: instead of comparing a structure to itself over time, potentially-damaged structures are compared to known-healthy reference structures. The purpose of INDEAM is to provide an alternative to conventional nondestructive evaluation (NDE) techniques for additively manufactured (AM) parts. In essence, the geometrical complexity characteristic of AM processes combined with a phase-change of the feedstock during fabrication complicate the application of conventional NDE techniques by limiting direct access for measurement probes to surfaces and permitting the introduction of internal defects that are not present in the feedstock, respectively. NDE approaches that are capable of surmounting these challenges are typically highly expensive. In the first portion of this work, the procedure for impedance-based NDE is examined in the context of INDEAM. In consideration of the additional variability inherent in inter-part comparisons - as opposed to part-to-itself comparisons - the metrics used to quantify damage or change to a structure are evaluated. Novel methods of assessing damage through impedance-based evaluation are proposed and compared to existing techniques. In the second portion of this work, the INDEAM process is applied to a wide variety of test objects. This portion considers how the sensitivity of the INDEAM process is affected by defect type, defect size, defect location, part material, and excitation frequency. Additionally, a procedure for studying the variance introduced during the process of instrumenting a structure is presented and demonstrated.
Doctor of Philosophy
Impedance-based Non-Destructive Evaluation for Additive Manufacturing (INDEAM) is a quality control approach for detecting defects in structures. As indicated by the name, impedance-based evaluation is discussed in this work in the context of qualifying additively manufactured (3D printed) structures. INDEAM fills a niche in the wider world of nondestructive evaluation techniques by providing a less expensive means to qualify structures with complex geometry. Complex geometry complicates inspection by preventing direct, physical access to all the surfaces of a part. Inspection approaches for parts with complex geometry suffuse a structure with energy and measure how the energy propagates through the structure. A prominent technique in this space is CT scanning, which measures how a structure attentuates x-rays passing through it. INDEAM uses piezoelectric materials to both vibrate a structure and measure its response, not unlike listening for the dull tone of a cracked bell. By applying voltage across a piezoelectric patch glued to a structure, the piezoelectric deforms itself and the bonded structure. By monitoring the electrical current needed to produce that voltage, the ratio of applied voltage to current draw---impedance---can be calculated, which can be thought of as a measure of how a system stores and dissipates energy. When the applied voltage oscillates near a resonant frequency of a structure (the pitch of a rung bell, for example) the structure vibrates much more intensely, and that additional movement dissipates more energy due to viscosity, friction, and transmitting sound into the air. This phenomenon is reflected in the measured impedance, so by calculating the impedance value over a large range of frequencies, it is possible to identify many resonances of the structure. So, the impedance value is tied to the vibrational properties of the structure, and the vibration of the structure is tied to its geometry and material properties. One application of this relationship is called impedance-based structural health monitoring: taking measurements of a structure when it is first built as a reference, then measuring it again later to watch for changes that indicate emerging damage. In this work, the reference measurement is established by measuring a group of control structures that are known to be free of defects. Then, every time a new part is fabricated, its impedance measurements will be compared to the reference. If it matches closely enough, it is assumed good. In both cases, impedance values don't indicate what the change is, just that there was a change. A large portion of this work is devoted to determining the types and sizes of defects that can be reliably detected through INDEAM, what effect the part material plays, and how and where the piezoelectric should be mounted to the part. The remainder of this work discusses new methods for conducting impedance-based evaluation. In particular, overcoming the extra uncertainty introduced by moving from part-to-itself structural health monitoring comparisons to the part-to-part quality control comparisons discussed in this work. A new method for mathematically comparing impedance values is introduced which involves extracting the resonant properties of the structure rather than using statistical tools on the raw impedance values. Additionally, a new method for assessing the influence of piezoelectric mounting conditions on the measured impedance values is demonstrated.

There is an upsurge of research interest on Ni-based superalloys additively manufactured (AM) in aerospace sectors. However, achieving the accuracy and quality of the AM part is a challenging task because it is a process of adding material layer by layer with different process parameters. Hence, defects can be observed, and these defects have a detrimental effect on the mechanical properties of the material. Also, AM materials commonly portray a columnar grain structure which also makes it difficult to determine the average grain size because while using the commonly used intercept method, the grain boundaries do not intercept to the test line appropriately. It is important to measure the defects and grain size before performing mechanical testing on the material. Defect measurement and grain size measurements are usually measured manually which results in longer lead time. This work is addressed towards testing recipes in the automated image analysis software to optimize the lead time with good accuracy. Haynes 282, a γ' strengthened superalloy is used in this work. It was assumed that 1,5mm of material from the surface will be machined away so defects had to be measured in this region of interest. The image analysis tools used to test its potentials are MIPAR and ImageJ. Initially, five images in MIPAR and Image J were tested keeping the manual measurements as a benchmark. From this part, it was concluded that metallography and image quality play an important role in the automated measurement. Also, basic Image J software cannot give the measurements of lack of fusion in terms of caliper diameter (longest measurable diameter). Hence, MIPAR was chosen for the application because it was more promising. In the next part, 15 samples were used with manual measurements from a stitched sample and batch processing with MIPAR. The total caliper diameter results were plotted to compare manual measurements and MIPAR. It was observed that scratches were measured as lack of fusion defects at few instances by MIPAR which were further refined using a post-processing function. The defect density results were plotted and compared as well. Due to the difference in calculation of region of interest, the difference in results was observed.To perform the grain size measurement, Haynes 282 was used in HIP and heat treated condition, achieving equiaxed grains. The etchant should be appropriate to reveal the grains. Hence four different etchants were used in this study hydrogen peroxide+HCl, Kallings (electro etch), Kallings (swab) and diluted oxalic acid. This measurement was performed on the material which was cut along the build direction as well as 90º to the growth direction. Since there is no standard for additively manufactured material yet, the results were tested with hall-petch equation to be convinced of the results obtained. It was observed that MIPAR recipe portrayed good results. The results of manual measurements and MIPAR measurements were plotted and compared. It was observed that Hydrogen peroxide and Kallings (swab) showed the grains evidently but twin boundaries were revealed as well. MIPAR calculated the twin boundaries as grains so it over calculated than manual measurements. Kallings (electro etch) and diluted oxalic acid did not reveal the grains so it was difficult for MIPAR to identify the grains.

Additive manufacturing processes of many alloys are known to develop texture during the deposition process due to the rapid reheating and the directionality of the dissipation of heat. Titanium alloys and with respect to this study beta titanium alloys are especially susceptible to these effects. This work examines Ti-20wt%V and Ti-12wt%Mo deposited under normal additive manufacturing process parameters to examine the texture of these beta-stabilized alloys. Both microstructures contained columnar prior beta grains 1-2 mm in length beginning at the substrate with no visible equiaxed grains. This microstructure remained constant in the vanadium system throughout the build. The microstructure of the alloy containing molybdenum changed from a columnar to an equiaxed structure as the build height increased. Eighteen additional samples of the Ti-Mo system were created under different processing parameters to identify what role laser power and travel speed have on the microstructure. There appears to be a correlation in alpha lath size and power density. The two binary alloys were again deposited under the same conditions with the addition of 0.5wt% boron to investigate the effects an insoluble interstitial alloying element would have on the microstructure. The size of the prior beta grains in these two alloys were reduced with the addition of boron by approximately 50 (V) and 100 (Mo) times.

The overall aim of this study is to explore the nature of Industrial Additive Manufacturing Systems as implemented by commercial practitioners, with a specific focus on flexibility within the system and wider supply chain. This study is conducted from an Operations Management perspective to identify management implications arising from the application of contemporary Industrial Additive Manufacturing in the fulfilment of demand. The generation of the theoretical constructs and their evaluation is achieved through an abductive approach. The concept of an Industrial Additive Manufacturing System is developed, through which activities, enabling mechanisms, and control architectures are demonstrated. This is complimented by the proposal of a typology of flexibilities both for the manufacturing system and its supply chain. Twelve case studies are examined through practitioner interviews, observation, and mapping of the production processes at three Industrial Additive Manufacturing companies. These explorations are complimented by interviews with customers downstream of the Additive Manufacturer, and with interviews and a survey of principal upstream machine and material suppliers. This study identifies and classifies types of flexibility relevant to Industrial Additive Manufacturing Systems. It is shown that to achieve requisite flexibilities, it is necessary to manage the whole manufacturing system, not just individual machines. By extension, the internal manufacturing systems’ ability to achieve flexibility is shown to be both facilitated and constrained by the environment in which it operates. In particular, inadequacies in the supply of materials are shown to result in suboptimal practices within the manufacturing system. The principal contribution of this thesis is therefore the development of Industrial Additive Manufacturing from a manufacturing systems perspective, and an evaluation of its implications for flexibility.

Selective laser sintering (SLS) and fused filament fabrication (FFF) are significant methods in additive manufacturing (AM). As AM is increasingly being used to manufacture functional parts, there is a need to have quality systems for AM process, to ensure repeatability of properties or quality of part made by the process. The primary aim of this research is to develop quality systems for SLS and FFF processes of AM. In order to develop a quality system for SLS process based on defining a minimum set of tests to qualify a build, two SLS materials of Nylon 11 and Nylon 12 were investigated. Melt flow index (MFI), impact, tensile and flexural tests were assessed, along with density, surface roughness, dimensional measurements and scanning electron microscopic (SEM). Two benchmark parts were designed for manufacture to track changes in key parameters from one build to another, and tests on this validated against ISO standards. Similarly, to develop a quality system for FFF process, the various mechanical properties of tensile, flexural properties, notched and un-notched impact strengths and sample mass of specimens made from biodegradable polylatic acid (PLA) FFF material were investigated. In order to identify the tests that can be most sensitive to changes in processing conditions and differences in interlayer bond strength which affect the structural integrity of part made by FFF. Analysis of variance (ANOVA) was used to compare the significance of the effect of processing parameters on the mechanical properties, while optical microscopy was also used to investigate failure pattern. A novel low cost method for evaluating fracture strength of FFF made parts was also developed for low cost FFF machines. Benchmark specimens and a low cost test jig were designed and fabricated to track changes in key quality characteristics of FFF made parts from one build to another. Tests conducted on the test jig were validated against those conducted on standard machine. Very good correlation was observed between them. On the basis of the data from experiments, impact strength was adopted as a key test of interlayer bond strengths which determines overall structural strengths of the materials for both SLS and FFF AM processes. A positive correlation exist between density and modulus of SLS parts, and also between sample mass and modulus of FFF made parts. ii This led to the impact strength and density/mass of parts being adopted as key indicators of mechanical integrity, with MFI a good indicator of input material quality, and dimensional accuracy of machine calibration. These tests were thus adopted as a quality assurance system in the respective developed quality system for AM processes of SLS and FFF. If the quality system is implemented, repeatability of properties can be achieved and the quality of product assured.