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A dissertation submitted to the Faculty of Arts, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Arts May 2016 / The technology of 3-D Printing is afforded extensive coverage in the media. Discourses surrounding this technology are charged with ideas of revolutions in manufacturing, democratisation of technology, and the potential to change the face of consumption and production. This technology is being marketed to the consumer and hobbyist. The consumer-grade 3-D printer is a result of the labour of a loose-knit worldwide community of hobbyists known as the "Maker movement". This movement, a convergence of the traditional "Hacker" culture and Do It Yourself (DIY) is constructed around ideas of affective labour. That is, labour performed for the sole purpose of enjoyment of doing so, and for a sense of well-being and community. The explosion of "affordable" 3-D printing as a technology is a result of this affective labour, yet little mention is made of any forms of labour in popular media discourses surrounding this technology. In this paper I construct a history of the Maker movement while theorising the forms of labour inherent to this movement using the Autonomist Marxism of Michael Hardt and Antonio Negri as a framework. Then, working within the field of Cultural Studies, and drawing on Actor-Network Theory (ANT), I perform Multimodal Critical Discourse Analysis (MCDA) on a small sample of texts to illustrate the occlusion and obfuscation of labour within these discourses of the consumer 3-D printer

Background: The applications for rapid prototyping have expanded dramatically over the last 20 years. In recent years, additive manufacturing has been intensely investigated for surgical implants, tissue scaffolds, and organs. There is, however, scant literature to date that has investigated the viability of 3D printing of surgical instruments. Materials and Methods: Using a fused deposition manufacturing (FDM) printer, an army/ navy surgical retractor was replicated from polylactic acid (PLA) filament. The retractor was sterilized using standard FDA approved glutaraldehyde protocols, tested for bacteria by PCR, and stressed until fracture in order to determine if the printed instrument could tolerate force beyond the demands of an operating room. Results: Printing required roughly 90 minutes. The instrument tolerated 13.6 kg of tangential force before failure, both before and after exposure to the sterilant. Freshly extruded PLA from the printer was sterile and produced no PCR product. Each instrument weighed 16g and required only $0.46 of PLA. Conclusions: Our estimates place the cost per unit of a 3D printed retractor to be roughly 1/10th the cost of a stainless steel instrument. The PLA Army/ Navy is strong enough for the demands of the operating room. Freshly extruded PLA in a clean environment, such as an OR, would produce a sterile, ready to use instrument. Due to the unprecedented accessibility of 3D printing technology world wide, and the cost efficiency of these instruments, there are far reaching implications for surgery in some underserved and less developed parts of the world.

Submitted by Newton Salvador Grande Neto (newsalgn@hotmail.com) on 2016-04-08T03:13:41Z No. of bitstreams: 1 Newton Salvador corrigido 30-03.pdf: 4627333 bytes, checksum: 32bbc790f76698649a60a184c85c6860 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-04-08T17:05:27Z (GMT) No. of bitstreams: 1 grandeneto_ns_me_ilha.pdf: 4627333 bytes, checksum: 32bbc790f76698649a60a184c85c6860 (MD5) / Made available in DSpace on 2016-04-08T17:05:27Z (GMT). No. of bitstreams: 1 grandeneto_ns_me_ilha.pdf: 4627333 bytes, checksum: 32bbc790f76698649a60a184c85c6860 (MD5) Previous issue date: 2016-03-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A técnica de replicar a morfologia de uma estrutura advinda do interior do corpo humano através de um modelo físico é conhecida como biomodelagem. Na área da saúde, um modelo da anatomia humana virtual ou físico é chamado de biomodelo, e este trouxe para a medicina um outro nível em relação a cirurgias modernas, como por exemplo, a possibilidade de o médico cirurgião realizar a simulação de uma cirurgia no biomodelo, analisando as melhores estratégias que serão adotadas para o sucesso da intervenção cirúrgica. Para a confecção de biomodelos são necessárias a execução de três etapas básicas: aquisição de imagens médicas via tomografia computadorizada, tratamento destas imagens utilizando um software específico e a confecção utilizando a manufatura aditiva, caracterizando assim todo o processo de biomodelagem. Todo este processo se tornou possível devido a integração entre as áreas de informática, engenharia, saúde, diagnóstico por imagens e principalmente pelo evento ímpar na área de processos de fabricação, o surgimento da manufatura aditiva. Utilizando um conjunto de tecnologias, a manufatura aditiva é capaz de reproduzir fisicamente, em vários materiais, um modelo virtual camada a camada. Diversas técnicas foram desenvolvidas na área de manufatura aditiva, em especial a impressão tridimensional (3DPrinter) tem seu funcionamento similar a uma impressora comercial a jato de tinta, porém deposita um aglutinante conhecido como binder ao invés de tinta, sobre camadas sucessivas de pó para prototipagem. A reação entre esses dois materiais consolida o formato bidimensional de cada camada, e depois de vários ciclos, um modelo tridimensional está completo. A não utilização de laser para a consolidação das camadas é uma vantagem desta técnica, ou seja, o valor de mercado do maquinário é relativamente mais barato quando comparado a outras técnicas vendidas no mercado. Pesquisas relacionadas a materiais alternativos nacionais são extremamente importantes, pois as descobertas de matérias-primas de baixo custo viabilizam cada vez mais a inclusão da biomodelagem em centros cirúrgicos. Este trabalho teve como objetivo a preparação de um material alternativo economicamente mais viável, utilizando uma proporção em volume de 94% pó de gesso comercial, 5% de ligante e 1% de agente higroscópico. Os resultados demonstram que o material alternativo proposto para este trabalho, se mostrou em torno de 121 vezes mais barato e também atingiu as características necessárias para a construção de biomodelos, como também se mostra tão eficiente em relação a resistência mecânica de manuseio, qualidade superficial e densidade quando comparado a materiais comerciais amplamente aceitos pelo mercado. Com a redução de custos, a técnica de biomodelagem poderá ser utilizada com mais frequência nas intervenções cirúrgicas, diminuindo os riscos existentes na cirurgia através de um planejamento cirúrgico de sucesso. / The technique to replicate a morphology of some interior structure of the human body through a physical model is known as biomodeling. In health care area, a virtual or physical human anatomy model is called biomodel, and this brings to the medicine another level in relation to moderns surgeries, for example, the surgeon has the possibility to perform a simulation of a surgery on a biomodel, making the opportunity to find the best strategies that will be adopted for the success of the surgery intervention. Three basic steps are required to ensure the fabrication of the biomodels: the acquisition of medical images via tomography or MRI, then, the treatment of these images using a specific software, to finally produce the biomodel by additive manufacturing, featuring then the whole process biomodeling. This entire process has become possible because of the integration of information technology, engineering, health, image diagnosis and especially the unique event in the area of manufacturing processes, the emergence of additive manufacturing. By a set of technologies, the additive manufacturing is able to physically reproduce, in several materials, a virtual model layer by layer. Several techniques have been developed in this area, especially the three-dimensional printing (3DPrinter), that operates similarly to a commercial inkjet printer, but, instead of ink, deposits an adhesive known as binder on successive layers of prototyping powder. The reaction between the binder and the powder consolidates the two-dimensional shape of each layer, and, after several cycles, a three-dimensional model is complete. Not utilizing lasers to consolidate the layers is the advantage of this technique that makes the market value of the machinery relatively inexpensive, compared to other market techniques. Researches related to national alternative materials are extremely important, because the Discovery of inexpensive raw materials can enable the inclusion of biomodeling in surgery rooms more and more. The aim of this study is the preparation of an alternative and economically viable material, using a volume proportion of 94% of comercial gypsum powder, 5% of binder and 1% of hygroscopic agent. The results show that the alternative material proposed by this study was about 121 times cheaper and also reached the necessary characteristics for the fabrication of the biomodels, as also shown as efficient regarding to mechanical strength handling, surface quality and density when compared to comercial materials widely accepted by the Market. By reducing the costs, the biomodeling technique can be used more often in surgical interventions, reducing the surgery risks through a success surgical planning.

Orientador: Ruís Camargo Tokimatsu / Resumo: A técnica de replicar a morfologia de uma estrutura advinda do interior do corpo humano através de um modelo físico é conhecida como biomodelagem. Na área da saúde, um modelo da anatomia humana virtual ou físico é chamado de biomodelo, e este trouxe para a medicina um outro nível em relação a cirurgias modernas, como por exemplo, a possibilidade de o médico cirurgião realizar a simulação de uma cirurgia no biomodelo, analisando as melhores estratégias que serão adotadas para o sucesso da intervenção cirúrgica. Para a confecção de biomodelos são necessárias a execução de três etapas básicas: aquisição de imagens médicas via tomografia computadorizada, tratamento destas imagens utilizando um software específico e a confecção utilizando a manufatura aditiva, caracterizando assim todo o processo de biomodelagem. Todo este processo se tornou possível devido a integração entre as áreas de informática, engenharia, saúde, diagnóstico por imagens e principalmente pelo evento ímpar na área de processos de fabricação, o surgimento da manufatura aditiva. Utilizando um conjunto de tecnologias, a manufatura aditiva é capaz de reproduzir fisicamente, em vários materiais, um modelo virtual camada a camada. Diversas técnicas foram desenvolvidas na área de manufatura aditiva, em especial a impressão tridimensional (3DPrinter) tem seu funcionamento similar a uma impressora comercial a jato de tinta, porém deposita um aglutinante conhecido como binder ao invés de tinta, sobre camadas sucessivas ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The technique to replicate a morphology of some interior structure of the human body through a physical model is known as biomodeling. In health care area, a virtual or physical human anatomy model is called biomodel, and this brings to the medicine another level in relation to moderns surgeries, for example, the surgeon has the possibility to perform a simulation of a surgery on a biomodel, making the opportunity to find the best strategies that will be adopted for the success of the surgery intervention. Three basic steps are required to ensure the fabrication of the biomodels: the acquisition of medical images via tomography or MRI, then, the treatment of these images using a specific software, to finally produce the biomodel by additive manufacturing, featuring then the whole process biomodeling. This entire process has become possible because of the integration of information technology, engineering, health, image diagnosis and especially the unique event in the area of manufacturing processes, the emergence of additive manufacturing. By a set of technologies, the additive manufacturing is able to physically reproduce, in several materials, a virtual model layer by layer. Several techniques have been developed in this area, especially the three-dimensional printing (3DPrinter), that operates similarly to a commercial inkjet printer, but, instead of ink, deposits an adhesive known as binder on successive layers of prototyping powder. The reaction between the binder and th... (Complete abstract click electronic access below) / Mestre

This experiment investigated the effect of infill pattern shape on structural stiffness for 3D printed components made out of carbon fiber reinforced nylon. In order to determine the natural frequency of each specimen, nondestructive vibrational testing was conducted and processed using data acquisition software. After obtaining the acceleration information of each component, in response to ambient vibrational conditions and excitation, frequency response functions were generated. These functions provided the natural frequency of each component, making it possible to calculate their respective stiffness values. The four infill patterns investigated in this experiment were: Zig Zag, Tri-Hex, Triangle, and Concentric. Results of the experiment showed that changing the infill pattern of a 3D printed component, while maintaining a constant geometry and density, could increase mechanical stiffness properties by a factor of two. Comprehensively, the experiment showed that infill pattern geometry directly attributes to the mechanical stiffness of 3D printed components. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

3D printing concrete (3DPC) became one of the most investigated topics in cement and concrete research in the last decade. Research within this topic includes examining the role of admixtures on the fresh-state properties, specifically cement rheology, along with the mechanical performance of the printed materials and structures. 3DPC offers a promising platform for sustainable binders, optimized design, and economic and rapid construction that can help reduce the high CO2 impact of Portland cement. This thesis is aimed towards engineering nano-modified cement binders for 3DPC by characterizing the effects of dispersion on fresh, hardening and hardened properties, examining the potential of combining inorganic nanoparticles with organic admixtures to tailor select rheological properties, and developing printing performance measurements, and applying the findings in promising applications. Nanoclays (NC) are one of the most attractive rheological modifiers for 3DPC as they increase structuration and buildability with minimal increase to viscosity or pumping requirements. This work starts by studying the impact of different dispersion techniques (sonication, magnetic stirring, dry powder mixing) on the rheological properties of NC-modified cement paste. In addition, a novel dry dispersion technique that coats cement grains with nanomaterials was developed and compared to conventional dispersion methods. The results revealed that dry dispersion enhanced NC efficiency in increasing the static yield stress of cement paste, effectively reducing NC content requirements by 33% compared to solution dispersion to achieve the same print height. The observed changes in rheological properties at different NC contents and dispersion techniques implied that the origin of structuration in NC-modified cement pastes is mainly driven by the interactive forces between NC needles (NC-NC) more so than with cement (NC-cement). This incentivized exploring partial treatment of cement with dry dispersion at a relatively high NC content of 10 wt.% to maximize the aforementioned NC-NC interactions. The results confirmed that the mixture of 10 wt.% NC-coated cement with uncoated ones performed similar or better than mixtures where dry dispersion was applied to all cement grains while maintaining the same NC dosage. From the collective findings of this investigation, it was deduced that partial treatment of cement with NC using dry dispersion can maximize NC efficiency in increasing the static yield stress for 3DPC. Moreover, because NC-NC interactions were more influential than NC-cement interactions on the structuration of cement paste, NC are likely to be successful in increasing the static yield stress and buildability of alternative binders for 3DPC. The promising performance of NC-coated cement motivated further exploration of dry dispersion on other nanomaterial types. The impact of dry dispersed versus solution sonicated NC, silica and calcium nanoparticles (SNP and CCNP), and graphene nanoplatelets (GNP), on hydration kinetics and mechanical performance was investigated. Results of isothermal calorimetry and quantitative x-ray diffraction for nano-modified cement pastes showed the critical role of the method of dispersion on the progression of cement hydration, which in turn altered strength development. For example, SNP-coated cement paste exhibited a delay in ettringite formation by a few hours compared to solution sonication, which likely caused the delayed compressive strength development observed in SNP-coated cement mortars. Nevertheless, for mortars modified with NC, SNP, and CCNP, processing via dry dispersion and solution sonication showed comparable 28-day compressive strengths, implying the successful application of dry dispersion for all three nanomaterials. In addition, results showed an increase in electrical conductivity of GNP-coated cement pastes with dry dispersion whereas GNP were not dispersible with sonication without surfactants or functionalization. The collective results show the efficacy of dry dispersion as an alternative dispersion technique to sonication but one that offers ready-to-mix or just-add-water nano-engineered cement products. Therefore, nano-coated cements via dry dispersion could be very beneficial for remote 3DPC applications or commercialization of nano-engineered binders. One of the drawbacks of NC reported in literature and confirmed in this work is the significant increase in stiffness that causes filament breakage and tearing during extrusion. To remedy this, a new hybrid rheological modifier combining NC with methyl cellulose (MC) was introduced to tailor cement paste rheology and meet 3DPC requirements. The hybrid mixture of NC and MC proved to increase NC efficiency by up to 900 Pa/1 wt.% of MC in cement paste without jeopardizing its extrudability, essentially decreasing the NC content requirement, and associated costs, to achieve greater print heights. In addition, the hybrid admixture maintained similar or better mechanical performance compared to unmodified cement mortars whereas addition of NC or MC alone showed reduced 28-day mechanical strengths. To capture the effects of the new admixture on ink or filament properties, three recently proposed printer-based ink tests were applied – elastic buckling of thin walls, slug test and cable sag test. The results confirmed that despite the softening effect of the hybrid admixture on elastic modulus of cement paste compared to NC alone, the critical buckling height, which measures structural stability, was not similarly impacted. In addition, ink cohesion measured by both slug and cable sag tests improved with the hybrid admixture compared to NC or MC alone. The collective results suggest that the hybrid admixture can tailor cement rheology to meet 3DPC requirements by enhancing ink or filament properties while maintaining mechanical performance. The last investigation applied the previous findings to enable 3D printing and facilitate CO₂ mineralization for a new alternative binder. Magnesium oxide (MgO), similar to Portland cement, hardens through hydration but only develops mechanical strength through carbonation. However, atmospheric carbonation is a self-depreciating diffusion process where the carbonation of the exterior retards and limits further internal carbonation. Building upon the new understanding of the origin of structuration of NC in cement pastes and the high performance of the hybrid combination of NC and MC, the new admixture was used to enable 3D printing of MgO binders. The results confirmed that NC enhanced shape stability by increasing static yield stress while MC maintained ink cohesion, thereby effectively making MgO pastes printable. Compression tests of 3D printed and conventionally mold cast MgO paste cylinders showed that 3D printing can significantly increase strength by up to an order of magnitude. Examining the effects of different infill patterns (<100% and 100% infill density) and water-to binder ratios, results indicated that the increase in strength is attributed to 3D printing effects like the lack of protective formwork, which increased water evaporation and consequently increased carbon diffusion and intake. This study was the first to be published on tailoring the rheology of MgO binder and studying the effects of infill patterns on the compressive strength of 3D printed MgO pastes. The summary of results demonstrates that 3D printing can introduce significant benefits for carbon cured material systems, such as reactive MgO based systems, to potentially reach CO2 neutrality or negativity. Chapter 1 is the introduction, which describes how the main goal of this work is to explore the use of nanomaterials for 3DPC. Chapter 2 presents a literature review on 3DPC properties, cement rheology, and nanomaterials. Chapter 3 discusses the effects of NC dispersion, including the novel dry dispersion technique, on the structuration behavior of cement pastes. Chapter 4 dives deeper into the application of dry dispersion on other types of nanoparticles, i.e. SNP, CCNP and GNP. Chapter 5 revisits NC with the addition of MC to tailor cement rheology for 3DPC. Chapter 6 utilizes the results of Chapters 3 and 5 by examining 3D printed MgO paste and carbon intake. Chapter 7 summarizes this work and lists all the chapters’ conclusions. Additional discussions of the printer and extrusion head that were designed and built in Columbia CEEM Carleton Laboratory are also included in the appendix of this work, detailing gantry versus delta printers for 3DPC and the development of a low-cost concrete extrusion head with an open-to-atmosphere hopper that eliminates the need for a pumping system. Lastly, multiple in-situ printing properties and ink performance tests developed by the author, which utilize the printing system to characterize the fresh properties of inks on site, were expanded and detailed

This research defined and evaluated mechanical properties of prototypes created using a plaster based three-dimensional printing (3DP) system commercialized by Z Corporation. 3DP is one of the fastest growing forms of rapid prototyping. Till date, there is little or no information available on material properties of infiltrants used in 3DP. This research work evaluated and documented some of the useful information for 3DP users by determining the effect of build position, build orientation and infiltration materials on the strength of prototypes. The study was performed in three different phases to limit the processing variables and to arrive at definite conclusions on relationship between materials properties and process variables. All specimens were built on the Z Corporation Spectrum Z510. In Phase 1, effects of build location on specimen strength was studied. Phase 2 evaluated the influence of build orientation on specimen strength. System Three Clear Coat epoxy was used during both Phase 1 and 2 for infiltration. The same infiltrant was in both of these phases to limit variables. Using results of Phase 1 & 2, the effects of infiltrant material on tensile strength of prototypes was calculated in Phase 3. Seven different infiltrating materials were tested during Phase 3. These materials included 2 cyanoacrylates and 5 epoxies. The tensile strength, flexural strength, and density and porosity of the specimens were determined and correlated. In each phase six specimens were built for each test performed. Two consistent methods of infiltration were utilized to infiltrate cyanoacrylates and epoxies into the as-processed specimens. It was found that the orientation of the specimen has more of an impact on strength than position within the build platform. The layering build process of rapid prototyping creates a variance in strength depending on the build orientation. Specimens infiltrated with epoxy achieved much higher strength than the specimens infiltrated with cyanoacrylate. Cyanoacrylates may be a good choice in making color concept models; however they are not good candidate materials where strength requirement is important. The epoxies with lower viscosities demonstrated higher part strength among the materials tested.

D. Tech. (Department of Electronic Engineering, Faculty of Engineering and Technology) --Vaal University of Technology / Opening up local markets for worldwide competition has led to the fundamental change in the development of new products. In order for the manufacturers to stay globally competitive, they should be able to attain and sustain themselves as ‘World Class Manufacturers’. These ‘World Class Manufacturers’ should be able to:  Deliver products in fulfilling the total satisfaction of customers.  Provide high quality products.  Offer short delivery time.  Charge reasonable cost.  Comply with all environmental concern and safety requirements. When a design is created for a new product there is great uncertainty as to whether the new design will actually do what it is desired for. New designs often have unexpected problems, hence prototypes are part of the designing process. The prototype enables the engineers and designers to explore design alternatives, test theories and confirm performance prior to standing production of new products. Additive Manufacturing (AM) technologies enable the manufacturers to produce prototypes and products which meet the requirements mentioned above. However the disadvantage of AM technologies, is that the printing material which is required is limited to that of the supplier. When uncommon printing materials must be used to manufacture a prototype or product, the 3D printing process stood out above the rest owing to its printing method. However the printing heads used in current commercially available 3D printers are limited to specific fluid properties, which limits new and unique powder binder combinations. Owing to the problem mentioned, the need arose to develop a more ‘rugged’ printing head (RPH) which will be able to print with different fluid properties. The RPH could then be used to print using unique and new powderbinder combinations. The RPH was designed and constructed using the solenoid inkjet technology as reference. In order to determine the effect which the fluid properties have on the droplet formation, fourteen different glycerol-water test solutions were prepared. The fluid properties were different for each of the glycerol-water solutions. The fluid properties included the viscosity, density and surface tension of the solution. The control parameters of the RPH were theoretically calculated for each of the glycerol-water solutions and nozzle orifice diameter sizes. The control parameters of the RPH included the critical pressure and time. Using an experimental setup, droplets ejected from the RPH could be photographed in order to be analysed. It was determined that the theoretically calculated critical times could not be used in the RPH, as the pulse widths were much lower than the recommended minimum valve pulse width of the solenoid valve used. The control parameters were then determined practically for each of the different glycerol-water solutions as well as for each nozzle orifice diameter size. The practically determined control parameters were also compared to that of the theoretically determined parameters. A mathematical model was formulated for each of the practically determined critical pressure and time parameters. Non-glycerol-water solutions were also prepared in order to determine whether the control parameters could be calculated using the practically determined mathematical models. It was found that the practically determined mathematical models, used to calculate the control parameters, could not be used with non-glycerol-water solutions. Using the practically determined mathematical models, the drop formation process of the non-glycerol-water solutions was not optimized and satellite droplets occurred. Although the practically determined models did not work for non-glycerol-water solutions, the methods used to determine the control parameters for the glycerol-water solutions could still be used to determine the practical critical pressure and time for Newtonian solutions.

Published Article / In this paper the time and cost parameters of tooling manufacturing by metal casting in rapid prototyping sand moulds are assessed and comparison is made with alternative tool making processes such as computer numerical control machining and investment casting (Paris Process). To that end two case studies obtained from local companies were carried out. The tool manufacturing was conducted according to a five steps process chain referred to as Rapid Casting for Tooling (RCT). These steps include CAD modelling, casting simulation, rapid prototyping, metal casting and finishing operations. In particular the Rapid Prototyping (RP) step for producing the sand moulds was achieved with the aid of an EOSINT S 550 Laser Sintering machine and a Spectrum 510 Three Dimensional Printer. The results indicate that RP is the rate determining step and cost driver of the proposed tooling manufacturing technique. In addition it was found that this tool making process is faster but more expensive than machining and investment casting.