To see the other types of publications on this topic, follow the link: Metal Manufacturing.
Dissertations / Theses on the topic 'Metal Manufacturing'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Metal Manufacturing.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
PEDEMONTE, LAURA CHIARA. "Laser in Metal Additive Manufacturing." Doctoral thesis, Università degli studi di Genova, 2019. http://hdl.handle.net/11567/973605.
Full textAbstract:
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.
2
Turner, David Bentley. "An assessment of Magic Metal Company." Online version, 1998. http://www.uwstout.edu/lib/thesis/1998/1998turnerd.pdf.
Full text
3
Jaques, Mark W. S. "Design by manufacturing simulation." Thesis, University of Portsmouth, 1994. https://researchportal.port.ac.uk/portal/en/theses/design-by-manufacturing-simulation(73339fbe-283d-4a11-a225-33cabf5e7332).html.
Full textAbstract:
An alternative approach to conventional geometric based computer aided design systems is presented. Within this new approach manufacturing modes are used as the primary input to the design process. By directly actuating a simulation of machine tools and displaying the response of the material to this machine action, manufacturing constraints are captured at the design stage. Both manufacturing and design data can be generated concurrently, leading to a reduction in prototyping development lead times. Geometric and physical models of the manufacturing process are combined through the development of an interaction rule base to form a manufacturing simulation of the bending and forming process. These interaction rules interpret interactions of the geometric models and automatically generates constraints information required by the finite element engine, which performs the physical modelling task, and allows it to be fully embedded. Design trials are presented in which designers successfully used the design by manufacturing simulation approach to design metallic fastenings significantly faster than the traditional computer aided design approach.
4
McCarthy, David Lee. "Creating Complex Hollow Metal Geometries Using Additive Manufacturing and Metal Plating." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/43530.
Full textAbstract:
Additive manufacturing introduces a new design paradigm that allows the fabrication of geometrically complex parts that cannot be produced by traditional manufacturing and assembly methods. Using a cellular heat exchanger as a motivational example, this thesis investigates the creation of a hybrid manufacturing approach that combines selective laser sintering with an electroforming process to produce complex, hollow, metal geometries. The developed process uses electroless nickel plating on laser sintered parts that then undergo a flash burnout procedure to remove the polymer, leaving a complex, hollow, metal part. The resulting geometries cannot be produced directly with other additive manufacturing systems.
Copper electroplating and electroless nickel plating are investigated as metal coating methods. Several parametric parts are tested while developing a manufacturing process. Copper electroplating is determined to be too dependent on the geometry of the part, with large changes in plate thickness between the exterior and interior of the tested parts. Even in relatively basic cellular structures, electroplating does not plate the interior of the part. Two phases of electroless nickel plating combined with a flash burnout procedure produce the desired geometry. The tested part has a density of 3.16g/cm3 and withstands pressures up to 25MPa. The cellular part produced has a nickel plate thickness of 800µm and consists of 35% nickel and 65% air (empty space). Detailed procedures are included for the electroplating and electroless plating processes developed.<br>Master of Science
5
Farshbaf, Mohamad Reza. "Mixed metal forming/machining flexible manufacturing system." Thesis, Open University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277924.
Full text
6
Byron, Andrew James. "Qualification and characterization of metal additive manufacturing." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104315.
Full textAbstract:
Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, 2016. In conjunction with the Leaders for Global Operations Program at MIT.<br>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.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 119-123).<br>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.<br>by Andrew James Byron.<br>M.B.A.<br>S.M. in Engineering Systems
7
Trumper, Richard Leslie. "Fabrication of metal matrix composites by low pressure liquid metal infiltration." Thesis, University of Bath, 1993. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358941.
Full text
8
Nyembwe, Kasongo Didier. "Tool manufacturing by metal casting in sand moulds produced by additive manufacturing processes." Thesis, Bloemfontein : Central University of Technology, Free State, 2012. http://hdl.handle.net/11462/162.
Full textAbstract:
Thesis (D. Tech. ( Mechanical Engineering )) - Central University of technology, Free State, 2012<br>In this study an alternative indirect Rapid Tooling process is proposed. It essentially consists of producing sand moulds by Additive Manufacturing (AM) processes followed by casting of tools in the moulds. Various features of this tool making method have been investigated.
A process chain for the proposed tool manufacturing method was conceptually developed. This process chain referred to as Rapid Casting for Tooling (RCT) is made up of five steps including Computer Aided Design (CAD) modeling, casting simulation, AM of moulds, metal casting and finishing operations. A validation stage is also provided to determine the suitability of the tool geometry and material for RCT. The theoretical assessment of the RCT process chain indicated that it has potential benefits such as short manufacturing time, low manufacturing cost and good quality of tools in terms of surface finish and dimensional accuracy.
Focusing on the step of AM of the sand moulds, the selection of available AM processes between the Laser Sintering (LS) using an EOSINT S 700 machine and Three Dimensional Printing using a Z-Corporation Spectrum 550 printer was addressed by means of the Analytic Hierarchy Process (AHP). The criteria considered at this stage were manufacturing time, manufacturing cost, surface finish and dimensional accuracy. LS was found to be the most suitable for RCT compared to Three Dimensional Printing. The overall preferences for these two alternatives were respectively calculated at 73% and 27%. LS was then used as the default AM process of sand moulds in the present research work.
A practical implementation of RCT to the manufacturing of foundry tooling used a case study provided by a local foundry. It consisted of the production of a sand casting pattern in cast iron for a high pressure moulding machine. The investigation confirmed the feasibility of RCT for producing foundry tools. In addition it demonstrated the crucial role of casting simulation in the prevention of casting defects and the prediction of tool properties. The challenges of RCT were found to be exogenous mainly related to workmanship.
An assessment of RCT manufacturing time and cost was conducted using the case study above mentioned as well as an additional one dealing with the manufacturing of an aluminium die for the production of lost wax patterns. Durations and prices of RCT steps were carefully recorded and aggregated. The results indicated that the AM of moulds was the rate determining and cost driving step of RCT if procurement of technology was considered to be a sunk cost. Overall RCT was found to be faster but more expensive than machining and investment casting.
Modern surface analyses and scanning techniques were used to assess the quality of RCT tools in terms of surface finish and dimensional accuracy. The best surface finish obtained for the cast dies had Ra and Rz respectively equal to 3.23 μm and 11.38 μm. In terms of dimensional accuracy, 82% of cast die points coincided with die Computer Aided Design (CAD) data which is within the typical tolerances of sand cast products. The investigation also showed that mould coating contributed slightly to the improvement of the cast tool surface finish. Finally this study also found that the additive manufacturing of the sand mould was the chief factor responsible for the loss of dimensional accuracy. Because of the above, it was concluded that light machining will always be required to improve the surface finish and the dimensional accuracy of cast tools.
Durability was the last characteristic of RCT tools to be assessed. This property was empirically inferred from the mechanical properties and metallographic analysis of castings. Merit of durability figures of 0.048 to 0.152 were obtained for the cast tools. It was found that tools obtained from Direct Croning (DC) moulds have merit of durability figures three times higher than the tools produced from Z-Cast moulds thus a better resistance to abrasion wear of the former tools compared to the latter.
9
GALATI, MANUELA. "Design of product and process for Metal Additive Manufacturing - From design to manufacturing." Doctoral thesis, Politecnico di Torino, 2017. http://hdl.handle.net/11583/2688272.
Full textAbstract:
Additive Manufacturing (AM) is a recent new manufacturing approach that is based on the fabrication of each object using a layer-by-layer strategy. From a manufacturability perspective of components, this approach involves the possibility to manufacture parts of any geometric complexity without using additional tools and machines. Particular attention is dedicated to the powder bed fusion (PBF) AM processes in which a laser beam or an electron beam is used to sinter or melt metallic powders which are named Selective Laser Melting (SLM) and Electron Beam Melting (EBM). In fact, in these last years, growing interesting of the industry has been outlined for metal AM, because they offer exclusive benefits such as the direct production of complex functional and/or end-usable parts made with excellent materials. Today it is thus recognised the need for guidelines and tools for effective introduction of the AM processes in the metal industry. To address this issue the aim of the presented thesis was to propose concurrent engineering (CE) tools based on a comprehensive approach from design to manufacturing. The metal PBF-AM processes have been dealt by two subsequent steps. The first one addressed the development of a process selection (PS) tool that combines materials, processes and designs for the choice of the best alternative to produce a metal component. The second one concerned with the development of a model for the process simulation that can contribute to the understanding of the process.
The proposed PS tool aimed to introduce the metal AM processes as alternative to producing components. In particular, the tool was implemented in order to consider the comparison between different metal AM manufacturing processes as well as AM, machining and casting. In this approach, each alternative is represented by a combination of the design, material and process features. A well-structured open architecture for PS has been suggested. The tool works by considering the requirements of the component regarding geometry constraints and specifications. A methodology based on mathematical modeling design decisions involving multiple attributes was suggested to assess the technical and economic aspects in order to analyse and rank the alternatives. For this purpose, an index, called DePri, was introduced to resume technical aspects and offers a quantitative comparison between the alternatives. On the other, the economic aspect for AM has been addressed by providing a detail model cost. The results of the process selection in which the technical aspect of each alternative has been considered and the alternatives can be compared with the corresponding manufacturing cost. An application of the proposed tool was demonstrated by an industrial case study in which the objective was to assess the best technology resource between 3-axis CNC machining, SLM and EBM for future investments of the company in the AM technologies.
The second issue addresses the optimisation of the metal PBF-AM process by virtual simulation for a suitable selection of the process parameters. In this context, the resulting review showed the SLM as a consolidated process respect to process simulation while EBM has received less attention despite the numerous applications in the medical and aerospace fields. In order to improve the effectiveness and reliability of EBM FE simulation, a new type of modelling has been introduced for the energy source and the powder material properties which have been included in a thermal numerical model. The potential of the proposed modelling was demonstrated using comparison with existing experimental literature data for a single straight line, existing model in published literature and experimental measurements for multibeam and continuous line melting. The model was then used to investigate the effects of the process parameters on the microstructures of a TiAl alloy.
10
Holtz, Heath M. (Heath Mikal). "Re-sourcing manufacturing processes in metal forming operations." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/34859.
Full textAbstract:
Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division; in conjunction with the Leaders for Manufacturing Program at MIT, 2005.<br>Includes bibliographical references (p. 75-76).<br>Deciding which activities to conduct in-house and which to outsource has become increasingly important due to its implications on a company's supply chain and overall business model. A number of factors can lead a company to outsource manufacturing processes. As a result of this outsourcing, the supply chain can become very complex and overwhelming to manage. This thesis will analyze this situation from the perspective of one manufacturer, American Axle and Manufacturing, Inc. (AAM). AAM's Metal Formed Products (MFP) Division currently has a number of challenges: rising steel prices, fixed labor costs and declining sales. All these factors have significantly impacted profitability, forcing senior management to take a comprehensive look at the division and consider developing a plan to improve divisional operations. As a part of this plan, MFP Division's senior management asked for a thorough look into all of the manufacturing processes performed by the division both internally and by outside suppliers. In addition to identifying the processes and suppliers, senior management sought to highlight opportunities for improving the process flow through the re-sourcing of manufacturing processes. This project develops a framework to analyze and evaluate these re-sourcing decisions. This framework employs a five-step approach and incorporates a number of diverse analytical tools. Process flow mapping provided a tool to visually highlight the best opportunities to resource. In addition to a visual representation, process flow mapping also provided the data to financially evaluate alternatives. Strategic and market factors were identified in order to target and prioritize re-sourcing efforts.<br>(cont.) This framework provides a structure for sourcing decisions that balances the financial and strategic concerns. The project concluded in a $2M investment to re-source heat treating to AAM facilities.<br>by Heath M. Holtz.<br>S.M.<br>M.B.A.
11
Pereira, M. F. V. T., M. Williams, and R. Bruwer. "Rapid die manufacturing using direct laser metal deposition." Journal for New Generation Sciences, Vol 7, Issue 3: Central University of Technology, Free State, Bloemfontein, 2009. http://hdl.handle.net/11462/542.
Full textAbstract:
Published Article<br>Global issues such as energy and climate changes have impacted on both the automotive and aerospace industries, forcing them to adopt measures to produce products that consume fewer combustibles and emit less carbon dioxide. Making vehicles lighter is one of the logical ways of reducing fuel consumption. The need for light components, able to fulfil technical and quality specifications, led to market growth for tooling that is able to mass produce parts using manufacturing processes such as high pressure die casting. Competitive pressures to reduce the lead time required for tooling-up has also increased dramatically. For this reason research into various methods, techniques and approaches to tool manufacture is being undertaken globally. This paper highlights the work undertaken at the CSIR on the issue of rapid die manufacturing through the application and evaluation of a rapid prototyping technique and coating technologies applied to die components of a high pressure casting die for the production of aluminium components. Criteria for determining suitability were developed against which the technique was evaluated that included time, cost and life-expectancy. Results of accelerated testing procedures to evaluate the die material produced by the rapid prototyping technique and surface coatings and treatments of die materials for their resistance to washout, erosion, heat checking and corrosion in a high pressure die casting environment, are presented. The outcomes of this research will be used for further development and application of specific techniques, design principles and criteria for this approach.
12
Scott, Andrew James. "Automated nesting of sheet metal parts." Thesis, University of Bath, 1996. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320561.
Full text
13
Rissanen, Leena. "Manufacturing and irradiation of thin transition metal nitride films." Doctoral thesis, [S.l. : s.n.], 1999. http://deposit.ddb.de/cgi-bin/dokserv?idn=963553887.
Full text
14
Cunningham, Ross W. "Defect Formation Mechanisms in Powder-Bed Metal Additive Manufacturing." Research Showcase @ CMU, 2018. http://repository.cmu.edu/dissertations/1160.
Full textAbstract:
Metal Additive Manufacturing (AM) provides the means to fabricate complex metallic parts with reduced time to market and material waste and improved design freedom. Industries with strict materials qualifications such as aerospace, biomedical, and automotive are increasingly looking to AM to meet their production needs. However, significant materials-related challenges impede the widespread adoption of these technologies for critical components. In particular, fatigue resistance in as-built parts has proven to be inferior and unpredictable due to the large and variable presence of porosity. This presents a challenge for the qualification of any load bearing part without extensive post-processing, such as Hot Isostatic Pressing, and thorough inspection. Improved understanding of the underlying mechanisms behind defect formation will assist in designing process improvements to minimize or eliminate defects without relying entirely on postprocessing. In this work, the effects of powder, processing parameters, and post-processing on porosity formation in powder-bed metal AM processes are investigated using X-ray microtomography and a newly developed in-situ high speed radiography technique, Dynamic Xray Radiography. High resolution X-ray computed tomography is used to characterize defect morphology, size, and spatial distribution as a function of process and material inputs. Dynamic X-ray Radiography, which enables the in-situ observation of the laser-metal interactions at frame rates on the order of 100 kHz (and faster), is utilized to understand the dynamic behavior and transitions that occur in the vapor depression across process space. Experimental validation of previously held assumptions regarding defect formation as well as new insights into the influence of the vapor cavity on defect formation are presented.
15
Gopalakrishnan, Srimathy. "Optimization models for production planning in metal sheet manufacturing." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/36427.
Full textAbstract:
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.<br>Includes bibliographical references (leaves 84-85).<br>by Srimathy Gopalakrishnan.<br>M.S.
16
Balsamy, Kamaraj Abishek. "Study of Localized Electrochemical Deposition for Metal Additive Manufacturing." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1539078938687749.
Full text
17
Brandal, Øystein. "Interfacial (o/w) Properties of Naphthenic Acids and Metal Naphthenates, Naphthenic Acid Characterization and Metal Naphthenate Inhibition." Doctoral thesis, Norwegian University of Science and Technology, Department of Chemical Engineering, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-651.
Full textAbstract:
<p>Deposition of metal naphthenates in process facilities is becoming a huge problem for petroleum companies producing highly acidic crudes. In this thesis, the main focus has been towards the oil-water (o/w) interfacial properties of naphthenic acids and their ability to react with different divalent cations across the interface to form metal naphthenates.</p><p>The pendant drop technique was utilized to determine dynamic interfacial tensions (IFT) between model oil containing naphthenic acid, synthetic as well as indigenous acid mixtures, and pH adjusted water upon addition of different divalent cations. Changes in IFT caused by the divalent cations were correlated to reaction mechanisms by considering two reaction steps with subsequent binding of acid monomers to the divalent cation. The results were discussed in light of degree of cation hydration and naphthenic acid conformation, which affect the interfacial conditions and thus the rate of formation of 2:1 complexes of acid and cations. Moreover, addition of non-ionic oil-soluble surfactants used as basis compounds in naphthenate inhibitors was found to hinder a completion of the reaction through interfacial dilution of the acid monomers.</p><p>Formation and stability of metal naphthenate films at o/w interfaces were studied by means of Langmuir technique with a trough designed for liquid-liquid systems. The effects of different naphthenic acids, divalent cations, and pH of the subphase were investigated. The results were correlated to acid structure, cation hydration, and degree of dissociation, which all affect the film stability against compression.</p><p>Naphthenic acids acquired from a metal naphthenate deposit were characterized by different spectroscopic techniques. The sample was found to consist of a narrow family of 4-protic naphthenic acids with molecular weights around 1230 g/mol. These acids were found to be very o/w interfacially active compared to normal crude acids, and to form Langmuir monolayers with stability depending on the aqueous pH. At high pH, addition of Ca<sup>2+</sup> increased the film stability due to formation of calcium naphthenate at the surface.</p><p>A new experimental setup based on near infrared spectroscopy was used to monitor the formation, growth, and inhibition of calcium naphthenate particles in o/w systems. This method was found to be suitable for studies of particle formation rate and growth qualitatively under different experimental conditions.</p>
18
Otieno, Andrew Michael Wasonga. "Computer-aided analysis of metal machining." Thesis, University of Leeds, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251490.
Full text
19
Kodira, Ganapathy D. "Investigation of an Investment Casting Method Combined with Additive Manufacturing Methods for Manufacturing Lattice Structures." Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc283786/.
Full textAbstract:
Cellular metals exhibit combinations of mechanical, thermal and acoustic properties that provide opportunities for various implementations and applications; light weight aerospace and automobile structures, impact and noise absorption, heat dissipation, and heat exchange. Engineered cell topologies enable one to control mechanical, thermal, and acoustic properties of the gross cell structures. A possible way to manufacture complex 3D metallic cellular solids for mass production with a relatively low cost, the investment casting (IC) method may be used by combining the rapid prototyping (RP) of wax or injection molding. In spite of its potential to produce mass products of various 3D cellular metals, the method is known to have significant casting porosity as a consequence of the complex cellular topology which makes continuous fluid's access to the solidification interface difficult. The effects of temperature on the viscosity of the fluids were studied. A comparative cost analysis between AM-IC and additive manufacturing methods is carried out. In order to manufacture 3D cellular metals with various topologies for multi-functional applications, the casting porosity should be resolved. In this study, the relations between casting porosity and processing conditions of molten metals while interconnecting with complex cellular geometries are investigated. Temperature, and pressure conditions on the rapid prototyping – investment casting (RP-IC) method are reported, thermal stresses induced are also studied. The manufactured samples are compared with those made by additive manufacturing methods.
20
Powell, Nicholas Newton. "Incremental forming of flanged sheet metal components." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357609.
Full text
21
Jenkins, Martin Anthony. "Rapid Prototyping by micro spray metal deposition." Thesis, University of Exeter, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363429.
Full text
22
Lindsay, Neil J. "Joining metal matrix composites and related alloys." Thesis, University of Bath, 1993. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332323.
Full text
23
Foschini, Alessandro. "Application of Additive Manufacturing to long fibers Metal Matrix Composites." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
Find full textAbstract:
The present thesis aims at verifying the possibility to combine the fabrication of long fibres Metal Matrix Composites with the innovative design possibilities provided by the Additive Manufacturing technology. This work documents how all the main physical and chemical interactions, defects and processing products are created starting from inputs until achieving the final mechanical and microstructure outputs. Firstly, the process limitations of SLM and of the fabrication of long fibres MMCs are evaluated through a deep study of the whole complex of variables characterizing the technologies. Secondly, thanks to the knowledge gained, a description of the possibility to combine these two technologies is made. Flowcharts are created and evaluated in order to obtain clear and simple mental schemes to understand how all variables impact on the manufacturing processes. The results achieved will help to comprehend how these processes may interact together and from this it will be possible to lay the foundations for future research.
24
Ba, Housseinou. "Manufacturing of metal-free carbon-based catalysts for styrene production." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAF026/document.
Full textAbstract:
Le styrène (ST) est l'un des monomères aromatiques insaturés les plus importants dans l'industrie pétrochimique moderne. Le procédé de déshydrogénation (DH) de l'éthylbenzène (EB) en ST, représentant actuellement 90% de la production de ST, nécessite l'utilisation de catalyseurs hautement actifs et stables, et permettant un grand transfert de masse. Dans ce travail, nous avons développé de nouveaux matériaux sans métaux à base de carbone, utilisant les nanodiamants (NDs) comme phase active pour la production de ST. Les NDs ont été déposés sur différents supports 2D et 3D à base de carbure de silicium et de carbone, permettant d'améliorer leur dispersion, et conduisant ainsi à un catalyseur exempt de métal très stable avec des performances en DH élevées. Nous avons également réussi à synthétiser des matériaux carbonés dopés à l'azote (N@C) présentant une activité élevée et stable en DH comparée à celle obtenue sur NDs. Cette phase active N@C a été obtenue à partir de produits alimentaires (le D-glucose, l'acide citrique et le carbonate d'ammonium) par un procédé facile à mettre en œuvre, et peut aussi très bien être déposée sur d'autres supports macroscopiques<br>Styrene (ST) is one of the most important unsaturated aromatic monomers in modern petrochemical industry. The catalytic dehydrogenation reaction (DH) of ethylbenzene (EB) into styrene, which accounts for 90% of the ST production, demands highly activated and stabilized catalysts, as well as easily handing and efficient mass diffusion. In this work, we developed novel metal-free carbon-based materials using nanodiamonds (NDs) as an active phase for potential industrial catalysts for the direct dehydrogenation route to produce ST. The NDs were successfully immobilized on different 2D and 3D carbon-based and silicon carbide supports which could help to improve their dispersion, leading to metal-free catalyst with high catalytic performance and stability. We have also succeeded in synthesizing nitrogen-doped carbon materials (N@C) displaying a high and stable dehydrogenation activity for the ST production in place of NDs. These active N@C catalysts were produced from food processing materials, i.e. D-glucose, citric acid and ammonium carbonate, and could be also easily dressed on macroscopic supports by a facile and scalable method
25
Hussein, Ahmed Yussuf. "The development of lightweight cellular structures for metal additive manufacturing." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/15023.
Full textAbstract:
Metal Additive Manufacturing (AM) technologies in particular powder bed fusion processes such as Selective Laser Melting (SLM) and Direct Metal Laser Sintering (DMLS) are capable of producing a fully-dense metal components directly from computer-aided design (CAD) model without the need of tooling. This unique capability offered by metal AM has allowed the manufacture of inter-connected lattice structures from metallic materials for different applications including, medical implants and aerospace lightweight components. Despite the many promising design freedoms, metal AM still faces some major technical and design barriers in building complex structures with overhang geometries. Any overhang geometry which exceeds the minimum allowable build angle must be supported. The function of support structure is to prevent the newly melted layer from curling due to thermal stresses by anchoring it in place. External support structures are usually removed from the part after the build; however, internal support structures are difficult or impossible to remove. These limitations are in contrast to what is perceived by designers as metal AM being able to generate all conceivable geometries. Because support structures consume expensive raw materials, use a considerable amount of laser consolidation energy, there is considerable interest in design optimisation of support structure to minimize the build time, energy, and material consumption. Similarly there is growing demand of developing more advanced and lightweight cellular structures which are self-supporting and manufacturable in wider range of cell sizes and volume fractions using metal AM. The main focuses of this research is to tackle the process limitation in metal AM and promote design freedom through advanced self-supporting and low-density Triply Periodic Minimal Surface (TPMS) cellular structures. Low density uniform, and graded, cellular structures have been developed for metal AM processes. This work presents comprehensive experimental test conducted in SLM and DMLS processes using different TPMS cell topologies and materials. This research has contributed to new knowledge in understanding the manufacturability and mechanical behaviour of TPMS cellular structures with varying cell sizes, orientations and volume fractions. The new support structure method will address the saving of material (via low volume cellular structures and easy removal of powder) and saving of energy (via reduced build-time).
26
Andersson, Dickfors Robin, and Nick Grannas. "OBJECT DETECTION USING DEEP LEARNING ON METAL CHIPS IN MANUFACTURING." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-55068.
Full textAbstract:
Designing cutting tools for the turning industry, providing optimal cutting parameters is of importance for both the client, and for the company's own research. By examining the metal chips that form in the turning process, operators can recommend optimal cutting parameters. Instead of doing manual classification of metal chips that come from the turning process, an automated approach of detecting chips and classification is preferred. This thesis aims to evaluate if such an approach is possible using either a Convolutional Neural Network (CNN) or a CNN feature extraction coupled with machine learning (ML). The thesis started with a research phase where we reviewed existing state of the art CNNs, image processing and ML algorithms. From the research, we implemented our own object detection algorithm, and we chose to implement two CNNs, AlexNet and VGG16. A third CNN was designed and implemented with our specific task in mind. The three models were tested against each other, both as standalone image classifiers and as a feature extractor coupled with a ML algorithm. Because the chips were inside a machine, different angles and light setup had to be tested to evaluate which setup provided the optimal image for classification. A top view of the cutting area was found to be the optimal angle with light focused on both below the cutting area, and in the chip disposal tray. The smaller proposed CNN with three convolutional layers, three pooling layers and two dense layers was found to rival both AlexNet and VGG16 in terms of both as a standalone classifier, and as a feature extractor. The proposed model was designed with a limited system in mind and is therefore more suited for those systems while still having a high accuracy. The classification accuracy of the proposed model as a standalone classifier was 92.03%. Compared to the state of the art classifier AlexNet which had an accuracy of 92.20%, and VGG16 which had an accuracy of 91.88%. When used as a feature extractor, all three models paired best with the Random Forest algorithm, but the accuracy between the feature extractors is not that significant. The proposed feature extractor combined with Random Forest had an accuracy of 82.56%, compared to AlexNet with an accuracy of 81.93%, and VGG16 with 79.14% accuracy.<br>DIGICOGS
27
Valli, Giuseppe <1989>. "Metal additive manufacturing of soft magnetic material for electric machines." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amsdottorato.unibo.it/10131/1/Valli_Giuseppe_tesi.pdf.
Full textAbstract:
This research work concerns the application of additive manufacturing (AM) technologies in new electric mobility sectors. The unmatched freedom that AM offers can potentially change the way electric motors are designed and manufactured. The thesis investigates the possibility of creating optimized electric machines that exploit AM technologies, with potential in various industrial sectors, including automotive and aerospace. In particular, we will evaluate how the design of electric motors can be improved by producing the rotor core using Laser Powder Bed Fusion (LPBF) and how the resulting design choices affect component performance. First, the metallurgical and soft magnetic properties of the pure iron and silicon iron alloy parts (Fe-3% wt.Si) produced by LPBF will be defined and discussed, considering the process parameters and the type of heat treatment. This research shows that using LPBF, both pure iron and iron silicon, the parts have mechanical and magnetic properties different from the laminated ones. Hence, FEM-based modeling will be employed to design the rotor core of an SYN RM machine to minimize torque ripple while maintaining structural integrity. Finally, we suggest that further research should extend the field of applicability to other electrical devices.
28
Ranjan, Rajit. "Design for Manufacturing and Topology Optimization in Additive Manufacturing." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439307951.
Full text
29
Khan, Shamsul Arefin. "Deep sub-micron MOS transistor design and manufacturing sensitivity analysis /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
Full text
30
Allwood, Julian Mark. "Online modelling and control and shape phenomena in metal rolling." Thesis, Imperial College London, 1993. http://hdl.handle.net/10044/1/7503.
Full text
31
Mahmoud, El-Amin A. "Machining with titanium nitride-coated metal tools." Thesis, Aston University, 1988. http://publications.aston.ac.uk/11912/.
Full text
32
Can, Yilmaz. "Incremental metal forming and analysis of tube spinning." Thesis, University of Bath, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390223.
Full text
33
Singh, Aparajita. "Improving Current-Asymmetry of Metal-Insulator-Metal Tunnel Junctions." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2827.
Full textAbstract:
In this research, Ni–NiOx–Cr and Ni–NiOx–ZnO–Cr metal-insulator-metal (MIM) junction based tunnel diodes have been investigated for the purpose of a wide-band detector. An MIM diode has a multitude of applications such as harmonic mixers, rectifiers, millimeter wave and infrared detectors. Femtosecond-fast electron transport in MIM tunnel diodes also makes them attractive for energy-harvesting devices. These applications require the tunnel diodes to have high current-asymmetry and non-linear current-voltage behavior at low applied voltages and high frequencies. Asymmetric and non-linear characteristics of Ni–NiOx-Cr MIM tunnel diodes were enhanced in this research by the addition of ZnO as a second insulator layer in the MIM junction to form metal-insulator-insulator-metal (MIIM) structure.
Electrical characteristics were studied in a voltage range of for the single-insulator Ni–NiOx–Cr and double-insulator Ni–NiOx–ZnO–Cr tunnel diodes. Since the electrical characteristics of the diode are sensitive to material selection, material arrangement, thickness, deposition techniques and conditions, understanding the diode behavior with respect to these factors is crucial to developing a robust diode structure. Thus, ZnO insulator layer in MIIM junction was deposited by two different techniques: sputtering and atomic layer deposition (ALD). Also, the optical properties were characterized for the sputter deposited NiOx insulator layers by ellipsometry and the impact of annealing was explored for the NiOx optical properties.
The Ni–NiOx–Cr MIM tunnel diodes provide low resistance but exhibit a low (~1) current-asymmetry. Asymmetry increased by an order of magnitude in case of Ni–NiOx–ZnO–Cr MIIM tunnel diode. The sensitivity of the MIM and MIIM diodes was 11 V-1 and 16 V-1, respectively. The results suggest that the MIIM diode can provide improved asymmetry at low voltages. The tunneling behavior of the device was also demonstrated in the 4-298K temperature range. It is hypothesized that the improved performance of the bilayer insulator diode is due to resonant tunneling enabled by the second insulator. Finally, the MIM and MIIM devices were investigated for wide-band detection up to 50GHz (RF) and 0.3THz (optical).
34
Miranda, Neiva Eric. "Large-scale tree-based unfitted finite elements for metal additive manufacturing." Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/669823.
Full textAbstract:
This thesis addresses large-scale numerical simulations of partial differential equations posed on evolving geometries. Our target application is the simulation of metal additive manufacturing (or 3D printing) with powder-bed fusion methods, such as Selective Laser Melting (SLM), Direct Metal Laser Sintering (DMLS) or Electron-Beam Melting (EBM). The simulation of metal additive manufacturing processes is a remarkable computational challenge, because processes are characterised by multiple scales in space and time and multiple complex physics that occur in intricate three-dimensional growing-in-time geometries. Only the synergy of advanced numerical algorithms and high-performance scientific computing tools can fully resolve, in the short run, the simulation needs in the area.
The main goal of this Thesis is to design a a novel highly-scalable numerical framework with multi-resolution capability in arbitrarily complex evolving geometries. To this end, the framework is built by combining three computational tools: (1) parallel mesh generation and adaptation with forest-of-trees meshes, (2) robust unfitted finite element methods and (3) parallel finite element modelling of the geometry evolution in time. Our numerical research is driven by several limitations and open questions in the state-of-the-art of the three aforementioned areas, which are vital to achieve our main objective. All our developments are deployed with high-end distributed-memory implementations in the large-scale open-source software project FEMPAR. In considering our target application, (4) temporal and spatial model reduction strategies for thermal finite element models are investigated. They are coupled to our new large-scale computational framework to simplify optimisation of the manufacturing process.
The contributions of this Thesis span the four ingredients above. Current understanding of (1) is substantially improved with rigorous proofs of the computational benefits of the 2:1 k-balance (ease of parallel implementation and high-scalability) and the minimum requirements a parallel tree-based mesh must fulfil to yield correct parallel finite element solvers atop them. Concerning (2), a robust, optimal and scalable formulation of the aggregated unfitted finite element method is proposed on parallel tree-based meshes for elliptic problems with unfitted external contour or unfitted interfaces. To the author’s best knowledge, this marks the first time techniques (1) and (2) are brought together. After enhancing (1)+(2) with a novel parallel approach for (3), the resulting framework is able to mitigate a major performance bottleneck in large-scale simulations of metal additive manufacturing processes by powder-bed fusion: scalable adaptive (re)meshing in arbitrarily complex geometries that grow in time. Along the development of this Thesis, our application problem (4) is investigated in two joint collaborations with the Monash Centre for Additive Manufacturing and Monash University in Melbourne, Australia. The first contribution is an experimentally-supported thorough numerical assessment of time-lumping methods, the second one is a novel experimentally-validated formulation of a new physics-based thermal contact model, accounting for thermal inertia and suitable for model localisation, the so-called virtual domain approximation.
By efficiently exploiting high-performance computing resources, our new computational framework enables large-scale finite element analysis of metal additive manufacturing processes, with increased fidelity of predictions and dramatical reductions of computing times. It can also be combined with the proposed model reductions for fast thermal optimisation of the manufacturing process. These tools open the path to accelerate the understanding of the process-to-performance link and digital product design and certification in metal additive manufacturing, two milestones that are vital to exploit the technology for mass-production.<br>Aquesta tesi tracta la simulació a gran escala d'equacions en derivades parcials sobre geometries variables. L'aplicació principal és la simulació de procesos de fabricació additiva (o impressió 3D) amb metalls i per mètodes de fusió de llit de pols, com ara Selective Laser Melting (SLM), Direct Metal Laser Sintering (DMLS) o Electron-Beam Melting (EBM). La simulació d'aquests processos és un repte computacional excepcional, perquè els processos estan caracteritzats per múltiples escales espaitemporals i múltiples físiques que tenen lloc sobre geometries tridimensionals complicades que creixen en el temps. La sinèrgia entre algorismes numèrics avançats i eines de computació científica d'alt rendiment és la única via per resoldre completament i a curt termini les necessitats en simulació d'aquesta àrea. El principal objectiu d'aquesta tesi és dissenyar un nou marc numèric escalable de simulació amb capacitat de multiresolució en geometries complexes i variables. El nou marc es construeix unint tres eines computacionals: (1) mallat paral·lel i adaptatiu amb malles de boscs d'arbre, (2) mètodes d'elements finits immersos robustos i (3) modelització en paral·lel amb elements finits de geometries que creixen en el temps. Algunes limitacions i problemes oberts en l'estat de l'art, que són claus per aconseguir el nostre objectiu, guien la nostra recerca. Tots els desenvolupaments s'implementen en arquitectures de memòria distribuïda amb el programari d'accés obert FEMPAR. Quant al problema d'aplicació, (4) s'investiguen models reduïts en espai i temps per models tèrmics del procés. Aquests models reduïts s'acoplen al nostre marc computacional per simplificar l'optimització del procés. Les contribucions d'aquesta tesi abasten els quatre punts de dalt. L'estat de l'art de (1) es millora substancialment amb proves riguroses dels beneficis computacionals del 2:1 balancejat (fàcil paral·lelització i alta escalabilitat), així com dels requisits mínims que aquest tipus de mallat han de complir per garantir que els espais d'elements finits que s'hi defineixin estiguin ben posats. Quant a (2), s'ha formulat un mètode robust, òptim i escalable per agregació per problemes el·líptics amb contorn o interface immerses. Després d'augmentar (1)+(2) amb un nova estratègia paral·lela per (3), el marc de simulació resultant mitiga de manera efectiva el principal coll d'ampolla en la simulació de processos de fabricació additiva en llits de pols de metall: adaptivitat i remallat escalable en geometries complexes que creixen en el temps. Durant el desenvolupament de la tesi, es col·labora amb el Monash Centre for Additive Manufacturing i la Universitat de Monash de Melbourne, Austràlia, per investigar el problema d'aplicació. En primer lloc, es fa una anàlisi experimental i numèrica exhaustiva dels mètodes d'aggregació temporal. En segon lloc, es proposa i valida experimental una nova formulació de contacte tèrmic que té en compte la inèrcia tèrmica i és adequat per a localitzar el model, l'anomenada aproximació per dominis virtuals. Mitjançant l'ús eficient de recursos computacionals d'alt rendiment, el nostre nou marc computacional fa possible l'anàlisi d'elements finits a gran escala dels processos de fabricació additiva amb metalls, amb augment de la fidelitat de les prediccions i reduccions significatives de temps de computació. Així mateix, es pot combinar amb els models reduïts que es proposen per l'optimització tèrmica del procés de fabricació. Aquestes eines contribueixen a accelerar la comprensió del lligam procés-rendiment i la digitalització del disseny i certificació de productes en fabricació additiva per metalls, dues fites crucials per explotar la tecnologia en producció en massa.
35
Butt, Javaid. "A novel additive manufacturing process for the production of metal parts." Thesis, Anglia Ruskin University, 2016. http://arro.anglia.ac.uk/701001/.
Full textAbstract:
The majority of additive manufacturing methods use different materials for the production of parts. The current methods employing powder metals have their limitations and are very expensive. This research presents a novel additive manufacturing process for the generation of modest and high quality metal parts. The procedure, referred to as Composite Metal Foil Manufacturing, is a blend of Laminated Object Manufacturing and soldering/brazing strategies. A calculated model of a machine in view of the new process has been outlined and its parts accepted for usefulness either by experimentation or recreations. The viability of the new process is accepted with lap-shear testing, peel testing, microstructural examination and tensile testing. Distinctive metals, such as copper and aluminium, with shifting thicknesses were used to demonstrate the adaptability of the procedure. Composites of aluminium and copper were additionally delivered and tried for their mechanical properties to show the flexibility of the process. The outcomes of the research attained have been promising and show that the new process is not just fit for delivering astounding metal parts efficiently but can create more grounded parts contrasted with customary subtractive techniques. The comparative tensile testing demonstrated that the parts created by the new process had force values that were 11%, 8% and 11% higher than the parent copper, aluminium and composite examples individually. This shows that the procedure has the capability to be a solid competitor in the field of metal prototyping. It has been demonstrated that the proposed procedure can have a gigantic effect as it has lessened the confinements, for example, cost, pace, material determinations and beyond. The additive manufacturing identified with the generation of metal parts using the new process can work with an extensive variety of metals under typical conditions regardless of their joining capacities. The feedback that parts delivered by added substance fabrication techniques are not sufficiently strong for genuine applications can without much of a stretch is hushed with the obtained trial results. Applications can extend from little bespoke parts to large scale functional products that can be utilized with minimal post handling.
36
Syed, Waheed Ul Haq. "Combined wire and powder deposition for laser direct metal additive manufacturing." Thesis, University of Manchester, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556499.
Full text
37
Gullapalli, Vikranth. "Study of Metal Whiskers Growth and Mitigation Technique Using Additive Manufacturing." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc804972/.
Full textAbstract:
For years, the alloy of choice for electroplating electronic components has been tin-lead (Sn-Pb) alloy. However, the legislation established in Europe on July 1, 2006, required significant lead (Pb) content reductions from electronic hardware due to its toxic nature. A popular alternative for coating electronic components is pure tin (Sn). However, pure tin has the tendency to spontaneously grow electrically conductive Sn whisker during storage. Sn whisker is usually a pure single crystal tin with filament or hair-like structures grown directly from the electroplated surfaces. Sn whisker is highly conductive, and can cause short circuits in electronic components, which is a very significant reliability problem. The damages caused by Sn whisker growth are reported in very critical applications such as aircraft, spacecraft, satellites, and military weapons systems. They are also naturally very strong and are believed to grow from compressive stresses developed in the Sn coating during deposition or over time. The new directive, even though environmentally friendly, has placed all lead-free electronic devices at risk because of whisker growth in pure tin. Additionally, interest has occurred about studying the nature of other metal whiskers such as zinc (Zn) whiskers and comparing their behavior to that of Sn whiskers. Zn whiskers can be found in flooring of data centers which can get inside electronic systems during equipment reorganization and movement and can also cause systems failure.Even though the topic of metal whiskers as reliability failure has been around for several decades to date, there is no successful method that can eliminate their growth. This thesis will give further insights towards the nature and behavior of Sn and Zn whiskers growth, and recommend a novel manufacturing technique that has potential to mitigate metal whiskers growth and extend life of many electronic devices.
38
Rossie, Kathleen Eaton. "An energy and environmental analysis of aerospace sheet metal part manufacturing." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/101487.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 223-246).<br>In this thesis we analyze the energy and environmental impacts of sheet metal manufacturing, focusing on the aerospace industry. The motivation of this work is the introduction of a new incremental sheet forming (ISF) technology called RAFFT, which substitutes heavy part specific dies for flexible generic tools but with a slower processing rate. The analysis has two sections. The first section analyzes the current aerospace sheet forming technological and economic landscape in order to determine RAFFT's probable adoption rate and predict which technologies it will displace. The second section includes four energy and lifecycle analysis (LCA) case studies on traditional forming technologies. The first section maps the process capabilities of twenty sheet forming technologies. It also describes the business needs and typical practices of the aerospace industry, including a classification of the different business needs for parts. We find that stretch forming and flexforming (also known as a bladder press or hydroforming) dominate current aerospace production, and superplastic forming SPF is used when high formability is required. Machining is used extensively for very low volume production, such as prototyping. We find that the new RAFFT technology is best suited for very low volume production such as the production of replacement parts. The second section includes energy and LCA case studies for titanium SPF, aluminum SPF, flexforming, and stretch forming. Moreover, case studies on kirksite and cast iron die manufacturing are completed because these materials are used in forming dies. We find that SPF uses more energy and has higher impacts than stretch and flexforming. We also find that each technology has high "baseload" (no forming) electricity use due to heat losses in SPF and circulation of hydraulic fluid in stretch and flexforming, meaning that cycle time is a critical factor in electricity use. Lastly, we find that the material for the blank, the die, and the electricity can each dominate impacts depending on the particular characteristics of each case because a) the aerospace industry is willing to invest significant resources, be it time, energy, or material, to produce the desired part and b) the required amount of blank, die, and electricity are dependent on uncorrelated factors.<br>by Kathleen Eaton Rossie.<br>S.M.
39
Famodimu, Omotoyosi Helen. "Additive manufacturing of aluminium-metal matrix composite developed through mechanical alloying." Thesis, University of Wolverhampton, 2016. http://hdl.handle.net/2436/620337.
Full textAbstract:
Laser melting of aluminium alloy - AlSi10Mg has increasingly been used to create specialised products in aerospace and automotive applications. However, research on utilising laser melting of Aluminium matrix composites in replacing specialised parts have been slow on the uptake. This has been attributed to the complexity of the laser melting process, metal/ceramic feedstock for the process and the reaction of the feedstock material to the laser. Thus an understanding of the process, material microstructure and mechanical properties is important for its adoption as a manufacturing route of Aluminium Metal Matrix Composites. The effect of the processing parameters (time and speed) on embedding the Silicon Carbide onto the surface of the AlSi10Mg alloy was initially investigated in Phase 1 and 2 of the research. The particle shape and maximum particle size for each milling time and speed was analysed in determining a suitable starting powder for the Laser Melting phase. An ideal shape and size for the composite powder was obtained at 500 rev/min when milled for 20 mins. The effects of several parameters of the Laser Melting process on the mechanical blended composite were investigated. Single track formations of the matrix alloy, 5% Aluminium Metal Matrix Composites and 10% Aluminium Metal Matrix Composites were studied for their reaction to the laser melting in Phase 3. Subsequently in Phase 4, density blocks were studied at different scan speeds and step-over for surface roughness, relative density and porosity. These were utilised in determining a process window to fabricate near fully dense components. Phase 5 of the research focused on microstructural and mechanical properties of the laser melted matrix alloy using the normal parameters for the matrix alloy and the modified LM parameters for the composite powders. Test coupons were built in one orientation and some coupons were heat-treated to initiate precipitation-hardening intermetallics in the matrix and composite. This study investigates the suitability of the mechanical alloying as a novel method of producing feedstock material for the LM process. This research further explores the interaction of the composite powders with the laser until suitable process parameters were obtained. Furthermore, the fractography, mechanical and microstructural evolution of the Al/SiC composite, with different percentage volume reinforcement manufactured by the LM and subsequently heat treated, was explored for the first time.
40
Butt, Javaid. "A novel additive manufacturing process for the production of metal parts." Thesis, Anglia Ruskin University, 2016. https://arro.anglia.ac.uk/id/eprint/701001/6/Butt_2016_thesis.pdf.
Full textAbstract:
The majority of additive manufacturing methods use different materials for the production of parts. The current methods employing powder metals have their limitations and are very expensive. This research presents a novel additive manufacturing process for the generation of modest and high quality metal parts. The procedure, referred to as Composite Metal Foil Manufacturing, is a blend of Laminated Object Manufacturing and soldering/brazing strategies. A calculated model of a machine in view of the new process has been outlined and its parts accepted for usefulness either by experimentation or recreations.
The viability of the new process is accepted with lap-shear testing, peel testing, microstructural examination and tensile testing. Distinctive metals, such as copper and aluminium, with shifting thicknesses were used to demonstrate the adaptability of the procedure. Composites of aluminium and copper were additionally delivered and tried for their mechanical properties to show the flexibility of the process. The outcomes of the research attained have been promising and show that the new process is not just fit for delivering astounding metal parts efficiently but can create more grounded parts contrasted with customary subtractive techniques.
The comparative tensile testing demonstrated that the parts created by the new process had force values that were 11%, 8% and 11% higher than the parent copper, aluminium and composite examples individually. This shows that the procedure has the capability to be a solid competitor in the field of metal prototyping. It has been demonstrated that the proposed procedure can have a gigantic effect as it has lessened the confinements, for example, cost, pace, material determinations and beyond.
The additive manufacturing identified with the generation of metal parts using the new process can work with an extensive variety of metals under typical conditions regardless of their joining capacities. The feedback that parts delivered by added substance fabrication techniques are not sufficiently strong for genuine applications can without much of a stretch is hushed with the obtained trial results. Applications can extend from little bespoke parts to large scale functional products that can be utilized with minimal post handling.
41
Snelling, Jr Dean Andrew. "A Process for Manufacturing Metal-Ceramic Cellular Materials with Designed Mesostructure." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/51606.
Full textAbstract:
The goal of this work is to develop and characterize a manufacturing process that is able to create metal matrix composites with complex cellular geometries. The novel manufacturing method uses two distinct additive manufacturing processes: i) fabrication of patternless molds for cellular metal castings and ii) printing an advanced cellular ceramic for embedding in a metal matrix. However, while the use of AM greatly improves the freedom in the design of MMCs, it is important to identify the constraints imposed by the process and its process relationships.
First, the author investigates potential differences in material properties (microstructure, porosity, mechanical strength) of A356 — T6 castings resulting from two different commercially available Binder Jetting media and traditional 'no-bake' silica sand. It was determined that they yielded statistically equivalent results in four of the seven tests performed: dendrite arm spacing, porosity, surface roughness, and tensile strength. They differed in sand tensile strength, hardness, and density.
Additionally, two critical sources of process constraints on part geometry are examined: (i) depowdering unbound material from intricate casting channels and (ii) metal flow and solidification distances through complex mold geometries. A Taguchi Design of Experiments is used to determine the relationships of important independent variables of each constraint. For depowdering, a minimum cleaning diameter of 3 mm was determined along with an equation relating cleaning distance as a function of channel diameter. Furthermore, for metal flow, choke diameter was found to be significantly significant variable.
Finally, the author presents methods to process complex ceramic structure from precursor powders via Binder Jetting AM technology to incorporate into a bonded sand mold and the subsequently casted metal matrix. Through sintering experiments, a sintering temperature of 1375 °C was established for the ceramic insert (78% cordierite). Upon printing and sintering the ceramic, three point bend tests showed the MMCs had less strength than the matrix material likely due to the relatively high porosity developed in the body. Additionally, it was found that the ceramic metal interface had minimal mechanical interlocking and chemical bonding limiting the strength of the final MMCs.<br>Ph. D.
42
Jonsson, Andreas. "New Manufacturing Technology for Volume Optimization of Parts : Amorphous Metal Moulding." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-85513.
Full textAbstract:
Amorphous metals have gained a lot of attention since its introduction in the 1960s, and the usage and knowledge are growing rapidly. The underlying reason for this trend is the desire to utilize these materials unique combinationof properties. New manufacturing techniques such as amorphous metal moulding (AMM) have enabled themanufacture of larger and more complex amorphous products in larger production volumes than before. In order to successfully implement AMM into the development and production of products, knowledge regarding its strengths and weaknesses, as well as how to relate to it when designing parts to be manufactured using the technology is needed. The objective in this master thesis was to investigate the implementation and potential gains of using amorphous alloys made with AMM, both in theory using academic research, and in practice by redesigning existing productsto be manufactured using the technology. Processes how to identify products that are suitable to manufacture and then design them for AMM were formulated. The academic research was compiled in a literature study and served as a base together with a dialog with a manufacturer to formulate these processes. The processes were then used toredesign the current fuze holder designs to accommodate the new manufacturing requirements posed by AMM. A 3D-model was designed and later analysed to provide a design with sufficient strength. It was shown that substantial volume reductions were possible but at a penalty of increased weight and cost, due to the higher density and material cost of the amorphous alloys compared to the current aluminium alloy. Furthermore, as of this writing, with the limitations that exists with the technology, it was not possible to design the fuze holders to fulfil all requirements that exist for AMM. But a small piston that is currently made of steel was shown to be possible to manufacture using AMM, which resulted in both reduced volume and weight, but also cost. In order toverify the results in this study and to progress further, a prototype should be manufactured and tested. This in order to verify both the integrity of the analysis, but also to verify that the design meets the other requirements posed onfuze holders, such as environmental and functional demands.<br>Amorfa metaller har fått mycket uppmärksamhet sedan deras introduktion under 1960-talet och användandet och kunskaperna ökar i snabb takt. Den bakomliggande orsaken för denna trend är viljan att utnyttja dessa materials unika kombination av egenskaper. Nya tillverkningstekniker såsom amorf metallgjutning (AMM) har möjliggjort tillverkningen av större och mer komplexa amorfa produkter i större produktionsvolymer än tidigare. För att framgångsrikt implementera AMM till utvecklingen och produktionen av produkter måste kunskap kring dess styrkor och svagheter utvärderas. Men även kunskap hur man ska förhålla sig till den när man konstruerar AMM detaljer. Målet med detta examensarbete var att undersöka genomförandet och potentiella fördelar av att använda amorfametaller gjorda med AMM både teoretiskt via akademisk forskning och i praktiken genom att omkonstruera en existerande produkt för att tillverkas med teknologin. Processer hur man identifierar produkter som är lämpliga att tillverka med AMM och sedan hur dessa ska konstrueras formulerades. Den akademiska litteraturen samlades i en litteraturstudie och användes tillsammans med en dialog med en tillverkare till att formulera dessa processer. Processerna användes sedan för att omkonstruera den nuvarande tändrörshållardesigner för att tillgodose de nya tillverkningskraven som uppstår från AMM. En 3D-modell konstruerades och analyserades sedan för att säkerställaen konstruktion med tillräcklig hållfasthet. Det visades att betydande volymminskningar var möjliga men till en följd av ökad vikt och kostnad på grund avden amorfa legeringens högre densitet och kostnad jämfört med nuvarande aluminiumlegering. Vidare demonstrerades att det vid skrivande stund inte var möjligt att tillverka tändrörshållarna med AMM på grund av teknologins nuvarande begränsningar. Dock visades att en liten kolv som i dagsläget tillverkas i stål kunde tillverkasmed AMM vilket resulterade i en minskning av volymen, massan och kostnaden. För att bekräfta resultaten i denna studie samt för att gå vidare bör en prototyp tillverkas och testas. Detta för att bekräfta både analysens integritet men även för att bekräfta att konstruktionen når upp till de andra kraven som ställs på tändrörshållare såsom miljö- och funktionskrav.
43
Snelling, Dean Andrew Jr. "A Process for Manufacturing Metal-Ceramic Cellular Materials with Designed Mesostructure." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/51606.
Full textAbstract:
The goal of this work is to develop and characterize a manufacturing process that is able to create metal matrix composites with complex cellular geometries. The novel manufacturing method uses two distinct additive manufacturing processes: i) fabrication of patternless molds for cellular metal castings and ii) printing an advanced cellular ceramic for embedding in a metal matrix. However, while the use of AM greatly improves the freedom in the design of MMCs, it is important to identify the constraints imposed by the process and its process relationships.
First, the author investigates potential differences in material properties (microstructure, porosity, mechanical strength) of A356 — T6 castings resulting from two different commercially available Binder Jetting media and traditional 'no-bake' silica sand. It was determined that they yielded statistically equivalent results in four of the seven tests performed: dendrite arm spacing, porosity, surface roughness, and tensile strength. They differed in sand tensile strength, hardness, and density.
Additionally, two critical sources of process constraints on part geometry are examined: (i) depowdering unbound material from intricate casting channels and (ii) metal flow and solidification distances through complex mold geometries. A Taguchi Design of Experiments is used to determine the relationships of important independent variables of each constraint. For depowdering, a minimum cleaning diameter of 3 mm was determined along with an equation relating cleaning distance as a function of channel diameter. Furthermore, for metal flow, choke diameter was found to be significantly significant variable.
Finally, the author presents methods to process complex ceramic structure from precursor powders via Binder Jetting AM technology to incorporate into a bonded sand mold and the subsequently casted metal matrix. Through sintering experiments, a sintering temperature of 1375 °C was established for the ceramic insert (78% cordierite). Upon printing and sintering the ceramic, three point bend tests showed the MMCs had less strength than the matrix material likely due to the relatively high porosity developed in the body. Additionally, it was found that the ceramic metal interface had minimal mechanical interlocking and chemical bonding limiting the strength of the final MMCs.<br>Ph. D.
44
TESTA, Cristian (ORCID:0000-0002-6064-9851). "Corrosion behaviour of metal alloys obtained by means of additive manufacturing." Doctoral thesis, Università degli studi di Bergamo, 2020. http://hdl.handle.net/10446/181512.
Full text
45
Ogbogu, S. O. E. "Electromagnetic stirring in the continuous casting of molten metal." Thesis, University of Bradford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374933.
Full text
46
Mahdi, Wathik Issa. "Tool contact stresses and chip formation in metal machining." Thesis, University of Bradford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254204.
Full text
47
Hirst, Adrian Anthony. "Fume formation in flux cored metal inert gas welding." Thesis, University of Bradford, 1990. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306180.
Full text
48
Sandford, Andrew Robert Brian. "Effect of manganese and nickel on the cleavage fracture strength of ferritic weld metal." Thesis, London Metropolitan University, 1990. http://repository.londonmet.ac.uk/3058/.
Full textAbstract:
All weld metal test pieces were produced from two commercial and six experimental 7016 type electrodes, each having different contents of manganese and nickel. These were tested in three point bending over a range of depressed temperatures in a cryostatic cell of the author’s devising. Notched samples were used to obtain values for the cleavage fracture strength. This was calculated by reference to slip line field theory from the fracture load at the test temperature where fracture was first coincident with general yielding. The commercial electrodes were first tested in the as welded condition and all eight electrodes were then tested after a heat treatment designed to give a microstructure similar to that found in re-heated weld metal. Notched and pre-cracked samples were then tested in the heat treated condition to determine KI values. Fracture surfaces were examined by scanning electron microscope and grain size measurements made by optical microscopy. Lower shelf impact energy measurements were also made. The results show that both manganese and nickel individually increased the cleavage fracture strength. In combination the best cleavage properties were given by alloying contents of 1.0% manganese and 1.5% nickel increasing alloying beyond this level had a detrimental effect. The mechanism for this was a combination of grain size effects, changes in the slip characteristics of the material, the size, distribution and nature of inclusions and the effects of alloying on grain boundary and matrix/inclusion cohesion. In re-heated material at test temperatures studied the plane strain fracture toughness is influenced by similar factors to those which determine cleavage fracture strength.
49
Gasser, Jonathan. "AN ANALYSIS OF ENERGY RESOURCES UTILIZATION FOR TWO METAL JOINING MANUFACTURING PROCESSES." UKnowledge, 2014. http://uknowledge.uky.edu/me_etds/32.
Full textAbstract:
Sustainable manufacturing involves utilizing energy resources efficiently. Currently, the state of sustainability for a given manufacturing process is described by most in a qualitative sense as opposed to using quantitative metrics. This thesis offers a segment of analysis needed to understand the state of sustainability in the context of energy resource utilization. This was accomplished by measuring the order of magnitude difference between the energy consumption of a manufacturing process vs. the theoretical minimum amount of energy required to complete the same task (aluminum T-joint bond). This analysis was completed for a TIG welding process and a controlled atmosphere brazing (CAB) process. Also, the energy Sankey diagram was constructed for the TIG welding process. The TIG welding process and CAB process consumed an average of 136.1 ± 16.5 kJ and 6,830 ± 77 kJ respectively to bond the same sample. The TIG welding process consumed O(102 kJ) more than the theoretical minimum amount needed to complete the same bond while the CAB process consumed O(104 kJ) more than the theoretical minimum. In the context of energy consumption, there are sizable margins for improvement for both metal joining processes analyzed in this study.
50
Koh, Yang Sook. "Cleaning of metal artefacts using pulsed lasers." Licentiate thesis, Luleå tekniska universitet, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18460.
Full textAbstract:
Preservation of cultural property in the form of historical artefacts for the future is an important interest in our society. The information which can be obtained from these materials is a valuable key to understand the past. One of the aims of any conservation procedure is to preserve both aesthetic and physical conditions of irreplaceable artefacts. Conservation involves a number of different steps. Cleaning is one of the critical steps needed to stabilise the material and to recover hidden details on the surface. It is therefore very important to choose suitable techniques and methods when cleaning to avoid damage to the artefact. Research and development to find more suitable conservation techniques are still going on. One of the new techniques under investigation is laser cleaning which has shown a good potential as a cleaning tool for many material categories met in conservation work. This thesis presents an investigation of the laser cleaning of metal artefacts using Nd:YAG and TEA CO2 lasers. The first part is a general overview of the laser technique applied to metal conservation and an outline of the practical work. The thesis then continues with four papers. Paper A concerns the removal of adhesives and coatings from iron samples using pulsed TEA CO2- and Nd:YAG-lasers. Trial samples were treated with different kinds of adhesives and coatings typically used in metals conservation and then cleaned using the lasers. The results were compared with cleaning using a conventional technique, micro blasting. Comparison of the different laser-cleaned surfaces was also performed by optical microscopy and Raman-spectroscopy. The comparative study showed that the best cleaning result was achieved by the TEA CO2 laser. The coatings were removed entirely without damage to the substrate. Paper B deals with cleaning of corroded iron samples using pulsed TEA CO2- and Nd:YAG-lasers. TEA CO2 lasers were successfully used to remove organic materials and rust. The Nd:YAG laser was able to clean the corroded samples, however, the risk for surface damage was found to be higher than using the TEA CO2 laser. Analysis of the surfaces cleaned by the two types of lasers was carried out by optical- and scanning electron microscopy, X-ray spectrometry and Raman-spectrometry. Paper C is a comparative study of the cleaning of iron samples using TEA CO2- and Nd:YAG lasers. In the first experiment a comparison of Nd:YAG laser and micro blasting for the cleaning of rust was made. The second experiment dealt with the removal of a wax coating from iron samples using a TEA CO2 laser with different power densities. The first experiment shows that the samples cleaned by pulsed laser retain a better surface structure than those cleaned by micro blasting. The second experiment showed how different energy densities affect the same surface. Paper D is an investigation of the cleaning of silver threads in textile using Nd:YAG laser at wavelengths of 1064 nm, 532 nm and 266 nm. The goal of this work was to find a technique to clean the tarnished silver without damaging the underlying silk. This was necessary since the conventional chemical treatment for cleaning tarnished silver is problematic to apply in this specific instance. The laser wavelength of 266 nm was found to be most appropriate for cleaning the silver threads without causing any damages either the silver or the underlying silk. However, the 1064 nm wavelength caused damage such as melting and burning of both the silver and silk.<br>Godkänd; 2002; 20070224 (ysko)