Academic literature on the topic 'Metal Manufacturing'

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.

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.

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

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

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.

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.

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.