An overview of the development of the Investment Casting market and Rapid Prototyping equipment is given in the introductory part of this diploma thesis. Basic methods of rapid prototyping and the FDM method are futher described in detail. The FDM method is consequently used in the practical part of this work for the preparation of the silicon mould. The largest part deals with the issue of the simulation of pouring process of wax into the silicon mould. A characteristics of the casting wax is made; the parametres, which are inserted into the simulation software ProCAST and the possibilities of their measurement are described. The process of the simulation of the mould filling and its validation with the real filling process are described in detail.

Während in der industriellen Schuhherstellung viele Schritte im Fertigungsprozess des Produktes Schuh bereits computergestützt ablaufen, wird der Bereich des Schuhdesigns erst langsam durch neue Technologien unterstützt. Mehrere Herausforderungen ergeben sich durch diesen Schritt, deren Bewältigung auch einen wichtigen Beitrag im virtuellen Design anderer Produkte liefern kann. Dazu zählen Erkenntnisse in den Bereichen der individuell auf Maß gefertigten Produkte, der intuitiven Konstruktion der Produktbestandteile und der haptischen Interaktion mit den virtuellen Prototypen. Die vorliegende Arbeit soll einen detaillierten Einblick in die im Rahmen des Forschungsprojektes "Dreidimensionales Stiefeldesign auf der Grundlage realer Beinmessdaten" bearbeiteten Themengebiete geben. Die wissenschaftliche Ausarbeitung wird zur weiteren Verwendung der Forschungsergebnisse durch einen realistischen technischen Detailgrad ergänzt.:1. Einleitung 4 1.1. Bezug zum Forschungsprojekt 1.2. Zielstellung und Organisation 2. 3D-Modellierung des Unterschenkels und Zusammenführung mit dem Leistenmodell 2.1. Problemstellung 2.2. Formfindung und -erstellung 2.2.1. Zusammenführung mit 3D-Beinscan 2.2.2. Zusammenführung mit Approximation des 3D-Beinscans 2.2.3. Zusammenführung mit umfangsbasierter Approximation 2.3. Auswertung 2.4. Erweiterte geometrische Betrachtungen 2.4.1. Ausrichtung des Leistenmodells 2.4.2. Zusammenführung Leisten- und Schaftmodell 3. Konzeption eines Arbeitsplatzes zum dreidimensionalen Stiefeldesign 3.1. Spezifikation 3.1.1. Mechanischer Aufbau 3.1.2. Softwaretechnologischer Teil 3.2. Konzept 3.2.1. Haptisches Interaktionsgerät 3.2.2. Sekundäres Eingabegerät 3.2.3. Display 3.2.4. Aufbau Arbeitsplatz 3.2.5. Visualisierung 3.2.6. Traditionelle Mausinteraktion 3.2.7. Programmsteuerung 3.2.8. Navigation 3.2.9. Gesamtkonzept 3.3. Umsetzung 4. Stiefelspezifische Designelemente 4.1. Designlinien-basierte Eingabe 4.1.1. Skizzeninterpretation 4.1.2. Modifikation der Designlinien 4.1.3. Semantische Untersuchung in der Modellierung 4.1.4. Zusammenfassung 4.2. Darstellungs- und Modellierungskonzept 4.2.1. Grundlagen des Texture Mappings 4.2.2. Geometriesimulation durch Relief Mapping 4.2.3. GPU-basierte Modifikation 4.2.4. Auswertung 4.3. Schaftbestandteile 4.3.1. Schaftmaterial 4.3.2. Nähte 4.3.3. Accessoires 4.3.4. Reißverschluss 4.3.5. Schnürsenkel 4.3.6. Materialdetail 4.3.7. Falten 4.4. Externalisierte Spezifikation 4.5. Zusammenfassung und Ausblick 5. Generierung einfacher Sohlen 5.1. Extraktion der Sohlenlinie 5.1.1. Formbetrachtung am Leisten 5.1.2. Problemstellung und Lösungsansätze 5.1.3. Aktive Konturen 5.1.4. Umsetzung 5.2. Sohlenmodell 5.2.1. Anforderungsanalyse 5.2.2. Spezifikation 5.2.3. Erzeugung 6. Designbewertung und Anpassung 6.1. Werkzeuge zur Bemessung 6.2. Vergleich und Anpassung 6.3. Externalisierte Beurteilung 7. Export in CAD 8. Zusammenfassung A. Prototypen

Aus der Einleitung: "Im Tissue Engineering und in der Medizintechnik gewinnt das Rapid Prototyping (RP), das zu den additiven Fertigungsverfahren zählt, zunehmend an Bedeutung (Zhang, et al. 2015) (Li, et al. 2014). Für die Verarbeitung von thermoplastischen Biopolymeren ist das Fused Deposition Modeling (FDM, schematische Darstellung in Abbildung 1) von zentralem Stellenwert. ..."

Aktuelle gesellschaftliche und politische Forderungen an die Produktionstechnik wie Nachhaltigkeit und Klimaschutz können bei der Fertigung flächiger Bauteile durch innovative Blechumformverfahren erreicht werden. Durch geschickte Kombinationen von inkrementellen und elektromagnetischen Fertigungsverfahren besteht hier besonders großes Potential. Aus diesem Grund wird im Rahmen dieser Arbeit die Erweiterung der elektromagnetischen Umformung um einen inkrementellen Ansatz untersucht. Dazu wird ein geeigneter Versuchsaufbau entwickelt und für eine ausführliche Prozessanalyse genutzt. Zusätzlich werden effiziente numerische Prozessmodelle entwickelt um eine schnelle Bestimmung weiterer Prozessgrößen zu ermöglichen. Im Ergebnis resultieren Hinweise mit denen das neuartige Verfahren auf beliebige Bauteile angewendet werden kann.

To facilitate the transition of Stereolithography (SLA) into the manufacturing domain and to increase its appeal to the micro manufacturing industry, process repeatability and surface finish need to be improved. Researchers have mostly focused on improving SLA surface finish within the capabilities of commercially available SLA machines. The capabilities of these machines are limited and a machine-specific approach for improving surface finish is based purely on empirical data. In order to improve surface finish of the SLA process, a more systematic approach that will incorporate process parameters is needed. To achieve this, the contribution of different laser and process parameters, such as laser beam angle, irradiance distribution, and scan speed, to SLA resolution and indirectly to surface finish, need to be quantified and incorporated into an analytical model. In response, a dynamic analytical SLA cure model has been developed. This model has been applied to SLA geometries of interest. Using flat surfaces, the efficacy of the model has been computationally and experimentally demonstrated. The model has been applied to process planning as a computational inverse design method by using parameter estimation techniques, where surface finish improvement on slanted surfaces has been achieved. The efficacy of this model and its improvement over the traditional cure models has been demonstrated computationally and experimentally. Based on the experimental results, use of the analytical model in process planning achieves an order of magnitude improvement in surface roughness average of SLA parts. The intellectual contributions of this research are the development of an analytical SLA cure model and the application of this model to process planning along with inverse design techniques for parameter estimation and subsequent surface finish improvement.

The introduction part of the thesis focuses on the overview of rapid prototyping in foundry industry. Principles of the most important RP methods are described and the FDM method is analyzed in more detail. This method was used in the practical part for the production of wax patterns with silicone moulds. The wax patterns were used for the production of castings using the lost wax method. The result of this work is determination of dimensional changes during the whole process of casting manufacture from the drawing to the final casting.

Scaffolds for bone tissue engineering are essentially characterized by porous three-dimensional structures with interconnected pores to facilitate the exchange of nutrients and removal of waste products from cells, thereby promoting cell proliferation in such engineered scaffolds. Although hydroxyapatite is widely being considered for bone tissue engineering applications due to its occurrence in the natural extracellular matrix of this tissue, limited reports are available on additive manufacturing of hydroxyapatite-based materials. In this perspective, hydroxyapatite-based three-dimensional porous scaffolds with two different binders (maltodextrin and sodium alginate) were fabricated using the extrusion method of three-dimensional plotting and the results were compared in reference to the structural properties of scaffolds processed via chemical stabilization and sintering routes, respectively. With the optimal processing conditions regarding to pH and viscosity of binder-loaded hydroxyapatite pastes, scaffolds with parallelepiped porous architecture having up to 74% porosity were fabricated. Interestingly, sintering of the as-plotted hydroxyapatite–sodium alginate (cross-linked with CaCl₂ solution) scaffolds led to the formation of chlorapatite (Ca₉.₅₄P₅.₉₈O₂₃.₈Cl₁.₆₀(OH)₂.₇₄). Both the sintered scaffolds displayed progressive deformation and delayed fracture under compressive loading, with hydroxyapatite–alginate scaffolds exhibiting a higher compressive strength (9.5±0.5 MPa) than hydroxyapatite–maltodextrin scaffolds (7.0±0.6 MPa). The difference in properties is explained in terms of the phase assemblage and microstructure

Thesis (M. Tech.) - Central University of Technology, Free State, 2008 / A company’s ability to produce products faster and more economically may lead to a competitive edge in the international market. The reduction of development costs and shortened development time will undeniably depend on effective organisational structures that are based on effective information- and communication techniques and manufacturing technologies. An innovative manufacturing technology that impacts on rapid product development is Rapid Prototyping (RP). The Centre for Rapid Prototyping and Manufacturing (CRPM) works closely with South African companies, supporting them with common mechanical engineering solutions and specialising in the manufacturing of prototypes. One of the options offered in the manufacture of prototypes is the Laser Sintering (LS) process. It is however, difficult to determine the product cost for the building volume used to manufacture the prototypes. Prototypes from different clients can be manufactured at the same time in the same process. The problem however, is how to calculate the costs for each prototype and to offer the clients an accurate quotation for the manufacture of the prototype. Therefore, it is necessary to design a calculation concept, which includes all accrued costs and allocate these to the different parts/prototypes. As it is problematic to calculate the manufacturing cost of prototypes, it is necessary to analyse all the effects, parameters and influences on the manufacturing process in order to determine the manufacturing time, and ultimately the machine costs. This is needed to calculate the total cost of one platform and the cost of each individual part. The project, through various experiments determined how to allocate the costs, through a correlation between part volume and platform height. The aim of the study was to determine a calculation concept to estimate the total platform cost and the cost of each individual part. Furthermore, the estimated cost was compared with the actual cost to determine the deviation between the calculation methods, and lead to a calculation concept that can be used to predict and reduce the manufacturing costs. The results obtained from the research were used for an exact calculation and reduction of prototype unit costs manufactured on LS machines, which gave three basic advantages: * Manufacturing costs were reduced to benefit clients, which meant that they could invest more in the design of new prototypes and products, to improve customer satisfaction * Prototype manufacturing on expensive RP machines could be optimised by using more prototypes and lower costs for entering the market. * The calculation risk could be minimised, which lowered the risk of losing money on a project and resulted in better planning for available resources.

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

Published Article / 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.