Thesis (MScEng (Industrial Engineering))--University of Stellenbosch, 2008. / This thesis forms part of the AMTS Project on Investment Casting Capabilities for Light Metal Alloys in South Africa, the focus area being Rapid Tooling Development. Various issues of the investment casting process are being discussed from an industrial engineering point of view. These issues are related to the possibilities of improving the investment casting process’ lead times by shortening it while still maintaining affordable costs and required quality. Hereby the possibilities given by the newly developed “rapid technologies” are investigated. The focus is on Rapid Pattern Making as one of the most essential components for accelerated development of new products. Three of the most widely used layer manufacturing processes available in South Africa are selected for the study, namely Three Dimensional Printing – Drop-on-Bed (ZCorporation), Selective Laser Sintering (EOS) and Three Dimensional Printing – Drop-on-Drop (ThermoJet - 3D Systems). These three methods represent different materials; therefore different mechanical properties, different process economics as well as different technological characteristics. A standard benchmark part is used as a study base. Four patterns are produced by these three methods. A comprehensive measurement programme is conducted, followed by an appropriate statistical analysis and evaluation regarding accuracy and surface finish. Rapid Die Making is analysed with the possibilities of using additive methods for rapid tooling. Two dies are built with the same technology – Selective Laser Sintering (EOS), but in different materials. The same evaluation methodology is used for the statistical analysis and comparison. The two dies are injected with wax in order to produce the original benchmark part. The best wax patterns from each die are selected and evaluated, using the same methodology for analysis and comparison. The current state of Direct Shell Production is shortly discussed. The research concludes that RP&T techniques can successfully be used for creating accurate patterns and dies in order to shorten lead times in the investment casting process chain. Each RP&T process has its own set of advantages and disadvantages. All users should evaluate their requirements and the capabilities of the variety of techniques before deciding on a process to apply.

Thesis (MScEng (Industrial Engineering))--University of Stellenbosch, 2010 / ENGLISH ABSTRACT: Additive Manufacturing (AM) refers to the technologies that use Computer Aided Design (CAD) data to produce plastic, metal, ceramic, paper, wax or composite materials parts. Their ability to join thin layers of liquid, powder or sheet materials together permits the production of parts, which are difficult or even impossible to produce, using any other manufacturing method. Even though these technologies are still developing, they are considered a major breakthrough in industry. One of the main problems that is facing the improvement and the spread of AM technologies, and its benefits worldwide, is the lack of knowledge about them. Still a lot of countries, educational and industrial organizations do not even know about AM technologies. This lack of knowledge of such technologies is keeping their cost artificially high, which is limiting the access to more AM advanced technologies and materials. It also makes it difficult to market the technologies and those who do not use AM technologies yet become unable to compete against those who do. The numbers of AM systems are continually growing, their capabilities and applications are improving and their cost is decreasing. Today there are more than 40 companies that produce over 100 different systems in Canada, China, France, Germany, Israel, Italy, Japan, South Korea, Sweden and the United States. These systems vary in their strengths, defects, applications, functions and limitations. This growth has led to an increase in current and potential users of AM from both the manufacturing and educational sectors. These users are however facing increasing complex problems when it comes to selecting the most appropriate commercial system(s) to suit their needs. The aim of this study is to develop an AM system selection program. The program will serve both as an educational tool and a decision making support tool to assist any potential purchasers in both the educational and industrial sectors. The AM system selection program is divided into two sections: the learning section and the selecting section. The learning section introduces the AM technologies by imparting knowledge to the new users; moreover, it inspires them to start using these technologies to get their benefits. Having a background in AM technologies enables the new users to make educated decisions and to discuss technical issues about the systems with the providers. The selecting section offers a decision making support tool to help the users to decide which system best suits their needs. This study can contribute to the promotion of AM technologies and their benefits worldwide, especially for the countries and organizations that have not yet used such technologies. / AFRIKAANSE OPSOMMING: Toevoegende vervaardiging verwys na al die tegnologie wat rekenaargesteunde ontwerp data gebruik om plastiek, metaal, keramiek, papier, saamgestelde materiale en waks parte te vervaardig. Die vermoë van die tegnologie om dun lae vloeistof, poeier of plaatmateriaal op mekaar te verbind laat die vervaardiging van parte wat moeilik of selfs onmoontlik is, deur die gebruik van ander vervaardigingsmetodes. Alhoewel hierdie tegnologieë nog in ‘n ontwikkelingsfase is, word dit as ‘n reuse deurbraak vir die bedryf beskou. Die verbetering, verspreiding en voordele van die tegnologie word hoofsaaklik belemmer deur ‘n tekort aan inligting daaroor. Baie lande, akademiese en industrieële organisasies is nog nie eens bewus dat sulke tegnologieë bestaan nie. Die tekort aan inligting veroorsaak dat kostes hoog bly en verhoed die vinnige uitbreiding van nog meer gevorderde tegnologieë en materiale. Verder bemoeilik dit ook die bemarking van die tegnologieë. Die aantal toevoegende vervaardigingsmasjiene groei jaarliks met beter vermoëns, laer kostes en ‘n groter verskeidenheid van toepassings. Tans is daar meer as 40 vervaardigers wat meer as 100 verskillende masjiene vervaardig in Kanada, China, Frankryk, Duitsland, Israel, Italië, Japan, Suid-Korea, Swede en Amerika. Al die masjiene verskil ten opsigte van hul funksies, beperkings en ook ten opsigte van sterkte, materiale en toepassings van parte. Die groei het gelei tot ‘n toename in gebruik van die tegnologie deur huidige en potensiële nuwe gebruikers van beide die vervaardigings en akademiese sektore. Die keuse van ‘n geskikte sisteem wat aan al ‘n gebruiker se vereistes voldoen, raak elke dag meer kompleks. Die doel van hierdie studie is die ontwikkeling van ‘n seleksie program vir toevoegende vervaardigingmasjiene. Die program sal dien as ‘n opleidingshulpmiddel en as ‘n basis vir masjienseleksie deur potensiële kopers. Die program bestaan uit twee dele: die opleidingsgedeelte en die selekteringsgedeelte. Die opleidingsgedeelte beskryf die verskeie toevoegende prosesse en motiveer gebruikers om die tegnologie aan te skaf weens die voordele. ‘n Agtergrond oor die verskeie tegnologieë stel die gebruiker in staat om ingeligte besluite te neem en tegniese vrae te kan stel aan verskaffers. Die selekteringsdeel het ‘n besluitnemingstruktuur wat help om die regte masjien te kies ten opsigte van verlangde vereistes. Hierdie studie kan help met die bevordering van toevoegende tegnologieë en hul voordele, veral vir lande en organisasies wat nog nooit voorheen sulke tegnologieë gebruik het nie.

The vision of automated driving demands a highly available system, especially in safety-critical functionalities. In automated driving when a driver is not binding to be a part of the control loop, the system needs to be operational even after failure of a critical component until driver regain the control of vehicle. In pursuit of such a fail-operational behavior, the developed design process with software redundancy in contrast to conventional dedicated backup requires the support of automatic configurator for scheduling relevant parameters to ensure real-time behavior of the system. Multiple implementation methods are introduced to provide an automatic service which also considers task criticality before assigning task to the processor. Also, a generic method is developed to generate adaptation plans automatically for an already monitoring and reconfiguration service to handle fault occurring environment.

Developing a tool supporting humans to design and evaluate CLB-based circuits requires a lot of know-how and research from different fields of computer science. In this work, the newly developed application q2d, especially its design and implementation will be introduced as a possible tool for approaching CLB circuit development with graphical UI support. Design decisions and implementation will be discussed and a workflow example will be given.:1 Introduction 1.1 Forethoughts 1.2 Theoretical Background 1.2.1 Definitions 1.2.2 Expressing Connections between Circuit Elements 1.2.3 Global Context and Target Function 1.2.4 Problem formulation as QBF and SAT 2 Description of the Implemented Tool 2.1 Design Decisions 2.1.1 Choice of Language, Libraries and Frameworks 2.1.2 Solving the QBF Problem 2.1.3 Design of the Internally Used Meta-Model 2.1.4 User Interface Ergonomics 2.1.5 Aspects of Schematic Visualization 2.1.6 Limitations 2.2 Implemented Features 2.2.1 Basic Interaction 2.2.2 User-Defined Components 2.2.3 Generation of Circuit Symbols 2.2.4 Methods for Specifying Functional Behaviour 3 Implementation Details 3.1 Classes Involved in the Component Meta-Model 3.2 The Document Entry Class and its Factory 3.3 Model and View 3.3.1 The Model Element Hierarchy 3.3.2 The Schematics Element Hierarchy 3.4 The Quantor Interface 4 An Example Workflow 4.1 The Task 4.2 A Component Descriptor for Xilinx’ LUT6-2 4.3 Designing the Model 4.4 Computing the Desired Configuration 5 Summary and Outlook 5.1 Achieved Results 5.2 Suggested Improvements References A Acronyms and Glossary B UML Diagrams

A composite part manufacturing mold was considered one of the most important factors that affected a successful composite part manufacturing process for this research. A highly durable surface was required for the mold to prevent surface damages and increase mold life. A high surface finish quality of the mold improved the surface quality of the composite part and lowered the demolding force. However, the surface of additively manufactured fiber reinforced composite molds usually had lower durability and surface finish quality compared to traditional metal molds. To solve these issues, the author applied an additional coating on top of the additively manufactured fiber reinforced composite mold surface. A thermal analysis of the additively manufactured fiber reinforced composite material and the coating material were performed to select an applicable coating technique and coating material. The thermoset polymer coating with ceramic particles that was applied with a liquid spray coating technique was selected as a coating material. Various surface property tests were performed to evaluate the coated surface compared to the non-coated surface. The additively manufactured fiber reinforced composite test specimen manufacturing process and the coating application process were demonstrated in this study. The surface durability of the test specimens was tested using a surface hardness test and an abrasion resistance test. The surface performance of the test specimens was measured using a surface roughness test and a demolding test. The sustainability of the coating material on the additively manufactured fiber reinforced composite was tested using coefficient of thermal expansion (CTE) test, coating adhesion test, and mold life experiment. In the mold life experiment, the non-coated and coated mold were used for multiple composite part manufacturing processes to investigate how the coating affected the life of the mold. The test results showed that the coated surface had a significantly improved surface abrasion resistance and demolding performance. However, the coating did not significantly improved surface hardness and roughness with the coating. The adhesion strength of the coating was not degraded even there was a coefficient of thermal expansion (CTE) mismatch between the additively manufactured fiber reinforced composite and the coating material. The coated additively manufactured fiber reinforced composite mold was able to be used for multiple autoclave composite part manufacturing cycles. The coating covered most of the small voids on the mold surface and provided a more homogeneous surface compared to the non-coated mold, but the voids which could not be covered with the coating caused a chipped coating issue. Once the chipped coating occurred, the size of chipped coating got larger each time the tool was used for a composite part manufacturing cycle. Although the additional coating provided some improvements for the surface properties, the coating applied in this research could not be an ultimate solution to meet all the surface property requirements for composite part manufacturing mold.

Nowdays biofuels are becoming a good alternative for petroleum fuels due to environmental issues like high carbon dioxide emission and increasing vehicles population, together with the high price and fast depletion of petroleum oils. This project aims to investigate the corrosive effects of wood Pyrolysis oil on a special grade of nitrogen alloyed tooling steels to be used for injector nozzles in Diesel engines, where high stress and strain encounter high acidity and corrosivity of the Pyrolysis oil and cause breakdown over short periods. Vanax 35 and Vanax 75 manufactured in Uddeholm are two types of powder metallurgy high nitrogen alloyed martensitic stainless steel with a high combination of hardness (over 56HRC), low friction properties, wear resistance, anti-galling and corrosion properties. In this work, the newly developed Vanax material together with the tool steels Elmax and AISI O1 were tempered at various temperatures from 200°Cto 500°C. The tempered steels were then exposed in pyrolysis oil at 4 different temperatures, 20°C, 70°C, 95°Cand 130°C. The materials were investigated by means of corrosion rate measurements, microscopy (LOM, SEM, confocal) and Thermo-Calc calculations. The corrosion rate measurement proved that Vanax tempered at lower ranges (200°C, 400°Cand 450°C) showed the best corrosion resistance while higher tempering temperatures such as 500°C, Elmax and AISI O1 tempered at 200°Csuffered a great deal of general corrosion attack. Thermo-Calc calculations showed the formation of a hard phase, VN as primary nitrides instead of primary chromium carbides at austenizing temperature for the Vanax group. Higher amount of chromium is dissolved in solid solution in Vanax at austenizing temperature hence the martensite matrix has, after quenching, a higher chromium content that helps passivation. The loss in corrosion properties at higher tempering temperatures was due to the formation of CrN secondary phase at around 400˚C which reduces the chromium content of the martensite matrix. The results of light optical and confocal microscopy showed the presence of pits when tempering at 400˚C and 450˚C. No pits were observed at 200˚C. Elmax was not passivated at all which resulted in general corrosion attacks, due to a high chromium loss from the austenite solid solution at the austenizing procedure temperature and also the tempering temperatures. The chromium depletion from the austenite can be explained by a high carbon and a low nitrogen content in the composition which resulted in formation of a high amount of Cr7C3.

<p>High pressure die casting is an industrial metal casting process used to manufacture goods for use in many aspects of society. Within this manufacturing process, the tooling is subjected to chemical attack from molten aluminum while also being responsible for heat removal during solidification. The purpose of this study is to develop and test materials that allow the tools to better withstand the chemical attack, and to develop design rules to guide the use of additive manufacturing for improving the heat exchange function of by way of conformal cooling.</p> <p> </p> <p>Within the material studies, a gooseneck with a niobium lining was developed to allow the successful implementation of hot chamber aluminum die casting. In addition, a manufacturing plan is described that will allow the niobium gooseneck design to be easily sourced by die casting companies. The material studies also included dunk testing of several coatings, including a plasma assisted chemical vapor deposition silicon doped diamond like carbon (PACVD Si-DLC). The Si-DLC coating performed the best in the dunk testing as compared to bare and nitrocarburized tool steel, and a number of other coating architectures.</p> <p> </p> Within the study of additively manufactured conformal cooling design, a finite difference model is developed that allows a simulated experiment that produced a number of useful equations that guide the design of die casting tooling. During the development of the models, it was discovered that little is known regarding the friction factors of additively manufactured steel pipes, so a factorial experiment was employed to empirically determine said friction factors. Charts allowing design engineers to quickly determine pressure drops and heat transfer coefficients of conformal cooling designs was produced as well.<br>

Digital painting is the field of software designed to provide artists a virtual medium to emulate the experience and results of physical drawing. Several hardware and software components come together to form a whole workflow, ranging from the physical input devices, to the stroking process, to the texture content authorship. This thesis explores an artist-friendly approach to synthesize the textures that give life to digital brush strokes. Most painting software provides a limited library of predefined brush textures. They aim to offer styles approximating physical media like paintbrushes, pencils, markers, and airbrushes. Often these are static bitmap textures that are stamped onto the canvas at repeating intervals, causing discernible repetition artifacts. When more variety is desired, artists often download commercially available brush packs that expand the library of styles. However, included and supplemental brush packs are not easily artist-customizable. In recent years, a separate field of digital art tooling has seen the popular growth of node-based procedural content generation. 3D models, shaders, and materials are commonly authored by artists using functions that can be linked together in a visual programming environment called a node graph. In this work, the feasibility is tested of using a node graph to procedurally generate highly customizable brush textures. The system synthesizes textures that adapt to parameters like pen pressure and stretch along the full length of each brush stroke instead of stamping repetitively. The result is a more flexible and artist-friendly way to define, share, and tweak brush textures used in digital painting.

Thesis (M. Tech.) -- Central University of Technology, Free State, 2010 / The aim of this study is to produce more cost effective carbon fibre (CF) parts. To achieve this there must be a saving on materials, labour and time. Thus, a production process to produce cost effective CF moulds while saving time and money is required. This procedure must be suited for the incorporation in the small to medium production ranges. The composite industry is one of the fastest growing industries in the world. Therefore, the faster a mould can be produced, the faster the end product will reach the market. This research project investigates the possibility to sinter CF moulds on the Electro Optical Systems (EOS) Laser Sintering (LS) machine cheaper and faster than the conventional method using computer numerically controlled (CNC) machining. The surface finish produced on the LS machine is not of the same quality as a CNC machined mould, but there are ways to enhance the surface quality of a LS part to the point that it is compatible to the surface quality of a CNC machined mould. The CF moulding process uses many different types of moulding processes. However, it is not possible to use LS parts for all of the available processes to produce CF parts. In this study only one CF moulding process will be investigated, namely compression moulding. The moulds will be designed to be manufactured as cheaply and as quickly as possible. Different methods of mould adapting have been studied to find the cheapest most suitable method of mould design for the LS process.

Additive manufacturing is an industrial process, developed in the early 1980s and currently used in several industries such as the medical, aircraft and automotive industries. In the first place,additive manufacturing was mostly usedby manufacturing industries to produce prototypes, models and patterns. Nowadays, this technology can be used at any point in the lifecycle of a product from pre-production(rapid prototyping and rapid tooling) to production (direct manufacturing). This technology is especially adapted for the production of limited series of small and geometrically complex components.The purpose of this study is to identify howadditive manufacturing affects operational performance during the development and production phases, specifically in the case of the automotive industry.With this purpose in mind, I have collected primary and secondary data through a qualitative study using both in-depth semi-structured interviewsand archival records found on automotive companies’ websites. The objective of collecting multiple sources datawas to gain a reliable and comprehensive perception of the situation and understand the effects of additive manufacturing on operational performance, and more precisely on the seven production wastesdefined on lean practices, to be able to answer my research question. The data are analyzed using an inductive thematic analysis approach and testthe presupposition that emerged from the empirical findings. Through the analysis of the data collected, I came to the conclusion that additive manufacturing is mostly used during the prototyping phase and sometimes also used for rapid tooling. But it appears that this technology is only used for direct manufacturing in some specific niche markets such as luxury carmakers. Another interesting finding concerns the use of additive manufacturing for marketing purpose. Concerning operational performance, the impacts of additivemanufacturing remainlimited, and contrary to what some authors said, the use of this technology is still marginal in the automotive industry compared to traditional manufacturing.