D. Tech. Mechanical Engineering. / Describes reconfigurable manufacturing (RM) is a paradigm that promises to meet the turbulent demands in current global manufacturing. The major findings of this thesis are as follows; 1. The functional description of the machine tool provides a handy mechanism of aiding COTS machine builders come up with vary configurations of machine tools and their classification from a predefined set of COTS modules. 2. The process of linking the respective part demands to the relevant COTS RMT is a rigorous and tiresome process that demands computational power provided for by the KBS. 3. The subjective linguistic manner of linking the parts and the machine configuration can be managed by including an objective constraint for the fuzzy model. 4. Coupling the decision making using a mathematical model with the use of a KBS brings about the optimum route to arriving to the desired configuration.

Modern trends in customer demand have resulted in the development of a class of manufacturing system known as Reconfigurable Manufacturing Systems (RMS). Reconfigurable systems are designed around the idea that they must be able to be reconfigured in both their production capacity as well as in the machining processes they perform. A subset of the RMS paradigm is a group of machines called Modular Reconfigurable Machines (MRMs). Modular machines are built up from different hardware modules. They offer the user the possibility of only purchasing the required tooling for the specific need at the time. As reconfigurable machines are able to offer flexibility in machining functions, their ability to have easy access to a variety of machine tools would greatly influence their effectiveness and production capacity. This project presents a machine tooling system that would provide MRMs with an efficient way to change tools. A major requirement of the unit was that it should automatically calibrate itself in terms of its position relative to the machine it was servicing. In order for the unit to realize this requirement, it needed a method that would provide it with real-time 3D tracking of the spindle with which it was interacting. Commercially available systems that offer this facility are very costly. A popular gaming controller, the Nintendo Wii remote, was used to provide the tool-changing unit with a very economical real-time 3D tracking capability. This dissertation details the design, implementation and testing of the positioning system for the tool-changing unit. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2011.

Five-axis CNC machining presents high efficiency and unparallel flexibility in the machining of complex curved surfaces. However, generation of gouge-free CNC tool path and cutter orientation in 5-axis CNC machining remains a challenge due to the complex nature of the geometry problem encountered and the wide variations of surface geometry. In particular, curvature gouge is the biggest obstacle that hinders the advantages of 5-axis CNC machining. At present to avoid curvature gouge. a ball mill cutter with simple cutter geometry is mostly used in machining complex curved surfaces, although this either leads to lengthy machining time or poor surface finish with larger cusps which require extensive amount of hand polishing later on. An end and/or torus mill cutters with better cutter-surface curvature match can considerably improve the efficiency of the machining and the quality of the machined surface. But generation of appropriate tool paths and orientations for the more complex cutter geometry in gouge-free 5-axis CNC machining of curved surface requires a better understanding and a rigorous model of cutter-surface interaction, which do not exist at present. In this work, a rigorous mathematical model of cutter-surface geometry that facilitate better understanding on the interactions between various mill cutters. including ball. torus and end mills. and curved surface is introduced. The model is based on the new Euler-Meusnier Sphere (EMS) concept from a generic mathematical and geometric model of the cutter and surface geometry. The EMS model determines the curvature gouge constraints with varying cutter size and maximum cutter tilting angle for any given surfaces. A generic. global curvature gouge detection and avoidance method for the 5-axis CNC machining of concave, curved surfaces has been introduced. The method also improves curvature match between the cutter and the machined surface by facilitating the use of torus and end mill cutters. Computer simulation tests and real part machining have been carried out to assess the effectiveness of the new theory and newly introduced curvature gouge detection and avoidance criteria. Five-axis CNC machining experiments on curved surface, e.g. ellipse and exponent surfaces, are carried out. The machined surfaces following different tool path and cutter orientation strategies are measured using a CMM to appraise the real benefit of the introduced approach. The method has been applied to all three types of commonly used mill cutters: end. torus and sphere, for concave curved surfaces with limited curvature variation. The machining experiments have demonstrated the superior capability of the new method in providing guaranteed gouge elimination. better surface quality, and simple implementation. in comparing with 5-axis tool path and cutter orientation planning methods. The new EMS concept and curvature gouge detection/elimination method form the foundation for generating highly efficient, high quality surface producing 5-axis CNC tool path. and cutter orientation planning, programming and optimization for machining curved surfaces.

In this study, the new predictive model for the micro-grinding process was developed by consolidating mechanical and thermal effects within the single grit interaction model at microscale material removal. The size effect of micro-machining was also included in the proposed model. In order to assess thermal effects, the heat partition ratio was experimentally calibrated and compared with the prediction of the Hahn model. Then, on the basis of this predictive model, a comparison between experimental data and analytical predictions was conducted in view of the overall micro-grinding forces in the x and y directions. Although there are deviations in the predicted micro-grinding forces at low depths of cut, these differences are reduced as the depth of cut increases. On the other hand, the optimization of micro machine tools was performed on the basis of the proposed design strategy. Individual mathematical modeling of key parameters such as volumetric error, machine working space, and static, thermal, and dynamic stiffness were conducted and supplemented with experimental analysis using a hammer impact test. These computations yield the optimal size of miniaturized machine tools with the technical information of other parameters.

La selección de centros de mecanizado de alta velocidad es un proceso complejo que requiere de mucha experiencia, puesto que en él intervienen un gran número de variables, tanto tecnológicas como económicas. Existen metodologías orientadas a seleccionar el centro de mecanizado óptimo, considerando únicamente una de estas dos tipologías de variables, sin embargo, esta tesis propone una metodología que contempla ambos tipos. Para ello se identifican las variables que tienen mayor influencia sobre los resultados del proceso de mecanizado, tanto desde un punto de vista de calidad de las piezas fabricadas como de la economía de la fabricación, y se propone un modelo de selección basado en los resultados de un trabajo experimental realizado sobre piezas de aluminio. Dicho modelo se implementa mediante redes neurales, cuyo entrenamiento se realiza en base a los resultados del trabajo experimental mencionado.

Thesis (Ph. D.)--Missouri University of Science and Technology, 2008. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 18, 2008) Includes bibliographical references.

Thesis (MEng)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: The purpose of this project is to find a means to evaluate a number of machines to optimise a process chain. Firstly seven machine types were identified to be included in the study. These machine types include: broach machines, EDM machines, GNG lathes, engine lathes, drilling machines, milling machines and grinders. The information requirements for these machines in terms of attributes for three areas were identified. Functionality, economical and reliability and availability attributes were identified. These attributes were subsequently incorporated into a MS-Access database to provide a database of machine information. Several methods for comparing machines were studied and the decision then fell on one existing method to be used for machine evaluation. A new method was developed to use for evaluating machines. The existing method is the Analytic Hierarchy Process, whereas the new method developed, is called the Quotient Exponential Method. These methods were implemented in the MS-Access database to enable the user to evaluate machines by means of both methods. The results indicate that these methods provide the correct answers according to test values used. It should be noted that the decision methods should, however, only serve as an aid towards an answer and do not necessarily provide the final answer. The AHP process is very time-consuming for this project because of the large number of criteria evaluated. / AFRIKAANSE OPSOMMING: Die doel van hierdie projek is om "n manier te vind om masjiene te evalueer om sodoende "n proses-ketting te optimeer. Eerstens is besluit op die soorte masjiene wat ingesluit gaan word in die projek. Sewe soorte masjiene is gekies en sluit in: RNB draaibanke, masjiendraaibanke, boormasjiene, skuurders, elektriese ontladings masjiene, veelvuldige punt snymasjiene en rubeitelmasj iene. Die inligting-vereistes van die sewe masjiene, in terme van hul attribute vir drie areas, is vervolgens geïdentifiseer. Hierdie drie areas is funksionaliteit, koste, asook beskikbaarheid en betroubaarheid. Hierdie attribute word in "n MS-Access databasis gebruik om "n databasis van masjien-inligting te skep. Verskeie metodes vir die vergelyking en evaluasie van masjiene is bestudeer en daar is op een bestaande metode besluit vir die evaluering van "n aantal masjiene. Daarbenewens is ook "n nuwe metode ontwikkel vir die evaluering van masjiene. Die bestaande metode is die Analitiese Hiërargiese Proses, terwyl die nuwe metode die Kwosiënt Eksponensiële Metode genoem word. Altwee hierdie metodes is in MS-Access geïmplemeteer om die gebruiker in staat te stelom masjiene met albei metodes te vergelyk. Die resultate verkry toon aan dat die korrekte resultaat verkry word volgens die toetsdata wat ingevoer is ten opsigte van die twee metodes. Dit moet in gedagte gehou word dat hierdie metodes egter slegs as "n hulpmiddel tot besluitneming gebruik behoort te word en nie noodwendig die finale antwoord lewer nie. AHP is baie tydsaam gevind, aangesien die masjiene in die projek baie attribute bevat het.

Esta tese assume como pressuposto teórico que crescimento e desenvolvimento econômicos são processos dinâmicos que ocorrem a partir da co-evolução da tecnologia, da estrutura industrial e das instituições. A trajetória do processo de industrialização por substituição de importações (PISI) brasileiro foi marcada pela ênfase na acumulação de capacidade produtiva, e menor disposição das empresas na acumulação de capacidade inovativa. As empresas optaram pelo licenciamento externo de tecnologia, enquanto uma minoria de empresas institucionalizou e complementou esses esforços inovativos através de investimentos em P&D e/ou outros tipos de aprendizados tecnológicos. Embora a capacidade produtiva seja importante para materialização do progresso técnico, o mesmo apenas é conseguido através da P&D e a partir da cooperação entre produtor-usuário, fornecedores e universidades. A proteção da concorrência externa gerou demanda suficiente para o crescimento do setor de máquinas-ferramenta, mas também poucas empresas desenvolveram capacidade inovativa. Ademais, chama atenção o caráter contraditório do arcabouço regulatório e competitivo do PISI para o setor de bens de capital: as importações foram estimuladas por taxas de câmbio diferenciadas, importações sem cobertura cambial e isenções fiscais, enquanto se protegia a produção nacional com barreiras tarifárias e não tarifárias. Essa ‘dinâmica’ institucional configurou a especialização do setor de máquinas-ferramenta em produtos com menor conteúdo tecnológico relativamente às importadas. Os ramos industriais capitaneados pelas empresas estrangeiras após 1956 também contribuíram para configurar tal quadro, pois as mesmas requeriam máquinas-ferramenta de elevado conteúdo tecnológico que deslocava a procura para o mercado externo. A mudança do paradigma tecnológico nas décadas de 1970/1980 e a abertura econômica na década de 1990 configuraram a trajetória e o processo de reestruturação empreendido pelo setor no momento seguinte. As empresas com maior capacidades tecnológicas conseguiram acessar os novos conhecimentos requeridos para entrarem e se manterem na nova trajetória tecnológica. O profundo processo de reestruturação baseou-se na reorganização, especialização e aumento da eficiência produtiva. Com a consolidação produtiva e tecnológica das empresas líderes houve aumento da já existente heterogeneidade competitiva entre os fabricantes. Tal heterogeneidade decorre não apenas dos distintos esforços inovativos entre os fabricantes, mas também é devida à estrutura da demanda e do grau de sofisticação do usuário. / This thesis assumes as a theoretical basis that the economic growth and development are dynamic processes that occur from the co-evolution of technology, industrial structure and institutions. The trajectory of the Brazilian industrialization process was characterized by the accumulation of productive capacity and not the accumulation of innovative capacity. Companies preferred to license foreign technology, while a minority of companies institutionalized and complemented these efforts through investments in innovative R&D and/or other types of technological know-how. Although the production capacity is important for the materialization of technical progress, it is only achieved through R&D and from the cooperation between user-producer, suppliers and universities, etc. Protection from foreign competition generated enough demand for the growth of the machine tool, but few companies have developed innovative capacity. Furthermore, our attention is called to the contradictory nature of the regulatory framework and competitive PISI for the capital goods sector: imports were stimulated by different exchange rates, imports without hedging and tax exemptions, while protecting domestic production with tariffs and nontariff barriers. This 'dynamic' institutional sector specialization configured machine tool products with lower technological content compared with the imported ones. The industries led by foreign companies after 1956 also contributed to set up such a framework because they required machine tools with high technological content which shifted the demand for the foreign market. The technological paradigm shift in the decades of 1970/1980 and economic opening in the 1990s shaped the trajectory and the restructuring process undertaken by the sector in the next moment. Firms with greater technological capabilities gained access to the new knowledge required to enter and remain in the new technological trajectory. The profound restructuring process was based on the reorganization, specialization and increased production efficiency. With the productive and technological consolidation of the leading, the was an increase in the existing competitive heterogeneity among manufacturers. Such heterogeneity arises not only from different innovative efforts between manufacturers, but it is also due to the structure of demand and the degree of sophistication of the end user.

Esta tese assume como pressuposto teórico que crescimento e desenvolvimento econômicos são processos dinâmicos que ocorrem a partir da co-evolução da tecnologia, da estrutura industrial e das instituições. A trajetória do processo de industrialização por substituição de importações (PISI) brasileiro foi marcada pela ênfase na acumulação de capacidade produtiva, e menor disposição das empresas na acumulação de capacidade inovativa. As empresas optaram pelo licenciamento externo de tecnologia, enquanto uma minoria de empresas institucionalizou e complementou esses esforços inovativos através de investimentos em P&D e/ou outros tipos de aprendizados tecnológicos. Embora a capacidade produtiva seja importante para materialização do progresso técnico, o mesmo apenas é conseguido através da P&D e a partir da cooperação entre produtor-usuário, fornecedores e universidades. A proteção da concorrência externa gerou demanda suficiente para o crescimento do setor de máquinas-ferramenta, mas também poucas empresas desenvolveram capacidade inovativa. Ademais, chama atenção o caráter contraditório do arcabouço regulatório e competitivo do PISI para o setor de bens de capital: as importações foram estimuladas por taxas de câmbio diferenciadas, importações sem cobertura cambial e isenções fiscais, enquanto se protegia a produção nacional com barreiras tarifárias e não tarifárias. Essa ‘dinâmica’ institucional configurou a especialização do setor de máquinas-ferramenta em produtos com menor conteúdo tecnológico relativamente às importadas. Os ramos industriais capitaneados pelas empresas estrangeiras após 1956 também contribuíram para configurar tal quadro, pois as mesmas requeriam máquinas-ferramenta de elevado conteúdo tecnológico que deslocava a procura para o mercado externo. A mudança do paradigma tecnológico nas décadas de 1970/1980 e a abertura econômica na década de 1990 configuraram a trajetória e o processo de reestruturação empreendido pelo setor no momento seguinte. As empresas com maior capacidades tecnológicas conseguiram acessar os novos conhecimentos requeridos para entrarem e se manterem na nova trajetória tecnológica. O profundo processo de reestruturação baseou-se na reorganização, especialização e aumento da eficiência produtiva. Com a consolidação produtiva e tecnológica das empresas líderes houve aumento da já existente heterogeneidade competitiva entre os fabricantes. Tal heterogeneidade decorre não apenas dos distintos esforços inovativos entre os fabricantes, mas também é devida à estrutura da demanda e do grau de sofisticação do usuário. / This thesis assumes as a theoretical basis that the economic growth and development are dynamic processes that occur from the co-evolution of technology, industrial structure and institutions. The trajectory of the Brazilian industrialization process was characterized by the accumulation of productive capacity and not the accumulation of innovative capacity. Companies preferred to license foreign technology, while a minority of companies institutionalized and complemented these efforts through investments in innovative R&D and/or other types of technological know-how. Although the production capacity is important for the materialization of technical progress, it is only achieved through R&D and from the cooperation between user-producer, suppliers and universities, etc. Protection from foreign competition generated enough demand for the growth of the machine tool, but few companies have developed innovative capacity. Furthermore, our attention is called to the contradictory nature of the regulatory framework and competitive PISI for the capital goods sector: imports were stimulated by different exchange rates, imports without hedging and tax exemptions, while protecting domestic production with tariffs and nontariff barriers. This 'dynamic' institutional sector specialization configured machine tool products with lower technological content compared with the imported ones. The industries led by foreign companies after 1956 also contributed to set up such a framework because they required machine tools with high technological content which shifted the demand for the foreign market. The technological paradigm shift in the decades of 1970/1980 and economic opening in the 1990s shaped the trajectory and the restructuring process undertaken by the sector in the next moment. Firms with greater technological capabilities gained access to the new knowledge required to enter and remain in the new technological trajectory. The profound restructuring process was based on the reorganization, specialization and increased production efficiency. With the productive and technological consolidation of the leading, the was an increase in the existing competitive heterogeneity among manufacturers. Such heterogeneity arises not only from different innovative efforts between manufacturers, but it is also due to the structure of demand and the degree of sophistication of the end user.

No description available.