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Estudo comparativo entre mancais aerostáticos com restritor de orifício e com elemento cerâmico poroso / Comparative survey between aerostatics bearings with opening restrictor and with porous ceramic elementTsukamoto, Renato 06 November 2003 (has links)
A fabricação de ultraprecisão - com suas dimensões atingindo níveis submicrométricos - tem-se mostrado um campo de trabalho que exige combinação do que há de mais avançado nas áreas de materiais, metrologia e controle. Para alcançar tais níveis de precisão, é necessário que se garanta excelente desempenho de cada um dos componentes e/ou subsistemas das máquinas. Sendo o par tribológico mancal - eixo-árvore elemento vital para o desempenho de uma máquina ferramenta, e baseado em estudos recentes que mostram que mancais convencionais de rolamento estão rapidamente atingindo seu limite, o estudo dos mancais pressurizados externamente se impõe. Com a crescente demanda por rigidez e precisão de giro, tais mancais tem-se tornado solução convencional ao contrário de condição especial. Os mancais aerostáticos, em particular, apresentam alta precisão de giro, baixa geração de calor, ausência de desgaste, alto amortecimento e limpeza. Essas características os tornam bastante atrativos em ambientes de fabricação de ultraprecisão, especialmente na indústria óptica e eletrônica, como por exemplo, na fabricação de semicondutores. O presente trabalho objetiva a comparação entre os comportamentos de dois mancais aerostáticos, com restritor do tipo orifício e com material cerâmico poroso, em relação as capacidades de carga e rigidez. Os resultados indicam a superioridade do mancal com restritor poroso quanto a capacidade de carga e também em relação à rigidez. / Ultra-precision machining - whose dimensions can reach sub-micrometric levels - has been shown to be an area of work requiring a combination of the best of materials, metrology and control. To achieve such accuracy levels, it is necessary to guarantee excellent performance of every component and/or machine subsystems. Being the tribological associated pair bearing/spindle a vital element for the performance of a machine tool, and based on recent researches that show that rolling bearings are reaching their limit very quickly, there has been an increasing demand for aerostatic bearings. These present good characteristics of stiffness, radial and axial accuracy, low heating generation, wear resistance and cleanliness. These features make them quite attractive in ultra-precision manufacturing environments, specially in the optics and electronics industries, such as in the manufacturing of semiconductors. The present work compares the stiffness and load carrying capacity of orifice restrictor and porous ceramic aerostatic bearings. The results show the superiority of porous aerostatic bearings as to loading capacity as well stiffness.
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Investigation of the energy efficient sustainable manufacturing approach and its implementation perspectivesKatchasuwanmanee, Kanet January 2016 (has links)
In the last two decades, energy is becoming one of the main issues in the manufacturing industry as it contributes substantially to production cost, CO2 emissions, and other destructive environmental impact. Due to rising energy costs, environmental concerns and stringent regulations, manufacturing is increasingly driven towards sustainable manufacturing which needs to address the associated environmental, social and economic aspects simultaneously. One common approach is to achieve sustainability and to implement energy-resource efficient production management systems that enable optimisation of energy consumption and resource utilisation in the production system. However, by reducing energy consumption, the product quality and production cost may be compromised. To remain competitive in the dynamic environment, the energy-efficient management system should not only concern energy consumption but also maintain product quality and production efficiency. This thesis presents a development of the Energy-smart Production Management (e-ProMan) system which provides a systematic, virtual simulation that integrates manufacturing data relating to thermal effect and correlation analysis between energy flow, work flow and data flow for the heating, ventilation and air conditioning (HVAC) system and production process. First, the e-ProMan system comprises of the multidimensional analysis between energy flow, work flow and data flow. The results showed that the product quality is significantly affected by ambient temperature in CNC precision machining. Product quality appears to be improved at lower temperatures. This research highlights the significance of ambient temperature in sustainable precision machining. Second, the simulation experiment was modelled at the production process due to it being the main source of energy consumption in manufacturing. An up-hill workload scenario was found to be the most energy and cost-efficient production processes. In other words, energy consumption, CO2 emission and total manufacturing cost could be reduced when workload capacity and operating machine increase incrementally. Moreover, the e-ProMan system was modelled and simulated using the weather forecast and real-time ambient temperature to reduce energy consumption of the HVAC system. The e-ProMan system results in less energy consumption compared to the fuzzy control system. To conclude, the e-ProMan demonstrates energy efficiency at all relevant levels in the manufacturing: machine, process and plant. For the future research, the e-ProMan system needs to be applied and validated in actual manufacturing environments.
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Fabrication of pyramid-shaped microlens arrayChen, Jia-lin 12 February 2009 (has links)
Brightness enhancement film (BEF) has been manufactured in foreign factories for backlight module of liquid crystal display (LCD), then it only have some interior factories to put in exploitation. Because of this, the study presents a precision machining and new step-imprint hot embossing process to fabricate pyramid-shaped microlens array. First, a tungsten (W) steel material is manufactured by precision machining. The dimension of a pyramid-shaped microlens on the W steel are about 300 £gm in the base line of three side, 222 £gm in bevel edge of three side, 139 £gm in height of bottom to top, 180 £gm in pitch of the left and right sides between two pyramid-shaped microlens tips, and 85 degree in top angle of three bevel. The W steel mold is used as the first mold. Second, the pyramid peaks of first mold pattern are transferred on bulk metallic glass (BMG) using step-imprint hot embossing method with position adjustable mechanism to form a smaller concave pyramid-shaped microlens array, it can avoid arc radius of cutting tools which is used as the second mold. Another the pyramid peaks are transferred on PMMA (Polymethylmethacrylate) for concave pyramid-shaped microlens array of optical film in the hot embossing system. Finally, the second mold is fabricated to emboss convex pyramid-shaped microlens array of optical film on PMMA. The foregoing method is provided for backlight module of optical films process.
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Optical biopsy systems using ultra-slim objectives for the diagnosis of breast cancerKyrish, Matthew 16 September 2013 (has links)
One in eight women in America will develop breast cancer at some point in their lives. Breast cancer is the second deadliest form of cancer for women in the United States. When a suspicious region of the breast is detected, the tissue is diagnosed by removing a sample, preparing an H&E section, and performing histopathology. This procedure is expensive, invasive, and can take days to return a diagnosis. An alternative to excision biopsies is to instead perform an optical biopsy. This work details endomicroscopes intended to perform optical biopsies in breast tissue. The work address two issues limiting current optical biopsy systems: insufficient resolution and inability to reject out of focus light. To improve the resolution of current endomicroscopes, ultra-slim objectives are developed using optical plastics and zero alignment fabrication techniques. These objectives can outperform current alternative endomicroscope objectives in terms of performance across the field of view and chromatic aberration correction, while remaining as narrow as a biopsy needle. Next, an endomicroscope which utilizes structured illumination to perform optical section is designed, tested, and evaluated on ex vivo breast biopsies. The new endomicroscope provides high contrast images by reducing out of focus background light. Finally, an achromatic, ultra-slim objective and the structured illumination endomicroscope are integrated to form an optical biopsy system with improved lateral resolution and axial response. This integrated system is a step forward for in vivo microscopy and cancer diagnoses.
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Development of a Small Envelope Precision Milling Machine.Kirk, Dean Frederick January 2006 (has links)
The credit card industry is huge with over two and a half billion cards shipped annually. A local card manufacturer, with a production volume in excess of forty million cards annually, approached the University of Canterbury to design and develop advanced card manufacturing technology. The motivation behind this development was the desire of the sponsoring company to keep abreast of new technologies and to have the ability to manufacture and supply cards with this new and emerging technology into a highly competitive world market. This thesis reports the research surrounding the development of a dedicated new machine tool explicitly designed to implement the emerging technologies found in the international credit card industry. The machine tool, a dedicated milling machine, was not developed in its entirety within these pages; however, three major constituents of the machine were researched and developed to a point where they could be implemented or become the subject of further research. The three areas of interest were; • A machine table system that avoided the increased zonal wear to which linear bearings are subject, typically due to short high frequency traversals, and also the high friction and mass generally found in dovetail slides. • Design requirements demanded the use of a single commercially available carbide cutter to produce 1500 components per hour. Therefore, a purpose built high (revs per minute) rpm spindle and drive system specifically for use with polymeric materials, (R-PVC in particular) was deemed necessary. • Tracking the cutter depth in relation to an RFID aerial track embedded within the credit card core. The aerial tracking was to be dynamic and occur during the machining process with the machine “remembering” the depth of cut at contact with the aerial. Each of the three areas was researched via an in-depth literature review to determine what and if any material had been published in these fields. For the development of the machine table a novel flexure hinge idea was considered. Considerable material was discovered about flexures, but very little was found to be relevant to the application of high displacement metal flexures necessary to meet the required levels of table movement. In effect the proposed machine table system and research in this field would be novel. The high performance spindle investigation became directed into a much narrower focus as it progressed; that of determining the power consumption required to machine the integrated circuit pockets in an R-PVC work piece. This was due to the lack of information pertaining to the physical properties of polymeric materials, in particular the specific cutting pressure. The depth following sensor array was configured using capacitance detection methods to determine the distance between the cutter?s end and the aerial tracks. Capacitance sensing methods, whilst not new, were developed into a novel arrangement to meet the specific cutter tracking requirements of the proposed new machine tool. Each of the respective development areas had concept designs completed and were prototyped before being tested to determine the effectiveness of the respective designs. The outcomes from the testing are reported herein, and show each constituent part to be basically feasible, in the application. The results were sufficient to indicate that each development showed distinct potential but further development and integration into the machine tool should ensue.
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Estudo comparativo entre mancais aerostáticos com restritor de orifício e com elemento cerâmico poroso / Comparative survey between aerostatics bearings with opening restrictor and with porous ceramic elementRenato Tsukamoto 06 November 2003 (has links)
A fabricação de ultraprecisão - com suas dimensões atingindo níveis submicrométricos - tem-se mostrado um campo de trabalho que exige combinação do que há de mais avançado nas áreas de materiais, metrologia e controle. Para alcançar tais níveis de precisão, é necessário que se garanta excelente desempenho de cada um dos componentes e/ou subsistemas das máquinas. Sendo o par tribológico mancal - eixo-árvore elemento vital para o desempenho de uma máquina ferramenta, e baseado em estudos recentes que mostram que mancais convencionais de rolamento estão rapidamente atingindo seu limite, o estudo dos mancais pressurizados externamente se impõe. Com a crescente demanda por rigidez e precisão de giro, tais mancais tem-se tornado solução convencional ao contrário de condição especial. Os mancais aerostáticos, em particular, apresentam alta precisão de giro, baixa geração de calor, ausência de desgaste, alto amortecimento e limpeza. Essas características os tornam bastante atrativos em ambientes de fabricação de ultraprecisão, especialmente na indústria óptica e eletrônica, como por exemplo, na fabricação de semicondutores. O presente trabalho objetiva a comparação entre os comportamentos de dois mancais aerostáticos, com restritor do tipo orifício e com material cerâmico poroso, em relação as capacidades de carga e rigidez. Os resultados indicam a superioridade do mancal com restritor poroso quanto a capacidade de carga e também em relação à rigidez. / Ultra-precision machining - whose dimensions can reach sub-micrometric levels - has been shown to be an area of work requiring a combination of the best of materials, metrology and control. To achieve such accuracy levels, it is necessary to guarantee excellent performance of every component and/or machine subsystems. Being the tribological associated pair bearing/spindle a vital element for the performance of a machine tool, and based on recent researches that show that rolling bearings are reaching their limit very quickly, there has been an increasing demand for aerostatic bearings. These present good characteristics of stiffness, radial and axial accuracy, low heating generation, wear resistance and cleanliness. These features make them quite attractive in ultra-precision manufacturing environments, specially in the optics and electronics industries, such as in the manufacturing of semiconductors. The present work compares the stiffness and load carrying capacity of orifice restrictor and porous ceramic aerostatic bearings. The results show the superiority of porous aerostatic bearings as to loading capacity as well stiffness.
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Extension of ultra precision machining to titanium alloysAbdul Gani, Rahmath Zareena 12 1900 (has links)
<p> High-end optical grade applications would benefit greatly from the unique mechanical and chemical properties of titanium alloys. However, the standard process of manufacturing optical components has not been explored in depth for titanium alloys. </p> <p> Thus the focus of this work was to extend ultra precision machining technology to produce optical grade surfaces on titanium components. An optical surface is characterized by surface roughness less than 10nm R_rms which are typically produced with single crystal diamond tools having a cutting edge radius on the order of 50-100 nm. A cutting speed of 60m/min, feed rate of 1.5 µm/ rev and depth of cut of 2 µm, was identified to achieve the surface finish target, but the practical limitation of this process was still with tool life and the rapid degradation of surface finish over time. </p> <p> This was attributed to the adhesion of titanium material on the tool that resulted in material pull out and side-flow during machining. Results obtained from the characterization of the tool and workpiece led to the identification of graphitization as the initial wear mechanism. As the cutting edge rounds-off due to graphitization, the rate of adhesion of the workpiece material onto the tool increased. For this reason solutions were explored that would reduce the graphitization process and delay the onset of intense adhension. </p> <p> Thus a coating technology involving Perfluoro Polyether (PFPE) was chosen. Tribometer analysis under a load of 500N and temperature of 450ºC between the uncoated and PFPE coated diamond tools and titanium pins showed a remarkable reduction in COF from 0.275 to 0.05. A significant enhancement in tool life and surface quality was also achieved in single point diamond turning (SPDT) of titanium alloys using PFPE coated diamond tools. Tool life was based on an assessment of the cutting length achieved before the surface roughness exceeded the targeted value of 10 nm R_rms and it improved from 1.25 km and 5.1 km with PFPE coated tools. </p> / Thesis / Doctor of Philosophy (PhD)
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Rough Cutting Of Germanium With Polycrystalline Diamond ToolsYergok, Caglar 01 July 2010 (has links) (PDF)
Germanium is a brittle semi-metal, used for lenses and windows in Thermal Imaging Systems since it transmits infrared energy in the 2 µ / m - 12 µ / m wavelength range at peak. In this thesis study, polycrystalline diamond is used as cutting tool material to machine germanium. Diamond is the hardest, most abrasion-resistant material and polycrystalline diamond is produced by compacting small diamond particles under high pressure and temperature conditions, which results more homogeneous, improved strength and a durable material. However, slightly reduced hardness is obtained when compared with natural diamond.
Different from finish cutting, rough cutting, performed before finishing, is used to remove most of the work-piece material. During rough cutting, surface roughness is still an important concern, since it affects the finishing operations. Roughness of the surface of product is affected by a number of factors such as cutting speed, depth of cut, feed rate as cutting parameters, and also rake angle as tool geometry parameter.
In the thesis, the optimum cutting and tool geometry parameters are investigated by experimental studies for rough cutting of germanium with polycrystalline diamond tools. Single Point Diamond Turning Machine is used for rough cutting, and the roughness values of the optical surfaces are measured by White Light Interferometer. Experiments are designed by making use of &ldquo / Full Factorial&rdquo / and &ldquo / Box-Behnken&rdquo / design methods at different levels considering cutting parameters as cutting speed, depth of cut, feed rate and tool geometry parameter as rake angle.
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Usinabilidade do carbeto de tungstênio no torneamento com ferramenta de diamante / Single point diamond turning of the tungsten carbideGonçalves, André da Motta 06 November 2009 (has links)
Este trabalho apresenta o estudo da usinabilidade do carbeto de tungstênio utilizando ferramenta de ponta única de diamante em máquina-ferramenta de ultraprecisão, em função de suas características de dureza e potencial uso para a fabricação de micromoldes. O carbeto de tungstênio foi submetido a testes de usinagem para a determinação dos parâmetros e condições de corte para a obtenção do regime dúctil. Com base nos resultados experimentais, concluiu-se que, para os avanços da ordem de 1 micrômetro/revolução, a profundidade de corte (AP) não influencia significativamente no resultado de rugosidade, e para avanços da ordem de 3 micrômetros, observou-se a formação de trincas na superfície usinada. Além disso, para profundidades de corte maiores que 2 micrômetros as ferramentas começaram a apresentar lascamento. Para avanços da ordem de 3 micrômetro/revolução a profundidade de corte influencia com grande significância no resultado de rugosidade. O torneamento do carbeto de tungstênio usando ferramenta de diamante mostrou-se uma opção viável à produção de superfícies em termos de qualidade óptica, porém, devido à alta dureza deste material (aproximadamente 4000HV) o torneamento mostrou ser um processo com condições limitadas para a produção em série de componentes em função da baixa taxa de remoção de material permitida. É possível que a retificação possa apresentar taxas de remoção maiores, mesmo assim garantindo a qualidade superficial atingida pelo torneamento, ou ainda, a retificação possa ser usada como um processo no desbaste do carbeto de tungstênio seguido do torneamento de ultraprecisão como a opção viável a produção em série de peças. Portanto, para obtenção de uma superfície de carbeto de tungstênio sem danos e com acabamentos da ordem de 10 nm, a profundidade e avanço não devem ser superiores a 2,00 \'mü\'micrômetros e 1,00 \'mü\'micrômetro/revolução, respectivamente, usando uma ferramenta de diamante nova com ângulo de saída 0 ou - 25 graus e uma máquina-ferramenta de alta precisão. / The single point diamond turning of the Tungsten Carbide is presented. The motivation for this study is the material´s high hardness and potential application for micromolds. A Tungsten Carbide sample was subjected to tests for determination of cutting parameters to achieve the ductile regime of material removal. Based on experimental results it was concluded that for the feedrate of the order of 1 \'mü\'m/revolution, the depth of cut did not affect significantly the surface roughness and for federates of the order of 3 \'mü\'m/revolution, the dept of cut influenced results of roughness greatly. Moreover chipping of the cutting edge occurs for depths of cut of 2 \'mü\'m. The diamond machining of tungsten carbide tool using diamond proved to be a viable option for the production of surfaces in terms of optical quality, but due to the high hardness of this material (approximately 4000HV) showed to be limited for the production of components due to the low material removal rate. It is possible that the precision griding may provide higher material removal rates along with the acceptable surface quality. Therefore, to obtain a damage free surface in tungsten carbide with surface finishe in the order of 10 nm, cutting depth and feedrate should be smaller than 2,00 \'mü\'m and 1,00 \'mü\'m/revolution, respectively, using a new diamond tool with rake angle of 0 or - 25 degrees and precision high stiffness machine tool.
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Usinabilidade do carbeto de tungstênio no torneamento com ferramenta de diamante / Single point diamond turning of the tungsten carbideAndré da Motta Gonçalves 06 November 2009 (has links)
Este trabalho apresenta o estudo da usinabilidade do carbeto de tungstênio utilizando ferramenta de ponta única de diamante em máquina-ferramenta de ultraprecisão, em função de suas características de dureza e potencial uso para a fabricação de micromoldes. O carbeto de tungstênio foi submetido a testes de usinagem para a determinação dos parâmetros e condições de corte para a obtenção do regime dúctil. Com base nos resultados experimentais, concluiu-se que, para os avanços da ordem de 1 micrômetro/revolução, a profundidade de corte (AP) não influencia significativamente no resultado de rugosidade, e para avanços da ordem de 3 micrômetros, observou-se a formação de trincas na superfície usinada. Além disso, para profundidades de corte maiores que 2 micrômetros as ferramentas começaram a apresentar lascamento. Para avanços da ordem de 3 micrômetro/revolução a profundidade de corte influencia com grande significância no resultado de rugosidade. O torneamento do carbeto de tungstênio usando ferramenta de diamante mostrou-se uma opção viável à produção de superfícies em termos de qualidade óptica, porém, devido à alta dureza deste material (aproximadamente 4000HV) o torneamento mostrou ser um processo com condições limitadas para a produção em série de componentes em função da baixa taxa de remoção de material permitida. É possível que a retificação possa apresentar taxas de remoção maiores, mesmo assim garantindo a qualidade superficial atingida pelo torneamento, ou ainda, a retificação possa ser usada como um processo no desbaste do carbeto de tungstênio seguido do torneamento de ultraprecisão como a opção viável a produção em série de peças. Portanto, para obtenção de uma superfície de carbeto de tungstênio sem danos e com acabamentos da ordem de 10 nm, a profundidade e avanço não devem ser superiores a 2,00 \'mü\'micrômetros e 1,00 \'mü\'micrômetro/revolução, respectivamente, usando uma ferramenta de diamante nova com ângulo de saída 0 ou - 25 graus e uma máquina-ferramenta de alta precisão. / The single point diamond turning of the Tungsten Carbide is presented. The motivation for this study is the material´s high hardness and potential application for micromolds. A Tungsten Carbide sample was subjected to tests for determination of cutting parameters to achieve the ductile regime of material removal. Based on experimental results it was concluded that for the feedrate of the order of 1 \'mü\'m/revolution, the depth of cut did not affect significantly the surface roughness and for federates of the order of 3 \'mü\'m/revolution, the dept of cut influenced results of roughness greatly. Moreover chipping of the cutting edge occurs for depths of cut of 2 \'mü\'m. The diamond machining of tungsten carbide tool using diamond proved to be a viable option for the production of surfaces in terms of optical quality, but due to the high hardness of this material (approximately 4000HV) showed to be limited for the production of components due to the low material removal rate. It is possible that the precision griding may provide higher material removal rates along with the acceptable surface quality. Therefore, to obtain a damage free surface in tungsten carbide with surface finishe in the order of 10 nm, cutting depth and feedrate should be smaller than 2,00 \'mü\'m and 1,00 \'mü\'m/revolution, respectively, using a new diamond tool with rake angle of 0 or - 25 degrees and precision high stiffness machine tool.
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