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1	Development of an electrochemical micromachining (μECM) machine Spieser, Alexandre Frederic Jean January 2015 (has links) Electrochemical machining (ECM) and especially electrochemical micromachining (μECM) became an attractive area of research due to the fact that this process does not create any defective layer after machining and that there is a growing demand for better surface integrity on different micro applications such as microfluidics systems and stressfree drilled holes in the automotive and aerospace sectors. Electrochemical machining is considered as a non-conventional machining process based on the phenomenon of electrolysis. This process requires maintaining a small gap - the interelectrode gap (IEG) - between the anode (workpiece) and the cathode (tool-electrode) in order to achieve acceptable machining results (i.e. accuracy, high aspect ratio with appropriate material removal rate and efficiency). This work presents the design of a next generation μECM machine for the automotive, aerospace, medical and metrology sectors. It has 3 axes of motion (X, Y and Z) and a spindle allowing the tool-electrode to rotate during machining. The linear slides for each axis use air bearings with linear DC brushless motors and 2nmresolution encoders for ultra-precise motion. The control system is based on the Power PMAC motion controller from Delta Tau. The electrolyte tank is located at the rear of the machine and allows the electrolyte to be changed quickly. A pulse power supply unit (PSU) and a special control algorithm have been implemented. The pulse power supply provides not only ultra-short pulses (50ns), but also plus and minus biases as well as a polarity switching functionality. It fulfils the requirements of tool preparation with reversed ECM on the machine. Moreover, the PSU is equipped with an ultrafast over current protection which prevents the tool-electrode from being damaged in case of short-circuits. Two different process control algorithms were made: one is fuzzy logic based and the other is adapting the feed rate according to the position and time at which short-circuits were detected. The developed machine is capable of drilling micro holes in hard-to-machine materials but also machine micro-styli and micro-needles for the metrology (micro CMM) and medical sectors. This work also presents drilling trials performed with the machine with an orbiting tool. Machining experiments were also carried out using electrolytes made of a combination of HCl and NaNO₃ aqueous solutions. The developed machine was used to fabricate micro tools out of 170μm WC-Co alloy shafts via micro electrochemical turning and drill deep holes via μECM in disks made of 18NiCr6 alloy. Results suggest that this process can be used for industrial applications for hard-to-machine materials. The author also suggests that the developed machine can be used to manufacture micro-probes and micro-tools for metrology and micro-manufacturing purposes. 671.3
2	A study on productivity enhancement in high-speed, high-precision micromilling processes Sodemann, Angela Ann 16 November 2009 (has links) This thesis presents a study into the enhancement of productivity in micromilling processes by considering a fundamental treatment of tool path trajectory generation techniques and process optimization strategies that account for the impact of scale effects present in high-speed, high-precision micromachining operations. Micromilling is increasingly applied to the production of a wide variety of micro components, due to its high precision and flexibility. However, the productivity of micromilling is limited by the low feedrates necessitated by the inherent high precision and small feature size. In this study, several scale effects present at the microscale are identified, in particular the increase of the ratio of tool size to feature size, and the corresponding impact on trajectory generation and process optimization is investigated. The scale effects are shown to cause increased geometric error when the standard method of VF-NURBS is applied to microscale feedrate optimization. The method of Enhanced Variable-Feedrate NURBS (EVF-NURBS) is proposed and shown to successfully compensate for the scale effects leading to reduced geometric error. A key contribution of this study is the construction and experimental validation of the Variable-Feedrate Intelligent Segmentation (VFIS) method for increased feedrates and improved stability. The VFIS method provides a cutting time reduction of more than 50% in some cases, while effectively constraining geometric error. Two tool size optimization schemes are presented for maximizing productivity and minimizing geometric error while accounting for dynamic effects uniquely present at the microscale. Finally, the development of a low-cost, high-precision micro-mesoscale machining center (mMC) is presented. Feedrate optimization Scale effects Micromilling Micromanufacturing Milling (Metal-work) Micromachining
3	Estudo teórico-experimental do efeito da flexão da ferramenta no processo de microfresamento / Theorical and experimental study on tool deflection effect in micromilling process Arai, Ricardo 15 September 2008 (has links) A flexão da ferramenta, em operações de fresamento de topo, é responsável por interferir negativamente na qualidade superficial da peça a ser usinada e, muitas vezes, pela quebra prematura da mesma. O presente trabalho tem como objetivo estudar experimentalmente os efeitos da flexão de fresas de topo com 0,8 mm de diâmetro no processo de microfresamento. Os ensaios experimentais foram realizados com o intuito de identificar quais parâmetros de corte apresentam maior influência na flexão da ferramenta. Os parâmetros de corte escolhidos para estudo foram: velocidade de corte, velocidade de avanço, profundidade de usinagem e penetração de trabalho. Os ensaios investigam, além das faixas de parâmetros recomendados pelo fabricante da ferramenta, uma condição 25% acima e outra 25% abaixo para todos os parâmetros estudados. O monitoramento de forças de corte foi realizado em todos os ensaios. As forças obtidas se mostraram diretamente relacionadas com a área de secção de corte, conforme teoria básica. Para fins comparativos, a força máxima obtida experimentalmente foi aplicada na simulação com elementos finitos (FEM - Finite Element Method) da ferramenta e indicou um comportamento similar ao de uma viga engastada. A análise microscópica do aspecto superficial da usinagem mostrou que menores avanços por dente resultam em um melhor acabamento confirmando resultados do processo convencional. O conhecimento do efeito dos parâmetros de corte no processo de microfresamento tem o intuito de oferecer informações às empresas do setor no sentido de melhorar o planejamento e processo de fabricação. / The tool deflection, in end milling operations, is responsible to intervene negatively on the workpiece surface quality and can also cause a premature tool failure (breakage).The present work aims at studying experimentally the effects of tool deflection when end milling with 0,8 mm diameter in microoperations. The experimental tests had intended to identify which parameters of milling show more influence in tool deflection. The chosen milling parameters for the study were: cutting speed, feed rate, depth of cut and step over. The tests aim to investigate, beside the recommended parameters from tool manufacturer, a 25% higher and 25% lower conditions. The force acquisition was made in all tests. The measured forces shown that they are directly related to the uncut chip cross section, in accordance with theory. For comparative purpose, the maximum experimental force value was applied in the finite elements method (FEM) simulation of the tool and indicates a similar behavior of an encastré beam. The microscopic analysis of the superficial aspect of the milling showed that smaller feed per tooth results in better finishing, as observed in the conventional process. The knowledge of the effect of the cutting parameters in the micromilling process has the intention of offering information for industries to improve the planning and process of manufacturing. Cutting forces Flexão de ferramenta Forças de corte Microfresamento Micromanufacturing Micromilling Processos de microfabricação Tool deflection
4	Estudo teórico-experimental do efeito da flexão da ferramenta no processo de microfresamento / Theorical and experimental study on tool deflection effect in micromilling process Ricardo Arai 15 September 2008 (has links) A flexão da ferramenta, em operações de fresamento de topo, é responsável por interferir negativamente na qualidade superficial da peça a ser usinada e, muitas vezes, pela quebra prematura da mesma. O presente trabalho tem como objetivo estudar experimentalmente os efeitos da flexão de fresas de topo com 0,8 mm de diâmetro no processo de microfresamento. Os ensaios experimentais foram realizados com o intuito de identificar quais parâmetros de corte apresentam maior influência na flexão da ferramenta. Os parâmetros de corte escolhidos para estudo foram: velocidade de corte, velocidade de avanço, profundidade de usinagem e penetração de trabalho. Os ensaios investigam, além das faixas de parâmetros recomendados pelo fabricante da ferramenta, uma condição 25% acima e outra 25% abaixo para todos os parâmetros estudados. O monitoramento de forças de corte foi realizado em todos os ensaios. As forças obtidas se mostraram diretamente relacionadas com a área de secção de corte, conforme teoria básica. Para fins comparativos, a força máxima obtida experimentalmente foi aplicada na simulação com elementos finitos (FEM - Finite Element Method) da ferramenta e indicou um comportamento similar ao de uma viga engastada. A análise microscópica do aspecto superficial da usinagem mostrou que menores avanços por dente resultam em um melhor acabamento confirmando resultados do processo convencional. O conhecimento do efeito dos parâmetros de corte no processo de microfresamento tem o intuito de oferecer informações às empresas do setor no sentido de melhorar o planejamento e processo de fabricação. / The tool deflection, in end milling operations, is responsible to intervene negatively on the workpiece surface quality and can also cause a premature tool failure (breakage).The present work aims at studying experimentally the effects of tool deflection when end milling with 0,8 mm diameter in microoperations. The experimental tests had intended to identify which parameters of milling show more influence in tool deflection. The chosen milling parameters for the study were: cutting speed, feed rate, depth of cut and step over. The tests aim to investigate, beside the recommended parameters from tool manufacturer, a 25% higher and 25% lower conditions. The force acquisition was made in all tests. The measured forces shown that they are directly related to the uncut chip cross section, in accordance with theory. For comparative purpose, the maximum experimental force value was applied in the finite elements method (FEM) simulation of the tool and indicates a similar behavior of an encastré beam. The microscopic analysis of the superficial aspect of the milling showed that smaller feed per tooth results in better finishing, as observed in the conventional process. The knowledge of the effect of the cutting parameters in the micromilling process has the intention of offering information for industries to improve the planning and process of manufacturing. Flexão de ferramenta Forças de corte Microfresamento Processos de microfabricação Cutting forces Micromanufacturing Micromilling Tool deflection
5	Process Fingerprinting of Microneedle Manufacturing Using Conventional and Ultrasonic Micro-injection Moulding Gulcur, Mert January 2019 (has links) This research work investigates the development and application of process fingerprinting for conventional micro-injection moulding and ultrasonic micro injection moulding manufacturing of microneedle arrays for drug delivery. The process fingerprinting method covers in-depth analysis, interrogation and selection of certain process data features and correlation of these features with product fingerprints which are defined by the geometrical outcomes of the microneedle arrays in micro scale. The method was developed using the data collected using extensive sensor technologies attached to the conventional and ultrasonic micromoulding machines. Moreover, a machine vision based microneedle product evaluation apparatus is presented. Micromachining capabilities of different processes is also assessed and presented where state-of-the-art laser machining was used for microneedle tool manufacturing in the work. By using process fingerprinting procedures, conventional and ultrasonic micromoulding processes has been characterised thoroughly and aspects of the process that is affecting the part quality was also addressed for microneedle manufacturing. It was found that polymer structure is of paramount importance in obtaining sufficient microneedle replication. An amorphous polymer have been found to be more suitable for conventional moulding whereas semi-crystalline materials performed better in ultrasonic micromoulding. In-line captured micromoulding process data for conventional and ultrasonic moulding provided detailed insight of machine dynamics and understanding. Linear correlations between process fingerprints and micro replication efficiency of the microneedles have been presented for both micromoulding technologies. The in-line process monitoring and product quality evaluation procedures presented in this work for micro-injection moulding techniques will pave ways for zero-defect micromanufacturing of miniature products towards Industry 4.0. Micro-injection moulding Microneedles Micromanufacturing Process monitoring Process fingerprinting In-line monitoring Microarrays Data acquisition Replication Laser machining
6	From Macro to Nano : Electrokinetic Transport and Surface Control Pardon, Gaspard January 2014 (has links) Today, the growing and aging population, and the rise of new global threats on human health puts an increasing demand on the healthcare system and calls for preventive actions. To make existing medical treatments more efficient and widely accessible and to prevent the emergence of new threats such as drug-resistant bacteria, improved diagnostic technologies are needed. Potential solutions to address these medical challenges could come from the development of novel lab-on-chip (LoC) for point-of-care (PoC) diagnostics. At the same time, the increasing demand for sustainable energy calls for the development of novel approaches for energy conversion and storage systems (ECS), to which micro- and nanotechnologies could also contribute. This thesis has for objective to contribute to these developments and presents the results of interdisciplinary research at the crossing of three disciplines of physics and engineering: electrokinetic transport in fluids, manufacturing of micro- and nanofluidic systems, and surface control and modification. By combining knowledge from each of these disciplines, novel solutions and functionalities were developed at the macro-, micro- and nanoscale, towards applications in PoC diagnostics and ECS systems. At the macroscale, electrokinetic transport was applied to the development of a novel PoC sampler for the efficient capture of exhaled breath aerosol onto a microfluidic platform. At the microscale, several methods for polymer micromanufacturing and surface modification were developed. Using direct photolithography in off-stoichiometry thiol-ene (OSTE) polymers, a novel manufacturing method for mold-free rapid prototyping of microfluidic devices was developed. An investigation of the photolithography of OSTE polymers revealed that a novel photopatterning mechanism arises from the off-stoichiometric polymer formulation. Using photografting on OSTE surfaces, a novel surface modification method was developed for the photopatterning of the surface energy. Finally, a novel method was developed for single-step microstructuring and micropatterning of surface energy, using a molecular self-alignment process resulting in spontaneous mimicking, in the replica, of the surface energy of the mold. At the nanoscale, several solutions for the study of electrokinetic transport toward selective biofiltration and energy conversion were developed. A novel, comprehensive model was developed for electrostatic gating of the electrokinetic transport in nanofluidics. A novel method for the manufacturing of electrostatically-gated nanofluidic membranes was developed, using atomic layer deposition (ALD) in deep anodic alumina oxide (AAO) nanopores. Finally, a preliminary investigation of the nanopatterning of OSTE polymers was performed for the manufacturing of polymer nanofluidic devices. / <p>QC 20140509</p> / Rappid / NanoGate / Norosensor microsystem nanosystem microfluidic nanofluidic surface modification surface property electrokinetics model simulation material polymer thiol-ene microfabrication nanofabrication micromanufacturing nanomanufacturing breath sampling aerosol precipitation corona discharge electrostatic precipitation grafting chemistry click chemistry nanopore nanoporous membrane photolithography photopatterning photografting microfluidics nanofluidics oste OSTE+ OSTEmer lab-on-chip loc point-of-care poc biocompatibility diagnostics breath analysis fuel cell

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