The lack of research on the impact of component degradation on the surface quality of machine tool spindles is limited and the primary motivation for this research. It is common in the manufacturing industry to replace components even if they still have some Remaining Useful Life (RUL), resulting in an ineffective maintenance strategy. The primary objective of this thesis is to design and construct an Exchangeable Spindle Unit (ESU) test stand that aims at capturing the influence of the failure transition of components during machining and its effects on the quality of the surface. Current machine tools cannot be tested with extreme component degradation, especially the spindle, since the degrading elements can lead to permanent damage, and machine tools are expensive to repair. The ESU substitutes and decouples the machine tool spindle to investigate the influence of deteriorated components on the response so that the machine tool spindle does not take the degrading effects. Data-driven quality control is another essential factor which many industries try to implement in their production line. In a traditional manufacturing scenario, quality inspections are performed to check if the parameters measured are within the nominal standards at the end of a production line or between processes. A significant flaw in the traditional approach is its inability to map the degradation of components to quality. Condition monitoring techniques can resolve this problem and help identify defects early in production. This research focuses on two objectives. The first one aims at capturing the component degradation by artificially inducing imbalance into the ESU shaft and capturing the excitation behavior during machining with an end mill tool. Imbalance effects are quantified by adding mass onto the ESU spindle shaft. The varying effects of the mass are captured and characterized using vibration signals. The second objective is to establish a correlation between the surface quality of the machined part with the characterized vibrations signals by Bagged Ensemble Tree (BET) machine learning models. The results show a good correlation between the surface roughness and the accelerometer signals. A comparison study between a balanced and imbalanced spindle along with its resultant surface quality is presented in this research. / Bristen på forskning om inverkan av komponentnedbrytning på ytkvaliteten hos verktygsmaskiner är begränsad och den primära motivationen för denna forskning. Det är vanligt inom tillverkningsindustrin att byta ut komponenter även om de fortfarande har en viss återstående livslängd, vilket resulterar i en ineffektiv underhållsstrategi. Det primära syftet med denna avhandling är att designa och konstruera en utbytbar spindelenhetstestsats som syftar till att fånga inverkan av komponentbrottsövergång under bearbetning och dess effekter på ytkvaliteten. Nuvarande verktygsmaskiner kan inte testas med extrem komponentnedbrytning, speciellt spindeln, eftersom de nedbrytande elementen kan leda till permanenta skador och verktygsmaskiner är dyra att reparera. Den utbytbara spindelenheten ersätter och kopplar bort verktygsmaskinens spindel för att undersöka effekten av försämrade komponenter på responsen så att verktygsmaskinens spindel inte absorberar de nedbrytande effekterna. Datadriven kvalitetskontroll är en annan viktig faktor som många industrier försöker implementera i sin produktionslinje. I ett traditionellt tillverkningsscenario utförs kvalitetsinspektioner för att kontrollera om de uppmätta parametrarna ligger inom de nominella normerna i slutet av en produktionslinje eller mellan processer. En betydande brist med det traditionella tillvägagångssättet är dess oförmåga att kartlägga komponenternas försämring till kvalitet. Tillståndsövervakningstekniker kan lösa detta problem och hjälpa till att identifiera defekter tidigt i produktionsprocessen. Denna forskning fokuserar på två mål. Den första syftar till att fånga komponentnedbrytning genom att artificiellt inducera obalans i axeln på den utbytbara spindelenheten och fånga excitationsbeteendet under bearbetning med ett fräsverktyg. Obalanseffekter kvantifieras genom att tillföra massa till spindelaxeln på den utbytbara spindelenheten. Massans varierande effekter fångas upp och karakteriseras med hjälp av vibrationssignaler. Det andra målet är att etablera en korrelation mellan ytkvaliteten hos den bearbetade delen med de karakteriserade vibrationssignalerna från Bagged Ensemble Tree maskininlärningsmodeller. Resultaten visar en god korrelation mellan ytjämnheten och accelerometerns signaler. En jämförande studie mellan en balanserad och obalanserad spindel tillsammans med dess resulterande ytkvalitet presenteras i denna forskning.

Purpose: This thesis aims to support the transition from dedicated to a changeable machining system ensuring long-term adaptability. To fulfill this purpose three research questions are developed.  Methodology: Literature studies are conducted to create the theoretical framework for this thesis and answer the research questions. The literature search is structured to focus on selected subjects of machining systems, changeability, fixtures & tools, reconfigurability, and flexibility. A single case study in the tier-1 automotive was conducted to gather empirical data through interviews which are backed up by document studies, and observations along with a theoretical framework. The data gathered is analyzed through a thematic analysis.  Results: The empirical results are presented on a thematic pyramid model consisting of three levels: machining level, production level, and organizational level. The findings are related to the case study.  Analysis: The three research questions are analyzed using a thematic process digging deeper into each pyramid level by comparing the answers from the interviews, document studies, and observations to the theoretical framework. For research question three a conceptual support map is developed using a holistic perspective providing support for the tier 1 automotive industry when transitioning.  Discussion& Conclusion: The industrial contribution of this thesis shows the gap in the changeable thinking approach for tier-1 automotive manufacturers. The presented transition from DMS to CMS is supported through a conceptual map based on the case study findings. The academic contribution includes emphasizing the importance of changeability for long-term planning through the theoretical findings of flexibility and reconfigurability.  Delimitations: This thesis is limited to the challenges found in the case study done in the tier-1 automotive manufacturer. However, a holistic perspective is provided with the conceptual map to provide a starting point for transitioning to CMS, making the map adaptable to other industrial or academic needs.

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.

The use of pre-hardened mold steels has increased appreciably over the years; more than 80% of the plastic mold steels are used in pre-hardened condition. These steels are delivered to the customer in finished state i.e. there is no need of any post treatment. With hardness around ~40HRC, they have properties such as good polishability, good weldability, corrosion resistance and thermal conductivity. Machinability is a very important parameter in pre-hardened mold steels as it has a direct impact on the cost of the mold. In normal machining operations involving intricate or near net shapes, machining constitutes around 60% of the total mold cost. Efforts are underway to explore every possible way to reduce costs associated with machining and to make production more economical. All the possible parameters which are considered to affect the machinability are being investigated by the researchers. This thesis work focuses on the effect of prior austenite grain size on the machinability of pre-hardened mold steel (Uddeholm Nimax).  Austenitizing temperatures and holding times were varied to obtain varying grain sized microstructures in different samples of the same material. As it was difficult to delineate prior-austenite grain boundaries, experimental and empirical methods were employed to obtain reference values. These different grain sized samples were thereafter subjected to machining tests, using two sets of cutting parameters. Maximum flank wear depth=0.2mm was defined for one series of test which were more akin to rough machining, and machining length of 43200mm or maximum wear depth=0.2mm were defined for second series of tests which were similar to finishing machining. The results were obtained after careful quantative and qualitative analysis of cutting tools. The results obtained for Uddeholm Nimax seemed to indicate that larger grain sized material was easier to machine. However, factors such as retained austenite content and work hardening on machined surface, which lead to degradation of machining operations were also taken into consideration. Uddeholm Nimax showed better machinability in large grained samples as retained austenite(less than 2%) content was minimal in the large grained sample. Small grained sample in Uddeholm Nimax had a higher retained austenite (7+2%) which resulted in degradation of machining operation and a lesser cutting tool life.

Doctor of Philosophy / Department of Industrial & Manufacturing Systems Engineering / Zhijian Pei / Titanium alloy is one of the most important materials used in major segments of industries such as aerospace, automobile, sporting goods, medical and chemical. Market survey has stated that the titanium shipment in the USA has increased significantly in last two decades, indicating its increased usage. Industries are always under tremendous pressure to meet the ever-increasing demand to lower cost and improve quality of the products manufactured from titanium alloy. Similar to titanium alloys, silicon carbide and dental ceramics are two important materials used in many applications. Rotary ultrasonic machining (RUM) is a non-traditional machining process that combines the material removal mechanisms of diamond grinding and ultrasonic machining. It comprises of a tool mounted on a rotary spindle attached to a piezo-electric transducer to produce the rotary and ultrasonic motion. No study has been reported on RUM of titanium alloy, silicon carbide and dental ceramics. The goal of this research was to provide new knowledge of machining these hard-to-machine materials with RUM for further improvements in the machining cost and surface quality. A thorough research has been conducted based on the feasibility study, effects of tool variables, effects of machining variables and wheel wear mechanisms while RUM of titanium alloy. The effects of machining variables (such as spindle speed, feed rate, ultrasonic vibration power) and tool variables (grit size, diamond grain concentration, bond type) have been studied on the output variables (such as cutting force, material removal rate, surface roughness, chipping size) and the wheel wear mechanisms for titanium alloy. Feasibility of machining silicon carbide and dental ceramics is also conducted along with a designed experimental study.

Le travail présenté dans cette thèse vise à comprendre les vibrations de pièce mince durant l’usinage. De nombreux travaux proposent des modélisations de ce phénomène, mais des écarts persistent entre résultats de modélisation et réalité. Ce constat nous pousse à nous interroger sur l’emploi dans les modèles des modes propres de la pièce, sans y intégrer le contact de l’outil. Face à l’incapacité de vérifier la validité de cette hypothèse par mesures ponctuelles, la mesure de champ s’impose comme une alternative prometteuse. La deuxième partie du travail porte sur la mise au point d’un protocole expérimental novateur. Il inclut le relevé des déformées vibratoires d’une pièce mince en usinage par mesure de champs de déplacements. La stéréo corrélation d’images numériques se confronte à de nombreuses limitations dans ce contexte. Nous avons développé une méthode de réglage des capteurs permettant de contourner rapidement certaines difficultés. Cette méthode présentée sous forme graphique souligne la nécessité d’optimiser les paramètres de mesure dans un tel contexte. La troisième partie met en oeuvre le protocole de mesures. Le test des capteurs montre le fort intérêt de la mesure sans contact vis-à-vis de l’objectif recherché. Des essais d’usinage sont présentés en se basant sur une modélisation existante du broutement. Les déformées mesurées pendant l’usinage livrent des informations d’un type nouveau. Leur exploitation a impliqué la mise en place d’une procédure spécifique de traitement. La dernière partie présente les analyses de deux usinages. L’étude est effectuée au regard des états de surface obtenus, du comportement temporel, fréquentiel, et spatial. Cette approche souligne les subtilités de la génération d’état de surface en la présence de vibrations. L’examen des mesures de champs permet de relever des incohérences avec l’emploi des modes propres, classiquement utilisés en modélisation. / The work presented in this thesis aims at understanding thin part vibrations during machining. Many works propose modelings of this phenomenon but differencies still exist between modeling results and tests. This observation lead us to wonder about the employment of natural modes of the part in the models, without taking into account the tool presence. The fact that punctual measurements don’t enable to verify the validity of this hypothesis, field measurement prove to be a hopeful alternative. The second part focuses on adjusting a novel experimental protocol. It includes the recording of the thin part vibrating shapes by displacement field measurement. Digital Image Stereo Correlation is confronted to many limitations in this context. We developed a method to set sensors enabling the quick avoidance of difficulties. This method is presented in a graphical form, and underlines the need of optimising measurement parameters in such an environment. In the third part of the work, the measurement protocol is used. The sensors testing shows the high interest of contactless measurement for the aimed goal. Machininng tests are presented in connection with an existing model of chatter. The measured shapes during machining give a new sort of informations. So, their analyse implied the building of a specific processing procedure. The last part presents analyses of two machining tests. The study is done by parallely looking at the machined surface, and the behavior in temporal and frequency space as so as the part displacement fields. This approach underlines subtleties of surface generation under vibration conditions. The fields inspection enables to mark inconsistencies if employing the natural modes that are classically used in models.

La réalisation de formes complexes comme les moules ou les prothèses médicales nécessite l’utilisation d’opérations de super finition pour obtenir de faibles défauts géométriques, pouvant aller jusqu’au poli-miroir. Ces opérations de pré-polissage et de polissage sont encore régulièrement réalisées manuellement. En effet, malgré des avantages en termes de répétabilité, de productivité et de qualité géométrique, les méthodes de polissage automatique sont peu utilisées car elles nécessitent une mise au point importante. Les travaux de recherche présentés participent à la maîtrise du procédé de polissage automatique tout en contrôlant la qualité géométrique des pièces. Pour parvenir à cette maîtrise, un outil de simulation de l’enlèvement de matière est mis en place. Cet outil permet de simuler l’enlèvement de matière au cours d’une opération de prépolissage réalisée sur centre d’usinage 5 axes. Il se base sur un modèle du contact obtenu entre l’outil de pré-polissage et la pièce, ainsi que sur un modèle du pouvoir abrasif intégrant l’usure et l’encrassement du disque. Cette simulation permet de vérifier la régularité de l’abrasion sur une surface et d’identifier les zones pouvant faire apparaitre des défauts macro-géométriques importants. Une méthode est également proposée pour compenser les variations du pouvoir abrasif au cours du temps. La compensation s’effectue en optimisant les consignes de vitesse d’avance et/ou de fréquence de broche le long de la trajectoire. Cette méthode de pilotage permet d’obtenir un taux d’enlèvement de matière plus constant et ainsi de réduire les défauts géométriques générés pendant une opération de prépolissage. / Complex shapes such as medical implants or injection molds require the use of super-finishing operations to minimize geometrical defects, down to mirror effect finish. These pre-polishing and polishing operations are still regularly performed manually by skilled workers. In spite of advantages in terms of repeatability, productivity and geometrical quality, automatic polishing methods are not widely used because they require systematic and significant developments. The present work contributes to enhance the automatic polishing process compared to the geometric quality of the parts. To achieve this control, a numerical simulation of material removal is implemented. This software simulates the material removal during a pre-polishing operation performed on 5-axis machining center. It is based on a contact model obtained between the pre-polishing tool and the part, as well as an abrasive model including wear of the disc. This simulation allows to check the uniformity of the material removal on the surface and to identify potential areas where macro-geometric defects appear. A method is also proposed to balance variations of the abrasive efficiency. The correction is performed by optimizing the federate and/or the spindle speed along the tool path. This method provides a constant material removal and reduces the geometrical deviations generated during pre-polishing operations.

The recent developments in Low Temperature Co-fired Ceramic (LTCC) as a substrate material enable it to be used in the micro and millimetre wave range providing low dissipation factors at high frequencies, good dielectric properties and a high degree of integration for further miniaturised devices. The most common metallisation method used in LTCC technology is screen printing with high cost noble metals such as silver and gold that are compatible with the high sintering temperatures (850°C). However, these techniques require high capital cost and maintenance cost. As the commercial world requires convenient and low cost process technologies for mass production, alternative metallisation methods should be considered. As a result, electroless copper plating of fired LTCC was mainly investigated in this research. The main goals of this project were to carry out electroless plating of fired LTCC with sufficient adhesion and to extend the process to metallise closed LTCC channel structures to manufacture Substrate Integrated Waveguide (SIW) components. The objectives were focused on electroless copper deposition on fired LTCC with improved adhesion. Electroless deposits on the Sn/Pd activated LTCC surface showed poor adhesion without any surface pre-treatments. Hence, chemical etching of fired LTCC was carried out using concentrated NaOH solution. NaOH pre-treatment of LTCC led to the formation of flake like structures on the LTCC surface. A number of surface and chemical analysis techniques and weight measurements were used to investigate the mechanism of the modification of the LTCC surface. The results showed that the flake like structures were dispersed in the LTCC material and a material model for the LTCC structure was proposed. SEM EDX elemental mapping showed that the flake like structure consisted of aluminium, calcium, boron and oxygen. Further experiments showed that both the concentration of NaOH and the immersion time affect the surface morphology and the roughness of fired LTCC. The measured Ra values were 0.6 μm for untreated LTCC and 1.1 μm for the LTCC sample treated with 4M NaOH for 270 minutes. Adhesion tests including peel test and scratch test were carried out to examine the adhesion strength of the deposited copper and both tests indicated that the NaOH pre-treatment led to an improvement, with the best results achieved for samples treated with 4M NaOH. A second aspect of the research focused on the selective metallisation of fired LTCC. Excimer laser machining was used to pattern a resist film laminated on the LTCC surface. This process also roughened the substrate and created channels that were characterised with respect to the laser operating parameters. After patterning the resist layer, samples were activated using Sn/Pd catalyst solution followed by the electroless copper deposition. Electroless copper was selectively deposited only on the patterned LTCC surface. Laser parameters clearly affected the copper plating rate. Even with a similar number of shots per area, the tracks machined with higher repetition rate showed relatively more machining depth as well as good plating conditions with low resistance values. The process was further implemented to realize a complete working circuit on fired LTCC. Passive components including a capacitor and an inductor were also fabricated on LTCC using the mask projection technique of the excimer laser system. This was successful for many designs, but when the separation between conductor lines dropped below 18 μm, electroless copper started to deposit on the areas between them. Finally, a method to deposit copper films on the internal walls of closed channel structures was developed. The method was first demonstrated by flowing electroless copper solutions through silane treated glass capillaries. A thin layer (approx. 60 nm) of electroless copper was deposited only on the internal walls of the glass capillaries. The flow rate of the electroless copper solution had to be maintained at a low level as the copper deposits tended to wash away with higher flow rates. The structures were tested for transmission losses and showed low (<10dB) transmission losses in the terahertz region of the electromagnetic spectrum. The process was further applied to deposit electroless copper on the internal walls of the LTCC closed channel structures to manufacture a LTCC Substrate Integrated Waveguide (SIW).

La technique d’usinage par impulsions laser femtosecondes possède de nombreux avantages du fait des spécificités physique de l’interaction laser/matière en mode ultra-bref et est donc susceptible d’intéresser le monde industriel. Néanmoins elle présente aussi certaines limitations, principalement en terme de flexibilité et de productivité, limitant l’accès à ce marché. Pour repousser ces limites, nous proposons d’adjoindre des techniques de contrôle du faisceau, à la fois en taille, et plus généralement en forme, exploités par ailleurs dans d’autres domaines scientifiques (pincettes optiques notamment). Ces techniques reposent sur l’utilisation de modulateurs spatiaux de lumière (SLM). Deux solutions sont proposées : la modulation d’amplitude en configuration d’imagerie, et la modulation de phase pure en configuration de Fourier. Le formalisme, les différentes problématiques et la mise en oeuvre de ces deux techniques au sein d’une station de travail prototype que nous avons développée sont présentés. Enfin, nous mettons en évidence le gain apporté par ces techniques sur des problématiques concrètes, tels que l’usinage de réseaux résonant à l’échelle nanométrique, la réduction du temps d’usinage de ces réseaux (ou d’autres motifs), et l’amélioration de la qualité d’usinage de rainures / Femtosecond laser machining processes present many interesting properties owing to the specificities of the light/matter interaction in ultrafast regime. Thus the process may be of prime interest in industrial applications. However some aspects are not compatible with industrialization: namely a lack of flexibility and productivity. To overcome this limitations we propose to add beam shaping techniques in the process that allow control of the beam both in size and shape. These techniques are based on Spatial Light Modulators (SLM). Two different solutions are proposed: amplitude modulation in a geometrical conjugation scheme, and pure phase modulation in a Fourier scheme. Both are integrated in a prototype workstation. We justify the different choices made during the development by the analysis of the formalisms and specific problematics. Finally, enhancements of the femtosecond laser machining process are practically demonstrated in three different fields: reducing the resolution to nanometric scale, reducing the processing time of different texturations and enhancing the quality of simple grooves by modifying only the beam shape

O objetivo deste trabalho foi a avaliação do comportamento à fadiga de materiais compósitos de matriz metálica (CMM) obtidos pela rota da metalurgia do pó, tendo como variáveis a fração volumétrica de reforços e o tipo de tratamento superficial mecânico utilizado. Foram obtidos materiais compósitos com matriz de alumínio AA 1100 reforçados com partículas de carboneto de silício (SiC) nas frações volumétricas de 5, 10 e 15%. Uma quantidade de material de controle, constituído unicamente pelo material da matriz também foi produzida para fins de comparação. Os materiais obtidos foram caracterizados física, mecânica e microestruturalmente. Os resultados mostraram, de maneira geral, uma distribuição homogênea das partículas de reforço e melhoria do limite de resistência dos compósitos com relação ao material de controle. Entretanto, alguns defeitos como porosidades e veios de alumínio puro foram detectados esporadicamente. Em outra etapa, foram realizados ensaios de fadiga do tipo axial nos materiais em modo tensão-tensão, com razão de tensões R = 0,1 e frequência de 15 Hz. Os tipos de tratamentos superficiais utilizados na confecção dos corpos de prova de fadiga foram: usinagem e jateamento. As variáveis de usinagem foram: taxa de avanço e tipo de ferramenta. Os materiais jateados não apresentaram melhorias significativas de vida à fadiga com relação ao material de controle. Os usinados grosseiramente apresentaram a pior vida em fadiga e as marcas de usinagem, nestes casos, funcionaram como fortes concentradores de tensão. Os reforçados com 5% de SiC, diferentemente daqueles reforçados com 10 e 15%, apresentaram vida à fadiga inferior à do material de controle, ou por causa do menor limite de escoamento ou devido à menor fração volumétrica de reforços. Os materiais usinados com metal duro (MD) não apresentaram diferenças de vida à fadiga com relação aos usinados com PCD, provavelmente devido à classe do metal duro utilizado. Os materiais reforçados com 5% de SiC e jateados apresentaram resultados de fadiga com os maiores desvios padrões. Os materiais reforçados com 5% de SiC apresentaram as menores sensibilidades à fadiga com a variação da carga. / The objective of this work was the evaluation of the fatigue behaviour of aluminium metal matrix composites (MMC) obtained by powder metallurgy. The testing variables were the volumetric fraction of reinforcements and the type of mechanical surface treatment used. Initially, the composite materials were obtained from aluminium AA 1100 matrix, reinforced with silicon carbide (SiC) particles in the volumetric fraction of 5, 10 and 15%. An amount of control material (unreinforced) was produced for comparison purposes. The obtained materials were physically, mechanically and microstructurally characterised. The results showed a homogeneous distribution of the reinforcement particles and an improvement of the ultimate tensile strength of the composites with relation to the control material. However, some defects such as porosity and streaks of pure aluminium were detected. In a second stage, the fatigue tests of the composites were accomplished. The types of surface treatments used in the fabrication of the fatigue test specimens were machining and shot peening. For machining the variables were feed rate and tool type. The shot peened materials did not present a significant fatigue life improvement when compared to the control material. The coarse machined materials presented the worst fatigue life and the machining marks worked as strong stress concentrators. The material reinforced with 5% of SiC, differently of those reinforced with 10 and 15% showed inferior fatigue life when compared to the control material, probably because of a lower yielding strength, or lower reinforcement volumetric fraction. The material machined with hard metal (MD) did not present differences of fatigue life with relation to the machined with PCD, probably due to the class of the hard metal used. The material reinforced with 5% of SiC and shot peened, presented fatigue results with the largest standard deviations. The materials reinforced with 5% of SiC presented the smallest fatigue sensibility with the load variation.