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Scopo del contributo è descrivere la costruzione e rappresentazione dell’identità nel corso della transizione adolescenziale. Ipotizzata circolarità e reciproca determinazione tra individui e società, lo studio tratta il tema dell’identità come frutto di riflessività e di chances di vita offerte dal contesto. Il fuoco dell’attenzione è sugli adolescenti di origine straniera, scelti come oggetto di studio perché chiamati a vivere la transizione identitaria in maniera amplificata dall’esperienza migratoria ed esemplificativa di traiettorie di costruzione del Sé percorse anche dai pari italiani. L’analisi sottolinea dunque l’analogia generazionale tra adolescenti italiani e stranieri e la pluralità di definizioni identitarie, anche prescindendo dall’eventuale esperienza migratoria. Lo studio ha seguito l’approccio della sociologia visuale, sia nei riferimenti teorici ed analitici, sia sul piano della ricerca empirica. Sono stati intervistati 12 adolescenti, italiani e stranieri, che hanno narrato di sé presentando immagini e video. A partire da ciò sono state individuate 3 tipologie di costruzione identitaria, quella dei relazionali, quella dei progettisti e quella dei sognatori, e si è confermata la reciproca connessione tra individui e società e la pluralità di traiettorie nella transizione alla vita adulta. / The study’s aim is to describe the construction and representation of identity during the adolescent transition. Hypothesizing circularity and reciprocal determination between individuals and society, the study deals with the topic of identity as the result of reflexivity and lifetime chances which are offered by the context. Attention is focused on adolescents with foreign origins, chosen as the subject of study because they are called to experience identity transition in a way which is broadened due to their migratory experiences, and exemplified by paths involving Self-construction which their Italian peers also follow. The analysis thus underscores the generational analogy between Italian and foreign adolescents and the plurality of definitions of identity, also irrespective of any migratory experience. The study followed the visual sociology approach, both in theoretical and analytical terms as well as at the level of empirical research. The 12 Italian and foreign adolescents who were interviewed spoke about themselves through images and videos. 3 types of identity construction were identified thanks to these presentations: relational, planners and dreamers, and a reciprocal connection between individuals and society, and the plurality of paths in the transition to adult life were confirmed.

Após a criação do Acordo Geral Sobre Pautas Aduaneiras e Comércio (GATT) em 1947, as barreiras não tarifárias passaram a ser o principal instrumento utilizado pelos países para a proteção do mercado nacional. Os países que buscavam a liberalização do comércio internacional passaram, então, a buscar soluções a fim de conter tais barreiras. Havia uma dificuldade em identificar quando uma medida que restringia o comércio internacional era uma proteção disfarçada ao comércio de quando ela perseguia fins legítimos como a proteção da saúde humana e animal. Com o advento da Organização Mundial do Comércio (OMC), alguns acordos anexos foram assinados que visavam diferenciar essas medidas e proteger a liberdade comercial alcançada nas rodadas do GATT. Entre esses acordos, entrou em vigor o Acordo sobre Barreiras Sanitárias e Fitossanitárias (SPS) que trata de medidas que visam proteger a vida e a saúde humana, animal e vegetal. Esse acordo, apesar de essencial para um país exportador de commodities como o Brasil, recebeu pouca atenção da academia jurídica brasileira. Buscando amenizar essa lacuna, o presente trabalho se propôs a aprofundar o estudo do acordo sob uma perspectiva jurídica. Assim, sua origem, seu escopo de aplicação, seus princípios e características, e sua aplicação no Sistema de Solução de Controvérsias (SSC) da OMC são explanados no primeiro capítulo dessa dissertação O Acordo SPS também estabeleceu a criação do Comitê sobre Barreiras Sanitárias e Fitossanitárias (Comitê SPS) que administra a aplicação e o debate dos temas relacionados ao acordo. E é sobre esse comitê que o segundo capítulo dessa pesquisa se debruça. O objetivo da dissertação é demonstrar e melhor compreender que, apesar do comitê possuir diversas funções, duas são de extrema relevância, a saber, seu papel como harmonizador internacional e como solucionador de conflitos. Na persecução desses objetivos, o comitê conta com diversos instrumentos como as notificações e as preocupações comerciais específicas (PCEs) que são estudadas e detalhadas no presente trabalho. Para desenvolver essa pesquisa, foram realizados levantamentos bibliográficos, documentais e jurisprudenciais junto à OMC e a outras instituições e, a partir dos dados coletados, foi aplicado o método hipotético-dedutivo. Os resultados vieram a comprovar e a limitar o escopo da natureza harmonizadora e solucionadora de conflitos do Comitê SPS, esclarecendo os meandros do trabalho diplomático no seio do comitê. Resta claro que o comitê é um ator essencial e ativo no comércio internacional. / After the creation of the General Agreement on Tariffs and Trade (GATT) in 1947, the non-tariff barriers have become the main instrument used by countries to protect their national markets. Countries seeking liberalization of international trade began, then, to seek solutions in order to restrain such barriers. There was a difficulty in identifying when a measure that restricting the international trade was a disguised trade protection from when it pursued legitimate purposes such as the protection of the human and animal health and lives. With the advent of the World Trade Organization (WTO), some attachments agreements were signed in order to differentiate between these measures and to protect the free trade achieved in the GATT rounds. Among these agreements, entered into force the Agreement on Sanitary and Phytosanitary Barriers (SPS) that deals with measures to protect human, animal and plant health and lives. This agreement, although essential to a commodities exporter such as Brazil, received little attention from the Brazilian legal academia. Seeking to mitigate this gap, this study aimed to further study the agreement in a legal perspective. Thus, its origin, its scope of application, its principles and features, and its application in the WTO Dispute Settlement System (SSC) are explained in the first chapter of this dissertation. The SPS Agreement also established the creation of the Committee on Sanitary and Phytosanitary Barriers (SPS Committee) that manages the application and discussion of issues related to the agreement. Moreover, it is on this committee that the second chapter of this research focuses The purpose of this research is to demonstrate and to understand that, although the committee has several functions, two are of utmost importance, namely its role as international harmonizer and as conflict solver. In pursuing these objectives, the committee uses several instruments such as the notifications and the specific trade concerns (STCs) that are studied and detailed in this paper. To develop this research, bibliographical, documentary and jurisprudential surveys within the data of WTO and other institutions were conducted, and based on the data collected, it was applied the hypothetical-deductive method. The results came to prove and to define the scope of the SPS Committee as an international harmonizer and as a conflict solver, explaining the intricacies of diplomatic work within the committee. Therefore, it is clear that the committee is an essential and active player in international trade.

Apprenant de la nature, les architectures spécifiques de certains organismes vivants sont devenues l'une des idées dominantes dans le développement de nouvelles générations de matériaux synthétiques. Dans cette optique, la structure lamellaire de la nacre peut servir de modèle pour la fabrication de nouveaux matériaux composites à matrices métalliques. Un nouveau procédé de métallurgie des poudres, appelée métallurgie des poudres « plaquettes » (FPM), a ainsi été développée pour fabriquer des matériaux composites à matrice métallique à structure lamellaire.L’objectif de ce travail de thèse est l'utilisation du procédé FPM (en utilisant le broyage mécanique (BM) et le frittage SPS), pour la fabrication de matériaux architecturés lamellaires et bioinspirés de structure nacre. Nous avons montré la possibilité de fabriquer, à partir de poudre plaquettes, des matériaux lamellaires anisotropes monolithiques à base de titane et d’alliages de titane ainsi que des matériaux composites Ti/C. Nous avons également montré les avantages de l'architecture multicouches sur l'amélioration des propriétés mécaniques (dureté) du Ti et de TA6V avec une anisotropie de la dureté entre les sections transversale et longitudinale. L’augmentation de la dureté de ces matériaux lamellaires, par rapport aux matériaux non-lamellaire, est liée principalement à l'épaisseur des "plaquettes" qui est contrôlée par le temps de BM, ainsi que par l’effet de la microstructure affinée et de l’écrouissage du matériau lamellaire.Nous avons également montré la possibilité de fabriquer des matériaux composites lamellaires in-situ Ti/TiC par BM (en présence d'acide stéarique) et frittage SPS, avec la possibilité de contrôler la teneur en TiC en jouant sur les conditions de BM (temps BM et taux d’acide stéarique). Ce matériau composite permet une amélioration de la dureté et du module de Young attribuée à la phase de TiC formée. / Learning from nature, biological design has become one of the prevailing ideas in developing new generations of synthetic materials. In the strengthening and toughening exploration of composite materials, nacre lamellar structure may serves as a model system of tremendous interest. A novel powder metallurgy (PM) strategy, called flake PM, was developed to fabricate bulk metal matrix composite materials with laminated structure.The aims of this thesis is the use of flakes PM (using ball milling and SPS sintering), for the fabrication of biomimetic titanium and titanium alloys nacre’s laminated structures and of titanium/carbon composite materials. This process showed the possibility of the fabrication of laminar material with anisotropic microstructure. We proved the advantages of the layer’s architecture on the improvement of Ti and TA6V mechanical properties (hardness) with hardness anisotropy between the cross section and the longitudinal one. The hardness of this material is related to the thickness of the "flakes" which is controlled by the time of BM. This strengthening was also attributed to the flake thickness, the refined microstructure and the hardening of the lamellar material.We showed also the possibility of fabrication of in-situ Ti/TiC laminated composite materials using BM (in the presence of stearic acid) and SPS sintering, with the possibility of the control of TiC content by controlling the BM conditions (BM time and stearic acid amount). This composite material exhibit improvement of the hardness and Young’s modulus, attributed to the TiC phase formed.

Após a criação do Acordo Geral Sobre Pautas Aduaneiras e Comércio (GATT) em 1947, as barreiras não tarifárias passaram a ser o principal instrumento utilizado pelos países para a proteção do mercado nacional. Os países que buscavam a liberalização do comércio internacional passaram, então, a buscar soluções a fim de conter tais barreiras. Havia uma dificuldade em identificar quando uma medida que restringia o comércio internacional era uma proteção disfarçada ao comércio de quando ela perseguia fins legítimos como a proteção da saúde humana e animal. Com o advento da Organização Mundial do Comércio (OMC), alguns acordos anexos foram assinados que visavam diferenciar essas medidas e proteger a liberdade comercial alcançada nas rodadas do GATT. Entre esses acordos, entrou em vigor o Acordo sobre Barreiras Sanitárias e Fitossanitárias (SPS) que trata de medidas que visam proteger a vida e a saúde humana, animal e vegetal. Esse acordo, apesar de essencial para um país exportador de commodities como o Brasil, recebeu pouca atenção da academia jurídica brasileira. Buscando amenizar essa lacuna, o presente trabalho se propôs a aprofundar o estudo do acordo sob uma perspectiva jurídica. Assim, sua origem, seu escopo de aplicação, seus princípios e características, e sua aplicação no Sistema de Solução de Controvérsias (SSC) da OMC são explanados no primeiro capítulo dessa dissertação O Acordo SPS também estabeleceu a criação do Comitê sobre Barreiras Sanitárias e Fitossanitárias (Comitê SPS) que administra a aplicação e o debate dos temas relacionados ao acordo. E é sobre esse comitê que o segundo capítulo dessa pesquisa se debruça. O objetivo da dissertação é demonstrar e melhor compreender que, apesar do comitê possuir diversas funções, duas são de extrema relevância, a saber, seu papel como harmonizador internacional e como solucionador de conflitos. Na persecução desses objetivos, o comitê conta com diversos instrumentos como as notificações e as preocupações comerciais específicas (PCEs) que são estudadas e detalhadas no presente trabalho. Para desenvolver essa pesquisa, foram realizados levantamentos bibliográficos, documentais e jurisprudenciais junto à OMC e a outras instituições e, a partir dos dados coletados, foi aplicado o método hipotético-dedutivo. Os resultados vieram a comprovar e a limitar o escopo da natureza harmonizadora e solucionadora de conflitos do Comitê SPS, esclarecendo os meandros do trabalho diplomático no seio do comitê. Resta claro que o comitê é um ator essencial e ativo no comércio internacional. / After the creation of the General Agreement on Tariffs and Trade (GATT) in 1947, the non-tariff barriers have become the main instrument used by countries to protect their national markets. Countries seeking liberalization of international trade began, then, to seek solutions in order to restrain such barriers. There was a difficulty in identifying when a measure that restricting the international trade was a disguised trade protection from when it pursued legitimate purposes such as the protection of the human and animal health and lives. With the advent of the World Trade Organization (WTO), some attachments agreements were signed in order to differentiate between these measures and to protect the free trade achieved in the GATT rounds. Among these agreements, entered into force the Agreement on Sanitary and Phytosanitary Barriers (SPS) that deals with measures to protect human, animal and plant health and lives. This agreement, although essential to a commodities exporter such as Brazil, received little attention from the Brazilian legal academia. Seeking to mitigate this gap, this study aimed to further study the agreement in a legal perspective. Thus, its origin, its scope of application, its principles and features, and its application in the WTO Dispute Settlement System (SSC) are explained in the first chapter of this dissertation. The SPS Agreement also established the creation of the Committee on Sanitary and Phytosanitary Barriers (SPS Committee) that manages the application and discussion of issues related to the agreement. Moreover, it is on this committee that the second chapter of this research focuses The purpose of this research is to demonstrate and to understand that, although the committee has several functions, two are of utmost importance, namely its role as international harmonizer and as conflict solver. In pursuing these objectives, the committee uses several instruments such as the notifications and the specific trade concerns (STCs) that are studied and detailed in this paper. To develop this research, bibliographical, documentary and jurisprudential surveys within the data of WTO and other institutions were conducted, and based on the data collected, it was applied the hypothetical-deductive method. The results came to prove and to define the scope of the SPS Committee as an international harmonizer and as a conflict solver, explaining the intricacies of diplomatic work within the committee. Therefore, it is clear that the committee is an essential and active player in international trade.

Les procédés existant pour la fabrication de sous-couches et de systèmes barrière thermique pour les aubes mobiles des turbomachines sont complexes, onéreux, et, de leur reproductibilité dépend la durée de vie de ces systèmes. Cette étude montre la faisabilité d'obtention de sous-couches γ-Ni + γ'-Ni3Al enrichies en platine et de systèmes barrière thermique complets, par l'utilisation du procédé de Spark Plasma Sintering (SPS). Les paramètres du procédé SPS (pression, durée, température et nombre de paliers) ont été ajustés afin de fabriquer les différents types de systèmes. Des améliorations ont été apportées à l'outillage, en vue notamment de mieux appréhender la température de la pièce lors du cycle thermique et, d'empêcher la formation de carbures. Les propriétés microstructurales des revêtements obtenus sont caractérisées et mises en relation avec les paramètres d'élaboration. De plus, les propriétés d'usage (cinétique d'oxydation, résistance au cyclage thermique et à la corrosion par les aluminosilicates fondus, CMAS, conductivité thermique) ont été évaluées. Un large domaine de composition de sous-couches a pu être exploré, notamment par l'addition, par pulvérisation cathodique, d'éléments réactifs (Hf, Y, Si) et d'autres éléments (Ag, Au, Cu) ayant un effet sur le domaine de stabilité de la phase γ'. La possibilité de réaliser des systèmes barrière thermique mono et bi-couches céramiques en une seule étape par le procédé SPS est également démontrée. Un mode d'endommagement spécifique des systèmes barrière thermique élaborés par SPS a été mis en évidence lors d'essais de cyclage thermique et interprété avec l'aide de simulations numériques par éléments finis. Les nombreuses compositions et architectures réalisées au cours de cette étude, sont un encouragement à poursuivre les améliorations apportées au procédé pour l'obtention de systèmes plus complexes et plus fiables. / Fabrication of bond coatings and thermal barrier coating systems for aircraft engine turbine blades and vanes, rely on complex and costly processes, and the lifetime of the systems highly depends on their reproducibility. This work demonstrates the feasibility of platinum rich γ-Ni + γ'-Ni3Al bond coatings and complete thermal barrier coating systems using the Spark Plasma Sintering (SPS) process. Processing parameters (pressure, number, temperature and duration of dwells) have been finely tuned to fabricate the different types of systems. Some necessary adjustments to the equipments have been made to prevent the specimens from pollution, and to better control the samples temperature, and are discussed. The microstructure characteristics and their relation with process parameters have been investigated. Properties such as oxidation kinetics, thermal cycling resistance and CMAS (molten aluminosilicate) corrosion are evaluated. Physical vapor deposition have been used for bond coat doping with reactive elements (Hf, Y, Si) and elements that extend the γ' phase stability domain (Au, Ag, Cu). The possibility to fabricate complete thermal barrier coating systems with a mono or a bi-ceramic top coat layer in a single step is demonstrated. SPS thermal barrier coating systems exhibit a singular spalling behavior during thermal cycling. A finite-element numerical model has been developed and allows its understanding. The versatility of the SPS process has allowed the fabrication of a large number of bond coat compositions and thermal barrier coatings architectures. There is a strong incentive in developing this process for fabricating more reliable and competitive systems.

Les packagings d’électronique embarquée sont actuellement en alliages d’aluminium. A partir d’une étude de sélection des matériaux, complétée par une simulation numérique thermique,nous avons démontré qu’un matériau composite constitué d’une matrice aluminium et de fibres de carbone à forte conductivité thermique, représente un fort potentiel de gain de masse sur ces équipements. Cependant, le couplage de ces deux matériaux génère des problèmes d’élaboration en raison d’incompatibilités fortes parmi lesquelles un mouillage très faible du carbone par l’aluminium liquide et une réactivité chimique élevée qui conduit à la formation de carbures d’aluminium préjudiciables pour le matériau final. Deux voies d’élaboration distinctes ont été envisagées : Une voie liquide où l’utilisation d’un agent de mouillage (un sel fluoré) a permis d’obtenir la montée par capillarité du métal dans des mèches de fibres. Une voie solide basée sur une technique originale d’empilements de feuillets d’aluminium et de fibres de carbone avec le procédé de Spark Plasma Sintering (SPS). .La seconde technique s’est révélée prometteuse en permettant d’obtenir des échantillons multicouches sans porosités, un endommagement très limité des fibres et une architecture contrôlée.Notre étude a montré que la formation de carbures d’aluminium est limitée. De plus, une meilleure compréhension du SPS ou l’application d’un revêtement sur les fibres devraient permettre d’éviter la formation de ces carbures. Les tentatives de caractérisations mécanique et thermique effectuées sur ces échantillons donnent un premier aperçu de l’efficacité du renforcement de l’aluminium par les fibres de carbone. / Embedded electronic packagings are currently made of aluminum. A first study – basedupon a material selection method completed by numerical analysis – showed that a metal matrixcomposite made of aluminum and highly thermal conductive continuous carbon fibers represents ahigh potential upon weight savings for those equipments. Though, coupling these componentsrepresents numerous challenges due to their incompatibility such as a really low wetting of carbonliquidaluminum system and its unavoidable chemical reactivity that leads to the formation ofaluminum carbides that are harmful for the final material. Two manufacturing routes were considered: A liquid route using a wetting agent (fluorinated salts) led the metal to rise alongcarbon fibers by capillarity. A solid route based upon a novel technique of aluminum foils and carbon fibersstacking using the Spark Plasma Sintering (SPS) process.This second technique revealed to be very promising and allowed to obtain multilayer samples with noporosities, highly limited fiber damages and controlled composite architecture. Our study shows thataluminum carbides formation is limited. Moreover, a deeper comprehension of SPS process or thedeposit of fiber coatings would prevent this carbide formation. Attempts of mechanical and thermalcharacterization led upon such samples give a first overview of the efficiency of the aluminumreinforcement by carbon fibers.

L’objectif principal de ce travail est de produire des pièces massives nanostructurées à partir des nanomatériauxd’alliages anisotropes à base des éléments de transition 3d (Co et Ni). Afin d’utiliser ces nanomatériaux àl’échelle industrielle, nous avons extrapolé la méthode de synthèse de l’échelle du laboratoire (procédé polyol) àl’échelle pilote. Tout d’abord, nous avons montré qu’en variant les paramètres de synthèse à l’échelle delaboratoire, nous pouvons contrôler non seulement la morphologie mais aussi la taille et la distribution de tailledes nanoparticules. En effet, des sphères de diamètre 10 nm et des nanofils de longueur 260 nm et de diamètre 7nm ont été obtenus pour la stoechiométrie Co80Ni20. Les paramètres clés de cette étude sont la concentration dela soude, le taux de l'agent nucléant, la vitesse d’agitation et le champ magnétique externe appliqué. Le choix dusystème de mélange approprié pour une géométrie du réacteur donnée a également un rôle important dans lecontrôle et la maîtrise de la taille et la forme des nanofils. Avec une turbine Rushton à six pâles droites, nousavons obtenu des nanofils plus courts avec de plus petites têtes coniques et une forte coercitivité. Par ailleurs, larésolution numérique des équations de Navier-Stocks qui gouvernent le transport de matière et de la quantité demouvement dans un fluide agité a permis d’obtenir une corrélation entre les profils d’énergie turbulente dissipéeet la taille des nanoparticules mesurée expérimentalement. Les études magnétiques montrent que les propriétésmagnétiques des nanofils sont intimement liées à leur forme et à leur taille. La synthèse à grande échelle apermis de produire 25 grammes de nanofils de cobalt-nickel par batch. Grâce au procédé de frittage SPS, nousavons élaboré avec succès des matériaux massifs nanostructurés à partir de la poudre formée des nanofils. Alorsque les nanofils présentent des champs coercitifs élevés et des aimantations relativement faibles, les matériauxdenses consolidés par SPS possèdent les caractéristiques d’un ferromagnétisme doux (faible champ coercitif)mais une aimantation à saturation élevée proche de celle attendue. Des champs coercitifs meilleurs sont obtenusavec le matériau dense nanostructuré élaboré en présence d’un champ magnétique permanent. Ce champmagnétique a permis un meilleur alignement des nanofils au cours du frittage. Le comportement mécanique desmatériaux nanostructurés dépend essentiellement de la taille des grains. La dureté et la résistance mécaniqueaugmentent quand la taille des grains diminue conformément à la relation de Hall-Petch. / The main objective of this PhD work is to produce nanostructured bulk from anisotropic nanomaterials alloysbased on 3d transition elements (Co and Ni). For using these nanomaterials on an industrial scale, we haveextrapolated the synthesis method (polyol process) from laboratory scale to pilot scale. First, we showed that byvarying the parameters synthesis in laboratory scale we can control not only the morphology but also the size andthe size distribution of the nanoparticles. Indeed, spheres with diameter of 10 nm and nanowires with meanlength of 260 nm and a diameter of 7 nm were obtained for a stoichiometry Co80Ni20. The key parameters of thissynthesis are the concentration of the sodium hydroxide, the nucleation rate, the agitation and the appliedexternal magnetic field. The choice of suitable mixing system for a given geometry of the reactor also has animportant role for the control of the size and shape of the nanowires. When a six-bladed Rushton turbine wasused, shorter nanowires with unconventional small conical-shaped heads and a higher coercive field wereobtained, confirming a strong relationship between flow patterns and nanowire growth. Moreover, numericalresolution of Navier-Stocks equations that govern the transport of matter and quantity of movement in anagitated fluid allowed us to obtain a correlation between turbulent energy dissipation profiles and nanoparticlesize measured experimentally. Magnetic studies revealed a narrow relationship between the magnetic propertiesand the shape of nano-objects. The large-scale synthesis has produced 25 grams of cobalt-nickel nanowires perbatch. Thanks to the SPS sintering process, we have successfully elaborated nanostructured bulk materials.Whereas nanofils show high coercive field and low saturation magnetization, dense materials produced at hightemperatures behave as soft ferromagnetic materials (low coercivity) but show high saturation magnetizationvery close to that expected. The best coercivities are obtained with the bulk nanostructured material using SPSassisted by a permanent magnetic field. This magnetic field succeeded to align the nanowires during sintering.The mechanical behavior of the nanostructured materials depends mainly on the grain size. Hardness andmechanical resistance increase when the grain size decreases in agreement with the Hall-Petch relationship.

Ovako är ett globalt stålföretag som har försäljning i Europa, USA och Asien. Deras omsättning under förra verksamhetsåret var 781 milj. Euro. Inom stålindustrin så har det under de sista åren överproducerats stål vilket bidragit till hög konkurrens på stålmarknaden. Utifrån detta så har ett optimeringsprojekt upprättats för att bibehålla konkurrenskraft mot omvärlden. [1,4] Denna studie syftar till att effektivisera en finslipslinje där två centerless-slipmaskiner används för att reducera omställningstiden med 13,5min vid stora omställningar. Det ska även upprättas en standard för hur arbetet vid omställningarna bör utföras för denna effektivisering. Studien utförs på Ovakos produktionsanläggning i Hällefors. Problemet som råder på arbetsplatsen är att osäkerhet hos personal vid omställningar bidrar till varierade omställningstider. Denna osäkerhet har även bidragit till att upplärningstiden för omställningar är ca 1år. För att lösa problemet så analyseras verksamheten med bland annat: Inspelningar utifrån SMED, träddiagram, lean, styrdiagram och utjämning. Detta för att få en helhetsbild av verksamheten. Resultatet av denna efterforskning blev tidsstudier, träddiagram över olika arbetsmoment, design av verktygstavla, omkonstruktion av stödhjul, omkonstruktion av gapinställningar, hur det går att följa upp med resultatet styrdiagram och en utjämningssimulering. Den slutgiltiga effektiviseringen motsvarar 16,5min om det investeras 8680 SEK. Studien benämner även extrainvesteringar för ännu högre effektivitet. Inom studien så förekommer vissa antagna värden då fakta för vissa delar inte kunnat inhämtats. Dessa antaganden är inte något som lyfts in i den slutgiltiga effektiviseringen vilket därför gör att studien kan anses trovärdig. / Ovako is a global steel producer that delivers products in Europe, USA and Asia. Their turnover during the last year was 781 million Euro. The steel industry has under the recent years overproduced steel which has contributed high competition in the steel market. Based on this, an optimization project has been established to maintain the global competitiveness, [1,4]. This study aims at streamlining a fine grinding line, where two centerless grinding machines are used, to reduce the changeover time by 13,5min in case of major changes. The project will also create new standards for how the work of conversion should be carried out for this efficiency. The study is carried out at Ovako´s production facility in Hällefors, Sweden. The problem in the workplace is that the uncertainty of staff in the event of changeover contributes to varied changeover times. This uncertainty has also contributed to the fact that the learning time for changeover in approximately 1 year. The project starts with an analysis in which mobile recording is used to get an overview of the problem. Methods like SMED, Lean, Tree diagram, SPS and production planning are then used. This investigation resulted in time studies, new tree diagram, design of a toolbar, reconstruction of supporting wheel, reconstruction of gap settings, result charts/control charts and a leveling simulation. This resulted finally in a new standard and suggestions for machine optimization. The final efficiency improvement corresponds to 16.5min, if 8680 SEK is invested. The study also mentions extra investments for even greater efficiency. Within the study there are some assumed values as the facts for certain parts cannot be obtained. These assumptions are not something that has been incorporated into the final streamlining, which means that the study can be considered credible.

1. Beim feldaktivierten Sintern im Temperaturbereich von 500 bis 1000 °C fließen elektrische Ströme mit einer Dichte von 1 bis 3 A/mm². 2. Daraus folgt für die größten verwendeten Pulverteilchen mit einem Radius von 50 µm ein Strom je Teilchenkontakt von 10 bis 50 mA. 3. Die durch das Aufbringen des prozesstechnisch notwendigen Pressdruckes gebildeten relativen Kontaktradien (Kontaktradius geteilt durch Teilchenradius) haben eine Größe von 0,05 bis 0,3. 4. Die Einengung der Strompfade im Kontakt der Pulverteilchen erhöht, zusammen mit dem elektrischen Widerstand der Oxidschicht auf den Pulverteilchen, den elektrischen Widerstand des Pulverpresslings. 5. Der Stromfluss durch die Teilchenkontakte führt mit dem zusätzlichen elektrischen Widerstand dieser Teilchenkontakte zu einer lokalen Temperaturerhöhung (Übertemperatur) von 10-4 bis 1 Kelvin für Kupfer- respektive Stahlpulver. 6. Der zusätzliche elektrische Widerstand der Oxidschicht kann die Übertemperatur beim Kupferpulver auf bis zu 1 mK erhöhen. 7. Mit abnehmendem Teilchenradius sinkt die Übertemperatur quadratisch. 8. Das Wachstum der Teilchenkontakte im Verlauf der Verdichtung führt zu einer kontinuierlichen Verringerung der Übertemperatur. 9. Das Auftreten von schmelzflüssiger Phase, von Metalldampf oder von Plasma wird in den untersuchten metallischen Systemen ausgeschlossen. 10. Auch Elektromigration, Thermomigration oder andere Wirkungen des elektrischen Stromes spielen keine Rolle für die Verdichtung beim feldaktivierten Sintern. 11. Die Verwendung von gepulstem anstelle von kontinuierlichem Gleichstrom beeinflusst die Verdichtung der untersuchten Werkstoffe nicht. 12. Die Verdichtung vom Pulver zum kompakten Werkstoff findet für Pulverteilchen mit einem Radius größer als R = 10 µm über plastische Verformung durch verschiedene Formen des Kriechens statt. 13. Die Verformung ist im Anfangsstadium auf den Kontaktbereich begrenzt. 14. Bei Pulverteilen mit Teilchenradien unter R = 10 µm findet die Verdichtung zunächst als Folge von Leerstellenströmen in die Kontaktkorngrenze statt (Sintern). 15. Durch die schnelle Verdichtung bei niedriger homologer Temperatur werden Kornwachstum und Rekristallisation verringert.