A micromanufatura via usinagem apresenta algumas dificuldades, principalmente aquelas relacionadas à formação do cavaco, pois a espessura de corte passa a ter a dimensão do tamanho de grão do material da peça e da microgeometria da aresta de corte. Em operações de microcorte, a microestrutura do material é um fator importante no controle da geração da superfície da peça, mecanismo de formação de cavaco, etc. Este trabalho de pesquisa avaliou o efeito do tamanho ultrafino dos grãos do material da peça sobre os fenômenos inerentes ao corte no microfresamento. As variáveis de usinagem investigadas foram avanço por dente (fz), velocidade de corte (vc), diâmetro da microfresa (d&#934) e raio de aresta de corte (re), visando avaliar o mecanismo de formação do cavaco, acabamento da peça e integridade superficial. Os materiais utilizados nos experimentos foram um aço bifásico (ferrita-perlita) com tamanho de grão ferrítico de 11 µm e outro de microestrutura homogênea de grãos ultrafinos com 0,7 µm, ambos com mesma composição química e baixo-carbono. Dois grupos de ensaios foram propostos: (1) macro e microfresamento e (2) microfresamento de canais. O tipo de usinagem foi o de fresamento de topo, sem emprego de fluido de corte. Os ensaios de usinagem foram executados em centros de usinagem CNC. As ferramentas de corte foram de metal duro com recobrimentos, diâmetro 16 mm na escala macro de usinagem, 200 e 800 µm na escala micro. A adequação da microestrutura do material da peça à redução da escala de usinagem, através do mecanismo de refino de grão, gerou alguns aspectos favoráveis à microusinagem, como melhor acabamento (Ssk≈0 e Sku≈3), formação de cavaco contínuo e menor formação de rebarbas com a redução da espessura de corte (fz&#8804re), possibilitando aplicações em microfabricação por corte com ferramenta de geometria definida utilizando aços baixo carbono, antes limitadas à estruturas na construção civil e peças obtidas por conformação mecânica. / Micro manufacturing by means of machining presents difficulties, mainly those related to chip formation, since chip thickness become as small as normal material grain size, as well as the cutting edge radius. At such micro cutting operations material microstructure ascends as a very important issue in terms of machining output, i.e. surface roughness, subsurface damages, cutting forces, etc. This research evaluated the effect of the intervention on the metallurgical microstructure of the material on the cutting phenomena inherent in micromachining. The variables investigated were the feed per tooth (ft), cutting speed (vc), micro end-mill diameter (d&#934) and cutting edge radius (re). The materials used in the experiments were a steel two-phase (ferrite-pearlite) with ferritic grain size of 11 µm and similar one with homogeneous microstructure and ultrafine grains (0.7 µm), both low carbon. The mechanism of chip formation, surface finish and surface integrity were investigated and correlated with the studied variables. Two groups of machining experiments were proposed: (1) macro and micro end-milling and (2) microchannels. Overall, the type of machining was the end milling, without using cutting fluid. The machining tests were carried on a CNC machining center. The cutting tools are coated, diameter 16 mm in macro scale of machining, 200 and 800 &#956m in micro scale. the adequacy of the microstructure of the workpiece material to the reduce the scale of machining generated some favorable aspects to micromachining, such as better finishing (Ssk≈0 e Sku≈3), continuous chip formation and lesser burr formation by reducing the cutting thickness (fz&#8804re), enabling micromanufacturing applications for low carbon steels, once limited to structures in the civil construction and pieces obtained by mechanical forming.

Trata do estudo experimental da energia específica de corte e sua relação com parâmetros de usinagem, características geométricas e tribológicas das ferramentas, e material da peça usinada. Dentre as variáveis investigadas são destaques a profundidade de usinagem, velocidade de corte, raio de ponta, geometria de quebra-cavaco, tipo de revestimento das ferramentas, dureza, microestrutura e composição química do material da peça. Os seguintes materiais foram empregados nos ensaios: aços SAE 1213, 1020, 1045, ASTM H13 recozido e temperado, e liga de alumínio 2024. As medições de energia específica foram realizadas em uma máquina Charpy instrumentada por meio de um dinamômetro piezelétrico e um encoder ótico rotacional. Vários resultados puderam ser comparados aos obtidos em torno e centro de usinagem CNC devidamente instrumentados. Testes na condição HSM foram implementados nas máquinas-ferramentas. Todas as variáveis pesquisadas mostraram exercer influência sobre a energia específica. O aumento da profundidade de usinagem em 2,3 vezes causou diminuição da energia específica em 21%, na usinagem da liga de alumínio 2024. A elevação da velocidade de corte em torno de 70% conduziu a uma queda da energia específica de 24% para o aço SAE 1020. A geometria da ferramenta influiu mais decisivamente na energia específica sob velocidades de corte convencionais que na condição HSM. Pequenas variações na geometria do quebra-cavaco dos insertos causaram diminuição da energia específica de até 29%, para velocidade de corte convencional, e de 14% para HSM, na usinagem do aço H13 temperado. Diversos resultados de energia específica de corte medidos pelo ensaio Charpy proposto por este trabalho apresentaram boa concordância com os valores equivalentes fornecidos pela literatura científica / This thesis presents an experimental study about the specific cutting energy and its relation with cutting parameters, geometrical and tribological characteristics of tools, and workpiece material. Depth of cut, cutting speed, tool nose radius, chip-breaker geometry, tool coating, hardness, microstructure and chemical composition of the workpiece material are some investigated variables. The following workpiece materials were tested: SAE 1213, 1020, 1045, annealed and tempered ASTM H13 steels, and 2024 aluminum alloy. The specific cutting energy values were measured by using a Charpy machine instrumented through piezoelectric dynamometer and incremental optical encoder. Several results could be compared to ones from instrumented CNC lathe and machining center. Tests under HSM condition were carried out in machine-tools. All researched variables have influence over specific cutting energy. The depth of cut rise in 2.3x caused a decrease of specific cutting energy around 21% when machining 2024 aluminum alloy. The elevation of the cutting speed about 70% leaded to reduction of specific cutting energy around 24% when machining SAE 1020 steel. The tool geometry present more influence on specific cutting energy under conventional cutting speed than at high speed cutting. Small variations of tool chip-breaker geometries caused diminution of the specific cutting energy up to 29% for conventional cutting speed, and 14% on average for HSM condition when machining tempered ASTM H13 steel. Various specific cutting energy results obtained from the Charpy test proposed by this work presented a good concordance with equivalent ones provided by scientific literature

A micromanufatura via usinagem apresenta algumas dificuldades, principalmente aquelas relacionadas à formação do cavaco, pois a espessura de corte passa a ter a dimensão do tamanho de grão do material da peça e da microgeometria da aresta de corte. Em operações de microcorte, a microestrutura do material é um fator importante no controle da geração da superfície da peça, mecanismo de formação de cavaco, etc. Este trabalho de pesquisa avaliou o efeito do tamanho ultrafino dos grãos do material da peça sobre os fenômenos inerentes ao corte no microfresamento. As variáveis de usinagem investigadas foram avanço por dente (fz), velocidade de corte (vc), diâmetro da microfresa (d&#934) e raio de aresta de corte (re), visando avaliar o mecanismo de formação do cavaco, acabamento da peça e integridade superficial. Os materiais utilizados nos experimentos foram um aço bifásico (ferrita-perlita) com tamanho de grão ferrítico de 11 µm e outro de microestrutura homogênea de grãos ultrafinos com 0,7 µm, ambos com mesma composição química e baixo-carbono. Dois grupos de ensaios foram propostos: (1) macro e microfresamento e (2) microfresamento de canais. O tipo de usinagem foi o de fresamento de topo, sem emprego de fluido de corte. Os ensaios de usinagem foram executados em centros de usinagem CNC. As ferramentas de corte foram de metal duro com recobrimentos, diâmetro 16 mm na escala macro de usinagem, 200 e 800 µm na escala micro. A adequação da microestrutura do material da peça à redução da escala de usinagem, através do mecanismo de refino de grão, gerou alguns aspectos favoráveis à microusinagem, como melhor acabamento (Ssk≈0 e Sku≈3), formação de cavaco contínuo e menor formação de rebarbas com a redução da espessura de corte (fz&#8804re), possibilitando aplicações em microfabricação por corte com ferramenta de geometria definida utilizando aços baixo carbono, antes limitadas à estruturas na construção civil e peças obtidas por conformação mecânica. / Micro manufacturing by means of machining presents difficulties, mainly those related to chip formation, since chip thickness become as small as normal material grain size, as well as the cutting edge radius. At such micro cutting operations material microstructure ascends as a very important issue in terms of machining output, i.e. surface roughness, subsurface damages, cutting forces, etc. This research evaluated the effect of the intervention on the metallurgical microstructure of the material on the cutting phenomena inherent in micromachining. The variables investigated were the feed per tooth (ft), cutting speed (vc), micro end-mill diameter (d&#934) and cutting edge radius (re). The materials used in the experiments were a steel two-phase (ferrite-pearlite) with ferritic grain size of 11 µm and similar one with homogeneous microstructure and ultrafine grains (0.7 µm), both low carbon. The mechanism of chip formation, surface finish and surface integrity were investigated and correlated with the studied variables. Two groups of machining experiments were proposed: (1) macro and micro end-milling and (2) microchannels. Overall, the type of machining was the end milling, without using cutting fluid. The machining tests were carried on a CNC machining center. The cutting tools are coated, diameter 16 mm in macro scale of machining, 200 and 800 &#956m in micro scale. the adequacy of the microstructure of the workpiece material to the reduce the scale of machining generated some favorable aspects to micromachining, such as better finishing (Ssk≈0 e Sku≈3), continuous chip formation and lesser burr formation by reducing the cutting thickness (fz&#8804re), enabling micromanufacturing applications for low carbon steels, once limited to structures in the civil construction and pieces obtained by mechanical forming.

Trata do estudo experimental da energia específica de corte e sua relação com parâmetros de usinagem, características geométricas e tribológicas das ferramentas, e material da peça usinada. Dentre as variáveis investigadas são destaques a profundidade de usinagem, velocidade de corte, raio de ponta, geometria de quebra-cavaco, tipo de revestimento das ferramentas, dureza, microestrutura e composição química do material da peça. Os seguintes materiais foram empregados nos ensaios: aços SAE 1213, 1020, 1045, ASTM H13 recozido e temperado, e liga de alumínio 2024. As medições de energia específica foram realizadas em uma máquina Charpy instrumentada por meio de um dinamômetro piezelétrico e um encoder ótico rotacional. Vários resultados puderam ser comparados aos obtidos em torno e centro de usinagem CNC devidamente instrumentados. Testes na condição HSM foram implementados nas máquinas-ferramentas. Todas as variáveis pesquisadas mostraram exercer influência sobre a energia específica. O aumento da profundidade de usinagem em 2,3 vezes causou diminuição da energia específica em 21%, na usinagem da liga de alumínio 2024. A elevação da velocidade de corte em torno de 70% conduziu a uma queda da energia específica de 24% para o aço SAE 1020. A geometria da ferramenta influiu mais decisivamente na energia específica sob velocidades de corte convencionais que na condição HSM. Pequenas variações na geometria do quebra-cavaco dos insertos causaram diminuição da energia específica de até 29%, para velocidade de corte convencional, e de 14% para HSM, na usinagem do aço H13 temperado. Diversos resultados de energia específica de corte medidos pelo ensaio Charpy proposto por este trabalho apresentaram boa concordância com os valores equivalentes fornecidos pela literatura científica / This thesis presents an experimental study about the specific cutting energy and its relation with cutting parameters, geometrical and tribological characteristics of tools, and workpiece material. Depth of cut, cutting speed, tool nose radius, chip-breaker geometry, tool coating, hardness, microstructure and chemical composition of the workpiece material are some investigated variables. The following workpiece materials were tested: SAE 1213, 1020, 1045, annealed and tempered ASTM H13 steels, and 2024 aluminum alloy. The specific cutting energy values were measured by using a Charpy machine instrumented through piezoelectric dynamometer and incremental optical encoder. Several results could be compared to ones from instrumented CNC lathe and machining center. Tests under HSM condition were carried out in machine-tools. All researched variables have influence over specific cutting energy. The depth of cut rise in 2.3x caused a decrease of specific cutting energy around 21% when machining 2024 aluminum alloy. The elevation of the cutting speed about 70% leaded to reduction of specific cutting energy around 24% when machining SAE 1020 steel. The tool geometry present more influence on specific cutting energy under conventional cutting speed than at high speed cutting. Small variations of tool chip-breaker geometries caused diminution of the specific cutting energy up to 29% for conventional cutting speed, and 14% on average for HSM condition when machining tempered ASTM H13 steel. Various specific cutting energy results obtained from the Charpy test proposed by this work presented a good concordance with equivalent ones provided by scientific literature

La mise en œuvre des matériaux composites, fait souvent appel à des procédés d’usinage conventionnel, comme l’opération de perçage utilisée lors de l’assemblage de structures par rivetage. Ces opérations peuvent générer dans la pièce usinée différents types d’endommagement: arrachement des fibres, rupture de la matrice, délaminage intralaminaire et interlaminaire, dégradation thermique de la matrice, ce qui peut provoquer une baisse des performances mécaniques de la structure. L’objectif de la thèse est de mettre en place un modèle numérique scientifiquement rigoureux pour analyser l’usinage des composites CFRP et prédire les mécanismes d’endommagement induits par l’outil coupant. Ce modèle basé sur une loi constitutive mésomécanique combine l’effet de la chute de rigidité dans le comportement du matériau, la plasticité, l’initiation et l’évolution de l’endommagement durant le processus d’usinage. Ensuite, deux modèles 2D et 3D adoptant un schéma explicite ont été implémentés via la sub-routine VUMAT dans Abaqus. Le délaminage interplis a été pris en considération à l’aide des éléments cohésifs disponibles dans le code ABAQUS/Explicit. Ce travail a permis de reproduire de manière réaliste les opérations de coupe orthogonale et de perçage des composites CFRP en termes de processus de formation du copeau, la prédiction des forces de coupe et celle de l’endommagement induit. Ces études ont montré que l’orientation des fibres et la profondeur de coupe sont les paramètres les plus influents en coupe orthogonale tandis que pour le perçage se sont les vitesses d’avance et la géométrie des outils / The machining of composite materials is often necessary for material removal operations by cutting tools such as drilling. These operations can generate a lot of damage in the machined workpiece (fiber fracture, matrix craking, intralaminar and interlaminar delamination and thermal degradation of the matrix), which can cause a decrease of mechanical performance of the structure. The PhD thesis objective is to set up a reliable accurate model to analyze the machining of CFRP composites and to predict the different damage modes induced by the cutting tool. This model is based on a mesomechanical constitutive law combining the stiffness degradation concept into the material behavior, the plasticity, the initiation and the evolution of the damage during the machining process. Two 2D and 3D models adopting an explicit scheme were implemented in Abaqus/Explicit analysis code through the user subroutine VUMAT. Furthermore, interlaminar delamination is taken into account using the cohesive elements available in the ABAQUS / Explicit code. This work allowed to realistic numerical simulation of orthogonal cutting and drilling operations of CFRP composites in terms of chip formation process, cutting forces prediction and induced damage. These studies have shown that the fiber orientation and the depth of cut were the most influential parameters in orthogonal cutting while for the drilling process, the feed rate and the tool geometry are the most important parameters

No description available.

This study focuses on developing explicit analytical and numerical process models for mechanical micro-machining of heterogeneous materials. These models are used to select suitable process parameters for preparing and micro-machining of these advanced materials. The material system studied in this research is Magnesium Metal Matrix Composites (Mg-MMCs) reinforced with nano-sized and micro-sized silicon carbide (SiC) particles. This research is motivated by increasing demands of miniaturized components with high mechanical performance in various industries. Mg-MMCs become one of the best candidates due to its light weight, high strength, and high creep/wear resistance. However, the improved strength and abrasive nature of the reinforcements bring great challenges for the subsequent micro-machining process. Systematic experimental investigations on the machinability of Mg-MMCs reinforced with SiC nano-particles have been conducted. The nanocomposites containing 5 Vol.%, 10 Vol.% and 15 Vol.% reinforcements, as well as pure magnesium, are studied by using the Design of Experiment (DOE) method. Cutting forces, surface morphology and surface roughness are characterized to understand the machinability of the four materials. Based on response surface methodology (RSM) design, experimental models and related contour plots have been developed to build a connection between different materials properties and cutting parameters. Those models can be used to predict the cutting force, the surface roughness, and then optimize the machining process. An analytical cutting force model has been developed to predict cutting forces of MgMMCs reinforced with nano-sized SiC particles in the micro-milling process. This model is iv different from previous ones by encompassing the behaviors of reinforcement nanoparticles in three cutting scenarios, i.e., shearing, ploughing and elastic recovery. By using the enhanced yield strength in the cutting force model, three major strengthening factors are incorporated, including load-bearing effect, enhanced dislocation density strengthening effect and Orowan strengthening effect. In this way, the particle size and volume fraction, as significant factors affecting the cutting forces, are explicitly considered. In order to validate the model, various cutting conditions using different size end mills (100 µm and 1 mm dia.) have been conducted on Mg-MMCs with volume fraction from 0 (pure magnesium) to 15 Vol.%. The simulated cutting forces show a good agreement with the experimental data. The proposed model can predict the major force amplitude variations and force profile changes as functions of the nanoparticles’ volume fraction. Next, a systematic evaluation of six ductile fracture models has been conducted to identify the most suitable fracture criterion for micro-scale cutting simulations. The evaluated fracture models include constant fracture strain, Johnson-Cook, Johnson-Cook coupling criterion, Wilkins, modified Cockcroft-Latham, and Bao-Wierzbicki fracture criterion. By means of a user material subroutine (VUMAT), these fracture models are implemented into a Finite Element (FE) orthogonal cutting model in ABAQUS/Explicit platform. The local parameters (stress, strain, fracture factor, velocity fields) and global variables (chip morphology, cutting forces, temperature, shear angle, and machined surface integrity) are evaluated. Results indicate that by coupling with the damage evolution, the capability of Johnson-Cook and Bao-Wierzbicki can be further extended to predict accurate chip morphology. Bao-Wierzbiki-based coupling model provides the best simulation results in this study. v The micro-cutting performance of MMCs materials has also been studied by using FE modeling method. A 2-D FE micro-cutting model has been constructed. Firstly, homogenized material properties are employed to evaluate the effect of particles’ volume fraction. Secondly, micro-structures of the two-phase material are modeled in FE cutting models. The effects of the existing micro-sized and nano-sized ceramic particles on micro-cutting performance are carefully evaluated in two case studies. Results show that by using the homogenized material properties based on Johnson-Cook plasticity and fracture model with damage evolution, the micro-cutting performance of nano-reinforced Mg-MMCs can be predicted. Crack generation for SiC particle reinforced MMCs is different from their homogeneous counterparts; the effect of micro-sized particles is different from the one of nano-sized particles. In summary, through this research, a better understanding of the unique cutting mechanism for particle reinforced heterogeneous materials has been obtained. The effect of reinforcements on micro-cutting performance is obtained, which will help material engineers tailor suitable material properties for special mechanical design, associated manufacturing method and application needs. Moreover, the proposed analytical and numerical models provide a guideline to optimize process parameters for preparing and micro-machining of heterogeneous MMCs materials. This will eventually facilitate the automation of MMCs’ machining process and realize high-efficiency, high-quality, and low-cost manufacturing of composite materials.

In both the chemical and mechanical pulping process, the logs are cut into wood chips by a disc chipper before fibre separation. To make the wood chipping process more efficient, one have to investigate in detail the coupling between process parameters and the quality of the chips. One objective of this thesis was to obtain an understanding of the fundamental mechanisms behind the creation of wood chips. Another objective with the thesis was to investigate whether it was possible to, in a way tailor the chipping process so as to reduce the energy consumption in a following mechanical refining process. Both experimental and analytical/numerical approaches have been taken in this work. The first part of the experimental investigations, were performed with an in-house developed chipping device and a digital speckle photography equipment. The results from the experimental investigation showed that the friction between the log and chipping tool is probably one crucial factor for the chip formation. Further more it was found that the indentation process is approximately self-similar, and that the stress field over the entire crack-plane is critical for chip creation. The developed analytical model predicts the normal and shear strain distribution and to be more specific, the model can predict the compressive stresses parallel to the fibre direction for an assumed linear elastic and orthotropic material. The analytical distributions were found to be in reasonable agreement with the corresponding distributions obtained from a finite element analysis. To be able to study the chipping process under realistic conditions, which for example means to use chipping rates representative for a real wood chipper, a laboratory chipper was developed. Details regarding the chipper and how to evaluate the force measurements are given together with an example of how the force on the cutting tool (the knife) varies with time during cutting. To investigate the influence of a certain chipping process parameter, the chips were after production in the laboratory chipper, refined in a pilot refiner during conditions optimized for TMP (thermomechanical pulp) and CTMP (chemithermomechanical pulp) processes. It was concluded that the details concerning the chip process had a large impact on e.g. the energy consumption in both first stage and second stage refining. Results showing this are given in this thesis. / För både kemisk och mekanisk pappersmassa så tillverkas flis av trädstockar med hjälp av en skivhugg innan fibrerna separeras. För att göra flisningsprocessen mer effektiv, måste kopplingen mellan processparametrar och fliskvalitet studeras. Ett mål med denna avhandling är att ge fundamental kunskap om mekanismerna bakom bildandet av träflis. Både experimentella och analytiska/numeriska metoder har använts i detta arbete. De experimentella undersökningarna har gjorts med hjälp av egen utvecklad utrustning. Resultaten från den experimentella undersökningen visar att friktionen mellan stammen och flisningsverktyget har betydelse vid flisning. Vidare observerades det att inträngnings processen är approximativt självlik (self similar) och att det är spänningsfältet över hela sprickplanet som är kritiskt för bildandet av en flis. Den utvecklade analytiska modellen förutsäger normal- och skjuvspänningsfördelningen över sprickplanet och kan mer specifikt förutsäga den kompressiva belastning som verkar parallellt fiberriktningen i ett linjärt elastiskt och ortotropt material (trä). De analytiskt bestämda fördelningarna stämmer relativt väl överens med motsvarande fördelningar beräknad med finit element analys. För att kunna studera flisningsprocessen under realistiska förhållanden, vilket bl.a. betyder att skärhastigheter som är representativa för en verklig process skall användas, så utvecklades inom ramen för avhandlingsarbetet, en laboratoriesflishugg. Detaljer rörande flishuggen samt hur uppmätta lastsignaler skall utvärderas ges tillsammans med ett exmpel på hur kraften på skärverktyget (kniven) varierar under ett skärförlopp. Inverkan av en viss flisningsprocessparameter undersöktes genom att flis tillverkades i laboratorieflishuggen varefter de raffinerades i en pilotraffinör under förhållanden som var optimerade för TMP (termomekanisk massa) och CTMP (kemitermomekanisk massa) processerna. Det konstaterades att detaljer i flisningsprocessen hade stor inverkan på t.ex. energiåtgången i både första stegs – och andrastegsraffinering. Resultat som verifierar detta ges i avhandlingen. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Submitted. Paper 5: Submitted.</p>

Diplomová práce se zabývá analýzou technologie vysoceproduktivního vystružování. V rámci práce byly provedeny testy vystružování za různých technologických podmínek (vc=40, 60, 80, 100 m/min; f=0.2, 0.4, 0.6, 0.8 mm) na materiálu austenitické oceli DIN 1.4404 při použití vystružovací hlavicí MT3. Jednotlivé operace vystružování byly porovnány z hlediska parametrů jako tlačná síla, krouticí moment, výsledná drsnost obrobeného povrchu a dále z hlediska tvaru třísky. Následně byly vypočítány průměrné hodnoty a směrodatná odchylka naměřených parametrů. Dále bylo provedeno porovnání pomocí diagramů. Výsledky ukazují lepší kvalitu, nižší drsnost povrchu (Ra 0,37 µm) a méně zdeformovanou třísku při pomalejších řezných rychlostech (40 m/min) a menším posuvu na otáčku (0,2 mm). Výsledky také ukazují nárůst tlačné síly a krouticího momentu za uvedených technologických podmínek. Při zvyšující se řezné rychlosti vystružování tyto silové účinky klesají.

Ce travail de thèse a été réalisé dans le cadre d'une collaboration internationale entre l'Université de Lorraine (France) et l'Université d'Oujda (Maroc). Les travaux réalisés concernent la modélisation de l'usinage par enlèvement de matière. Deux aspects importants de l'usinage ont été abordés : le processus de la formation de copeaux et les échanges thermiques à l'interface outil-copeau. Dans la première partie de la thèse, une modélisation par élément finis (EF) du processus de la coupe a été mise en place. La segmentation des copeaux a été particulièrement analysée grâce à l'introduction d'un nouveau paramètre, le Rapport d'Intensité de Segmentation, permettant de quantifier ce phénomène. Une corrélation entre la réduction de l'effort de coupe et l'intensité de segmentation a été établie. La deuxième partie de la thèse a été consacrée à l'étude des échanges thermiques à l'interface outil-copeau, qui contribuent entre autres à l'usure de l'outil de coupe. Un des points importants de l'étude est la mise en place d'une procédure d'identification hybride (analytique/numérique) permettant d'estimer le flux thermique transmis dans l'outil de coupe et de remonter au coefficient de partage de la chaleur à l'interface outil-copeau pour chaque vitesse de coupe. Avec les valeurs identifiées du coefficient de partage de la chaleur pour chaque vitesse de coupe, une loi d'échange thermique multi-branches a été proposée et ses paramètres identifiés. Cette loi donnant l'évolution du coefficient de partage de la chaleur en fonction de la vitesse de coupe a également été définie en fonction de la vitesse relative de glissement à l'interface outil-copeau dans le but de l'implanter dans un code de calcul EF. L'interface utilisateur VUINTER du code Abaqus/Explicit a été exploitée pour implanter la loi proposée, afin d'appréhender complètement le contact d'un point de vue mécanique et thermique. Il est désormais possible d'implanter via cette interface-utilisateur n'importe quelle autre loi de contact thermomécanique (frottement, coefficient de partage de la chaleur, etc.). L'implantation via la subroutine VUINTER a été validée sur des cas tests d'abord, et puis ensuite en usinage. Les résultats obtenus pour les flux thermiques avec cette nouvelle procédure sont en très bon accord avec les mesures expérimentales pour le couple outil-matière considéré : AA2024-T351/WC-Co / This PhD. thesis is realised in the framework of an international cooperation between the University of Lorraine (France) and the University of Oujda (Morocco). The work done concerns the modelling of machining process by material removal. Two important aspects of machining have been investigated: the chip formation process and the heat exchange at the tool-chip interface. In the first part of the thesis, a FE modelling of the cutting process has been established. Chips segmentation have been particularly analysed using à new parameter (Segmentation Intensity Ratio) allowing the quantification of the phenomenon. A correlation has been established between the cutting force reduction and the chip segmentation intensity. The second part of the thesis has been devoted to the study of heat exchange at the tool-chip interface, among other phenomena that contribute to the tool wear. One important point of the study is the establishment of a hybrid identification procedure (analytical/numerical) to estimate the heat flux transmitted into the cutting tool, and identification of the heat partition coefficient at the contact interface for each cutting speed. With identified values of the heat partition coefficient obtained by varying the cutting speed, a heat exchange multi-branch law has been proposed and parameters of this law have been identified. This law corresponds firstly to the evolution of the heat partition coefficient as a function of the cutting speed. Thereafter, it was defined in term of the relative sliding velocity at the tool-chip contact interface, in order to implement it in a FE code. The user interface VUINTER of Abaqus/Explicit has been used to implement the proposed law, to fully control the mechanical and thermal contact. It is henceforth possible to implement with this user interface any thermomechanical contact (friction, heat partition coefficient, etc.). The implementation via the user subroutine VUINTER was validated first on adequate tests, then on machining. The obtained results for heat fluxes with this new procedure are in good agreement with experimental measurements for the tool-workmaterial couple considered: AA2024-T351/WC-Co