Pressing of metallic powders is a manufacturing process widely investigated in the research field and in the industry. This thesis project is focused on optimizing the pressing process of cemented carbide powder utilized for the production of triangular shaped cutting tool inserts. In particular, the filling of powder into the die cavity was investigated with respect to different pressing parameters. The aim of the project was to obtain a uniform density distribution of the powder into the die cavity, and hence to reduce the variation of the height of the insert obtaining more precise dimension of the latter. The tests were carried out at the Sandvik Coromant production department which is the creator of the project. The optimization of the pressing process was performed according to the Design of experiments theory. The dynamic of the sintering process was also investigated. The results showed a significant improvement in the filling of the die cavity and a significant decrease of the variation of the height of the inserts. The new insert obtained has more precise dimensions and is able to meet the more demanding requirements of the customers. The results achieved are directly applicable to a larger number of products, and indicate the direction to follow for further development of the manufacturing process.

Cutting tool inserts are often coated with thin layers either through chemical vapor deposition (CVD) or physical vapor deposition (PVD) processes. In order to have a better wear resistance cutting tools are mostly subjected to post-coating treatment processes. Shot peening is one of the processes that is used to improve the fatigue life of metallic components. In this study, the finite element (FE) method is employed to model the elastic-plastic deformation and development of residual stress distributions in a cutting tool after the impact of a shot medium. To carry out the work, CVD coated cemented carbide has been chosen to be the workpiece (insert), and the coatings of the chosen insert are Titanium Carbo Nitride (TiCN)  and Aluminum Oxide (Al2O3). Aim of the study is to model a single impact in the shot peening process on a surface of a coated cemented carbide insert while simulating the plastic deformation of the materials. In addition, the objective of the study is also to understand and explain the mechanics of shot peening process and find applicable mechanical properties of the materials for FE modeling. Conjugately, the influence of shot peening process parameters (e.g. velocity, diameter or shape of the peening media) on residual stress distribution has been investigated and the results obtained were compared to the one observed from experiment. The modeling in the study is carried out both with and without initial residual stresses in the materials. The initial residual stresses are estimated by applying a thermal load to the model. The results show that the compressive residual stresses achieved while shot peening by an edge-shaped medium are significantly higher at the surface (i.e. in a coated layer) than compared to a globular medium. In contrast, it is observed that the compressive residual stresses in the cemented carbide are significantly higher and deeper when shot peened with globular medium than the edge-shaped medium. Furthermore, the results of parameteric study demonstrate that the smaller medium induces higher residual stresses at the surface (i.e. in a coated layer) than in the cemented carbide. In contrast, it is observed that the bigger medium induces less residual stresses at the surface (i.e. in a coated layer) and higher residual stresses deeper in the cemented carbide. Whereas, it is observed that the higher residual stresses at the surface (i.e. in a coated layer) and in the cemeneted carbide can be achieved simultaneously by shot peens having a  higher velocity. Residual stress profiles modelled in this report correlate with data from previous studies.   This study has been carried out at Sandvik Coromant, Edge and Surfaces department in Stockholm, Sweden.

This thesis compares the force load of two kinds of cutting tool inserts while milling. The thesis is devided into two main parts – research and experiment. The research part is focused on the theory of the force load measuring, cutting tools and cutting tool inserts and their coating. 14 grooves were made with each cutting insert while the force load was measured. Constant cutting conditions were applied. The experiment was repeated four times for each kind of cutting insert. The aim of the thesis is to determine if both kinds of inserts mill with the same force load. The results reveal that one kind of cutting tool inserts mill with the force load higher up to 85 %.

O objetivo principal desse trabalho é investigar a aplicação de cerâmica á base de Zirconia em ferramentas de corte na usinagem de aço temperado (VND) utilizando um torno de ultraprecisão. Foram analisados dois tipos de composições de cerâmicas com estrutura cristalina diferentes, sendo elas: monoclínica e tetragonal. A diferença destas estruturas é devido à adição de Ytria. A fase monoclínica não contém Ytria em sua composição, enquanto, a fase tetragonal é obtida com Ytria (\'Y IND.3\') (chamada zirconia parcialmente estabilizada com Ytria). A fase tetragonal apresenta uma resistência elevada ao impacto junto com alta dureza (1800 kgf/\'MM POT.2\') quando comparada com a fase monoclínica que apresenta alta dureza mas menor tenacidade. Devido a este fato, esses materiais têm chamado à atenção dos pesquisadores para a usinagem de aços endurecidos. A geração de superfície é influenciada por diversos fatores, sendo eles: material peça, condições de corte, erros macro geométrico, erros de micro geometricos e do estado da aresta da ferramenta. Na usinagem de ultraprecisão a alta rigidez e vibração/trepidação máquina ferramenta é usada para evitar erros de micro geometria e macro geometria que conseqüentemente são transferidos para superfície da peça. Neste trabalho, devido ao fato de se usar um torno de ultraprecisão é possível afirmar que o perfil da rugosidade é gerado pela replicação do perfil da aresta da ferramenta de corte para a superfície da peça. A rugosidade da superfície foi medida com um perfilometro óptico com resolução de 0,1 nm. Os resultados mostraram que a rugosidade da superfície obtida após os testes de usinagem com as ferramantas de cerâmicas chegou á valores em torno de 0,140 microns, o que equivale ao acabamento com processo de retificação. Outro aspecto importante refere-se ao desgaste das ferramentas que, conseqüentemente, tem uma grande influência nos resultados obtidos. As ferramentas de corte foram analisadas antes e depois da usinagem por microscópio eletrônico de varredura. Verificou-se que as ferramentas de corte na fase tetragonal apresentaram desgaste do tipo cratera na aresta da ferramenta enquanto a aresta da ferramenta monoclínica apresentou desgaste do tipo lascamento. / The main objective of this work is to investigate the application of a ceramic composite of Alumina-Zirconia cutting tools inserts in the machining of hardened steel (VND) in an ultraprecision lathe. Two different ceramic compositions with different crystalline structure were tested, to know: monoclinic and tetragonal. The difference in these structures is due the addition of Yttrium. The monoclinic phase has no Yttrium in its composition while the tetragonal phase is obtained with Ytrium (\'Y IND.3\') (named partially stabilized zirconium). The tetragonal phase presents a high impact toughness along with high hardness (1800 kgf/\'MM POT.2\') when compared to the monoclinic phase which presents high hardness but lower toughness. Due to this fact, these materials have draw attention of researchers in the field of machining of hardened steels. The surface generation is influenced by several factors, to know: workpiece material, cutting conditions, macro geometry errors, micro geometry errors and the sharpness of the cutting edge. In ultraprecision machining, a high stiffness and chatter/vibration free machine tool is used in order to avoid common macro and micro geometry errors replicated into the workpiece surface. In this case, it is possible to assert that the roughness profile is generated by the replication of the cutting tool edge profile to the workpiece surface. The surface roughness was measured by an optical profiler with resolution of 0,1 nm. The results showed that the surface roughness obtained after machining tests with these ceramic inserts were in the range of 0,140 micrometers, which is in the same range of roughness obtained by the grinding process. Another important aspect refers to the wear of the ceramic inserts which has direct influence in the performance as a cutting tool material. The cutting inserts were evaluated before and after machining by scanning electron microscope. It was found that the tetragonal phase cutting tools presented crater wear on the rake face while the monoclinic phase presented cutting edge chipping as the main main type of wear.

O objetivo principal desse trabalho é investigar a aplicação de cerâmica á base de Zirconia em ferramentas de corte na usinagem de aço temperado (VND) utilizando um torno de ultraprecisão. Foram analisados dois tipos de composições de cerâmicas com estrutura cristalina diferentes, sendo elas: monoclínica e tetragonal. A diferença destas estruturas é devido à adição de Ytria. A fase monoclínica não contém Ytria em sua composição, enquanto, a fase tetragonal é obtida com Ytria (\'Y IND.3\') (chamada zirconia parcialmente estabilizada com Ytria). A fase tetragonal apresenta uma resistência elevada ao impacto junto com alta dureza (1800 kgf/\'MM POT.2\') quando comparada com a fase monoclínica que apresenta alta dureza mas menor tenacidade. Devido a este fato, esses materiais têm chamado à atenção dos pesquisadores para a usinagem de aços endurecidos. A geração de superfície é influenciada por diversos fatores, sendo eles: material peça, condições de corte, erros macro geométrico, erros de micro geometricos e do estado da aresta da ferramenta. Na usinagem de ultraprecisão a alta rigidez e vibração/trepidação máquina ferramenta é usada para evitar erros de micro geometria e macro geometria que conseqüentemente são transferidos para superfície da peça. Neste trabalho, devido ao fato de se usar um torno de ultraprecisão é possível afirmar que o perfil da rugosidade é gerado pela replicação do perfil da aresta da ferramenta de corte para a superfície da peça. A rugosidade da superfície foi medida com um perfilometro óptico com resolução de 0,1 nm. Os resultados mostraram que a rugosidade da superfície obtida após os testes de usinagem com as ferramantas de cerâmicas chegou á valores em torno de 0,140 microns, o que equivale ao acabamento com processo de retificação. Outro aspecto importante refere-se ao desgaste das ferramentas que, conseqüentemente, tem uma grande influência nos resultados obtidos. As ferramentas de corte foram analisadas antes e depois da usinagem por microscópio eletrônico de varredura. Verificou-se que as ferramentas de corte na fase tetragonal apresentaram desgaste do tipo cratera na aresta da ferramenta enquanto a aresta da ferramenta monoclínica apresentou desgaste do tipo lascamento. / The main objective of this work is to investigate the application of a ceramic composite of Alumina-Zirconia cutting tools inserts in the machining of hardened steel (VND) in an ultraprecision lathe. Two different ceramic compositions with different crystalline structure were tested, to know: monoclinic and tetragonal. The difference in these structures is due the addition of Yttrium. The monoclinic phase has no Yttrium in its composition while the tetragonal phase is obtained with Ytrium (\'Y IND.3\') (named partially stabilized zirconium). The tetragonal phase presents a high impact toughness along with high hardness (1800 kgf/\'MM POT.2\') when compared to the monoclinic phase which presents high hardness but lower toughness. Due to this fact, these materials have draw attention of researchers in the field of machining of hardened steels. The surface generation is influenced by several factors, to know: workpiece material, cutting conditions, macro geometry errors, micro geometry errors and the sharpness of the cutting edge. In ultraprecision machining, a high stiffness and chatter/vibration free machine tool is used in order to avoid common macro and micro geometry errors replicated into the workpiece surface. In this case, it is possible to assert that the roughness profile is generated by the replication of the cutting tool edge profile to the workpiece surface. The surface roughness was measured by an optical profiler with resolution of 0,1 nm. The results showed that the surface roughness obtained after machining tests with these ceramic inserts were in the range of 0,140 micrometers, which is in the same range of roughness obtained by the grinding process. Another important aspect refers to the wear of the ceramic inserts which has direct influence in the performance as a cutting tool material. The cutting inserts were evaluated before and after machining by scanning electron microscope. It was found that the tetragonal phase cutting tools presented crater wear on the rake face while the monoclinic phase presented cutting edge chipping as the main main type of wear.