The introduction of ceramics into the market of wood cutting tools has failed so far due to the generally low toughness of ceramics which is causing brittle failure of the cutting edge. A feasibility study showed that Si3N4/SiC composites with fine elongated β-Si3N4 grains are a promising material for industrial wood machining and outperform commercial standard tungsten carbide tools in terms of lifetime. However, they were produced by hot pressing followed by very costly diamond cutting and grinding. The costs associated with the above production route are too high for an industrial viability. In this thesis Si3N4/SiC composites suitable for industrial wood milling are produced by a near net shape processing route including gas pressure sintering. These newly developed tools show less abrasive wear and consequently twice as long lifecycles than commercial standard tungsten carbide tools. Microscopic properties determine the performance of the Si3N4/SiC cutting tools. Therefore, an adequate selection of sintering additives is crucial. 12 wt% sintering additives are included in the composite as a combination of Al2O3 and the refractory oxides La2O3 and Y2O3. Important for the production of effective Si3N4/SiC wood cutting tools is the formation of a partly crystalline silicate phase within the multiple grain junctions during the final treatment by hot isostatic pressing. The use of MgO as a sintering additive for facilitating the densification of the Si3N4 ceramics inhibits the formation of the favourable silicate phase and must be avoided for the production of these wood cutting tools.

L’étude présentée est consacrée à l’usinabilité de la fonte à graphite vermiculaire. Celle-ci se situe entre la fonte à graphite lamellaire et la fonte à graphite sphéroïdale par rapport à la forme du graphite constituant ce matériau. Elle est utilisée depuis plus de cinq ans dans les blocs moteurs diesel afin d’améliorer les performances et de diminuer les rejets atmosphériques pour respecter les nouvelles normes Européennes. Pour évaluer l’usinabilité d’un matériau, il faut s’étalonner par rapport à un matériau de référence. Dans notre cas, la fonte à graphite vermiculaire a été comparée à la fonte à graphite lamellaire. Des essais de tractions ont permis d’obtenir les propriétés mécaniques du lot de matière utilisé pour la campagne d’essais d’usinage ; ceci, afin de se situer dans la gamme de ce type de fonte. Les plaquettes d’usinage ont été caractérisées par nano-indentation. Les revêtements PVD et CVD ont subit des essais de micro-rayure afin de caractériser leur adhésion sur leurs substrats respectifs. La mise en place d’un plan d’expérience a permis de limiter le nombre de plaquettes d’usinage prototypes à réaliser. Des essais tribologiques de type pion/disque ont révélé des pistes exploitables pour la compréhension des phénomènes de frottement et d’usures mis en jeu lors de l’usinage de la fonte à graphite vermiculaire. / This study deals with machinability of compacted graphite iron. This material is in-between grey cast iron and nodular cast iron due to the graphite particle shape. It is used for manufacturing diesel engine blocks so as to increase performances and reduce carbon emissions to comply with Euro 5 norm. It is necessary to compare one material to a reference material to evalute machinability criterium. In our case, compacted graphite iron has been compared to grey cast iron. Tensile tests have given us mechanical properties of our test pieces batch used for machining tests. It helped us to qualify the material in its own material range. Inserts have been characterized by nanoindentation. PVD and CVD coatings were benchmarked in microscratch way to determine their respective adhesion to theirs substrates A design of experiment has been setted up so as to reduce number of inserts protypes to be manufactured. Pin on disk tribologic tests gave few hints to have a better understanding of friction phenomena and wear during compacted graphite iron machining.

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-03-17T11:04:02Z No. of bitstreams: 0 / Made available in DSpace on 2015-03-17T11:04:02Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-03-17T11:04:02Z No. of bitstreams: 0 / Made available in DSpace on 2015-03-17T11:04:02Z (GMT). No. of bitstreams: 0 / Cerâmicas à base de alumina pertencem à classe de materiais denominados estruturais, muito utilizados em ferramentas de corte. A alumina possui boas propriedades para uso como cerâmica estrutural e com o objetivo de melhorar suas tenacidade à fratura e resistência mecânica, são produzidos compósitos com diferentes aditivos. Novos estudos apontam para os micro-nanocompósitos, onde a adição de partículas micrométricas deve auxiliar no aumento da resistência mecânica, e de partículas nanométricas, no aumento da tenacidade à fratura. Neste trabalho foram obtidos micro-nanocompósitos à base de Al2O3 com inclusão de partículas nanométricas de NbC e micrométricas de WC com proporções de 2:1, 6:4, 10:5 e 15:10 e micro-nanocompósitos à base de Al2O3 com inclusão de partículas nanométricas de NbC e micrométricas de TaC com proporção de 2:1 em relação à alumina. Para o estudo de densificação, os micro-nanocompósitos foram sinterizados em dilatômetro com taxa de aquecimento de 20 °C / min até a temperatura de 1800 °C, em atmosfera de argônio. Com base nos resultados de dilatometria, corpos de prova foram sinterizados entre 1500°C e 1700°C, com patamar de 30 minutos, em forno resistivo de grafite e atmosfera de argônio. Foram determinadas as densidades, fases cristalinas formadas, durezas e tenacidades, e analisadas as microestruturas dos micro-nanocompósitos. As amostras Al2O3:NbC:TaC sinterizadas a 1700°C atingiram as maiores densidades aparentes (~95%DT) e a amostra sinterizada a 1600°C apresentou microestrutura homogênea e valor de dureza (15,8 GPa) em comparação à alumina pura. As composições com 3% de inclusões são as mais promissoras para aplicações futuras como ferramentas de corte. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Táto diplomová práca popisuje optimizáciu obrábacieho procesu za účelom zvýšenia produktivity výrobnej linky. Zadanie bolo vypracované v priebehu priemyselnej stáže vo firme Stellantis na obábacej linke blokov valcov motoru DV. Práca vysvetľuje metódy analýzy strát produktivity na výrobnej linke a aplikácii opatrení smerujúcich ku zvýšeniu produktivity, obzvlásť nasadenie nástrojov štíhlej výroby. Najviac boli nasadené nástroje SMED, ktorého cieľom je optimizácia výmeny rezných nástrojov, a TPM, ktorý ma za cieľ zvýšiť spoľahlivosť výrobných prostriedkov.

The thesis is focused on the characteristic of coating methods and their division, on the morphology of defects and cause of wear in coated cutting tools of sintered carbides. The experimental part is focused on a comparing cutting performance testing of indexable cutting inserts coated with nanocrystaline composite TiAlSiN at the longitudinal turning.

The presented diploma thesis is devided into two parts. The theoretical part deals with types of milling, the choice of the cutters, choice of material of exchangeable cutting plates and also with types of wear and their classification. The second part of the thesis deals with experiments where the power load of the tool was measured. The observed data were processed and graphs of power load were created by software. Conclusions are based on these graphs.

The presented diploma thesis is divided into two parts. The theoretical part deals with modern catting tools for grooving and cutting-off, choice of material of catting inserts, and with types of tool wear and their classification. The second part of the thesis deals with calculation of volumetric wear of catting tool for grooving. There was measured the power load of the new and worn tool in the experimental part and the observed data were evaluated by software. The graphs of power load and volumetric wear of tool were created.

Cutting tools in a manufacturing system play a significant role in metal cutting process. Cutting tools arc consumable. Tool wear affects the outcomes of machining processes such as machined· surface quality and it is normally used as an indicating parameter for tool life. It is crucial to calculate and record the wear size of different cutting tools. The tool wear is classified into many different categories according to its existing location and wear patterns. Flank wear and crater wear are the two most common types of tool wear which are used to assess the tool's life. The measurements of flank and crater wear in cutting tools have been extensively studied. There are still many challenges when these research results are applied practically. Manufacturing industry demands· accurate and rapid methods for the tool wear measurement. There are two primary objectives in this research. The first is to develop a new tool wear measurement technology by using the active contour model based image processing method for the flank wear measurement. A MATLAB program is developed to verify the suggested image processing algorithm. Many cutting experiments were conducted with different tools on a CNC machine tool. The experimental results show that the developed technology is feasible and can be used to measure the tool wear area. It needs to be noted that this method. can only extract the wear area. This method is not able to estimate the depth of the crater wear. The second objective is to develop a method for crater wear measurement by use of developed stereo vision system. This system consists of a single camera with necessary lighting devices and fixtures. A MATLAB based software is developed to estimate and represent the volume of tool wear. The proposed algorithm and feasibility of the system for the crater wear (3D tool wear) is discussed. Its effectiveness is verified in this research.

<p>The high pressure and high temperature (HPHT) behavior of Ti_1-xAl_xN coatings on cutting tool inserts have been of interest for this diploma work. A literature study of HPHT techniques as well as measurement methods has been done. A diamond anvil cell (DAC) would be a good device to achieve high pressure and high temperature conditions on small samples. Another way to obtain these conditions would be a cutting test, which has been performed on a Ti_1-xAl_xN coated cutting tool insert with x = 0.67. Also a cubic press could be used to apply HPHT on a     Ti_1-xAl_xN sample or a large volume press on a whole cutting tool insert. To measure hardness on thin coatings a nanoindentor could be used, which have been done on heat-treated Ti_0.33Al_0.67N and TiN samples. X-ray diffraction (XRD) is a suitable method to measure phase composition of a sample and was performed on the cutting tested insert as well as on an untreated reference insert. Three ways to continue this project have been outlined all starting with more comprehensive cutting tests.</p>