Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Paul Dudley Hartung. / M.S.

Thesis. 1977. Mech.E.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by K. Subramanian. / Mech.E.

The cutting tool industry has evolved over the last half century to the point where an increasing range and complexity of cutting tools are available for metal machining. This highlighted a need to provide an intelligent, user-friendly system of tool selection and recommendation that can also provide predictive economic performance data for engineers and end-users alike. Such an 'expert system' was developed for a local manufacturer of cutting tools in the form of a relational database to be accessed over the Internet. A number of performance predictive models were reviewed for various machining processes, however they did not encompass the wide range of variables encountered in metal machining, thus adaptation of these existing models for an expert system was reasoned to be economically prohibitive at this time. Interrogation of published expert systems from cutting tool manufacturers, showed the knowledge-engineered principle to be a common approach to transferring economic and technological information to an end-user. The key advantage being the flexibility to allow further improvements as new knowledge is gained. As such, a relational database was built upon the knowledge-engineered principle, based on skilled craft oriented knowledge to establish an expert system for selection and performance assessment of cutting tools. An investigation into tapping of austenitic stainless steels was undertaken to develop part of a larger expert system. The expert system was then interrogated in this specific area in order to challenge by experiment, the skilled craft oriented knowledge in this area. The experimental results were incorporated into the database where appropriate, providing a user-friendly working expert system for intelligent cutting tool selection, recommendation and performance data.

This study presents a novel methodology to characterize material plastic behavior within a practical range of stresses, strains, strain rates, and temperatures encountered in the metal cutting process. The methodology is based on integrating a newly developed analytical model with quasi-static tests and orthogonal cutting experiments that incorporate a laser heating system. Friction and heat transfer models are developed to describe the tribological and thermal interactions at the tool-chip interface. These models are implemented in a FEM package in order to improve the accuracy of the simulation of the machining process. / The new analytical model, which is developed to predict the distributions of the stress, the strain, the strain rate, and the temperature in the primary shear zone, is based on conceptual considerations, as well as characterization of the plastic deformation process through comprehensive FEM simulations. / Orthogonal cutting experiments at room temperature and preheated conditions were carefully designed. While the cutting tests at room temperature provided the constitutive data encountered in the primary shear zone, the preheated cutting tests were designed to capture the material behavior at the high level of temperature and strain encountered in the secondary shear zone. In these preheated cutting tests, a laser beam was employed. Quasi-static tests were also utilized to identify some of the coefficients in the constitutive equations, in order to improve the convergence to a unique solution for the constitutive law. / Evaluation criteria were developed to assess the performance of constitutive equations. Based on the developed methodology and the evaluation criteria, a new constitutive equation for Inconel 718 has been proposed. This constitutive equation was further validated by Split Hopkinson Pressure Bar (SHPB) tests and cutting tests in conjunction with FEM simulations. The SHPB test data show an excellent agreement with the proposed material model. The cutting tests and the FEM simulation results also proved the validity of the proposed material constitutive law.

The vision of this thesis is to improve the metal cutting process, with emphasis on the cutting tool, to enable stable and economical industrial production while using expensive tools such as hobs. The aim is to increase the tribological understanding of the mechanisms operating at a cutting edge and of how these can be controlled using different tool parameters. Such understanding will facilitate the development and implementation of future, tribologically designed, cutting tools. Common wear and failure mechanisms in gear hobbing have been identified and focused studies of the material transferred to the tool, in both metal cutting operations and in simplified tribological tests, have been conducted. Interactions between residual stresses in the tool coating and the shape of the cutting edge have also been studied. It was concluded that tool failure is often initiated via small defects in the coated tool system, and it is necessary to eliminate, or minimize, these defects in order to manufacture more reliable and efficient gear cutting tools. Furthermore, the geometry of a cutting edge should be optimized with the residual stress state in the coating, in mind. The interaction between a compressive stress and the geometry of the cutting edge will affect the stress state at the cutting edge and thus affect the practical toughness and the wear resistance of the coating in that area. An intermittent sliding contact test is presented and shown to be of high relevance for studying the interaction between the tool rake face and the chip in milling. It was also demonstrated that material transfer, that can have large effects on the cutting performance, commences already after very short contact times. The nature of the transfer may differ in different areas on the tool. It may include glassy layers, with accumulations of specific elements from the workpiece, and transfer of steel in more or less oxidized form. Both tool coating material, its surface roughness, and the relative speed between the tool surface and the chip, may influence the extent to which the different transfer will occur.

Thesis (MEng) - School of Engineering and Science, Swinburne University of Technology, 2004. / Thesis submitted for the degree of Master of Engineering by Research, School of Engineering and Science, Swinburne University of Technology, 2004. Typescript. Includes bibliographical references: p. 116-122.

Thesis (M.S.)--Brigham Young University. School of Technology, 2005. / Includes bibliographical references (p. 77-79).

A furação por eletroerosão e furação a laser são duas técnicas utilizadas na fabricação de furos de pequeno diâmetro (entre 0,18 e 2 mm) em materiais com alta dureza, elevada resistência a abrasão e com capacidade de manutenção das propriedades mecânicas a alta temperatura. Os furos de pequeno diâmetro são comumente utilizados em componentes da indústria aeronáutica, médica, odontológica e em componentes de turbinas a gás como rotores e pás. Os furos nos componentes de turbinas a gás atuam como mecanismos de arrefecimento desses componentes, os quais são submetidos a altas temperaturas. O objetivo do presente trabalho foi caracterizar os microfuros obtidos por meio das duas técnicas de fabricação citadas. Por meio da avaliação da produtividade do processo e avaliação do acabamento e dimensão dos furos fabricados em Inconel 718, foi possível caracterizar cada técnica. Foram realizados furos de aproximadamente 0,9 mm, por eletroerosão de penetração de furo rápido utilizando dois materiais de eletrodo: cobre e latão; e foi realizada furação a laser por trepanação. Definiu-se um planejamento estatístico composto central para avaliar a influência dos principais parâmetros de entrada. Os resultados mostraram a influência dos parâmetros na variação das respostas dos seguintes aspectos de avaliação: a variação das taxas de remoção de material, taxa de desgaste de eletrodo (para furação com eletroerosão), dilatação dos furos, rugosidade do canal do furo, espessura da zona termicamente afetada, respingos, crateras e alteração na composição química da região do metal base usinado. Apesar da produtividade do processo a laser por trepanação ser maior que na eletroerosão foi verificado que a furação a laser gera maior concentração de trincas e maior espessura da ZTA, se comparados aos furos fabricados por eletroerosão. Portanto não há um processo que se sobressai em todos os aspectos de avaliações. Cada processo de fabricação possui vantagens e limitações que devem ser ponderadas para a seleção de uma das técnicas. / Fast hole EDM and trepanning laser drilling are two techniques used in the manufacture of small diameter holes (between 0.18 and 2 mm) in materials with high hardness, high abrasion resistance and an ability to maintain mechanical properties at a high temperature. The small diameter holes are commonly used for aerospace components, and the medical and dental industry, as well as for gas turbine components such as rotors, vanes and blades.The holes in gas turbine components act as cooling mechanism for these components which are subjected to high temperatures.The objective of this study is to characterize the micro-holes obtained through the two manufacturing techniques cited. Through a work process and productivity assessment and inspection of the finish and size of the holes manufactured by Inconel 718, it was possible to characterize each technique cited. Holes were formed of approximately 0.9 mm diameter, by fast hole EDM drilling using two electrode materials: copper and brass; and was carried out by trepanning laser drilling. A central composite (statistical) design was created to determine the influence of the main input parameters. The results showed the influence of parameters on the variation of responses in the following aspects of the assessment: the variation in the removal rates of material, electrode wear rate (for drilling with EDM), dilatation of holes, hole channel roughness, the thickness of the heat-affected zone, splashing, craters and a change in the chemical composition in the region of the machined metal base. Although greater productivity is achieved through trepanning with a laser technique than the EDM it was found that laser drilling causes a higher concentration of cracks and increased the thickness of the HAZ as compared with the holes made by EDM. Thus, there is no single process that meets the requirements of every aspect of the evaluation. Each manufacturing process has its own benefits and drawbacks and these must be taken into account when selecting one of the techniques.

A furação por eletroerosão e furação a laser são duas técnicas utilizadas na fabricação de furos de pequeno diâmetro (entre 0,18 e 2 mm) em materiais com alta dureza, elevada resistência a abrasão e com capacidade de manutenção das propriedades mecânicas a alta temperatura. Os furos de pequeno diâmetro são comumente utilizados em componentes da indústria aeronáutica, médica, odontológica e em componentes de turbinas a gás como rotores e pás. Os furos nos componentes de turbinas a gás atuam como mecanismos de arrefecimento desses componentes, os quais são submetidos a altas temperaturas. O objetivo do presente trabalho foi caracterizar os microfuros obtidos por meio das duas técnicas de fabricação citadas. Por meio da avaliação da produtividade do processo e avaliação do acabamento e dimensão dos furos fabricados em Inconel 718, foi possível caracterizar cada técnica. Foram realizados furos de aproximadamente 0,9 mm, por eletroerosão de penetração de furo rápido utilizando dois materiais de eletrodo: cobre e latão; e foi realizada furação a laser por trepanação. Definiu-se um planejamento estatístico composto central para avaliar a influência dos principais parâmetros de entrada. Os resultados mostraram a influência dos parâmetros na variação das respostas dos seguintes aspectos de avaliação: a variação das taxas de remoção de material, taxa de desgaste de eletrodo (para furação com eletroerosão), dilatação dos furos, rugosidade do canal do furo, espessura da zona termicamente afetada, respingos, crateras e alteração na composição química da região do metal base usinado. Apesar da produtividade do processo a laser por trepanação ser maior que na eletroerosão foi verificado que a furação a laser gera maior concentração de trincas e maior espessura da ZTA, se comparados aos furos fabricados por eletroerosão. Portanto não há um processo que se sobressai em todos os aspectos de avaliações. Cada processo de fabricação possui vantagens e limitações que devem ser ponderadas para a seleção de uma das técnicas. / Fast hole EDM and trepanning laser drilling are two techniques used in the manufacture of small diameter holes (between 0.18 and 2 mm) in materials with high hardness, high abrasion resistance and an ability to maintain mechanical properties at a high temperature. The small diameter holes are commonly used for aerospace components, and the medical and dental industry, as well as for gas turbine components such as rotors, vanes and blades.The holes in gas turbine components act as cooling mechanism for these components which are subjected to high temperatures.The objective of this study is to characterize the micro-holes obtained through the two manufacturing techniques cited. Through a work process and productivity assessment and inspection of the finish and size of the holes manufactured by Inconel 718, it was possible to characterize each technique cited. Holes were formed of approximately 0.9 mm diameter, by fast hole EDM drilling using two electrode materials: copper and brass; and was carried out by trepanning laser drilling. A central composite (statistical) design was created to determine the influence of the main input parameters. The results showed the influence of parameters on the variation of responses in the following aspects of the assessment: the variation in the removal rates of material, electrode wear rate (for drilling with EDM), dilatation of holes, hole channel roughness, the thickness of the heat-affected zone, splashing, craters and a change in the chemical composition in the region of the machined metal base. Although greater productivity is achieved through trepanning with a laser technique than the EDM it was found that laser drilling causes a higher concentration of cracks and increased the thickness of the HAZ as compared with the holes made by EDM. Thus, there is no single process that meets the requirements of every aspect of the evaluation. Each manufacturing process has its own benefits and drawbacks and these must be taken into account when selecting one of the techniques.

Orientador: Anselmo Eduardo Diniz / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-13T03:28:51Z (GMT). No. of bitstreams: 1 ArroyoOsorio_JoseManuel_D.pdf: 25100736 bytes, checksum: 163b1aa900bc2b44578e310b2fccbe2b (MD5) Previous issue date: 2009 / Resumo: A usinagem é um dos processos de fabricação fundamentais da indústria contemporânea sendo o metal duro recoberto o material mais utilizado na fabricação das ferramentas de corte. A manufatura deste tipo de ferramentas inclui o processamento da superfície do substrato, previamente à deposição do recobrimento, com o objetivo de obter uma elevada resistência de aderência na interface substrato-recobrimento. O método mais difundido com este propósito e o jateamento do substrato com micropartículas de alumina que, embora amplamente utilizado e efetivo, gera poluição, risco à saúde do operador, consome muitos recursos de tempo e mão de obra e apresenta dificuldade no controle da rugosidade. Por outro lado a texturização a laser é uma tecnologia de engenharia de superfície baseada num laser pulsado que modifica a superfície do material através de fusão, evaporação, sublimação e subsequente solidificação. Nesta tese foi explorada a efetividade da texturização a laser como método alternativo ao jateamento na preparação pré-recobrimento da superfície do substrato. Este processo não apresenta poluição, permite o processamento seletivo de áreas especificas da ferramenta e, sendo automatizável, potencialmente utiliza menos recursos de tempo e mão de obra. As ferramentas selecionadas para experimentar foram duas classes de metal duro com recobrimento composto de TiCN+Al2O3+TiN depositado pelo processo MT-CVD, e, na preparação pré-recobrimento da superfície dos substratos experimentais foi utilizado um laser CuHBr pulsado. De acordo com a dinâmica do processo laser utilizado, é possível controlar a rugosidade do substrato e produzir uma grande diversidade de topografias e estruturas de superfície através da variação da intensidade e/ou da quantidade de pulsos do laser. Também foi verificado que o processamento com laser produz sempre transformações do WC, presente no substrato do metal duro, em novas fases não estequiométricas com menor teor de C. Por tentativa e erro, foram determinados dois conjuntos de parâmetros laser que produziram a melhor resistência de aderência avaliada através de ensaios de indentação: 02 pulsos, 410 MW·cm-2 e 64 pulsos, 239 MW. cm-2. Em ensaios de corte, tipo fresamento de topo a seco de aço molde P20 com ferramentas toroidais, foi comparado o desempenho de arestas microjateadas (comerciais) contra arestas texturizadas a laser (experimentais) encontrando uma vida média igual para ambos os tipos de arestas. Na análise detalhada dos mecanismos de desgaste foram encontradas em todas as arestas evidências de difusão, attrition, abrasão, deformação, delaminação, trincas e um mecanismo secundário, chamado desgaste por microfusão do material da aresta. Não houve diferenças notáveis entre as arestas comerciais e as experimentais que fossem atribuíveis ao processo de preparação da superfície do substrato para a deposição do recobrimento / Abstract: Machining is one of the fundamental manufacturing processes of contemporary industry and coated cemented carbide is the most used cutting tool material. Manufacturing of this kind of tools includes the substrate surface processing previously to coating deposition in order to achieve high adhesion resistance in the substrate-coating interface. The most spread out method with this intention is the substrate blasting with alumina micro-particles, which, although so widely used and effective, generates pollution, operator health risks, consumes considerable time and labor resources and presents roughness control difficulty. In the other hand, laser texturing is a surface engineering technology based on a pulsed laser which modifies the material surface through melting, evaporation, sublimation and subsequent solidification. This thesis aims to explore the laser texturing effectiveness as an alternative method for substrate surface pre-coating preparation. This process does not generate pollution, allows selective tool areas for processing and, being automated, it potentially requires less time and labor resources. The tools selected for the experiments were two kinds of coated cemented carbide with a composed TiCN+Al2O3+TiN MT-CVD coating and for the experimental substrate surface pre-coating preparation, a pulsed CuHBr laser was used. With the laser process dynamics used, it is possible to control the substrate roughness and to produce a great diversity of surface topographies and structures by adjusting the intensity and/or the amount of laser pulses. Also, it was verified that the laser processing always produces WC (present in the substrate) transformations in new non- stoichiometric phases with less C content. By trial and error method, two laser parameters sets were determined which produced the best adhesion resistance as evaluated through indentation tests: 02 pulses, 410 MW·cm-2 and 64 pulses, 239 MW·cm-2. In dry face milling cutting tests of mould P20 steel with toroidal tools, it was compared the performance of micro-blasted tools (commercial) against laser textured (experimental) ones finding an equal average life for both tool types. Detailed wear mechanisms analysis showed evidences in all the cutting edges of diffusion, attrition, abrasion, deformation, delamination, cracks and a secondary mechanism, called micro-melting wear of the material of the edge. There were no remarkable wear differences between the commercial edges and the experimental ones which could be attributable to the substrate surface pre-coating preparation process / Doutorado / Materiais e Processos de Fabricação / Doutor em Engenharia Mecânica