Made available in DSpace on 2014-06-11T19:30:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-10-19Bitstream added on 2014-06-13T20:00:19Z : No. of bitstreams: 1 funesjunior_h_me_bauru.pdf: 883904 bytes, checksum: fec351d42aa10096507c21b8bdf9b1d8 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O uso do fluído de corte é imprescindível para processos de usinagem em que há elevada geração de calor, principalmente no processo de retificação. A utilização de fluido de corte, no entanto, causa uma série de complicações, especialmente nos aspectos ambientais, econômicos e com relação à saúde dos operadores de máquinas. Assim, intensificaram-se estudos para novos métodos de aplicação e otimização do fluido de corte visando a sua redução, bem como os problemas ocasionados por esse. Sobre essa tendência, este trabalho analisa o comportamento de um método recente, até então aplicado somente em processos de usinagem com ferramenta de geometria definida, que consiste na adição de água no método da mínima quantidade de lubrificante (MQL). Foram avaliados três tipos de proporção na mistura óleo-ar e água (1:1, 1:3 e 1:5 parte de óleo de água). Para uma melhor avaliação desse método, os resultados obtidos foram comparados com outros dois métodos de lubri-refrigeração, a lubri-refrigeração convencional (fluído em abundância) e o MQL tradicional (óleo-ar). Os métodos de lubri-refrigeração foram avaliados com base nos resultados das variáveis de saída: rugosidade, circularidade, desgaste diametral do rebolo, tensão residual e microdureza. Os resultados obtidos para o método MQL com adição de água consuzem a melhorias significativas com relação ao método da MQL tradicional e estes resultados são bem próximos aos obtidos com a lubri-refrigeração convencional, para os resultados de rugosidade, circularidade e desgaste diametral do rebolo, além da isenção de danos térmicos às peças / The use of cutting fluid is essential for the grinding process where there is high temperature, as in the grinding process. The use of cutting fluid, however causes a series of complication, especially in the environmental and economical aspects and in relation to the health of the machine operators. Therefore, there were more studies to develop new methods of application and optimization of fluid, aiming at the reduction, as well as the problems caused by the fluids. Regarding this trend, this paper has as an objective the analyzes of the behavior of a recent method, applied only to the grinding process with tools with defined geometry, it consists of the addition of water in the minimum quantity of lubrication method (MQL). This paper has analyzed three types of proportion in the mixture oil-air and water (1:1; 1:3 and 1:5). For a better assessment of this method, the obtained results were compared to other two lubri-cooling methods, the conventional method (fluid in abundance) and the traditional MQL (oil-air). The methods of the lubri-cooling studied were analyzed through the output of the variables of the grinding process: roughness, roundness, wear of the grinding wheel (relation G) and microhardness. The obtained results show that the minimum quantity of lubrification (MQL) with addition of water have a significant improvement in relation to the conventional method and these resuls are close to the obtained results with the conventional lubri-cooling (in abundance), for the results of roughness, roundness and wear of the grinding wheel, as well as examption of the thermal damage of pieces

Orientador: Olivio Novaski / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-11T11:32:42Z (GMT). No. of bitstreams: 1 Camargo_Robsonde_M.pdf: 2931963 bytes, checksum: b31c2bc8d3db8a81c83a498c961b4717 (MD5) Previous issue date: 2008 / Resumo: Graças a suas propriedades mecânicas e a boa resistência à corrosão, os aços inoxidáveis austeníticos representam aproximadamente 70% de todo o aço inoxidável produzido. O aço ABNT 304 tem excelente resistência à corrosão, alta resistência ao ataque de agentes corrosivos e possui boa tenacidade em baixas temperaturas. A condutibilidade térmica, todavia, corresponde a ¼ do aço ao carbono, tanto que o calor gerado durante a usinagem não é transferido ao material ou aos cavacos e sim se concentra na aresta de corte, e a alta tenacidade dos mesmos torna difícil sua saída devido ao alongamento. O mecanismo de encruamento, que é um fenômeno que acontece próximo da aresta de corte, piora a usinabilidade do aço inoxidável. O aço inoxidável, com controle metalúrgico das inclusões e adição de cálcio, é apresentado como uma alternativa, em termos de usinagem, sem perda de resistência à corrosão. O presente trabalho compara, por meio do processo de furação, a usinabilidade do aço ABNT 304 com o aço similar, V304 UF, com adição de cálcio e controle de inclusões. Foram utilizadas brocas de aço rápido recobertas com TiN nos dois diferentes aços com velocidades de corte diferentes para avaliar o efeito da adição de cálcio na usinabilidade. A possível formação da camada protetiva na superfície da ferramenta de aço rápido com revestimento de TiN foi encontrada. Após testes de usinagem, a presença de cálcio e elementos de liga na superfície da ferramenta foi constatada usando a análise por difração de raios X. Com as análises dos resultados obtidos na medição da força de avanço, momento de torção e vida da ferramenta, fica evidente afirmar que a usinabilidade do aço inoxidável Villares 304 UF foi superior / Abstract: Thanks to its mechanical properties and good corrosion resistance embraced, the austenitic stainless steels represent about 70% of all kind stainless steel produced. The ABNT 304 steel has excellent corrosion resistance the in the environment, high resistance to attack of corrosive agents and keep good tenacity in low temperatures. Unfortunately the of heat conduction is about ¼ that of regular steel, so much of the heat generated during machining is not transferred to the work material or the chips and concentrate on the cutting edge, and high malleability that indicates softness and tenacity makes chip evacuation difficult due to chip elongation. Yet the work hardening, a phenomenon that occurs near the cutting edge gives poor machinability to the stainless steel. The stainless steel with metallurgical control of the inclusions and calcium addition is presented as alternative, without loss of corrosion resistance. The present work compares the machinability of ABNT 304 steel with the similar steel, Villares 304 UF, with calcium addition using the drilling process. HSS TiN coated twisted drills had been used in the two different steels with different cutting speeds to evaluate the effect of the calcium addition in the machinability. The possible formation of a protective layer on the surface the tool of TiNcoated HSS was found. After cutting tests, the enrichment of calcium and alloying elements in the surface of the tool was studied using energy dispersive X-ray spectrometry. The feed force, torsion moment and tool life measured allow to explain the upper machinability of the stainless steel Villares 304 UF / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

Made available in DSpace on 2016-03-15T19:37:02Z (GMT). No. of bitstreams: 1 Rafael Vieira Silva Junior.pdf: 2081250 bytes, checksum: a979dfc000e476a709bb4450523c5a84 (MD5) Previous issue date: 2010-04-09 / The effect of the addition of bismuth, boron, aluminum, titanium, sulphur and nitrogen in steel 1045 had been investigated to also improve the machinability of the modified steel and its influence in mechanical properties. It is considered to substitute the use of the lead as a used lement to earn in machinability to keep the mechanical characteristics of 1045 steel. They will be presented results of machinability tests, hardness measurements and microstructural characterizations by optical and scanning electron microscopy. The results of the impact tests had indicated that 1045 steel with addition of boron, titanium, nitrogen and sulphur presented the best tenacity whereas the usinabilidade results had indicated the 1045 steel added with boron, bismuth, nitrogen and sulphur as most favorable. / Foram investigados os efeitos da adição do Bismuto, do Boro, do Alumínio, do Titânio, do Enxofre e do Nitrogênio no aço 1045 para melhorar a usinabilidade do aço e também sua influência em propriedades mecânicas. Propõe-se substituir o uso do Pb por Bi como um elemento usado para melhorar a usinabilidade mantendo-se as características mecânicas do aço 1045. São apresentados resultados obtidos dos ensaios de usinabilidade, dureza e caracterizações microestruturais por microscopia óptica e eletrônica de varredura. Os resultados de impacto realizados indicaram que o aço 1045 com adição de boro, titânio, nitrogênio e enxofre apresentou a melhor tenacidade enquanto que os resultados de usinabilidade indicaram o aço 1045 adicionado com B, Bi, Ni e S como o melhor.

Orientador: Anselmo Eduardo Diniz / Dissertação (mestrado profissional) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-19T06:16:14Z (GMT). No. of bitstreams: 1 Dalo_MarcoAurelio_M.pdf: 3765565 bytes, checksum: f1d967a8742c941a83bb6de2d800ed64 (MD5) Previous issue date: 2011 / Resumo: Existe hoje uma tendência no mercado de veículos de motor diesel a fabricarem os blocos dos motores em ferro fundido vermicular devido à melhor eficiência de combustão e maior resistência à compressão, permitindo paredes de galerias mais finas com conseqüência na redução do peso do bloco, quando comparado ao bloco usual feito de ferro fundido cinzento. Desta forma, seria possível atender às novas exigências do mercado e do meio ambiente. Porém, a difícil usinabilidade deste material obriga ao levantamento de condições de usinagem e ao desenvolvimento de ferramentas que possam melhorar a produtividade dos processos de usinagem dos blocos. O mandrilamento em desbaste dos mancais do bloco do motor é uma das operações de usinagem mais carentes de desenvolvimento dentre as utilizadas na produção do bloco de ferro fundido vermicular. A variação do material da ferramenta e as condições de corte utilizadas no processo de usinagem foram as variáveis testadas neste trabalho para buscar o melhor desempenho do processo de mandrilamento do bloco. Os resultados demonstraram que ferramentas de material cerâmico sofreram um desgaste frontal excessivo da aresta de corte por difusão e as ferramentas de metal duro obtiveram um melhor resultado em comparação com a cerâmica. Com relação às condições de corte, resultados com o uso de menores velocidades de corte demonstraram um menor desgaste frontal das arestas de corte. A potência consumida do fuso foi o limitante para o máximo avanço por dente utilizado nos experimentos / Abstract: Today there is a trend in the market for diesel vehicles manufactured in compacted graphite iron due to better combustion efficiency of the engine and greater resistance to compression, allowing thinner walls of galleries with a result in reducing the weight of the block, when compared to the usual block made of the gray cast iron. Thus, it would be possible to meet new market demands and the environment. However, the difficult machinability of this material requires the survey of the machining conditions and development of the tools that can improve productivity of machining processes of the blocks. The rough boring in the bearings of the engine block is one of the machining operations of the poorest development among those used in the production of compacted graphite iron block. The variation of the tool material and cutting conditions used in the machining process variables were tested in this work to get the best performance of the process of boring the block. The results show that ceramic tools have suffered excessive front wear of the cutting edge diffusion and carbide tools had a better outcome in comparison with the ceramic. With respect to cutting conditions, results from the use of lower cutting speeds showed a lower front wear of the cutting edges. The power consumption of the spindle was limited for maximum feed per tooth used in the experiments / Mestrado / Manufatura / Mestre em Engenharia Automobilistica

Orientador: Anselmo Eduardo Diniz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-19T10:37:14Z (GMT). No. of bitstreams: 1 MunozDias_LuizRoberto_M.pdf: 3936007 bytes, checksum: fb9f262c5583315e04e019d84e27c1c1 (MD5) Previous issue date: 2011 / Resumo: Os ferros fundidos cinzentos são muito empregados em diversos segmentos da indústria, sendo sua utilização preferida para composição de bases de máquinas por ter baixo custo de aquisição, alta capacidade de amortecimento a vibrações e facilidade de fabricação. As normas que norteiam a produção destas ligas determinam as classes divididas por faixas de resistência à tração e forma da grafita presente na estrutura. A classe GG-25, determina resistência à tração situada entre 250Kgf/mm² e 300Kgf/mm² e forma de grafita lamelar. Esta pesquisa tem como objetivo investigar a diferença de usinabilidade entre ferros fundidos cinzentos desta mesma classe, ou seja, dentro da tolerância da norma, com diferentes concentrações de perlita e ferrita. Avaliou-se a usinabilidade em termos de vida de ferramenta, esforços de corte e rugosidade em operações de fresamento em acabamento com ferramentas de metal duro e cerâmica (com geometrias de corte idênticas) e diferentes velocidades de corte em um material contendo 100% de perlita e em outro com 50% de perlita. Os resultados mostraram que os lotes perlíticos, em função de resistência e dureza maiores, provocam desgaste das ferramentas mais rapidamente que os lotes 50% perlíticos e também consomem maiores esforços de corte. Também foi possível notar que as ferramentas de cerâmica apresentaram vida maior que as ferramentas de metal duro. Os mecanismos causadores de desgastes da ferramenta foram: difusão, adesão de ferro com conseqüente remoção de partículas (attrition) e trincas térmicas / Abstract: The gray cast irons are frequently used in various fields of industry, mainly for machine bed due to the low cost, high vibration damping capacity and easiness of manufacturing. The standards that guide the production of these alloys determine the classes based on the range of tensile strength and shape of graphite in the structure. The class GG-25 determines the tensile strength between 250Kgf/mm² and 300Kgf/mm2 and lamellar shape of graphite flakes. This research aims at investigate the difference of machinability between two gray cast irons belonging to the same class, i.e., within tolerance of the standard, with different pearlitic / ferritic concentrations. Machinability was evaluated in terms of tool life, cutting forces and workpiece surface roughness in finish milling with carbide and ceramic tools (with similar cutting geometries) and different cutting in a material containing 100% pearlite and another with 50% pearlite. The results showed that in the milling of the pearlitic alloy, due to higher strength and hardness, tool wear progressed faster than in the milling of ferritic alloy and also consumed higher cutting forces. It was also possible to note that ceramic tools showed longer life than carbide tools. The main observed mechanisms of wear were diffusion, adhesion of iron with consequent removal of tool material (attrition) and thermal cracks. / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

Orientador: Amauri Hassui / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-19T21:26:46Z (GMT). No. of bitstreams: 1 Therezani_DouglasFellipe_M.pdf: 8921001 bytes, checksum: 07f18992fbada55cf604b764eaafe4f8 (MD5) Previous issue date: 2012 / Resumo: A super liga Inconel 713C é uma liga cujo principal elemento de sua composição é o Níquel. A combinação do alto teor deste elemento mais a estrutura desse material faz com que ele seja muito difícil de ser usinado. Devido a esta dificuldade e carência de informações a respeito da usinagem desse material, o objetivo deste trabalho foi buscar uma combinação de ferramenta e parâmetros de corte que apresentassem uma vida da ferramenta em torno de 15 minutos, valor considerado viável economicamente pela prática industrial. Para isso foram testadas ferramentas de metal duro com duas geometrias diferentes, quatro tipos de revestimentos (TiAlN, TiAlN-TiN, TiCN-Al2O3-TiN e Al2O3) além da ferramenta de metal duro sem revestimento. Foram testadas também ferramentas cerâmicas (Al2O3 (pura), Si3N4 (sialon), Al2O3+SiCw (whiskers)) e de CBN. Dentre os ensaios realizados, a ferramenta de metal duro com a geometria CNMX e revestimento TiAlN apresentou uma taxa de desgaste menor que as demais testadas com uma vida de aproximadamente 17 minutos de corte / Abstract: The super alloy Inconel 713C is an alloy whose main element of its composition is nickel. The combination of high levels of this element and the structure of this material makes it very difficult to be transformed by the machining process. Because of this difficulty and lack of information about the machining of this material, the purpose of this study was to find a combination of tool and cutting parameters to present a tool life of around 15 minutes, which is considered economically viable for industrial practice. To achieve this purpose it was tested cemented carbide tools with two different geometries, four types of coatings (TiAlN, TiN, TiAlN, TiCN-Al2O3-TiN and Al2O3) in addition to the carbide tool without coating were tested. Tools were also tested ceramics (Al2O3 (pure), Si3N4 (sialon) + Al2O3 SiCw (whiskers)) and CBN. Among the tests, the carbide tool geometry CNMX and coating TiAlN presented a lower wear rate than the others tested with a life of approximately 17 minutes of cutting / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

Este trabalho apresenta estudos de usinabilidade de chapas MDF (Medium Density Fiberboard), tendo por objetivo principal efetuar uma análise do desempenho de corte em relação à qualidade da superfície usinada e à força específica de corte paralela necessária, a fim de se verificar a influência dos parâmetros estudados para operações de usinagem de acabamento e desbaste, respectivamente. No estudo para operação de acabamento verificou-se a influência da espessura de corte,velocidade de avanço e sentido de corte, em operação de fresamento cilíndrico periférico, sobre a rugosidade superficial da borda das chapas MDF. Uma fresadora vertical foi utilizada para gerar as superfícies, cuja rugosidade superficial foi medida por um perfilômetro de apalpamento. No estudo para operação de desbaste, a força específica de corte paralela foi avaliada em função da variação do ângulo de saída, da espessura de corte e da profundidade de corte, em operação de corte ortogonal. Para tanto, foram empregadas uma plaina limadora e uma célula de carga de extensômetros resistivos, conectada a um programa de aquisição e análise de dados. A partir da análise dos resultados obtidos, foi possível identificar a influência de cada parâmetro de corte empregado. / This work presents a MDF (Medium Density Fiberboard) machinability study aiming to carry out a cutting performance analysis regarding to surface quality and parallel specific cutting force, in order to verify the cutting parameters effect on the finishing and roughing machining operations, respectively. In the finishing study, it was verified the effect of the cutting thickness, cutting speed and direction of cutterhead rotation with relation to feed direction, in peripheral milling, on the MDF edges surface roughness. The surfaces were developed by a moulder, which roughness were measured by a stylus perfilometer. In the roughing study, the parallel specific cutting force was assessed in relation to the variation of the rake angle, cutting thickness and depth of cut, for the orthogonal cut. For this, it was used a planing machine and a resistance dynamometer, coupled in a data acquisition and analysis system. From the analysis of the obtained results, it was possible to identify the influence of each cutting parameter considered.

General perspective of this diploma thesis was aimed at machining of hard-to-machine materials. Theoretical part contains division and specification of these types of materials. Ways of classification and evaluation were also listed. Causes of worsened machinability were defined with the design of possible technological solutions, which eliminates these features. The main target of experimental part was turning nickel-based superalloy Inconel® 718 with the purpose of increase process productivity. Knowledge about appropriate types of cutting tool material and his coating were necessary for process optimization. It was achieved by replacing reference cutting tool material (coated carbide inserts) with SiAlON ceramic. Cutting tool edge was tested with an intention to discover appropriate deal between tool life and volume of material removed. Measured cutting forces, generated by machining of reference and optimize technology, were processed by using simulation software. Total deformation of workpiece material was statistically evaluated. The conclusion of diploma thesis is technical-economic evaluation of both options.

The diploma thesis deals with the topic of machinability of materials. The theoretical part describes the aspects according to which machinability can be evaluated. The material side of the thesis is focused on various types of difficult-to-machine materials. The cobalt alloy UmCo50 belongs to the group of difficult-to-machine materials and it is the subject of the experimental part. UmCo50 is an alloy for high temperature use. The primary aim of the thesis was to monitor the wear of the selected cutting tool when turning this alloy. Other aspects of the selected machining process were also monitored, such as force effects or the quality of the machined surface. Despite the fact that machinability of tested materials cannot be expressed in terms of the absolute value of a quantity, it is necessary to compare the various aspects of the machining processes by reference materials. However, certain conditions of this comparison must be met. Based on this, a comparison of tested and reference material was performed.

OBJECTIVES: To assess the viability of using high-strength polymers as framework materials for full arch implant-supported fixed prostheses, veneered with full-coverage restorations of different materials. The machinability, mechanical performance, and damping capacity of the polymer-based materials was of interest. METHODS: The two framework polymers – a polyetheretherketone (JUVORA™ Dental Disk, Juvora) (PEEK) and a fiber-reinforced composite (TRINIA™ CAD/CAM Disk, Trinia) (TR) – were characterized with Fourier-Transform Infrared (FTIR) Spectroscopy and energy-dispersive X-ray spectroscopy (EDS). Phase 1 consisted of a machinability study involving the merlon fracture test, which tested the milling success of PEEK and TR at 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, and 0.5 mm. 10 four-walled merlons of each thickness and material were milled out of CAD/CAM Disks (n = 100 merlons, n = 400 walls) using a 5-axis milling machine, inLab MC X5 (Dentsply Sirona, Germany). Milling success rate, fracture height, fracture length, fracture position, fracture direction, and chipping factor were assessed. In phase 2, 20 bars of dimensions 3.3 mm x 10 mm x 40 mm were milled from each of the two framework materials, PEEK and TR, and two veneer materials – a composite resin material (Shofu Disk HC, Shofu, Inc., Kyoto, Japan) (COM), and a high-translucency 3 mol% yttria-stabilized tetragonal zirconia polycrystal material (Cercon® ht, Dentsply Sirona, Bensheim, Germany) (ZR). Framework and veneer bars were bonded to each other in 4 framework/veneer combinations of 10 bilayers each: PEEK/COM (PCB), PEEK/ZR (PZB), TR/COM (TCB), and TR/ZR (TZB). Bilayer bars were loaded to failure in a 3-point bending test. Failure load, biaxial flexural strength, failure pattern and failure mode were documented. In Phase 3, 10 full arch fixed implant-supported frameworks were designed and fabricated in TR material over an epoxy resin model containing 4 implants in the second premolar and lateral incisor positions. 5 frameworks were veneered by COM in the canine to first molar region, while the other 5 were veneered by ZR. Four loading sites were designated per prosthesis in the occlusal surface of the first molars and the first premolars. Prostheses were loaded at the four occlusal sites in 5 cycles of loading and unloading. The damping capacity of the prostheses was calculated based on energy absorbed during loading and unloading. Displacement and permanent deformation values of the prosthesis structures were obtained from the load-displacement data. Prostheses were loaded to failure at the same sites, and failure load and failure mode were observed. RESULTS: The minimum machined thickness of PEEK and TR was 0.5 mm. There was no significant difference between milling success of PEEK and TR, but cumulative success rate was slightly superior in PEEK. PEEK exhibited a ductile response to machining damage, while TR showed a more brittle response. Chipping factor of PEEK was higher than TR eightfold, meaning TR showed an improved marginal integrity at 0.5 mm. Both materials showed concerning signs of machining damage with the milling parameters and tools used in this study. Bilayer bars with a TR framework withstood significantly higher loads at failure compared to bilayers with a PEEK framework. Bilayer bars with a ZR veneer withstood significantly higher loads at failure compared to bilayers with a COM veneer. The biaxial flexural strength of the four framework/veneer combinations could not be compared due to the occurrence of delamination in 3 of the 4 groups. The PZB group was the only group with fracture of both the veneer and framework without any delamination and exhibited a mean biaxial flexural strength of 46.15 ± 5.76 MPa. None of the bilayer bars with a TR framework exhibited framework fracture. In delaminated specimens, bilayer bars with a TR framework exhibited mixed adhesive-cohesive failure on both layers, while bilayer bars with a PEEK framework exhibited purely adhesive failure on the PEEK-cement interface. Full arch implant prostheses with a TR framework demonstrated elastic hysteresis in continuous cycles of cyclic loading, which is evidence of viscoelastic damping. Significantly higher energy absorption was observed in prostheses veneered with COM compared to ZR. Energy absorption decreased with increasing cycles of loading-unloading. Significantly higher maximum displacement was observed in prostheses veneered with COM compared to ZR, and in cantilever support compared to bounded support. Maximum displacement was inversely related to the thickness of the veneer and framework materials. Permanent deformation of the prosthesis was negligible after 10 cycles. The failure pattern of all prostheses presented as fracture in the veneer only and partial delamination of the veneer with mixed adhesive-cohesive failure mode. The mean failure load at ZR-veneered bounded sites was significantly higher than that of COM-veneered bounded sites. The mean failure load at bounded loading sites was significantly higher than that of cantilever loading sites. ZR-veneered prostheses demonstrated failure load values above 1000 N at all sites. CONCLUSION: The merlon fracture test is well-complemented by several quantitative and qualitative measures to assess the machinability of materials. Optimized tools and parameters for milling PEEK and TR should be investigated. Full arch implant prostheses with TR framework and ZR veneer are a viable option for fixed implant rehabilitation demonstrating damping capacity, adequate failure load values, and easy repairability.