Minimum quantity lubrication replaces the traditional method of flood cooling with small amounts of high-efficient lubrication. Limited studies have been performed to determine the characteristics of mist produced during MQL. This study investigated the mist concentration levels produced while drilling 1018 steel using a vegetable based lubricant. ANOVA was performed to determine whether speed and feed rates or their interactions have a significant effect on mist concentration levels and particle diameter. It was observed that the concentration levels obtained under all four speed and feed rate combinations studied exceeded the current OSHA and NIOSH standards.

Cutting fluids have some drawbacks, like health hazards, extra manufacturing cost and environmental contamination. To decrease the disadvantages of using cutting fluids, conventional cutting is a better choice. However, conventional cutting has no advantages of using cutting fluids, such as lubrication. Therefore, vibration assisted cutting (VAC) is a new technology to achieve both purposes of the above machining techniques. Hence, the goal of this study focuses on the mechanical performance of vibration assisted grinding (VAG) for micro grinding of SKD61 steel based on tool life and surface finish. In this study, it is observed that chatter happens under VAG in the condition of feed 5.76 £gm/rev. Surface roughness (Ra) for the condition of feed 1.92 £gm/rev is better than that of 5.76 £gm/rev. The best surface finish is 0.05 £gm in this study when the feed is 1.92 £gm/rev. Spindle speed does not have significant effect on surface roughness in this study. However, the tool life is short under high spindle speed (35000rpm). Experimental results show that tool life will be prolonged two-thirds for VAG combined with MQL. As changing the amplitude of vibration (for a fixed frequency of 9 kHz) , the larger the amplitude, the better the surface roughness.

Vibration assisted cutting (VAC) is a new metal machining technique in recent years, where high-frequency and low-amplitude vibrations are imposed to the cutting tool or the workpiece. It has many advantages than conventional cutting (CC), especially improvements in surface finish and tool life. Nowadays, the use of VAC is a good strategy for micro-machining due to long tool life and high product dimension accuracy. This study presents an experimental investigation of the VAC in micro milling. The tool wear, surface roughness, and burr formation are investigated for different cutting parameters under conventional and vibration assisted cutting. When the vibration speed is higher than 3 times of the cutting speed, the tool life can be prolonged in this study. The experimental results show that VAC process has better surface finish (43.51% reduction in value) compared to that in CC, when the cutting conditions are feed of 4 £gm/rev and cutting speed of 3.39 m/min. It is also found that VAC can diminish the formation of burr formation. By introducing MQL to VAC, the tool life is extended because the MQL could reduce the friction between the tool and workpiece.

The use of cutting fluids in machining process is very essential for achieving desired machining performance. Due to the strict environmental protection laws now in effect, there is a wide-scale evaluation of the use of cutting fluids in machining. Consequently, minimal quantity lubrication (MQL), which uses very small quantity of cutting fluids and still offers the same functionality as flood cooling, can be considered as an alternative solution. This thesis presents an experimental study of face milling of automotive aluminum alloy A380 under four different lubrication/cooling conditions: dry cutting, flood cooling, MQL (Oil), and MQL (Water). Experiments were design using Taguchi method for design of experiments. Empirical models for predicting surface roughness and cutting forces were developed for these four conditions in terms of cutting speed, feed and depth of cut. Optimization technique using Genetic Algorithms (GA) was used to optimize performance measures under different lubrication/cooling conditions, based on a comprehensive optimization criterion integrating the effects of all major machining performance measures. Case studies are also presented for two pass face milling operation comparing flood cooling condition with MQL. The comparison of the results predicted by the models developed in this work shows that the cutting force for MQL (Oil) is either lower or equal to flood cooling. The surface roughness for MQL (Oil) is comparable to flood cooling for higher range of feed and depth of cut. A comparison of the optimized results from the case studies, based on value of utility function, shows that the optimum point for two pass face milling operation having MQL (Oil) as finish pass has highest utility function value.

Submitted by MARCELO ANTUNES DE PAULA null (marcelo13.antunes@yahoo.com.br) on 2016-10-01T16:36:44Z No. of bitstreams: 1 Dissertação de Mestrado - Correção da DEFESA - REV04.pdf: 4198970 bytes, checksum: 93b55a568d4e3eb31cf4efbb257c4894 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-10-05T14:42:07Z (GMT) No. of bitstreams: 1 paula_ma_me_guara.pdf: 4198970 bytes, checksum: 93b55a568d4e3eb31cf4efbb257c4894 (MD5) / Made available in DSpace on 2016-10-05T14:42:07Z (GMT). No. of bitstreams: 1 paula_ma_me_guara.pdf: 4198970 bytes, checksum: 93b55a568d4e3eb31cf4efbb257c4894 (MD5) Previous issue date: 2016-08-04 / Pró-Reitoria de Pós-Graduação (PROPG UNESP) / Muitos materiais são utilizados para diversas aplicações em projetos de engenharia. Os aços inoxidáveis martensíticos que são ligas de ferro e cromo (11-18%) com teor de carbono acima de 0,1% são aplicados na fabricação de válvulas, bombas de equipamentos, ferramentas de cutelaria, eixos acionadores, hastes de pistão, componentes de turbinas hidráulicas e instrumentos cirúrgicos. A evolução das propriedades e desempenho dos materiais utilizados em componentes para aplicações em engenharia é contínua ao longo dos anos, consequentemente os processos e as ferramentas utilizadas para fabricação desses componentes precisam evoluir conjuntamente. A proposta desse trabalho é avaliar o desempenho das ferramentas de corte de Metal Duro revestidas pelos processos (PVD-Physical vapor deposition e CVD-Chemical vapor deposition) na usinagem a seco e MQL do aço inoxidável martensítico AISI 410 tratado termicamente e a qualidade do acabamento superficial da peça, nas condições de corte com (vc = 125-150-175 m/min, f = 0,1-0,25 mm/rev e ap = 0,5 mm). A análise dos desgastes das ferramentas de corte foi realizada com auxilio de microscópios. A medição da rugosidade foi realizada com auxílio de um rugosímetro. Resultados finais evidenciaram que a ferramenta com revestimento CVD apresentou um melhor desempenho em ambas às condições de corte porque a amostra teve um bom acabamento superficial. A ferramenta com revestimento PVD apresentou avarias durante a realização dos ensaios, as avarias ocorreram na ferramenta em ambas às condições de corte durante os testes, primeiramente, na forma de pequenas lascas, em seguida, ocorrendo à quebra da ferramenta. Os cavacos obtidos durante os ensaios de uma forma geral foram na forma de lascas. / Many materials are used for various applications in engineering projects. The Martensitic Stainless Steels are alloys containing from 11.5 to 18% of chromium and 0.09 to 0.15% of carbon, which are widely used in the manufacturing of valves, pumps, cutlery tools, drive shafts, piston rods, hydraulic turbine components and surgical instruments. The evolution of the properties and performance of materials used in components for engineering applications is continuous over the years, therefore processes and tools used to manufacture these components must develop together. The purpose of this work is to evaluate the performance and wear of coated carbide tools (PVD - Physical vapor deposition e CVD - Chemical vapor deposition) in dry machining and MQL of Martensitic Stainless Steel AISI 410 heat-treated and the quality of workpiece surface finishing in cutting conditions (vc = 125-150-175 m/min, f = 0,1-0.25 mm/rev, ap = 0.5 mm). The tool wear analysis was realized with the aid of microscopes. The measurement of roughness was obtained with the aid of roughness meter. Final results showed that the coated carbide tool (CVD) performed well in both cutting conditions because the piece had a good surface finishing, the flank wear were not significant for the tested cutting lengths and the tool no damage showed. The coated carbide tool (PVD) showed damage in both cutting conditions during the tests, firstly on shape of small splinters, then to break the tool. The chips were obtained during tests on shape of small splinters. / CAPES: 175.715

L'industrie automobile cherche à réduire son utilisation des liquides de coupe en usinage pour des raisons économiques, environnementales et sanitaires. Les fabricants développent ainsi la démarche Minimum Quantity Lubrication qui vise à réduire au strict minimum l'utilisation des liquides de coupes en usinage. En l'absence de liquide de coupe, la stabilisation thermique de la pièce n'est plus assurée et des échauffements locaux apparaissent. Ces échauffements créent des déformations qui doivent être quantifiés et pris en compte afin d'assurer la conformité de la géométrie produite.Une démarche de modélisation de l'échauffement d'une pièce pendant l'usinage est présentée. Le modèle obtenu permet à la fois de quantifier la quantité de chaleur introduit dans la pièce pour des usinages simples et de simuler les déformations d'une pièce complexe lors de l'enchainement d'opération d'usinage. Cette quantification repose sur une méthode inverse. Elle est appliquée à des opérations de fraisage, perçage et taraudage d'un alliage d'aluminium AS9U3. Dans un second temps, une étude de l'influence de l'ordonnancement des opérations d'usinage d'un carter de boite de vitesses automobile sur la qualité de la géométrie produite est conduite. Cette étude illustre l'intérêt du modèle de simulation et des outils développés pendant la thèse. Enfin, les enjeux économiques et environnementaux de la technologie MQL seront abordés. / The application of MQL or dry machining in mass production becomes more and more accepted. Dry (MQL) machining is a very efficient solution to reduce the usage of cutting fluids and represents an effective measure for an environmental friendly production. However, these techniques do not benefit any more from the stabilization in temperature obtained with cutting fluids. More important and more heterogeneous increases of the temperature are observed. This leads to distortions of the work piece during machining which are necessary to be taken into account to maintain the geometrical quality of the manufactured surfaces.A model of the warm-up of a part during machining is presented. The obtained model allows to quantify heat introduced into the work piece for simple operations and to feign the distortions of a complex part when operations are enchained. This quantification is based on an inverse method. It is applied for reaming, drilling and tapping process for an aluminum alloy AS9U3. Secondly, a study about influence of operations organization is done. We use the model to quantify distortions an aluminum clutch case along machining. This study illustrates interest of the model and of tools developed during the PhD. In a last part, economic and environmental stakes of the MQL approach are discussed.

It has been reported that minimum quantity lubrication (MQL) provides better tool life compared to flood cooling under some drilling conditions. In this study, I evaluate the performance of uncoated HSS twist drill when machining AISI 1018 steel using a newly developed lubricant designed for MQL (EQO-Kut 718 by QualiChem Inc.). A randomized factorial design was used in the experiment. The results show that a tool life of 1110 holes with a corresponding flank wear of 0.058 mm was realized.

Submitted by Ricardo Bega de Andrade null (r-b-andrade@hotmail.com) on 2017-08-28T17:12:54Z No. of bitstreams: 1 Andrade, Ricardo Bega de_Dissertação de Mestrado.pdf: 3187731 bytes, checksum: 5e3efba5a483cb1e9e4533e06bf87209 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-08-29T17:50:53Z (GMT) No. of bitstreams: 1 andrade_rb_me_bauru.pdf: 3187731 bytes, checksum: 5e3efba5a483cb1e9e4533e06bf87209 (MD5) / Made available in DSpace on 2017-08-29T17:50:53Z (GMT). No. of bitstreams: 1 andrade_rb_me_bauru.pdf: 3187731 bytes, checksum: 5e3efba5a483cb1e9e4533e06bf87209 (MD5) Previous issue date: 2017-07-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O processo de retificação é um processo de usinagem por abrasão que visa principalmente obtenção de superfícies com baixa rugosidade e tolerância dimensional estreita. Essa combinação é possível por causa das múltiplas arestas de corte sem geometria definida que removem material da peça em pequenas penetrações de trabalho. Contudo é um processo que apresenta problemas para a peça, devido à elevada geração de calor. Este calor pode causar alterações metalúrgicas, dentre outras. Por esta razão é necessário utilizar fluido de corte para refrigerar a zona de retificação. Ao mesmo tempo é preciso buscar uma produção mais sustentável em relação à técnica de lubri-refrigeração convencional. Esta técnica vem sendo substituída por outras que visam redução de custo e redução e/ou eliminação do impacto ambiental, sem prejuízos para qualidade da peça. Uma técnica de lubri-refrigeração que vem substituindo a técnica convencional competitivamente é a técnica de Mínima Quantidade de Lubrificação (MQL), que é bem difundida em processos de usinagem com geometria de corte definida (por exemplo, torneamento, fresamento e furação) e com resultados promissores também em processos de retificação. Entretanto, pelo fato da técnica MQL ser menos estudada no processo de retificação, seu desempenho ainda apresenta algumas restrições devido à sua baixa eficiência de refrigeração, que pode ocasionar danos térmicos à peça. Neste sentido, a realização deste trabalho consistiu em substituir o ar à temperatura ambiente do MQL por um ar a menor temperatura. Foi retificado o aço ABNT 4340 temperado e revenido com rebolo convencional de óxido de alumínio. Os experimentos foram realizados para as três diferentes técnicas de lubri-refrigeração (convencional, MQL e MQL com ar frio [MQL+AF]), com velocidade de corte igual a 30 m/s e com velocidade de mergulho variada em três graus de severidade (0,25; 0,50 e 0,75) mm/min. Para promover a redução da temperatura do ar misturado ao MQL, foi utilizado um sistema de refrigeração de ar por tubo de vórtice, visando aumentar a eficiência na retirada de calor do processo. Foram analisadas como variáveis de saída, a viscosidade relacionada ao fluido de corte utilizado nas técnicas MQL, a rugosidade (Ra), circularidade e integridade microestrutural relacionadas à peça, o desgaste relacionado ao rebolo e a potência de retificação relacionada ao processo. As técnicas MQL, nas duas formas de aplicação, apresentaram desempenho superior à técnica convencional. A técnica MQL+AF, mesmo com o ar frio atuando na retirada de mais calor da zona de retificação, apresentou desempenho geral inferior à técnica MQL, devido à influência exercida pela viscosidade do fluido à menor temperatura de aplicação. / The grinding process is an abrasion machining process that is mainly aimed at obtaining surfaces with low roughness and narrow dimensional tolerance. This combination is possible because of the multiple cutting edges without defined geometry that remove material from the workpiece at small work penetrations. However, it is a process that presents problems for the workpiece, due to the high generation of heat. This heat can cause metallurgical changes, among others. For this reason it is necessary to use cutting fluid to cool the grinding zone. At the same time it is necessary to seek a more sustainable production compared to the conventional lubri-cooling technique. This technique has been replaced by others that aim at cost reduction and reduction and/or elimination of environmental impact, without any damage to the quality of the part. A lubri-cooling technique that is replacing the conventional technique, competitively, is the Minimum Quantity of Lubricant (MQL) technique, which is well diffused in machining processes with defined cutting geometry (for example, turning, milling and drilling) and with promising results also in grinding processes. However, due the MQL technique is less studied in the grinding process, its performance still presents some restrictions due to its low cooling efficiency, which can cause thermal damage to the part. In this sense, the accomplishment of this work consisted in replacing the air at the ambient temperature of the MQL by air at a lower temperature. The quenched and tempered ABNT 4340 steel was ground with conventional aluminum oxide grinding wheel. The tests were carried out for three different lubri-cooling techniques (conventional, MQL and MQL with cold air [MQL + AF]), with a cutting speed of 30 m/s and a plunge speed varied in three degrees of severity (0.25, 0.50 and 0.75) mm/min. To promote the reduction of the temperature of the air mixed to the MQL, a vortex tube air cooling system was used aiming to increase the heat removal efficiency of the process. As output variables were analyzed the viscosity related to the cutting fluid used in MQL techniques, the roughness, roundness and microstructural integrity related to the workpiece, the wear related to the grinding wheel and the grinding power related to the grinding process. The MQL techniques, in both forms of application, presented superior performance to the conventional technique. The MQL+AF technique, even with the cold air acting to remove more heat from the grinding zone, presented worst general performance than the MQL technique, due to the influence exerted by the viscosity of the fluid at the lower application temperature.

Flood cooling is primarily used to cool and lubricate the cutting tool and workpiece interface during a machining process. But the adverse health effects caused by the use of flood coolants are drawing manufacturers' attention to develop methods for controlling occupational exposure to cutting fluids. Microlubrication serves as an alternative to flood cooling by reducing the volume of cutting fluid used in the machining process. Microlubrication minimizes the exposure of metal working fluids to the machining operators leading to an economical, safer and healthy workplace environment. In this dissertation, a vegetable based lubricant is used to conduct mist, microstructure and wear analyses during end milling AISI 1018 steel using microlubrication. A two-flute solid carbide cutting tool was used with varying cutting speed and feed rate levels with a constant depth of cut. A full factorial experiment with Multivariate Analysis of Variance (MANOVA) was conducted and regression models were generated along with parameter optimization for the flank wear, aerosol mass concentration and the aerosol particle size. MANOVA indicated that the speed and feed variables main effects are significant, but the interaction of (speed*feed) was not significant at 95% confidence level. The model was able to predict 69.44%, 68.06% and 42.90% of the variation in the data for both the flank wear side 1 and 2 and aerosol mass concentration, respectively. An adequate signal-to-noise precision ratio more than 4 was obtained for the models, indicating adequate signal to use the model as a predictor for both the flank wear sides and aerosol mass concentration. The highest average mass concentration of 8.32 mg/m3 was realized using cutting speed of 80 Surface feet per minute (SFM) and a feed rate of 0.003 Inches per tooth (IPT). The lowest average mass concentration of 5.91 mg/m3 was realized using treatment 120 SFM and 0.005 IPT. The cutting performance under microlubrication is five times better in terms of tool life and two times better in terms of materials removal volume under low cutting speed and feed rate combination as compared to high cutting speed and feed rate combination. Abrasion was the dominant wear mechanism for all the cutting tools under consideration. Other than abrasion, sliding adhesive wear of the workpiece materials was also observed. The scanning electron microscope investigation of the used cutting tools revealed micro-fatigue cracks, welded micro-chips and unusual built-up edges on the cutting tools flank and rake side. Higher tool life was observed in the lowest cutting speed and feed rate combination. Transmission electron microscopy analysis at failure for the treatment 120 SFM and 0.005 IPT helped to quantify the dislocation densities. Electron backscatter diffraction (EBSD) identified 4 to 8 µm grain size growth on the machined surface due to residual stresses that are the driving force for the grain boundaries motion to reduce its overall energy resulting in the slight grain growth. EBSD also showed that (001) textured ferrite grains before machining exhibited randomly orientated grains after machining. The study shows that with a proper selection of the cutting parameters, it is possible to obtain higher tool life in end milling under microlubrication. But more scientific studies are needed to lower the mass concentration of the aerosol particles, below the recommended value of 5 mg/m3 established by Occupational Safety and Health Administration (OSHA).

L'industrie automobile cherche à réduire son utilisation des liquides de coupe en usinage pour des raisons économiques, environnementales et sanitaires. Les fabricants développent ainsi la démarche Minimum Quantity Lubrication qui vise à réduire au strict minimum l'utilisation des liquides de coupes en usinage. En l'absence de liquide de coupe, la stabilisation thermique de la pièce n'est plus assurée et des échauffements locaux apparaissent. Ces échauffements créent des déformations qui doivent être quantifiés et pris en compte afin d'assurer la conformité de la géométrie produite.Une démarche de modélisation de l'échauffement d'une pièce pendant l'usinage est présentée. Le modèle obtenu permet à la fois de quantifier la quantité de chaleur introduit dans la pièce pour des usinages simples et de simuler les déformations d'une pièce complexe lors de l'enchainement d'opération d'usinage. Cette quantification repose sur une méthode inverse. Elle est appliquée à des opérations de fraisage, perçage et taraudage d'un alliage d'aluminium AS9U3. Dans un second temps, une étude de l'influence de l'ordonnancement des opérations d'usinage d'un carter de boite de vitesses automobile sur la qualité de la géométrie produite est conduite. Cette étude illustre l'intérêt du modèle de simulation et des outils développés pendant la thèse. Enfin, les enjeux économiques et environnementaux de la technologie MQL seront abordés.