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- Estudo da qualidade micrográfica de juntas soldadas em ligas de alumínio pelo processo MIGPublication . Costa, Sharlane; Ribeiro, J.E.; Gonçalves, José; Medeiros, Bruno BelliniO objetivo desta dissertação de mestrado é o estudo da qualidade micrográfica de juntas soldadas em ligas de alumínio pelo processo MIG robotizado. O ciclo de tratamentos realizados foi constituído por solubilização, têmpera e envelhecimento artificial. Também foi definido um intervalo de espera entre os dois últimos tratamentos afim de avaliar o efeito de um possível envelhecimento natural. Para definição do quadro de variáveis recorreu-se a literatura e a trabalhos antigos, para a solubilização foram definidas 3 temperaturas: 480, 500 e 520ºC, e tempos de 30, 60 e 90 minutos. O intervalo de espera entre a têmpera e o envelhecimento foi de 0, 12 e 24 horas. E por último, as variáveis definidas para o tratamento de envelhecimento artificial foram temperaturas de 160, 175 e 190ºC, e tempos de 6, 14 e 20 horas. Utilizando o método das matrizes ortogonais de Taguchi, definiu-se que, para o número de parâmetros selecionados, seriam necessários 18 ensaios diferentes. Para realização do estudo foram soldadas chapas da liga AA6082-T6, através do processo MIG robotizado, a seguir foram cortadas as amostras e realizados os tratamentos térmicos. Na sequência as amostras, foram caracterizadas por microscopia ótica e por medição das microdurezas na junta soldada. Verificou-se que a temperatura de solubilização tem efeito sobre os valores de dureza, amostras solubilizadas a 520ºC indicam durezas cerca de 13% maiores quando comparadas as amostras que foram solubilizadas a 480ºC. Além disso, comparando a amostra que atingiu o maior valor de microdureza com uma amostra com ausência de tratamento térmico, constatou-se um aumento de 43% na dureza média da peça.
- CFD and experimental investigation of channel diameter effects in structured internally cooled grinding wheelsPublication . Costa, Sharlane; Capela, Paulina; Sousa, Maria; Hassui, Amauri; Ribeiro, J.E.; Pereira, Mário; Soares, DelfimEfficient cooling and lubrication are critical in grinding due to the high specific energy and limited contact area involved. Conventional external methods often fail to penetrate the air barrier formed by the rotating wheel, leading to excessive heat generation and reduced process stability. To overcome this limitation, this study investigates vitrified alumina grinding wheels with internal cooling channels designed for directed fluid delivery. Three structured configurations were developed, all with identical total outlet area (similar to 54 mm(2)) but different channel diameters (0.6, 1.0, and 1.5 mm), to isolate the effect of channel size on fluid flow and grinding behavior. Computational fluid dynamics (CFD) simulations were performed to assess outlet velocity and surface coverage, while grinding tests quantified tangential and normal forces, temperature variation (Delta T), force ratio (F-t/F-n), and specific grinding energy. Narrow channels provided uniform surface coverage but limited jet velocity due to higher hydraulic resistance, whereas wider channels enhanced outlet velocity at the expense of flow uniformity. The intermediate configuration (& Oslash; 1.0 mm) yielded the most balanced performance, achieving up to 38 % lower tangential force and 41 % lower temperature than the & Oslash; 0.6 mm design, while maintaining low specific energy across all depths of cut. Correlation between CFD and experimental results confirmed that both jet intensity and spatial distribution govern cooling and lubrication efficiency. These insights support the design of more efficient and sustainable grinding wheels through tailored channel geometries.
- A New Grinding Wheel Design with a 3D Internal Cooling Structure SystemPublication . Costa, Sharlane; Capela, Paulina; Souza, Maria S.; Gomes, José R.; Carvalho, Luís; Pereira, Mário J.; Soares, DelfimThis work discusses challenges in conventional grinding wheels: heat-induced tool wear and workpiece thermal damage. While textured abrasive wheels improve heat dissipation, the current surface-only methods, such as those based on laser and machining, have high renewal costs. The proposed manufacturing technology introduces an innovative 3D cooling channel structure throughout the wheel, enabling various channel geometries for specific abrasive wheel applications. The production steps were designed to accommodate the conventional pressing and sintering phases. During pressing, a 3D organic structure was included in the green body. A drying cycle eliminated all present fluids, and a sintering one burnt away the structure, revealing channels in the final product. Key parameters, such as binder type/content and heating rate, were optimized for reproducibility and scalability. Wear tests showed a huge efficiency increase (>100%) in performance and durability compared of this system to conventional wheels. Hexagonal channel structures decreased the wear rates by 64%, displaying superior wear resistance. Comprehensive CFD simulations evaluated the coolant flow through the cooling channels. This new design methodology for three-dimensionally structured grinding wheels innovates the operation configuration by delivering the coolant directly where it is needed. It allows for increasing the overall efficiency by optimizing cooling, reducing tool wear, and enhancing manufacturing precision. This 3D channel structure eliminates the need for reconditioning, thus lowering the operation costs.
- Coolant flow in structured grinding wheels: CFD validation via high-speed imaging and particle trackingPublication . Costa, Sharlane; Souza, Andrews; Neves, Lucas B.; Ribeiro, J.E.; Pereira, Mário; Soares, DelfimEfficient coolant delivery is essential in grinding to control heat generation, minimize tool wear, and preserve workpiece integrity. However, Computational Fluid Dynamics (CFD) models commonly used for coolant system design remain rarely validated due to the extreme speeds and complex multiphase flows involved. This work addresses this gap by combining CFD simulations with targeted experiments to evaluate heat removal effectiveness in internally cooled grinding wheels with three channel inclinations: positive, straight, and negative. Transparent resin prototypes enabled high-speed imaging and particle tracking for flow field validation, while grinding tests measured temperature rise and mechanical loads. Results demonstrate that channel inclination strongly affects fluid acceleration, jet coherence, and penetration into the grinding zone, with the positive inclination producing the highest outlet velocities and reducing temperature rise by up to 67%. Particle tracking confirmed CFD predictions within 16% deviation, validating the model’s reliability. By establishing a direct correlation between coolant jet dynamics, heat dissipation, and process performance, this study demonstrates a methodology for the thermal optimization of internal cooling systems in rotating tools. The approach provides a pathway for improving energy efficiency, extending tool life, and reducing coolant consumption in industrial machining processes.