Browsing by Keyword "Aluminum"
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Item Analysis and comparative study of factors affecting quality in the hemming of 6016T4AA performed by means of electromagnetic forming and process characterization(2011-05-01) Jimbert, P.; Eguia, I.; Perez, I.; Gutierrez, M.A.; Hurtado, I.; COMPOSITE; Tecnalia Research & Innovation; PROMETALHemming is commonly one of the last operations for stamped parts. For this reason it is of critical importance on the performance and perceived quality of assembled vehicles. However, designing the hemmed unión is a complicated task and is deeply influenced by the mechanical properties of the materail of the bent part. Significant problems can arise in this operation when bending aluminum alloys, because cracks can appera due to the localized strain during hemming as a result of the low ductility of automotive aluminum alloys. This paper presents the devlopment of the lectromagnetic forming (EMF) technology for auto body-in-white parts hemming. A relatively simple experimental procedure to perform a hemming operation based on th eprinciple of EMF is presented in order to compare the variation in the quality parameters of a hemmed joint. The achieved results are compared with the corrresponding geometry hemmed utilizing the conventional process. At the same time, the study is completed with the development of a new simulation method for the EMF technology. The results obtained during this study prove the capability of the EMF to obatin quality hem unions simplifying the complicated conventional hemming operation. In this study a loose coupling EMF hemming simulation method has been developed using Maxwell 3D to solve the electromagnetic field computation and Abaqus to solve the mechanical computation. Thsi simulation method shows good agreement with the physiscal experiments. Finally, the EMF hemming process is characterized by analyzing the influence of main input parameters on the quality output parameters.Item Determination of Solidification of Rigidity Point Temperature Using a New Method(2020-04-03) Villanueva, Ester; Vicario, Iban; Sánchez, Jon Mikel; Crespo, Ignacio; PROMETAL; CIRMETALThis work aims to calculate the rigidity point temperature of aluminum alloys by three new methods and compare them with currently employed methods. The influence of major and minor alloying elements over the rigidity point temperature is also discussed. Until now it has been difficult to determine the exact temperature of the rigidity point, since small variations in the data obtained give variable results, making it difficult to automate the process with high accuracy. In this work we suggested three new mathematic methods based on the calculation of higher order derivatives of (dT/dt) with respect to time or temperature compared to those currently employed. A design of experiments based on the Taguchi method was employed to compare the effect of the major and minor alloying elements for the AlSi10Mg alloy, and to evaluate the accuracy of each developed method. Therefore, these systems will allow better automation of rigidity point temperature (RPT) determination, which is one of the most important solidification parameters for solidification simulators. The importance of the correct determination of this parameter lies in its relation to quality problems related to solidification, such as hot tearing. If the RPT presents very low-temperature values, the aluminum casting will be more sensitive to hot tearing, promoting the presence of cracks during the solidification process. This is why it is so important to correctly determine the temperature of the RPT. An adequate design of chemical composition by applying the methodology and the novel methods proposed in this work, and also the optimization of process parameters of the whole casting process with the help of the integrated computational modeling, will certainly help to decrease any internal defective by predicting one of the most important defects present in the aluminum industry.Item Development of an Innovative Low Pressure Die Casting Process for Aluminum Powertrain and Structural Components(Wiley-VCH Verlag, 2018) Merchán, Mikel; Egizabal, Pedro; García de Cortázar, Maider; Irazustabarrena, Ane; Galarraga, HaizeAn innovative Low Pressure Die Casting (LPDC) process has been developed for aluminum cast components based on the application of an extra pressure during the solidification process. The new process, named “Low Pressure Squeeze Casting” (LPSC) has been proved to be able to increase the solidification rate, refining the microstructure of the casting, and reducing its shrinkage porosity. Furthermore, the cycle time is also reduced, increasing the productivity of the process. Two demonstrators from the automotive and wind power industries have been produced to validate the process in a relevant industrial environment.Item Metamodels’ Development for High Pressure Die Casting of Aluminum Alloy(2021-10-31) Anglada, Eva; Boto, Fernando; García de Cortazar, Maider; Garmendia, Iñaki; CIRMETAL; Tecnalia Research & Innovation; FACTORYSimulation is a very useful tool in the design of the part and process conditions of high pressure die casting (HPDC), due to the intrinsic complexity of this manufacturing process. Usually, physics-based models solved by finite element or finite volume methods are used, but their main drawback is the long calculation time. In order to apply optimization strategies in the design process or to implement online predictive systems, faster models are required. One solution is the use of surrogate models, also called metamodels or grey-box models. The novelty of the work presented here lies in the development of several metamodels for the HPDC process. These metamodels are based on a gradient boosting regressor technique and derived from a physics-based finite element model. The results show that the developed metamodels are able to predict with high accuracy the secondary dendrite arm spacing (SDAS) of the cast parts and, with good accuracy, the misrun risk and the shrinkage level. Results obtained in the predictions of microporosity and macroporosity, eutectic percentage, and grain density were less accurate. The metamodels were very fast (less than 1 s); therefore, they can be used for optimization activities or be integrated into online prediction systems for the HPDC industry. The case study corresponds to several parts of aluminum cast alloys, used in the automotive industry, manufactured by high-pressure die casting in a multicavity mold.Item Solid Fraction Determination at the Rigidity Point by Advanced Thermal Analysis(2021-12-27) Villanueva, Ester; Vicario, Iban; Sánchez, Jon Mikel; Albizuri, Joseba; Montero, Jessica; PROMETAL; CIRMETALThe aim of this work is to determine the Solid Fraction (SF) at the rigidity point (FRP) by applying advanced thermal analysis techniques. The variation of the FRP value is important to explain the solidification behavior and the presence or absence of defects in aluminum alloys. As the final alloy composition plays a key role on obtained properties, the influence of major and minor alloying elements on FRP has been studied. A Taguchi design of experiments and a previously developed calculating method, based on the application of high rank derivatives has been employed to determinate first the rigidity point temperature (RPT) and after the corresponding FRP for AlSi10Mg alloys. A correlation factor of r2 of 0.81 was obtained for FRP calculation formula in function of the alloy composition.Item Superhydrophobic and oleophobic microtextured aluminum surface with long durability under corrosive environment(2023-01-31) Adarraga, Olatz; Agustín-Sáenz, Cecilia; Bustero, Izaskun; Brusciotti, Fabiola; Tecnalia Research & Innovation; PRINTEX; VALORIZACIÓN DE RESIDUOS; INGENIERÍA DE SUPERFICIESSuperhydrophobic (SHP) and oleophobic aluminum surfaces have been prepared through the combination of a scalable chemical microtexturing process and surface functionalization with long-chained polyfluoroalkyl moieties. The effect of an anodic layer on the microtextured surface has been assessed considering surface morphology, superhydrophobicity, surface mechanical properties and corrosion protection enhancement. The surface functionalization with polyfluoroalkyl moieties has been tackled in two different ways: (i) grafting of the polyfluoroalkyl moieties and (ii) deposition of a thin hybrid coating with low content of polyfluoroalkyl-containing compound. Aluminum surfaces showing high durability in salt spray environments, which maintain SHP and oleophobic properties at least up to 2016 h have been attained. Applications for this kind of surfaces range from easy-to-clean surfaces to anti-icing or anti-condensation functionalities that could be of interest for several sectors.