Browsing by Author "Eguizabal, P."
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Item Development of aluminium alloys for the thixoforming process(2004) Azpilgain, Z.; Hurtado, I.; Basterrechea, G.; Gandarias, E.; Goñi, J.; Eguizabal, P.; Lakehal, M.; Sarriés, I.; Landa, I.; Wielanek, L.; Centros PRE-FUSION TECNALIA - (FORMER); Tecnalia Research & InnovationThe aluminium alloys A356 and A357 remain, up to the present, the most used alloys for the semisolid processing of components. Nevertheless, several authors have pointed out the gain in properties or economics that other alloy families could provide. In the present work two complementary alloy families are considered. From an economical point of view, modifications necessary to increase the properties of second fusion alloys are carried out. From the point of view of the potential of their properties, wrought alloys are modified and tested. A New Rheocasting pilot unit is used for obtaining the alloys with thixotropic characteristics. Previous work on the identification of the microstructural variables which determine the properties of the components allow to reduce those variables to the variation of the solid-liquid fraction as a function of the temperature, the particle size distribution, the particle aspect ratio and the esqueletonization. The composition variations in both alloy families are thus considered under the point of view of the control and optimisation of those parameters. In addition to the metallographic studies, thermodynamic calculations and calorimetry experiments have been performed to determine the optimum process window of the new alloys. A "direct squeeze casting method" with a preheated die has been used to obtain samples for the determination of mechanical properties.Item Development of new aluminium alloys for semisolid processing(2003) Romera, R.; Goǹi, J.; Coleto, J.; Eguizabal, P.; Estevan, R.; Sainz, X.; Hurtado, I.; Azpilgain, Z.; Lete, I.; Armendariz, A.; Akizu, A.; Wielanek, L.; Centros PRE-FUSION TECNALIA - (FORMER); Mercado; Tecnalia Research & InnovationSemisolid metallurgy (SSM) or semisolid forming is an emerging technology that enables the forming of complicated shapes and the processing of materials increasing their mechanical properties compared with conventional methods. In the present article the advantages of SSM process are described in terms of fundamentals of the forming process and the microstructural characteristics of the product. An overview of the main casting methods in the semisolid state are also shown: Thixocasting and New Rheocasting (NRC). Each process is briefly analysed, their advantages/disadvantages identified and an attempt made to suggest that the latter one finds the optimal performance.Item High pressure die casting (HPDC) of advanced reinforced aluminium alloys(2004-06) Goñi, J.; Eguizabal, P.; Coleto, J.; Guridi, J. R.; Garitagoitia, I.; Garitagoitia, E.; Barbarias, E.; Centros PRE-FUSION TECNALIA - (FORMER); Tecnalia Research & Innovation; MercadoAn advanced material based on a AlSi8Cu3Fe alloy reinforced with 6%wt. of Titanium Diboride (TiB2) particles was employed to produce demonstrator clutch discs and to compare the obtained properties with those of the corresponding non reinforced alloy. The new material was produced through an in-situ reaction in which two salts were incorporated into the aluminium alloy melt to produce the reinforcing particles through an exothermal chemical reaction. The material so formed was first used to obtain samples through the direct Squeeze Casting technology at lab scale. Afterwards, it was also employed to produce some demonstrator prototypes with a conventional industrial High Pressure Die Casting (HPDC) equipment. Results obtained with the reinforced material with the Squeeze Casting and HPDC technologies are presented and compared to those obtained with the corresponding non reinforced equivalent. The effect of the TiB2 particles was analysed in terms of enhancement of mechanical properties at high temperatures, thermal properties, processing, etc. Minor changes had to be implemented in the moulds and equipments used to produce the final samples and components. The melt was stirred in order to avoid the settling phenomenon that might have taken place due to the difference of the density of the particles and the alloy. The processing parameters had to be fixed in order to take into account the different viscosity, castability and solidification pattern of the new material. Information on the optimization of the casting processes and properties of the Squeeze Casting and HPDC samples obtained are shown.Item Influence of the processing parameters on glass mat reinforced thermoplastic (GMT) stamping(1992) Rubio, A.; Eguizabal, P.; Mendizabal, M. A.; Liceaga, J. F.; Tecnalia Research & Innovation; POLIMEROS; Centros PRE-FUSION TECNALIA - (FORMER)The influence of both the processing parameters and mould geometry on the mechanical properties and surface quality of polypropylene based glass mat reinforced thermoplastic (gmt) parts was studied. The parameters controlled were the forming pressure, the temperature in the surface of the blank, and the mould temperature. The influence of the geometry was also studied using three different moulds. It was seen that the mechanical properties did not vary substantially for the ranges of temperature and pressure used. Some differences were seen among the data collected from different moulds and a correlation existed between the surface quality of the parts and the mould temperature and design.Item Mise en forme des alliages d'aluminium à l'état semi-solide: Une technologie compétitive pour les pièces automobiles(2004-11) Goñi, J.; Eguizabal, P.; Lakehal, M.; Sarriés, I.; Akizu, A.; Landa, I.; Wielanek, L.; Azpilgain, Z.; Hurtado, I.; Centros PRE-FUSION TECNALIA - (FORMER); Tecnalia Research & InnovationThe achievement of lighter automotive components is an important driving force m the development and optimization of casting techniques. Among these, Thixocasting and Squeeze Casting of aluminium alloys are presently used in the production of security components. In the present work, several production routes and aluminium alloys are considered. A die has been designed to produce a standard security component an automotive brake caliper. Simulation studies have been carried out to detect possible filling or solidification problems during casting and to solve them beforehand. Afterwards, automotive components have been produced with both a commercial globular structured A357 alloy through a semi-solid technology (Thixocasting) and a conventional A357 alloy by Squeeze Casting. General considerations of both casting processes are presented and some specific problems encountered are outlined. For comparison purposes, the automotive component selected has been also manufactured by means of other conventional casting technologies: sand casting, gravity die casting and low pressure die casting. Components from both sets of experiments have been heat treated and metallographic samples from problematic areas of the component selected have been thoroughly analyzed. Mechanical properties have been measured from tensile samples and the results compared for the different casting techniques evaluated.Item Processing of aluminium alloys in semi-solid state: A competitive technology for automotive components(2004) Goñi, J.; Eguizabal, P.; Lakehal, M.; Sarriés, I.; Akizu, A.; Landa, I.; Wielanek, L.; Azpilgain, Z.; Hurtado, I.; Centros PRE-FUSION TECNALIA - (FORMER); Tecnalia Research & InnovationThe achievement of lighter automotive components is an important driving force in the development and optimization of casting techniques. Among these, Thixocasting and Squeeze Casting of aluminium alloys are presently used in the production of security components. In the present work, several production routes and aluminium alloys are considered. A die has been designed to produce a standard security component: an automotive brake caliper. Simulation studies have been carried out to detect possible filling or solidification problems during casting and to solve them beforehand. Afterwards, automotive components have been produced with both a commercial globular structured A357 alloy through a semi-solid technology (Thixocasting) and a conventional A357 alloy by Squeeze Casting. General considerations of both casting processes are presented and some specific problems encountered are outlined. For comparison purposes, the automotive component selected has been also manufactured by means of other conventional casting technologies: sand casting, gravity die casting and low pressure die casting. Components from both sets of experiments have been heat treated and metallographic samples from problematic areas of the component selected have been thoroughly analyzed. Mechanical properties have been measured from tensile samples and the results compared for the different casting techniques evaluated.