Ignacio Puertas

A study on the machining parameters optimisation of electrical discharge machining

Abstract The optimum selection of manufacturing conditions is very important in manufacturing processes as these ones determine surface quality and dimensional precision of the so-obtained parts. Thus, it is necessary to know, in advance, properties relating to surface quality and dimensional precision by means of theoretical models which allow to do some predictions taking into account operation conditions such as gap, dielectric fluid, penetration speed, etc. Manufacturing materials with non-conventional processes such as electrical discharge machining, shows really important aspects to study from the point of view of materials science, heat transmission, mechanics and manufacturing processes optimisation. This study is mainly focused on aspects related to surface quality and dimensional precision, which are one of the most important parameters form the point of view of selecting the optimum conditions of processes, as well as economical aspects. Functions making it possible to optimise parameters related to surface quality in such manufacturing processes will be obtained by means of using mathematical models that will allow us to select the optimum manufacturing conditions.

FEM Modelling and Experimental Analysis of an AA5083 Turbine Blade from ECAP Processed Material

This present research work deals with the design by finite element method (FEM) of the dies required for the isothermal forging of a Francis turbine blade taking into account that the starting material has been previously nanostructured through severe plastic deformation by equal channel angular extrusion. This nanostructured material possesses improved mechanical properties and hardness, better forgeability, and, under specific conditions, a superplastic behavior. Once this material is obtained, its flow rule has been determined through compression tests at different temperature values along with its subsequent fitting with artificial neural networks. Later on, these rules will be employed in the FEM simulations included in this present study. Furthermore, the results of the processing of these materials are shown comparing the properties of the mechanical components after their isothermal forging at different temperature values both with predeformed and non-predeformed material. This work is at the cutting-edge of technology because there are only a few technical papers about forging applications of nanostructured material.

Grain Refinement of Pure Copper by ECAP

Pure commercial Cu of 99,98 wt % purity was processed at room temperature by Equal- Channel Angular Pressing (ECAP) following route Bc. Heavy deformation was introduced in the samples after a considerable number of ECAP passes, namely 1, 4, 8, 12 and 16. A significant grain refinement was observed by transmission electron microscopy (TEM). Tensile and microhardness tests were also carried out on the deformed material in order to correlate microstructure and mechanical properties. Microhardness measurements displayed a quite homogeneous strain distribution. The most significative microstructural and mechanical changes were introduced in the first ECAP pass although a gradual increment in strength and a slight further grain refinement was noticed in the consecutive ECAP passes.

Comparison between FEM and Experimental Results in the Upsetting of Nano-Structured Materials

Over recent years, some severe plastic deformation processes have been developed with the aim of obtaining a material with sub-micrometric or even nanometric grain size, such as: ECAE (Equal channel angular extrusion) and HPT (High pressure torsion) among many others. The main aim of this present study is to analyse the upsetting of the 5083 Al-Mg-Mn alloy, which had been previously deformed by ECAE. Different processing temperatures will be used and the final properties of the resulting material will be determined.

Simulation and analysis of isothermal forging of AA6063 obtained from material processed by equal channel angular pressing severe plastic deformation

In this research study, a comparative examination on the mechanical properties of AA6063 has been carried out after having been processed by isothermal forging, using plane-shape dies and starting from different initial deformation states. It introduces the novelty of employing experimental data obtained from the isothermal forging so as to model the flow rules of AA6063 processed by equal channel angular pressing taking temperature into account and using artificial neural networks to this end. Subsequently, these flow rules are employed to model the behaviour of AA6063 by means of finite element simulation. Furthermore, a validation of the experimental results is made with those obtained from the simulations using the flow rules attained with the neural networks. It is shown that it is possible to achieve higher precision than with traditional fitting methods of flow rules. In addition, this study presents the novelty of carrying out a comparative study between different starting material states, prior to forging, including among these material previously processed by the severe plastic deformation process, which is referred to as equal channel angular pressing. Moreover, the experimental results obtained when processing the aluminium alloy by equal channel angular pressing are compared to those states, which correspond to the traditional way of working on aluminium alloys, which can be quenched and aged for the purpose of improving their mechanical properties.

Analysis on the Manufacturing of an AA5083 Straight Blade Previously ECAE Processed

Over these past few years, there have been a large number of technical papers published related to the problem of improving the mechanical properties of materials obtained through severe plastic deformation. Nevertheless, the number of technical papers dealing with improvement in the mechanical properties of mechanical components manufactured from submicrometric grain size material has not been so proficient. Therefore, in this present research work, a straight blade has been manufactured starting from AA-5083 previously processed by ECAE twice (N2) with route C. This material will be manipulated so as to be isothermally forged at different temperature values. This present research work shows the results that are inherent in an improvement in the mechanical properties and the microstructure achieved in the thus obtained components, compared with the starting material. In addition, the optimum forging temperature to achieve these components will be determined. As shown in this research work, it is possible to obtain submicrometric grain size mechanical components with a higher mechanical strength than those obtained in nonultrafine grained materials. The originality of this research work lies in the manufacturing of actual mechanical components from ECAE processed material and the analysis of their properties.

A Method for Obtaining Spur Gears from Nanostructured Materials

ECAE process is a novel technology which allows us to obtain materials of sub-micrometric and/or nanometric grain size as a result of accumulating very high levels of plastic deformation in the presence of high hydrostatic pressure. This avoids the material being fractured and permits very high values of plastic deformation to be obtained (ε>>1). Therefore, these nanostructured materials can be used as starting materials for other manufacturing processes such as: extrusion, rolling and forging among others; with the advantage of providing nanostructure and hence improving the mechanical properties. In this present study, forging by finite element of materials that have been previously predeformed by ECAE is analysed. MSC.MarcTM software will be employed with the aim of analysing the possibility of manufacturing mechanical components (spur gears) from materials nanostructured by ECAE.

Experimental and FEM Analysis of the AA 6082 Processed by Equal Channel Angular Extrusion

Recent studies have shown that severe plastic deformation processes (SPD) improve the mechanical properties of the processed parts. Some of the most outstanding SPD processes are as follows: High Pressure Torsion (HPT), Repetitive Corrugation and Straightening (RCS), Cyclic Extrusion Compression (CEC), Accumulative Roll Bonding (ARB), Conform and Continuous Combined Drawing and Rolling (CCDR), among others, but the most well-known is Equal Channel Angular Extrusion or Pressure (ECAE/ECAP). The aim of these processes is to introduce high values of deformation inside the parts in order to reduce the grain size and thus to improve the mechanical properties of the starting material. The study of the damage imparted to an AA-6082 alloy is made in the present work. This alloy is received as cast and it is quenched at a temperature of 530 °C during 4 hours in order to be processed by ECAE at room temperature using different geometries of the dies. The imparted damage is also studied by using FEM simulations.

Comparative analysis of injection systems for manufacturing parts

Abstract The present study focuses on aspects of the surface qualities of prototypes obtained by injection techniques. The surface finish and dimensional precision of parts obtained through these manufacturing processes is often highly important. Moreover, it is important to have an estimation of the average surface roughness in order to select the operation parameters adequately. Although there are a lot of different techniques for evaluating the surface roughness, one of the most commonly employed methods for characterising roughness involves assessment of surface roughness average by means of stylus instruments. Prototype manufacturing using two different systems of multijet injection technology was carried out, modifying the manufacturing conditions for obtaining the prototypes. After parts were obtained, an experimental study of effective roughness was done. Also, a comparative study using two injection systems with different accuracy was performed in order to evaluate the capability of these rapid prototyping techniques for manufacturing parts.

Modeling of the Behavior of an Aluminum Metallic Foam by Both FEM and Experimental Results

Aluminum foams are porous metallic materials which possess an outstanding combination of physical and mechanical properties such as: a high rigidity with a very low density. In this present research work, a study on the upsetting of an aluminum foam (with a density = 0.73 g/cm3) is carried out by employing different compression velocity values. From the results obtained, it is possible to determine the material flow stress for its subsequent use in finite element simulations (FEM). Once the material flow stress has been determined, it will be employed in order to analyze the conformability of several parts by FEM.