Papers by Author: Miguel Álvarez

Abstract: University studies have changed in Spain in the last five years in order to adequate them to the European Space for Higher Education. Under these changes Spanish law fixes the skills and abilities that must acquire the Graduates in Engineering with competences and applications in the Industrial Field. Among them, it can be found the corresponding to Manufacturing Engineering. In this work an Integrated Lab-Practical Class has been performed including different stages of a Manufacturing Process from the Product/Process Design to the Final Product. This Practical Class is developed in six sessions. This experience has shown the interest of the students for the contents of the subject and its relationship with the theoretical concepts.

Abstract: Project Based Learning techniques have given rise to other learning techniques as Research Works Based Learning (RWBL). This technique is especially interested in the teching-learning process of Materials Processing Technologies related disciplines. This work reports on the results of the application of RWBL techniques in a subject of the Cadiz University’s Master in Manufacturing Engineering: Engineering of Non-Conventional Materials Removing Processes. Proposed research works have been designed on the basis of a classic research paper structure: Introduction, State of the Art, Experimental Procedure, Results, Discussion and Conclusions. These proposed works were focused on a comparative analysis of different machining processes, mainly, electro-discharge machining, abrasive waterjet machining and high speed machining. This experience can be considered highly successful because the 100% of the students reached the learning objectives of the subject.

Abstract: In this work, Stereoscopic Optical Microscopy (SOM), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) have been applied for analyzing the evolution of tool wear during the dry turning process of aerospace Al-Cu alloys. The results derived from this analysis have revealed that secondary adhesion is the main tool wear mechanism that takes place in such process. So, in the first instants of the machining process, a Built-Up Layer (BUL) is developed onto the tool rake face by thermomechanical causes, promoting the conditions for developing a Built-Up Edge (BUE) which grows to a critical size. Starting from it, BUE is extruded giving rise to secondary BUL-BUE effects. When these are removed, tool particles are dragged out provoking the tool wear.

Abstract: Titanium based alloys, mainly UNS R56400 (Ti6Al4V), are increasingly being applied in the airship building industry due to its excellent physicochemical properties. Machining operations are usually required in the manufacturing processes of Ti based aerospace structural elements. However, high reactivity of Ti provokes a quick tool wear. So, in order to reach an economically acceptable production level, it is necessary to minimize the costs associated to tool wear. In this work, Scanning Electron Microscopy (SEM), Stereoscopic Optical Microscopy (SOM) and Energy Dispersive Spectroscopy (EDS) have been used for both analysing and identifying secondary adhesion mechanisms that are taking place when an aeronautical titanium alloy is machined. Special severe cutting conditions have been applied. Thus, titanium alloy have been dry machined with TiN coated WC-Co tools. Results obtained have shown that tool wear is controlled by a secondary adhesion mechanism, which presents two stages. A first stage is constituted by a TiOx multi-film formed onto the tool surfaces. A second step involves the mechanical adhesion of the alloy material to those surfaces. When this material is removed, tool particles are dragged off causing tool wear.

Abstract: Carbon Fiber (CF)/Metallic Alloy (MA) laminar structures, also known as Fiber Metal Laminates (FML) allow diminishing the airship weight. Because of that the use of these materials is growing continuously in the aerospace industry. These composites materials need to be drilled because of the assembly requirements in the different airship elements. The most common problems that can appeared when those structures are machined are related with the interaction of the tool with dissimilar materials, which need different cutting parameters for the optimized machining process. This work reports on the results about a study of the dry drilling processes of hybrid composites Carbon Fiber/aluminum alloy, and especially CF/AA2024.