M. Batista

Sustainable Manufacturing in Aerospace Industry – Analysis of the Viability of Intermediate Stages Elimination in Sheet Processing

Manufacturing performance improvement must take into account energetic, environmental and economic considerations. Thus, when intermediate manufacturing processes are avoided, that performance is improved from the cited viewpoints. In the aeronautical industry, pre-shaped elements of UNS A92024 alloy based structural elements are machined in T3 temper state previously to be thermally treated to reach an O state in order to facilitate its posterior plastic forming process. In this work, a comparative study on the dry turning of UNS A92024 alloy in both states has been achieved in order to analyze the possibilities of eliminating the thermal treatment process, so improving the three above commented considerations. This study has been carried out on the basis of the analysis of surface finish and cutting tool wear.

Identification, Analysis and Evolution of the Mechanisms of Wear for Secondary Adhesion for Dry Turning Processes of Al-Cu Alloys

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.

Image Based Analysis Evaluation of the Elements of Secondary Adhesion Wear in Dry Turning of Aluminum Alloys

Minimizing downtime in machine tools is one of the factors that determine the performance increase of the production processes involved. This increase can be considered from different points of view: economic, energetic and environmental. Machining processes can be stopped by needing to change the tool as a consequence of the loss of their initial properties due to the wear process that suffer during machining. One of the wear processes which takes place in a wider range of temperatures in the machining of metal alloys is the adhesion wear, and specially in the case of light alloys, secondary adhesion wear, which can be placed in the tool rake face as a layer (Built-Up Layer, BUL) and in the tool edge (Built-Up Edge, BUE). This paper analyzes the influence of cutting parameters on the secondary adhesion wear effects in the dry turning of UNS A92024 (Al-Cu) alloy.

SOM-SEM-EDS Identification of Tool Wear Mechanisms in the Dry-Machining of Aerospace Titanium Alloys

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.

A SEM and EDS based Study of the Microstructural Modifications of Turning Inserts in the Dry Machining of Ti6Al4V Alloy

Titanium and its alloys are considered as low machinability materials because of its low thermal conductivity, which provokes a high temperature in the tool‐chip interface. However, thanks to its excellent relationship weight/mechanical properties, this material is widely used in the aerospace industrial sector. This paper reports on the results of an analysis of the surface changes of hard metal (WC‐Co) turning inserts employed in the dry turning of alloy UNS 56400 (Ti‐6Al‐4V), widely used in aerospace industry. The analysis has been developed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques.

Processing and Quality Evaluation of Additive Manufacturing Monolayer Specimens

Although its importance has increased significantly, Additive Manufacturing is not yet a fully accepted industrial manufacturing process for load-carrying parts. The future success of the process group depends on its standardization. This work proposes a methodology for the design, manufacturing, and quality evaluation of specimens manufactured by Fused Layer Modeling that are composed of only one layer (so-called monolayers). The processing methodology and properties of monolayers have not been studied systematically yet. A first systematic design of monolayers for mechanical testing is presented. Rectangular and circular monolayers adapted to the loads of tensile and compression testing are manufactured using different trajectory strategies. Frequently occurring macro- and microgeometrical defects are evaluated and categorized in order to optimize the part quality. This work also studies the effect of some manufacturing parameters such as the gap between print head and machine bed, trajectory strategy, bed leveling, and temperatures on part quality. The most suitable specimens are tested mechanically in tensile or compression tests. In the case of study, tensile strength values are only 8.6% lower than the values for reference tests on the unextruded filament. However, the properties deviate more strongly for compression tests which may be due to the selected specimen geometry.

Cutting Speed-Feed Based Parametric Model for Macro-Geometrical Deviations in the Dry Turning of UNS A92024 Al-Cu Alloys

This work reports on the results of a study of different macro-geometrical deviation parameters, such as Straightness (SD), Parallelism (PD) and Circularity (CD) as a function of cutting speed (v) and feed (f) of dry turned UNS A92024 (Al-Cu) cylindrical bars. The results obtained have allowed establishing exponentials parametric model for predicting these deviations as a function of those cutting parameters. As a consequence of that, geometrical surfaces SD(f,v), PD(f,v) and CD(f,v) have been developed for this alloy. These surfaces allows determining marginal curves for specific v and f values, respectively, out the parameter ranges employed. So, macro-geometrical deviations can be predicted through this model for v and f values out of those considered in the study for each alloys.

CAL-CBT based virtual learning and training in Machining Engineering. A case study: CNC Lathe

Computer-Aided Learning is currently applied for improving educational methods in order to reach teaching objectives in experimental fields, which are in a continuous renovation process. So, handling new machines learning cannot be usually carried out in Teaching Centres because of the high economical inversion required. Furthermore, the number of students / number of machines ratio is too high. This acquires special relevance in technical studies where practical learning is essential. In this work, a virtual learning and training application for a CNC lathe is presented into a virtual learning environment developed in the Manufacturing Engineering Labs of the University of Cadiz.

A Study of Macrogeometrical Deviations in the Dry Turning of UNS R56400 Ti Alloy

The UNS R56400 is a Titanium alloy commonly used in the aircraft industry. This alloy can be processed by machining depending on its final application. Drilling and turning are the most usual machining processes for working this alloy. Aerospace requirements involve high quality levels and, if possible, an on-line monitoring in order to preserve the workpiece design conditions. The machining process can be monitored by different methods. One of the most single methods involves the analysis of the finishing quality of the workpieces. This analysis is usually related to micro and macro geometrical considerations. In this paper a study of the finishing quality of dry turned UNS R56400 Ti alloy has been achieved. This study has been carried out based on the analysis of straightness and parallelism deviations as functions of cutting parameters, such as feed and cutting speed.

Digital Modeling of End-Mill Cutting Tools for FEM Applications from the Active Cutting Contour

A very current technique in the research field of machining by material removal is the use of simulations using the Finite Element Method (FEM). Nevertheless, and although is widely used in processes that allows approximations to orthogonal cutting, such as shaping, is scarcely used in more complexes processes, such as milling. This fact is due principally to the complex geometry of the cutting tools in these processes, and the need to realize the studi es in an oblique cutting configuration. This paper shows a methodology for the geometrical characterization of commercial end-mill cutting tools, by the extraction of the cutting tool contour, making use of optical metrology, and using this geometry to model the active cutting zone with a 3D CAD software. This model is easily exportable to different CAD formats, such as IGES or STEP, and importable from FEM software, where is possible to study the behavior in service of the same ones.