The Ti6Al4V alloy is included in the group of difficult-to-cut materials. Segmented chips are generated for a wide range of cutting parameters. This kind of chip geometry leads to the periodic variation of machining forces, tool vibrations, and work part-tolerance inaccuracies. Therefore, the analysis of chip morphology and geometry becomes a fundamental machinability criterion. However, few studies propose experimental parametric relationships that allow predicting chip-geometry evolution as a function of cutting parameters. In this work, an experimental analysis of the influence of cutting speed and feed rate on various chip-geometric parameters in dry machining of the Ti6Al4V alloy was carried out. In addition, the chip morphology and chip microstructure were studied. A clear dependence of certain chip-geometric parameters on the cutting parameters studied was found. From the experimental data, several parametric relationships were developed. These relationships were able to predict the evolution of different geometric parameters as a function of cutting speed and feed, within the tested range of values. The differences between the proposed models and the experimental data were also highlighted. These parametric equations allowed quantifying the value of parameters in which the trend was clear.

Macro-geometrical deviations play a very important role in the functionality and reliability of structural parts for aircraft. The use of environmentally friendly techniques, such as dry machining, may negatively affect these deviations. Despite its importance, there is a lack of research that analyzes them as a function of the cutting parameters in the case of aluminum alloys for aeronautical purpose. In this work, the cutting speed and feed influence on several macro-geometrical deviations (parallelism, straightness, circular run-out, roundness, concentricity, total circular run-out and cylindricity) in dry turning of UNS A97075 alloy was analyzed. The main novelty of this work lies in the use of high slenderness parts used in further fatigue tests. The results showed that feed seems to be the most influential parameter in most of the deviations studied. In addition, the parts with lower rigidity exhibited higher sensitivity to change with the cutting parameters. Finally, different parametric models were proposed to obtain the geometrical deviations as a function of the cutting parameters.

Aluminum alloys are widely used in the manufacturing of structural parts for aircraft, frequently in combination with other materials such as CFRP (Carbon Fiber Reinforced Polymer), to form FML (Fiber Metal Laminates) structures (CFRP/Al). The dry machining of these structures presents several problems, some of which are related to chip evacuation, either when machining aluminum alloys as an isotropic material, or during hybridization with composites. In this work, a study of the way in which cutting parameters influence the chip morphology in the dry machining of UNS A97075-T6 (Al-Zn) and UNS A92024-T3 (Al-Cu) alloys, is performed. Thus, different geometric parameters of the chip morphology have been obtained, and their evolution with feed has been analysed. Finally, the different relationships which occur between these geometric parameters and feed, have been obtained. These relationships allow a prediction of the evolution of some of the geometric parameters of the chip, as a function of feed.

In this work, an analysis of the cutting speed and feed influence on surface roughness and microhardness of UNS A97075-T6 alloy, turned under dry conditions, was carried out. The results were compared before and after a corrosion process. The influence of these cutting parameters on each of these variables was analyzed, as well as the possible interrelation between them. The microgeometrical deviations showed a general trend to increase with feed. However, no significant modifications were observed as a function of the cutting speed. This trend was softer after the corrosion process, due to the surface alterations produced by pitting corrosion, which resulted in higher dispersion of the experimental data. In addition, a surface microhardness increment was observed in all samples, after machining and before corrosion, regardless of the cutting parameter values. The experimental results revealed that the mechanical effects, produced by the feed, should not be neglected against the thermal effects, produced by the cutting speed, within the range of the tested cutting speed. Finally, the corrosion process negatively affected the microhardness, but it was not possible to establish a direct relationship between the cutting parameters, surface roughness, and microhardness after a corrosion process.

Nowadays, localized forming operations, such as incremental forming processes, are being developed as an alternative to conventional machining or forming techniques. An indentation process is the main action that takes places in these forming activities, allowing small, localized deformations. It is essential to have the knowledge of the material behavior under the punch and the transmitted forces to achieve correct control of the entire procedure. This paper presents the work carried out with the digital image correlation (DIC) technique applied to the study of the material flow that takes place under an indentation process. The material flow analysis is performed under 2D and 3D conditions, establishing the methodology for the calibration and implementation for each alternative. Two-dimensional DIC has been proven to be a satisfactory technique compared with the 3D method, showing results in good agreement with experimental tests and models developed by the finite element method. Notwithstanding, part of the indented material flows under the punch, emerging on the front surface and generating a dead zone that can only be addressed with a 3D technique. So, the main objective is to carry out a comparison between the 2D and 3D techniques to identify if the 3D application could be mandatory for this type of process. Also, a 2D-3D mix analysis is proposed for study cases in which it is necessary to know the material flow in that specific area of the workpiece.

Fatigue behavior takes special relevance in structural parts for aircraft due to safety reasons. Despite its environmental advantages, dry machining of these parts may negatively affect their surface integrity, which may lead to a reduction in fatigue life. Nevertheless, there is a lack of research focused on the analysis of the cutting parameters influence on fatigue behavior in dry machining of aeronautical aluminum alloys, in spite of its importance. Therefore, in this work, an analysis of the cutting speed and feed influence on fatigue behavior of dry turned UNS A97075-T6 alloy is presented. The stress-fatigue life curves have been obtained and corrected according to the applied cutting parameters values. Additionally, the surface roughness and two macro-geometrical deviations (cylindricity and concentricity) have been controlled. The experimental results have revealed that fatigue life is reduced when high values of cutting speed and feed are combined. Finally, a parametric potential equation for fatigue life, as a function of the load and the cutting parameters, has been developed. The relation has been obtained for the theoretical fracture section and, as the main novelty, corrected for the real one.

Geometrical tolerances play a very important role in the functionality and assembly of parts made of light alloys for aeronautical applications. These parts are frequently machined in dry conditions. Under these conditions, the tool wear becomes one of the most important variables that influence geometrical tolerances. In this work, the influence of tool wear on roundness, straightness and cylindricity of dry-turned UNS A97075 alloy has been analyzed. The tool wear and form deviations evolution as a function of the cutting parameters and the cutting time has been assessed. In addition, the predominant tool wear mechanisms have been checked. The experimental results revealed that the indirect adhesion wear (BUL and BUE) was the main tool-wear mechanism, with the feed being the most influential cutting parameter. The combination of high feed and low cutting speed values resulted in the highest tool wear. The analyzed form deviations showed a general trend to increase with both cutting parameters. The tool wear and the form deviations tend to increase with the cutting time only within the intermediate range of feed tested. As the main novelty, a relationship between the cutting parameters, the cutting time (and, indirectly, the tool wear) and the analyzed form deviations has been found.

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