Open Access
Weld joint reconstruction and classification algorithm for trajectory generation in robotic welding
(Trans Tech Publications, 2023) Curiel Braco, David; Veiga Suárez, Fernando; Suárez, Alfredo; Villanueva Roldán, Pedro; Aldalur, Eider; Ingeniería; Ingeniaritza
Open Access
Advancements and methodologies in directed energy deposition (DED-Arc) manufacturing: design strategies, material hybridization, process optimization and artificial intelligence
(IntechOpen, 2024-09-27) Uralde Jiménez, Virginia; Suárez, Alfredo; Veiga Suárez, Fernando; Villanueva Roldán, Pedro; Ballesteros Egüés, Tomás; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC
This chapter explores the latest advancements and methodologies in directed energy deposition (DED-arc) manufacturing. The introduction sets the stage for understanding the significance of these developments in the context of modern manufacturing needs. The discussion includes design strategies for DED-arc, emphasizing topological optimization, functional design, and generative design, alongside the application of artificial intelligence (AI) in enhancing design processes. Innovative approaches to material hybridization are detailed, focusing on both multilayer and in situ techniques for combining different materials to optimize component performance. The paper also covers slicing and pathing, examining slicing strategies, the use of lattice structures, and the implementation of 2D and 3D patterns to improve manufacturing efficiency and product quality. The conclusion summarizes key findings, discusses their implications for the additive manufacturing industry, and suggests potential future research directions in DED-arc technology, highlighting the emerging trends and innovations that are shaping the field.
Open Access
Wire arc additive manufacturing Ti6Al4V aeronautical parts using plasma arc welding: Analysis of heat-treatment processes in different atmospheres
(Elsevier, 2020-11-20) Artaza, Teresa; Suárez, Alfredo; Veiga Suárez, Fernando; Braceras, Íñigo; Tabernero, Iván; Larrañaga, Oihane; Lamikiz, Aitzol; Ingeniería; Ingeniaritza
PAW (Plasma Arc Welding), a WAAM (Wire Arc Additive Manufacturing) technology with high deposition rates, can produce metallic components, layer by layer, of varied sizes, from different alloys, yielding high mechanical performance. Two Ti6Al4V walls are manufactured in an inert argon atmosphere using WAAM-PAW to analyze the deposition process in terms of growth in height per layer, deposition process temperature, and cooling times. The properties of the walls are compared with the values obtained from a thermo-mechanical simulation and both the microstructural and mechanical properties of the annealed WAAM-PAW wall are studied. Moreover, the effect of the media on the oxidation layer and on the mechanical properties are also analyzed throughout the heat treatment process, as well as the microstructure of Ti6Al4V. Stable deposition rates were achieved for a high deposition ratio of Ti6Al4V at 2 kg/h, restricting the oxygen levels to under 100 ppm. No significant differences were found in either the microstructural or the mechanical properties following heat treatments in a vacuum, in air or in argon. All the heat-treated samples met the AMS4928 standard for Yield Strength (YS) and Ultimate Tensile Strength (UTS).
Open Access
Metal transfer modes for Wire Arc Additive Manufacturing Al-Mg alloys: influence of heat input in microstructure and porosity
(Elsevier, 2021-06-28) Aldalur, Eider; Suárez, Alfredo; Veiga Suárez, Fernando; Ingeniería; Ingeniaritza
Wire Arc Additive Manufacturing (WAAM), an additive manufacturing technology for the manufacture of medium-to-large size metallic parts, is generating great interest. This technology employs aluminum alloys that are of immense interest for manufacturing, due to their high strength-weight ratio, corrosion resistance and utilization in different industries. Among these materials, some of the most widely used in various industrial fields are alloys classified within the 5000 series that are of good weldability and, consequently, very suitable for WAAM technology. In this paper, aluminum alloy 5356 is analyzed in the Gas Metal Arc Welding (GMAW)-based WAAM technological process. From among the various recommended working modes of different manufacturers, three working modes for aluminum alloys are compared: pulsed-GMAW mode, Cold Arc mode and pulsed-AC mode. To do so, test samples composed of single mono-layer weld beads and single-bead walls are manufactured using each working mode and micro and macro-structural properties, geometrical shape and porosity levels of the finished products are evaluated. As a novelty, this paper includes pulsed-AC as a new transfer mode for application on aluminum. Not only does it show its viability for the manufacture of parts by WAAM, but it also allows the reduction of the presence of pores by more than six times compared to Cold Arc mode and ten times compared to pulsed-GMAW mode. This aspect makes it a very attractive mode for use on this aluminum alloy.
Open Access
The use of virtual sensors for bead size measurements in wire-arc directed energy deposition
(MDPI, 2024) Fernández Zabalza, Aitor; Veiga Suárez, Fernando; Suárez, Alfredo; Alfaro López, José Ramón; Ingeniería; Ingeniaritza
Having garnered significant attention in the scientific community over the past decade, wire-arc directed energy deposition (arc-DED) technology is at the heart of this investigation into additive manufacturing parameters. Singularly focused on Invar as the selected material, the primary objective revolves around devising a virtual sensor for the indirect size measurement of the bead. This innovative methodology involves the seamless integration of internal signals and sensors, enabling the derivation of crucial measurements sans the requirement for direct physical interaction or conventional measurement methodologies. The internal signals recorded, the comprising voltage, the current, the energy from the welding heat source generator, the wire feed speed from the feeding system, the traverse speed from the machine axes, and the temperature from a pyrometer located in the head were all captured through the control of the machine specially dedicated to the arc-DED process during a phase of optimizing and modeling the bead geometry. Finally, a feedforward neural network (FNN), also known as a multi-layer perceptron (MLP), is designed, with the internal signals serving as the input and the height and width of the bead constituting the output. Remarkably cost-effective, this solution circumvents the need for intricate measurements and significantly contributes to the proper layer-by-layer growth process. Furthermore, a neural network model is implemented with a test loss of 0.144 and a test accuracy of 1.0 in order to predict weld bead geometry based on process parameters, thus offering a promising approach for real-time monitoring and defect detection.
Open Access
Wire arc additive manufacturing of invar parts: bead geometry and melt pool monitoring
(Elsevier, 2022-02-15) Veiga Suárez, Fernando; Suárez, Alfredo; Aldalur, Eider; Artaza, Teresa; Ingeniería; Ingeniaritza
Additive manufacturing processes using the direct energy deposition method, one of which is the Wire Arc Additive Manufacturing (WAAM), have gained much attention in the scientific community over the last decade. The application of WAAM to Invar, an iron-nickel and manganese alloy, with a low amount of chromium carbon, also called FeNi36 or Nivarox has been the subject of various reports due to its challenging nature. This paper utilizes and unifies research material previously investigated in this technology, taking a new approach based on the study of symmetrical phenomena that guarantee the quality of the process. On the one hand, a method of analysis of the geometry of the manufactured wall is presented based on its symmetrical quality which guarantees the maximum use of material and, on the other hand, the monitoring of the symmetry of the melting pool utilizing thermography techniques.
Open Access
Analysis of the machining process of short carbon fiber-reinforced polyamide additive manufactured parts
(Elsevier, 2024) Suárez, Alfredo; Veiga Suárez, Fernando; Penalva Oscoz, Mariluz; Ramiro, Pedro; Ballesteros Egüés, Tomás; Ingeniería; Ingeniaritza
In recent years, additive manufacturing technologies have revolutionized the production of parts, particularly in the aeronautical sector. This new manufacturing paradigm has created significant challenges and opportunities for researchers in materials and manufacturing processes. One important aspect is the development of optimal strategies for finishing-oriented machining of parts produced through additive manufacturing. This article focuses on the analysis of reinforced polyamide materials and the integration of large-scale additive manufacturing using Big Area Additive Manufacturing (BAAM) technology, along with robotic systems for subtractive machining. The aim is to explore the potential of integrating additive and subtractive processes to produce high-quality, large-scale components. The study examines the production and subsequent machining of reinforced polyamide parts using BAAM technology, showcasing the advantages and promising results observed. By combining additive manufacturing with subtractive machining, this research contributes to the ongoing advancements in the field of manufacturing, particularly in relation to reinforced polyamide materials. The findings presented in this article shed light on the potential of integrating additive and subtractive processes in the manufacturing industry, paving the way for more efficient and high-quality production methods.
Open Access
Validation of the use of concept maps as an evaluation tool for the teaching and learning of mechanical and industrial engineering
(Springer, 2024) Veiga Suárez, Fernando; Gil del Val, Alain; Iriondo, Edurne; Eslava Adot, Urko; Ingeniería; Ingeniaritza; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
This paper presents the experimental work developed to measure the learning process through concept map analysis. The development of a concept map is requested by the students for each chapter or theme of the subject. As a result, maps from engineering courses have been analyzed. The measurements carried out consider several parameters, such as individual and team map building, student progressive knowledge level, and map complexity. Concerning the complexity analysis, the focus is qualitative, and it is based on the data extracted from the concept maps elaborated by the students. The study, conducted during the 2018-2019 academic year, included students from various academic levels and institutions, such as the Public University of Navarra UPNA and the University of the Basque Country UPV-EHU, covering first-degree students of Bachelor's Degree in Mechanical Engineering and first-degree students of Master's Degree in Industrial Engineering at UPNA, third-degree students of Bachelor's Degree in Mechanical Engineering at UPV-EHU. The data collected from 37 individual maps in Industrial Drawing, 31 group maps in Industrial Drawing, 12 individual maps in Design of Machinery, and 12 group maps in Design of Machinery, along with a control group of 79 students who did not participate in any activity, provided valuable insights into the effectiveness of concept maps for evaluating understanding levels and learning outcomes across various engineering subjects and academic levels. The learning outcome of the students is treated to obtain the level of understanding of complex systems shown by the students through the concept maps previously drawn and the questionnaire answered by each student about the achievement of learning results through the use of concept maps. This work shows the research methodology established and the learning results achieved qualitatively: measuring the maps by means of a rubric, self-assessment based on a survey, and through the questionnaires. Also, the results obtained in the final exams have been compared. From the observed results, this methodology is presented as a suitable alternative for evaluating the correct acquisition of concepts in online teaching situations.
Open Access
Effect of the metal transfer mode on the symmetry of bead geometry in WAAM aluminum
(MDPI, 2021) Veiga Suárez, Fernando; Suárez, Alfredo; Aldalur, Eider; Bhujangrao, Trunal; Ingeniería; Ingeniaritza
The symmetrical nature in the case of wall fabrication by wire arc additive manufacturing (WAAM) has been observed in the literature, but it has not been studied as a source of knowledge. This paper focuses on the comparative study of three drop transfer methods employing Gas Metal Arc Welding (GMAW) technology, one of the most reported for the manufacture of aluminum alloys. The transfer modes studied are the well-known pulsed GMAW, cold arc, and the newer pulsed AC. The novelty of the last transfer mode is the reversal of the polarity during the preparation phase of the substance for droplet deposition. This study compares the symmetry of zero beads to deter-mine the best parameters and transfer modes for wire arc additive manufacturing of 5 series aluminum. The pulsed transfer modes show values of 0.6 for symmetry ratio, which makes them more interesting strategies than cold arc with a symmetry ratio of 0.5. Furthermore, the methodology proposed in this study can be extrapolated to other materials manufactured with this technology.
Open Access
Modeling of cutting force and final thickness for low stiffness 2024-T3 aluminum alloy part milling considering its geometry and fixtures
(Elsevier, 2022) Casuso, Mikel; Rubio Mateos, Antonio; Veiga Suárez, Fernando; Lamikiz, Aitzol; Ingeniería; Ingeniaritza
The aeronautic industry is facing many challenges regarding the lifetime, weight and accuracy that aircraft skins must comply to meet stringent structural and aerodynamic requirements. Currently, mechanical milling of aircraft skin parts of 2024-T3 aluminum alloy is displacing the highly pollutant chemical milling. Consequently, flexible and reconfigurable vacuum holding fixtures are being increasingly employed, because they are adaptable to several part geometries, but, since their rigidity is extremely reduced, the low stiffness of parts limits severely their deployment. Aiming to harness the full potential of these holding systems for aluminum alloy skin parts, a complete analysis of final thickness achieved and cutting force is developed. Thin floor parts of different geometries are pocket milled, simply screwed at their corners, emulating a skin part supported by four vacuum cups. Process forces are continuously monitored, and final thickness is measured. It has been proven that the reduction of mass and stiffness during milling causes a corresponding reduction of the natural frequencies of the parts. Also, as long as natural frequencies are not excited, final thickness error is almost constant and not affected by the tool position, but only by the initial geometry and fixtures distribution of the part. Additionally, a new cutting force model for skin parts is empirically calculated. Unlike models designed for fully supported parts, this model is designed for skins held in flexible fixtures. It has a relative error of 5.6% and it allows to optimize the trajectory, geometry and support distribution, thus boosting the use of flexible fixtures.