Browsing by Author "Lamikiz, Aitzol"
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Item Analysis of the Wall Geometry with Different Strategies for High Deposition Wire Arc Additive Manufacturing of Mild Steel(Multidisciplinary Digital Publishing Institute (MDPI), 2020-07) Aldalur, Eider; Veiga, Fernando; Suárez, Alfredo; Bilbao, Jon; Lamikiz, AitzolAdditive manufacturing has gained relevance in recent decades as an alternative to the manufacture of metal parts. Among the additive technologies, those that are classified as Directed Energy Deposition (DED) are characterized by their high deposition rate, noticeably, Wire Arc Additive Manufacturing (WAAM). However, having the inability to produce parts with acceptable final surface quality and high geometric precision is to be considered an important disadvantage in this process. In this paper, different torch trajectory strategies (oscillatory motion and overlap) in the fabrication of low carbon steel walls will be compared using Gas Metal Arc Welding (GMAW)-based WAAM technology. The comparison is done with a study of the mechanical and microstructural characteristics of the produced walls and finally, addressing the productivity obtained utilizing each strategy. The oscillation strategy shows better results, regarding the utilization rate of deposited material and the flatness of the upper surface, this being advantageous for subsequent machining steps.Item Characteristics of Fe-, Ni- and Co-based Powder Coatings Fabricated by Laser Metal Deposition without Preheating the base Material(2018) Ramiro, Pedro; Alberdi, Amaia; Ortiz, Mikel; Lamikiz, Aitzol; Ukar, Eneko; FABRIC_INTELThe objective of this work was to select the best material from Fe-, Ni- and Co-based alloy powder for coating, by Laser Metal Deposition (LMD) the filets of a hardened 42CrMoS4 extrusion screw without preheating process. Even though most of the articles recommended preheating the base material as a condition for a crack free coating, the time wasted in the process decrease the productivity and distortions can be also generated in the part. In this work, a comparison of the main characteristics of the coatings done on preheated and non-preheated base material has been made. The relationships between the relevant LMD parameters (feed rate, laser power, and powder feeding rate) and the main geometrical characteristics of a single clad (height, width, dilution, deposition rate, efficiency, etc.) were examined. In addition, different characteristics of overlapped clads in a preheated, non-preheated and a hardened base material have been also analyzed. All the study was made in the Ibarmia ZVH 45/1600 Add+Process hybrid machine with a high power Yb-Fiber laser (3 kW) and discrete coaxial LMD head. Coatings with thickness from 1.2 to 0.76 were created without cracks and other defects except in the case of Ni-based coating. The microstructural features of these coatings were studied using optical and scanning electron microscopy. The mechanical properties were determined using microhardness measurements and a pin on disk tribometer.Item Characteristics of Fe-based powder coatings fabricated by laser metal deposition with annular and four stream nozzles(2018) Ramiro, Pedro; Ortiz, Mikel; Alberdi, Amaia; Lamikiz, Aitzol; FABRIC_INTELThe present work focuses on performing a comparative study in the field of Laser Metal Deposition (LMD) analyzing the obtained clads in terms of geometry and quality when vertically using a discrete coaxial nozzle or an annular one. A Fe-based alloy powder (Eutroloy 16606A.04) was used for the study, a heat treatable alloy, with high wear-resistant to abrasion and fatigue stress, typically employed for coating applications. The possibility of controlling the coating process with a non-coaxial thermographic camera has also been evaluated.Item Effects of Gravity and Non-Perpendicularity during Powder-Fed Directed Energy Deposition of Ni-Based Alloy 718 through Two Types of Coaxial Nozzle(2020-04) Ramiro-Castro, Pedro; Ortiz, Mikel; Alberdi, Amaia; Lamikiz, Aitzol; Tecnalia Research & Innovation; FABRIC_INTELThe consequences of gravity and the nozzle inclination angle in the powder-fed Directed Energy Deposition (DED) process were examined in this study. We also sought to define guidelines and manufacturing strategies, depending on the DED system configuration and the nozzle type. To do so, two nozzle types were used: a continuous coaxial nozzle with a slit of 0.5 mm and a four-stream discrete coaxial nozzle. Although the main effects of the configurations and the nozzles are well-known, their effects on the clad characteristics and the deposition strategy are as yet unclear. In this paper, measurements of a single clad and the effects of different deposition strategies on cladding applications and inclined walls are presented, and the consequences for manufacturing processes are discussed. Based on a complete study of a single clad, working vertically, five different tilted deposition strategies were applied: three to a single clad and two to an inclined wall. The results for both the single clad and the inclined wall reflect a pattern of changes to height, width, area, and efficiency, at both small and large nozzle angles and deposition strategies. The inclined wall presents a maximum horizontal displacement that can be reached per layer, without geometrical distortions. The amount of material per layer has to be adapted to this limitation.Item Effects of the Nozzle Tip Clogging and the Scanning Direction on the Deposition Process During Laser Metal Deposition of Alloy 718 Using a Four-Stream Discrete Nozzle(2019) Artaza, Teresa; Ramiro, Pedro; Ortiz, Mikel; Alberdi, Amaia; Lamikiz, Aitzol; FABRIC_INTELDepending on the configuration of the LMD system, the nozzle tilting is necessary to be able to manufacture parts with complex geometry. In these cases, the use of discrete coaxial nozzles is recommended. With this type of nozzle, the powder can clog the internal tips of the nozzle streams due to an inappropriate shape, size distribution, humidity or temperature conditions of the powder particles during the deposition process. This undesired effect can be an opportunity depending on the combination of the activated powder tips for coating complex surfaces when the geometry of the substrate acts as a barrier for the powder stream. This work presents for first time the effect of the scanning direction and the stream clogging on the deposition process in terms of powder efficiency, Material Deposition Rate (MDR) and clad geometry and dimensions, when Alloy 718 is deposited by LMD using a four-stream discrete coaxial nozzle.Item Geometrical model and strategy in single and multilayer structures deposited by powder-fed Directed Energy Deposition(2020) Ramiro, Pedro; Ortiz, Mikel; Alberdi, Amaia; Lamikiz, Aitzol; FABRIC_INTELThis work presents a geometrical model of coatings fabricated by powder-fed Directed Energy Deposition (DED) and defines guidelines and manufacturing strategies for multilayered structures based on the geometrical model results. This model obtains as output both the overlapped clad geometry and the dilution area of the coating at different input parameters and defines the strategy of multi-layer structures. The results of this work validate the model that comes in handy: a) To understand the influence of each parameter and the single clad geometry when fabricating coatings and structures; b) To select the parameters depending on the requirements of the coating like effective thickness and dilution; c) To detect lack of fusion with the substrate due to an excessive overlap percentage; d) To select the deposition strategy and the tool path for additive manufacturing; e) To select the subsequent machining strategy based on the predicted geometry of the model.Item Hardness, grainsize and porosity formation prediction on the Laser Metal Deposition of AISI 304 stainless steel(2018-12) Arrizubieta, Jon Iñaki; Lamikiz, Aitzol; Cortina, Magdalena; Ukar, Eneko; Alberdi, Amaia; FABRIC_INTELThe presented numerical model solves the heat and mass transfer equations in the Laser Metal Deposition process and based on the evolution of the thermal field predicts the grainsize, the resulting hardness and evaluates the pores formation probability in an AISI 304 stainless steel. For this purpose, in a first step, the model calculates the shape of the deposited material and the variations of the temperature field. In a second step, and based on the evolution of the thermal field, the model calculates the resulting hardness of the deposited material, the grainsize and the porosity formation probability after the deposition process. Numerical results are experimentally validated, and good agreement is obtained. Consequently, besides predicting the geometry of the resulting part and the evolution of the thermal field, the developed model enables to evaluate the quality of the deposited material. Therefore, the optimum process conditions and strategy when depositing AISI 304 stainless steel can be determined without initial trial-and-error tests.Item Influence of Axial Depth of Cut and Tool Position on Surface Quality and Chatter Appearance in Locally Supported Thin Floor Milling(2022-01-19) Casuso, Mikel; Rubio-Mateos, Antonio; Veiga, Fernando; Lamikiz, Aitzol; Tecnalia Research & Innovation; FABRIC_INTELThin floor machining is a challenging and demanding issue, due to vibrations that create poor surface quality. Several technologies have been developed to overcome this problem. Ad hoc fixtures for a given part geometry lead to meeting quality tolerances, but since they lack flexibility, they are expensive and not suitable for low manufacturing batches. On the contrary, flexible fixtures consisting of vacuum cups adaptable to a diversity of part geometries may not totally avoid vibrations, which greatly limits its use. The present study analyses the feasibility of thin floor milling in terms of vibration and roughness, in the cases where milling is conducted without back support, a usual situation when flexible fixtures are employed, so as to define the conditions for a stable milling in them and thus avoid the use of ad hoc fixtures. For that purpose, the change of modal parameters due to material removal and its influence on chatter appearance have been studied, by means of stability lobe diagrams and Fourier Transform analysis. Additionally, the relationship between surface roughness and chatter frequency, tooth passing frequency, and spindle frequency have been studied. Ploughing effect has also been observed during milling, and the factors that lead to the appearance of this undesirable effect have been analyzed, in order to avoid it. It has been proven that finish milling of thin floors without support in the axial direction of the mill can meet aeronautic tolerances and requirements, providing that proper cutting conditions and machining zones are selected.Item Influence of Elastomer Layers in the Quality of Aluminum Parts on Finishing Operations(2020-02-22) Rubio-Mateos, Antonio; Rivero, Asuncion; Ukar, Eneko; Lamikiz, Aitzol; Tecnalia Research & Innovation; FABRIC_INTEL; SGIn finishing processes, the quality of aluminum parts is mostly influenced by static and dynamic phenomena. Different solutions have been studied toward a stable milling process attainment. However, the improvements obtained with the tuning of process parameters are limited by the system stiffness and external dampers devices interfere with the machining process. To deal with this challenge, this work analyzes the suitability of elastomer layers as passive damping elements directly located under the part to be machined. Thus, exploiting the sealing properties of nitrile butadiene rubber (NBR), a suitable flexible vacuum fixture is developed, enabling a proper implementation in the manufacturing process. Two different compounds are characterized under axial compression and under finishing operations. The compression tests present the effect of the feed rate and the strain accumulative effect in the fixture compressive behavior. Despite the higher strain variability of the softer rubber, different milling process parameters, such as the tool feed rate, can lead to a similar compressive behavior of the fixture regardless the elastomer hardness. On the other hand, the characterization of these flexible fixtures is completed over AA2024 floor milling of rigid parts and compared with the use of a rigid part clamping. These results show that, as the cutting speed and the feed rate increases, due to the strain evolution of the rubber, the part quality obtained tend to equalize between the flexible and the rigid clamping of the workpiece. Due to the versatility of the NBR for clamping different part geometries without new fixture redesigns, this leads to a competitive advantage of these flexible solutions against the classic rigid vacuum fixtures. Finally, a model to predict the grooving forces with a bull-nose end mill regardless of the stiffness of the part support is proposed and validated for the working range.Item Influence of Heat Input on the Formation of Laves Phases and Hot Cracking in Plasma Arc Welding (PAW) Additive Manufacturing of Inconel 718(2020-06) Artaza, Teresa; Bhujangrao, Trunal; Suárez, Alfredo; Veiga, Fernando; Lamikiz, Aitzol; FABRIC_INTEL; Tecnalia Research & InnovationNickel-based alloys have had extensive immersion in the manufacturing world in recent decades, especially in high added value sectors such as the aeronautical sector. Inconel 718 is the most widespread in terms of implantation. Therefore, the interest in adapting the manufacture of this material to additive manufacturing technologies is a significant objective within the scientific community. Among these technologies for the manufacture of parts by material deposition, plasma arc welding (PAW) has advantages derived from its simplicity for automation and integration on the work floor with high deposition ratios. These characteristics make it very economically appetizing. However, given the tendency of this material to form precipitates in its microstructure, its manufacturing by additive methods is very challenging. In this article, three deposition conditions are analyzed in which the energy and deposition ratio used are varied, and two cooling strategies are studied. The interpass cooling strategy (ICS) in which a fixed time is expected between passes and controlled overlay strategy (COS) in which the temperature at which the next welding pass starts is controlled. This COS strategy turns out to be advantageous from the point of view of the manufacturing time, but the deposition conditions must be correctly defined to avoid the formation of Laves phases and hot cracking in the final workpiece.Item Model for the Prediction of Deformations in the Manufacture of Thin-Walled Parts by Wire Arc Additive Manufacturing Technology(2021-04-21) Casuso, Mikel; Veiga, Fernando; Suárez, Alfredo; Bhujangrao, Trunal; Aldalur, Eider; Artaza, Teresa; Amondarain, Jaime; Lamikiz, Aitzol; FABRIC_INTEL; Tecnalia Research & InnovationGas Metal Arc Welding (GMAW) is a manufacturing technology included within the differentWire Arc Additive Manufacturing alternatives. These technologies have been generating great attention among scientists in recent decades. Its main qualities that make it highly productive with a large use of material with relatively inexpensive machine solutions make it a very advantageous technology. This paper covers the application of this technology for the manufacture of thin-walled parts. A finite element model is presented for estimating the deformations in this type of parts. This paper presents a simulation model that predicts temperatures with less than 5% error and deformations of the final part that, although quantitatively has errors of 20%, qualitatively allows to know the deformation modes of the part. Knowing the part areas subject to greater deformation may allow the future adaptation of deposition strategies or redesigns for their adaptation. These models are very useful both at a scientific and industrial level since when we find ourselves with a technology oriented to Near Net Shape (NNS) manufacturing where deformations are critical for obtaining the final part in a quality regime.Item Strategy Development for the Manufacturing of Multilayered Structures of Variable Thickness of Ni-Based Alloy 718 by Powder-Fed Directed Energy Deposition(Multidisciplinary Digital Publishing Institute (MDPI), 2020-09-24) Ramiro, Pedro; Ortiz, Mikel; Alberdi, Amaia; Lamikiz, AitzolIn this study, a manufacturing strategy, and guidelines for inclined and multi-layered structures of variable thickness are presented, which are based on the results of an own-developed geometrical model that obtains both the coating thickness and dilution. This model is developed for the powder-fed directed energy deposition process (DED) and it only uses the DED single-track cladding characteristics (height, width, area, and dilution depth), the overlap percentage, and the laser head tilting-angle as inputs. As outputs, it calculates both the cladding geometry and the dilution area of the coating. This model for the Ni-based alloy 718 was improved, based on previous studies of the single clad working both vertically and at an inclined angle, adding the equations of the single clad characteristics with respect to the main process parameters. The strategy proposed in this paper for multilayered cladding consisted of both adding an extra clad at the edges of the layer and using a variable value of the overlap percentage between clads for geometric adaptations. With this strategy, the material deposition is more accurate than otherwise, and it shows stable growth. Manufacturing a multilayered wall of wider thicknesses at higher heights was utilized to validate the strategy.Item Wire Arc Additive Manufacturing of Mn4Ni2CrMo Steel: Comparison of Mechanical and Metallographic Properties of PAW and GMAW(Elsevier B.V., 2019) Artaza, Teresa; Suárez, Alfredo; Murua, Maialen; García, J.C.; Tabernero, Iván; Lamikiz, AitzolWire arc additive manufacturing, WAAM, is a popular wire-feed additive manufacturing technology that creates components through the deposition of material layer-by-layer. WAAM has become a promising alternative to conventional machining due to its high deposition rate, environmental friendliness and cost competitiveness. In this research work, a comparison is made between two different WAAM technologies, GMAW (gas metal arc welding) and PAW (plasma arc welding). Comparative between processes is centered in the main variations while manufacturing Mn4Ni2CrMo steel walls concerning geometry and process parameters maintaining the same deposition ratio as well as the mechanical and metallographic properties obtained in the walls with both processes, in which the applied energy is significantly different. This study shows that acceptable mechanical characteristics are obtained in both processes compared to the corresponding forging standard for the tested material, values are 23% higher for UTS and 56% for elongation in vertical direction in the PAW process compared to GMAW (no differences in UTS and elongation results for horizontal direction and in Charpy for both directions) and without significant directional effects of the additive manufacturing technology used.