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Manufacture of complex thin-walled metallic objects using weld-deposition based additive manufacturing
... WAAM allows parts characterized by low-to-medium complexity and large sizes, which, if manufactured with traditional manufacturing routes, would lead to high buy-to-fly (BTF) ratios (i.e., the ratios between the starting workpiece to the final part mass [4]), to be produced. Together with their high material and power demand efficiency, low investment costs, simple setups, and low environmental impact [3], one of the most important advantages of MWD processes over others is ...
... Deposition Rates (DRs) as high as possible are desirable, while considering the productivity limits dictated by physics, to obtain low production times and low related costs [2]. To this aim, as metal AM has grown, the interest of industry has been focusing on those technologies that are suitable for producing large components at high DRs [3]. Metal Wire Deposition (MWD) processes, and Wire Arc Additive Manufacturing (WAAM) in particular, have captured attention as valid alternatives to conventional manufacturing processes. ...
... WAAM allows parts characterized by low-to-medium complexity and large sizes, which, if manufactured with traditional manufacturing routes, would lead to high buy-to-fly (BTF) ratios (i.e., the ratios between the starting workpiece to the final part mass [4]), to be produced. Together with their high material and power demand efficiency, low investment costs, simple setups, and low environmental impact [3], one of the most important advantages of MWD processes over others is their high DR [5]. The literature has reported several examples of experimental tests that show higher DRs for MWD processes than for powder-bed based processes. ...
... Modern additive manufacturing technologies have found extensive applications in various fields, including aerospace, maritime, medical, automotive, and energy sectors, owing to their capacity to generate integrated and complex geometries, high production speed, desirable strength, high density, optimal material utilization, design freedom, and potential for cost reduction [4][5][6][7][8]. Notable techniques among these methods include Selective Laser Sintering (SLS), Direct Metal Deposition (DMD), Laser-Based Additive Manufacturing (LBAM), Directed Light Fabrication (DLF), Electron Beam Additive Manufacturing (EBM), and Wire Arc Additive Manufacturing (WAAM) [9][10][11][12]. ...
... Production of additive materials for wire and arc welding-based structures is an upand-coming technology for large-scale metal construction due to its rapid deposition rate, high energy efficiency, and cost-effectiveness [8]. These components can be fabricated almost identical to the original piece through layer-by-layer deposition of metallic materials using welding processes. ...
Additive manufacturing encompasses technologies that produce three-dimensional computer-aided design (CAD) models through a layer-by-layer production process. Compared to traditional manufacturing methods, additive manufacturing technologies offer significant advantages in producing intricate components with minimal energy consumption, reduced raw material waste, and shortened production timelines. AM methods based on shielded gas welding have recently piqued the interest of researchers due to their high efficiency and cost-effectiveness in manufacturing critical components. However, one of the most formidable challenges in additive manufacturing methods based on shielded gas welding lies in the irregularity of weld bead height at different points, compromising the precision of components produced using these techniques. In this current research, we aimed to achieve uniform weld heights along the welding path by considering the most influential parameters on weld bead geometry and conducting experimental tests. Input parameters of the process, including nozzle angle, welding speed, wire speed, and voltage, were considered. Simultaneously, image processing and wavelet transform were employed to assess the uniformity of weld bead height. These parameters were applied to produce intricate parts after identifying optimal parameters that yielded the smoothest weld lines. According to the results, the appropriate bead for manufacturing the part was extracted. The results show that the smoothest bead line is achieved in 27 V as the highest level of voltage, at a 90° nozzle position and the maximum wire feed rate. Parts manufactured using this method across different layers exhibited no distortions, and the repeatability of production substantiated the high reliability of this approach for component manufacturing.
... Além disso, a fabricação de peças metálicas inclinadas pode ser realizada utilizando uma mesa de trabalho com eixos rotativos e inclináveis, os quais são responsáveis pela geração das peças com saliência. Esse processo foi descrito por Panchagnula e Simhambhatla [46], os quais realizaram a deposição de cones com ângulos variando de 10° a 35° via CMT convencional, conforme ilustrado na Figura 17a. Para depositar esses componentes, a tocha foi mantida em posição plana enquanto a mesa foi inclinada em um ângulo equivalente ao da parede do cone, conforme evidenciado na Figura 17b. ...
... (a) Componente depositado com 20°; e (b) substrato inclinado no ângulo necessário para alinhar o componente com a tocha[46]. ...
Resumo A manufatura aditiva é uma tecnologia que permite a fabricação de peças através da adição sucessiva de material em camadas. Essa técnica permite a impressão de polímeros, metais, cerâmicas, biomateriais e materiais compósitos. Os materiais depositados podem ser arame, pó ou líquido. A Manufatura Aditiva por Deposição a Arco (MADA) é uma técnica promissora no processamento de ligas metálicas, onde, o Cold Metal Transfer (CMT) é uma variação do processo MIG/MAG que proporciona menor aporte térmico durante a transferência de material, influenciando na qualidade final da peça. Sendo assim, este trabalho tem como objetivo apresentar uma revisão bibliográfica das estratégias de deposições e comparar os efeitos causados ao se utilizarem diferentes parâmetros, especificamente pela MADA. Com isso, foi possível identificar que o controle do aporte térmico é um fator decisivo para evitar defeitos e melhorar o acabamento superficial das peças. Diferentes estratégias e parâmetros alteram a microestrutura e, como consequência, as propriedades mecânicas da peça.
... In modern times, the prediction of bead geometry size can be achieved through applications such as the artificial neural network (Karmuhilan & Sood, 2018). The diagram of this approach is shown in Figure 3. Panchagnula and Simhambhatla (2018) also introduced a mathematical model that predicts the geometry of subsequent layers based on the height and width of the first layer. The mathematical model can also demonstrate the relationship between the parameters and bead geometry (Panchagnula & Simhambhatla, 2018). ...
... The diagram of this approach is shown in Figure 3. Panchagnula and Simhambhatla (2018) also introduced a mathematical model that predicts the geometry of subsequent layers based on the height and width of the first layer. The mathematical model can also demonstrate the relationship between the parameters and bead geometry (Panchagnula & Simhambhatla, 2018). Li, Ma et al. (2018) discovered that the stability of the formed bead is also important in the fabrication of large parts using weave beads. ...
Wire arc additive manufacturing (WAAM) is a well-established additive manufacturing method that produces 3D profiles. A better deposition efficiency can be achieved by understanding the parameters that may influence the geometry of the bead. This paper provides a review that focuses on the factors that may influence the formation of the 3D profile. The included factors are the flow pattern of the molten pool after deposition, the built structure and orientation, the heat input and cooling conditions, the welding parameters, and other uncertainties. This review aims to facilitate a better understanding of these factors and achieve the optimum geometry of the 3D parts produced. According to the literature, the behavior of molten pools is identified as one of the major factors that can impact the deposition efficiency of a bead and govern its geometry. The review indicated that the flow behavior of the molten pool and the geometry of the deposited bead are significantly affected by most welding parameters, such as torch angle, wire travel speed, filler feed rate, and cooling conditions. Furthermore, this paper incorporates the technology utilized for comprehending the behaviors of the molten pool, as it constitutes an integral component of the control strategy. It has been concluded that automated planning and strategy are necessary to ensure efficient deposition by controlling those factors. The integration of artificial intelligence could bring benefits in planning to address the variation and complexity of shapes.
... In WAAM, an electric arc is used to melt the filler wire material. Different processes can be used for WAAM [24], such as gas metal arc welding (GMAW) [25,26], cold metal transfer (CMT) [25,27], gas tungsten arc welding (GTAW) [28][29][30][31] and plasma welding [32][33][34]. While the filler material is introduced separately from the energy in the plasma and GTAW processes, the energy and material introduction are coupled in the CMT and GMAW processes. ...
... In WAAM, an electric arc is used to melt the filler wire material. Different processes can be used for WAAM [24], such as gas metal arc welding (GMAW) [25,26], cold metal transfer (CMT) [25,27], gas tungsten arc welding (GTAW) [28][29][30][31] and plasma welding [32][33][34]. While the filler material is introduced separately from the energy in the plasma and GTAW processes, the energy and material introduction are coupled in the CMT and GMAW processes. ...
... In GMAW-WAAM, also known as metal inert gas welding, an arc is struck among the base metal workpiece and consumable electrode that provides filler material for welding. GMAW is appropriate for mass production because of its high deposition rate of 3 to 4 kg/h, high energy efficiency of 84%, high welding speed, high-quality welding with lower spatter, ability to weld thin materials, etc [4][5][6][7]. The process parameters such as shield gas composition, wire feed, shielding gas flow rate, wire material, voltage, travel speed of torch, and torch route are crucial parameters for the bead deposition created using GMAW. ...
... Além do processo com alta eficiência de deposição, a MADA apresenta inúmeras vantagens como produzir componentes metálicos variados, em larga escala, de geometria complexa e com baixo custo de equipamentos e fácil acesso no mercado nacional (PANCHAGNULA, 2018). Pode-se fabricar componentes com mais de 10 kg de materiais como aço, titânio, alumínio entre outros (WILLIAMS et al., 2016). ...
O processo de fabricação por meio da tecnologia MADA (Manufatura Aditiva por Deposição a Arco) é uma excelente solução na construção de peças, garantindo qualidade e eficiência. A produção de componentes com geometrias complexas, viabilizada por trajetórias contínuas e estratégias otimizadas, reforça a importância dessa tecnologia no contexto industrial. Além de reduzir custos e prazos, a MADA destaca-se como uma ferramenta indispensável para confecção de componentes para os setores aeroespacial, automotivo e de dispositivos médicos, consolidando seu papel como uma das principais tendências industriais da atualidade. Normalmente, o processo começa com o desenvolvimento de um modelo computacional detalhado da peça, que pode incluir processos de engenharia reversa. A aplicação da tecnologia MADA utilizando o processo MIG-PV (Polaridade Variável) ganhou destaque por sua eficiência e versatilidade na manufatura aditiva. Neste contexto, o objetivo deste estudo é investigar a morfologia da deposição vertical em uma parede de seis camadas e avaliar a viabilidade do processo MIG-PV em MADA através da fabricação de geometria de duas peças (chave de boca) usando o metal de adição AISI 904L (AWS A5.9 ER385) em substrato ASTM A36. Os resultados demonstraram que o processo MIG-PV é altamente eficaz em aplicações de MADA devido a robustez estatística do processo apresentado, para confecção de ferramentas em materiais de elevado valor agregado, com baixos níveis de diluição. Além disso, a equalização dos parâmetros de entrada através de análise estatística permitiu o controle sobre as características finais do revestimento, juntamente com desvios mínimos na morfologia do cordão.
... Wire Arc Additive Manufacturing (WAAM) is a layer-bylayer fabrication methodology that uses traditional welding methods to produce three-dimensional components. The process has the benefits of cost effectiveness, maximum material utilisation, and formation rates while ensuring the fabrication of complex parts of large sizes [1,2]. The successful deposition of beads and their quality is contingent upon process factors like supplied current, voltage, wire feed speed (wfs), and deposition speed. ...
The temperature dependent feedback-based control system was implemented in wire arc additive manufacturing utilising tungsten inert gas as a power source (WAAM-TIG) to prevent overheating and improve the overall process efficiency. In-situ monitoring of voltage and current utilised during the deposition was also performed to ensure arc stability. The PID (Proportional–Integral–Derivative) based controller was implemented to maintain the desired setpoint temperature behind the deposition point. The developed system successfully minimises the specific energy requirement by supplying enough input energy only to deposit a unit volume of material and prevent overheating which is often observed in multilayer deposition at constant parameters. The overall process efficiency was found to be increased by ~ 22%. The multilayer deposited wall showed an increase in bead height of ~ 27.1% and a decrease in width of ~ 14.7%, with improvement in geometrical uniformity. However, the proposed system demonstrated a negligible impact on mechanical parameters, including tensile strength, hardness, and resultant microstructure.
... There are many researchers worked towards the WAAM technique to improvise surface finish, microstructure, and mechanical properties [22]. The main goal of the majority of these investigations is to determine whether using a special purpose welding robot or a specific GMAW setup for producing or repairing metal parts using the layered AM principle is process more feasible [23,24]. To increase deposition rate tandum welding torch is used, tandum torch feeded two wire simultaneously to get thicker section while at the same it needed external cooling to reduce the lead time [25,26]. ...
In the realm of Industry 4.0, additive manufacturing (AM) techniques are poised to revolutionize conventional manufacturing processes. Unlike traditional methods where component complexity often escalates costs, AM offers a unique advantage by not adding extra expenses with increasing intricacy. Employing powder or wire feedstock, AM fabricates metal components, with wire-based AM demonstrating a higher deposition rate and reduced fabrication time compared to powder-based methods. This makes Wire Arc Additive Manufacturing (WAAM) particularly suitable for large-scale production. Nickel-based superalloys stand out for their exceptional tensile strength, corrosion resistance, and fatigue endurance at elevated temperatures, rendering them ideal for demanding applications such as aircraft, nuclear, oil and gas, turbocharger rotors, gas turbines, and the chemical industry. This article delineates various AM methodologies employed for fabricating Ni-based alloys, encompassing diverse WAAM approaches utilizing Gas Tungsten Arc Welding (GTAW), Gas Metal Arc Welding (GMAW), Plasma Arc Welding (PAW), and other wire-based AM techniques such as Electron Beam Wire feed AM and Laser Wire feed AM. It delves into the microstructural characteristics, mechanical properties, and the challenges inherent in fabrication and post-processing, crucial for achieving the desired component attributes.
... Suryakumar et al. [24] modeled the beads with a parabolic curve and reported that the bead width and height were primarily influenced by the wire feed speed and torch travel speed. A geometrical model was developed [25] to predict the layer heights for multilayered thin-walled structures, fitting the beads with a circular arc profile. The model was validated by depositing various components, and the prediction error was ~ 3%. ...
A novel single-camera-based vision system is developed for real-time measurement of bead dimensions of multilayered deposits during wire arc additive manufacturing (WAAM). Bead widths were detected during deposition using image processing algorithms, while heights were estimated from the widths by fitting the bead cross-section area with curve equations. The measurements obtained from the vision system were compared against the measured deposit dimensions. The vision system detected bead widths with an average error of 5.65%. Fitting the bead cross-sections with a semi-elliptic curve profile gave an accurate estimation of the bead heights, with an average error in height measurement of 9.78%. The vision system was then employed to analyze the effect of deposition strategies on the bead dimensions of thin-walled cylinders. The system accurately captured the bead height variation arising from different deposition strategies. These results demonstrate the system’s effectiveness in monitoring thin-walled WAAM depositions.
... Controlled heat input and material transfer make CMT more suitable for thin-walled components. Wire feed rate (5-8 m/min) and torch speed (0.35 -0.9 m/min) are identified as the essential factors for stable and continuous weld deposition [18]. Manufacturing" explore the applications of WAAM in creating large-dimensional metallic parts required for heavy-duty applications. ...
Wire Arc Additive Manufacturing (WAAM) using 308 stainless steel offers a versatile method for producing large, complex components with superior mechanical properties and corrosion resistance. This process involves precise control of welding parameters and real-time monitoring to ensure consistent quality. WAAM effectively addresses challenges such as residual stresses through preheating, controlled cooling, and post-processing techniques. The use of 308 stainless steel, known for its excellent weldability and durability, makes it ideal for applications in various industries. With potential advancements in process control and material development, WAAM stands as a promising technology for efficient and high-quality metal fabrication.
... The precision achieved was ± 0.5°, showing the effectiveness of the deposition technique using the inclined torch. Panchagnula et al. [10] used a table with rotating and tilting axes to deposit cones with angles of 10°, 15°, 20°, 25°, 30°and 35°. To deposit these components, the torch was held in a flat position and the substrate was tilted at an angle equal to the angle of the cone wall. ...
... The structure shown to the right in Figure 10.7 was also built using CMT, with continuous material deposition along an upward spiralling helix path with a continuously increasing radius, thereby creating an overhang. This could have been solved using a mobile building surface around a fixed point of material deposition, as demonstrated by [26] and [27], and this seemed to be the dominating approach at the time. However, if the building surface could remain fixed with a mobile and flexible point of material deposition, it could be possible to use the technique in a more practical scenario, as discussed further in [21]. ...
... Therefore, selecting the process parameters with their required levels is necessary to deposit multiple layers in WAAM. Efforts have been made to optimize these process parameters for different steel grades [21,22]. Vora et al. [23] utilized the WAAM technique based on GMAW to manufacture a multi-facet structure using metal wire on 2.25 Cr-1.0 Mo steel. ...
Gas metal arc welding (GMAW) based wire-arc additive manufacturing (WAAM) is a promising manufacturing method widely used in various industries. In this study, for the first time, a new type of combined electrode wire with multi-element composition has been designed and developed for arc additive manufacturing of a composite alloy Fe rich-Al-Cu-Ni alloy. GMAW-based WAAM technique technology composed of 4 filaments and 4 elements has the advantages of high deposition efficiency, self-rotation of welding arc, and energy-saving capability. Thin composite alloy walls were fabricated under pure CO2 gas using GMAW-based WAAM technique technology. To investigate the effect of the parameters introduced by the gas metal arc welding process based on wire arc additive manufacturing, the produced components of the sample layer by layer with different parameters after production are characterized by scanning electron microscope morphologies, X-ray diffraction Microstructural observations of the developed combined electrode reveal (i) BCC and FCC phases, (ii) Good bonding between layers and (iii) defect-free microstructure. Therefore, an experimental design using the Taguchi method was used to determine the parameters affecting the studied properties, including yield strength (YS) and elongation (E). The developed combined electrode alloy exhibits high compression strength (~294 GPa) coupled with high elongation (~0.22%) values (possess both strength and ductility). It has been identified that by varying the heat input via torch travel speed, the microstructure and mechanical properties of the combined electrode can be controlled. Therefore, optimizing GMAW process parameters to produce effective products is of great importance. The experimental results show that voltage and wire speed are the dominant variables that affect the values of YS and E at the test surface. In addition, the contribution of each factor to YS and E was determined. Which can be effectively Corrected with this method.
... Deposition material is fed through the deposition head which is guided to trace the planned path for additive manufacturing of a product. Technical versatility, distinctive features, customizable design, and ease of use make a DED process capable of repairing, coating, cladding, surface texturing, remanufacturing, freeform manufacturing of complicated parts, rapid prototyping, and rapid tooling [14][15][16][17]. It finds typical applications in biomedical engineering, post-injury rehabilitation, pharmaceutical industry, automobile, aerospace, marine, power generation, electronics, robotics, sensing, automation, sports equipment manufacturing, and oil and gas extraction [18][19][20][21][22][23]. ...
This paper presents the development of a model of powder catchment efficiency of micro-plasma transferred arc metal additive manufacturing (µ-PTAMAM) process in terms of nozzle size, nozzle inclination angle, powder stream divergence angle, and stand-off-distance (SOD). It involved the development of models to evaluate powder concentration diameters in different zones of powder flow stream and melt pool. The developed theoretical model has been validated experimentally. Effects of SOD on surface defects in the manufactured product and deterioration of nozzle and gas lens of the deposition head have also been studied. It was observed that SOD has a negligible effect on the melt pool area implying that powder concentration area predominantly affects the powder catchment efficiency. It has been found that powder catchment efficiency is maximum when the base material is placed closer to the initial point of powder convergence which is 8–9 mm. Wastage of deposition material and surface defects in the manufactured product is reduced in this region. It also extends the life of deposition head components by reducing molten and spattered particle adhesion. The developed model will be useful to identify optimum SOD, minimizing wastage of the deposition material, maximizing powder catchment efficiency, and optimizing the design of the deposition head. This will lead to improvement in the techno-economical aspects of the µ-PTAMAM process.
... Complex geometry WAAM is conducted through multi-directional deposition [9]. A WAAM system with CNC welder and 2-dof positioner can produce complex geometry [10]. For WAAM geometry evaluation, ultrasonic sensing is used to examine the part geometry [11] and optical microscope is used to study microstructure properties [12]. ...
Wire Arc Additive Manufacturing (WAAM) is a metal 3D printing technology that deposits molten metal wire on a substrate to form desired geometries. Articulated robot arms are commonly used in WAAM to produce complex geometric shapes. However, they mostly rely on proprietary robot and weld control software that limits process tuning and customization, incorporation of third-party sensors, implementation on robots and weld controllers from multiple vendors, and customizable user programming. This paper presents a general open-source software architecture for WAAM that addresses these limitations. The foundation of this architecture is Robot Raconteur, an open-source control and communication framework that serves as the middleware for integrating robots and sensors from different vendors. Based on this architecture, we developed an end-to-end robotic WAAM implementation that takes a CAD file to a printed WAAM part and evaluates the accuracy of the result. The major components in the architecture include part slicing, robot motion planning, part metrology, in-process sensing, and process tuning. The current implementation is based on Motoman robots and Fronius weld controller, but the approach is applicable to other industrial robots and weld controllers. The capability of the WAAM tested is demonstrated through the printing of parts of various geometries and acquisition of in-process sensor data for motion adjustment.
... These processing parameters were optimized in prior work by Panchagnula and Simhambhatla so as to avoid flaw formation and provide an acceptable quality build [35]. The elapsed time between the deposition of subsequent layers, known as the interlayer dwell time ( t d ) was varied between experiments. ...
The objective of this paper is to develop, verify, and experimentally validate a mesh-free spectral graph theory-based approach for rapid prediction of thermal history in metal parts made using the wire arc additive manufacturing (WAAM) process. Accurate and rapid prediction of the thermal history is a critical prerequisite for functional quality assurance of WAAM parts. In the spectral graph method, the WAAM part is represented as a set of discrete nodes encompassed by a network graph. The thermal history is obtained by solving the heat equation on the network graph. The spectral graph theory approach thus bypasses the cumbersome computational burden associated with mesh generation in the finite element method. To validate the spectral graph theory approach, experimental temperature data is acquired for multi-layer mild steel WAAM parts processed under six different combinations of shape and inter-layer dwell time conditions. Further, each experiment was replicated resulting in a total of 12 parts. The accuracy of the thermal trends predicted by the spectral graph theory approach was quantified in terms of the symmetric mean absolute percent error (SMAPE) and root mean squared error (RMSE, °C). The thermal history trends were predicted with SMAPE < 5% and RMSE < 11 °C relative to the experimental temperature measurements. The computation time to obtain the thermal history of each 21-layer part was approximately 3.5 to 4 h. The spectral graph theory predictions were further verified with a commercial finite element software package (Simufact-Welding). For a similar level of SMAPE and RMSE as the spectral graph theory approach, the FE-based Simufact predictions required over 7.5 h. The computational advantage of the spectral graph theory approach is particularly valuable for devising physics-based process parameter optimization and feedforward control strategies to mitigate flaw formation in WAAM parts.
... Additive manufacturing technology is a new manufacturing technology based on the principle of layered dispersion and layered stacking, which realizes material molding through the "bottom-up" process [1][2][3]. This technology can quickly and accurately manufacture objects with complex shapes [4]. In addition, it has the advantages of simple structure, low technical cost, and high manufacturing efficiency [5]. ...
Wire-arc additive manufacturing (WAAM) is favored by the industry for its high material utilization rate and low cost. However, wire-arc additive manufacturing of lattice structures faces problems with forming accuracy such as broken rod and surface morphology defects, which cannot meet the industrial demand. This article innovatively combines the melt pool stress theory with visual perception algorithms to visually study the force balance of the near-suspended melt pool to predict the state of the melt pool. First, the method for melt pool segmentation was studied. The results show that the optimized U-net achieved high accuracy in melt pool segmentation tasks, with accuracies of 98.18%, MIOU 96.64%, and Recall 98.34%. In addition, a method for estimating melt pool force balance and predicting normal, sagging, and collapsing states of the melt pool is proposed. By combining experimental testing with computer vision technology, an analysis of the force balance of the melt pool during the inclined rod forming process was conducted, showing a prediction rate as high as 90% for the testing set. By using this method, monitoring and predicting the state of the melt pool is achieved, preemptively avoiding issues of broken rods during the printing process. This approach can effectively assist in adjusting process parameters and improving welding quality. The application of this method will further promote the development of intelligent unmanned WAAM and provide some references for the development of artificial intelligence monitoring systems in the manufacturing field.
... No entanto, os graus de liberdade (DOFs) adicionados ao sistema pela mesa posicionadora permitem o desenvolvimento de deposições multi-direcionais reorientando a peça durante o processo de deposição, reduzindo significantemente o tempo de produção e aumentando a uniformidade de peças com geometria complexa. Convencionalmente, em processos de manufatura aditiva, a orientação da tochaé ortogonal a superfície de deposição (substrato), então as mesas posicionadoras são normalmente usada para alinhar a normal da superfície de deposição com o vetor de gravidade Panchagnula and Simhambhatla, 2018) ou incorporar uma seção do substrato a peça final de forma a minimizar os gastos de produção (Lockett et al., 2017). ...
This paper considers the trajectory tracking control of a robotic system for Wire Arc Additive Manufacturing (WAAM) of complex geometry parts. The considered (redundant) robotic system is composed by a robotic manipulator and a positioning table. In order to use the system redundancy, a task-priority based kinematic control scheme to control a manipulator and a positioning table coordinately is proposed. The manipulator and positioning table are considered as a single kinematic chain, defining the primary task as the trajectory tracking of the welding torch defined in the positioning table deposition frame and setting a secondary task to align the welding torch with a desired direction defined in the inertial frame (e.g., gravity direction). A complete Lyapunov stability analysis is performed considering unmodelled dynamics in the kinematic control loop. The effectiveness of the proposed method is shown experimentally on a WAAM robotic system composed of a six-axis industrial manipulator, a two-axis positioning table and a Cold Metal Transfer (CMT) power source.
... However, conventional techniques cannot cope with the current manufacturing revolution that involves the need to manufacture highly complex designs. To solve this problem, Additive Manufacturing (AM) can be used due to its ability to manufacture highly complex designs [10][11][12]. AM is a trending manufacturing technology that can produce parts from 3D CAD models layer by layer [13]. The AM process includes seven techniques defined by the ISO/ASTM 52900 [13]: Powder Bed Fusion (PBF), binder jetting, vat-photopolymerisation, extrusion, direct energy deposition, material jetting, and sheet lamination. ...
The one-step AM process is considered the goal many researchers seek in the field of Additive Manufacturing (AM) of high-technology ceramics. Among the several AM techniques, only Powder Bed Fusion (PBF) can directly print high-technology ceramics using one step. However, the PBF technique faces numerous challenges to efficiently be employed in the PBF of ceramics. These challenges include the formation of cracks, generated thermal stress, effective laser–powder interaction, and low acquired relative density. This study developed a new preheating mechanism for ceramic materials using two laser systems to surpass beyond these challenges and successfully print ceramics with a single-step AM method. One laser is used to preheat the powder particles before the second laser is utilised to complete the melting/sintering process. Both lasers travel along the same scanning path. There is a slight delay (0.0001 s) between the preheating laser and the melting/sintering laser to guarantee that the melting/sintering laser scans a properly preheated powder. To further facilitate testing of the preheating system, a numerical model has been developed to simulate the preheating and melting process and to acquire proper process parameters. The developed numerical model was shown to determine the correct process parameters without needing costly and time-consuming experiments. Alumina samples (10 × 10 × 6 mm3) were successfully printed using alumina powder as feedstock. The surface of the samples was nearly defect-free. The samples’ relative densities exceeded 80%, the highest reported relative density for alumina produced by a single-step AM method. This discovery can significantly accelerate the transition to a one-step AM process of ceramics.
... Stability of metal transfer and weld formation is the main challenge during the deposition in welding-based technologies. Such problems can be overcome by using an inclined welding torch at some angle [103] and providing offset to the welding torch [104]. Yan et al. [105] introduced slanted short-circuit transfer (SSCT) to understand the metal transfer behavior of step-over deposition mode-fabricated slant features via CMT-based WAAM. ...
Cold metal transfer-based additive manufacturing technique is a new promising approach based on wire-feed AM. It is gaining more popularity than its contemporary additive manufacturing processes for metal additive manufacturing due to its capability of economically producing large-size components with relatively high deposition rates and lower heat input. This article introduces cold metal transfer-based wire arc additive manufacturing (CMT-WAAM), starting with an overview of CMT-WAAM and the detailed mechanism of the cold metal transfer (CMT) process and its selection preference over the other variants of WAAM. A critical review of the microstructure and mechanical properties of various metals and alloys fabricated through CMT-WAAM technique has been reported. Research indicates an exciting result as the mechanical properties of CMT-WAAM-fabricated materials, such as titanium, steels, aluminum alloys, and nickel-based alloys, have been found relatively comparable to wrought materials and superior to as-cast materials. The advantages of CMT-WAAM have piqued the interest of many industrial experts and researchers for further developments in this technique; thus, the recent advances performed in this sector have been summarized in the last section of this manuscript. This article suggests that CMT-WAAM can be a viable alternative for high-quality manufacturing and offers a vision for the future of this technology.
... Other applications may include rapid prototyping [14,118] and fabrication of special structures with a low lot size [119,120]. Fig. 31 depicts an exemplary motorcycle piston using a novel design [121], which has been fabricated by WAAM using cold metal transfer of a novel Al-Mg-Zn-Cu alloy [93]. Via topological optimization and an adapted deposition strategy, a reduction of weight and material was achieved with respect to the reference piston. ...
Additive manufacturing (AM) is the latest type of manufacturing technology in which layers of materials are built up using a predefined geometry. It has witnessed substantial growth both in terms of techniques and materials in recent years. In the previous chapters, various techniques for metal additive manufacturing have been described along with their current standards and practices. In this chapter, we focus our attention on wire arc additive manufacturing (WAAM), which is a type of directed energy deposition (DED) AM process as outlined in ISO/ASTM 52900:2015 [1]. In WAAM, an electric or plasma arc is used as the heat source to melt a wire feed stock, which results in fusion with the previously deposited layers, thus building up material in the process. Compared to other AM methods, the advantages of WAAM are a higher productivity rate, the ability to manufacture large components, and the ready availability, lower cost, and handling safety of the welding wire compared to the powder feed stock.
... Therefore, many scholars attempted to build single-pass multi-layer bead profile model by geometric relationship. Panchagnula et al. [20] established mathematical relationships of geometric features such as bead height, width, and area of the upper and lower passes in the vertical direction to build single-pass multi-layer profile model. Nenadl et al. [21] constructed a multi-layer profile model by existing recursive mathematical relationships. ...
Robotic Wire and Arc Additive Manufacturing (WAAM) is an ideal process for manufacturing large-scale or large-format parts efficiently and economically, as compared with other AM methods, and therefore finds extensive applications in diverse fields including aerospace, automotive and mould. Accurate prediction of WAAM part dimension is fundamentally dependent on the modeling accuracy of single-bead profile and its subsequent overlapping ones. This paper proposes a new recursive model, based on coordinate transformation, to predict single-layer multi-bead overlapping profile. Firstly, commonly used single-bead profile functions are reviewed, followed by detailed description of conventional and proposed recursive profile model. The properties of developed recursive model are then investigated for understanding the effects of overlapping ratio and single-bead aspect ratio. The influence of function type is also analysed from the surface quality divergence of single-layer multi-bead overlapping profile. Finally, multi-bead overlapping experimental tests are carried out to validate the feasibility of presented recursive profile model. The results show that the modified recursive model is more accurate than the conventional one for its better accountability of valley area. It is also indicated that parabola and arc function are more suitable for the robotic WAAM process. The research outcome is beneficial to improving the forming accuracy of WAAM parts, and also provides a new method for predicting geometry of other additive manufactured products.
... There are several areas being researched to improve WAAM such as thin-walled structures [9], computer vision [10], control [11], metal droplet transfer modeling [12], part size prediction [13], and more. The relevant literature to this paper includes the latest works in supportless robotic WAAM and sensor-based WAAM, and we will discuss a few works in those fields. ...
Metal additive manufacturing technology that uses arc welding technology to deposit material is called wire arc additive manufacturing. Robotic manipulators that have a large workspace to size ratio are used to enable wire arc additive manufacturing. Wire arc additive manufacturing is gaining popularity due to the fast build time achieved by the high material deposition rates. It can build large-scale parts at a faster speed compared to other metal additive manufacturing processes. Utilizing a tilting build platform along with a robotic manipulator referred to as a multi-axis setup can enhance the capability of wire arc additive manufacturing. It will allow the setup to build complex supportless geometries that are not possible otherwise. However, maintaining a constant layer height while performing multi-axis wire arc additive manufacturing is challenging due to the forces involved in the process. This paper presents a new sensor-based two-step process along with the tool trajectory generation for maintaining constant layer height while performing multi-axis wire arc additive manufacturing. As the first step, we regulate the tool trajectory velocity to minimize the variation in the layer height. In the second step, we develop a sensor-based intervention scheme to fix the variation in the layer height by introducing additional height compensation layers. Finally, we test our approach by building a few parts, including a tool for the composite layup process.
... Furthermore, if the welding application (such as military applications) makes weldability dominate the other criteria, it should be considered as a special pre-filter for candidate welding processes, linked with advanced PRIMAs (refer to Fig. 9). • It will be promising to include a special module in SWP for welding-based additive manufacturing [163][164][165][166][167][168][169][170]. ...
This study aims to report the progress and latest status of the “selection of welding process” problem in terms of research, developments, and applications. In addition, it introduces guidelines to serve constructing future expert systems for the problem. Therefore, it presents an extensive literature review on the approaches used to model and solve the problem over 36 years. Hence, several findings and proposed insights are reported. The paper recommends some existing approaches based on their performance in general and literature reporting in addition to simple statistics. A structure for prospected expert systems is proposed. The paper collected and rearranged decision criteria/sub-criteria of the problem, in a manageable form, to construct a modifiable hierarchical scheme. Additional criteria were merged based on recent trends in manufacturing system evaluation such as sustainability and performability. Finally, an agenda is introduced to recognize research opportunities in this area based on prospected industrial and business revolutions.
Three-dimensional chiral mechanical metamaterials with either compression-torsion, tension-torsion, or thermal-torsion couplings, simply called twisting mechanical metamaterials, have been attracting attention due to unique deformation coupling under loadings, unlocking unique mechanical properties, applicable in robotics, automotive and aerospace industries. This paper reviews design, assembly, fabrication, testing, properties, and applications of twisting chiral metamaterials from emergence of the topic in 2016 to the most recently-published papers. This review article aims to assist scientists, researchers, and engineers in better understanding the wide capabilities of this growing class of metamaterials and help them in using the step-wise methodology to design, analyze, fabricate, and apply twisting mechanical metamaterials.
Wire arc additive manufacturing (WAAM) has emerged as a versatile and cost-effective technique for fabricating complex, large-scale components with enhanced material flexibility. The bead profile, like width, height, and penetration, is critical in WAAM fabrication, influencing the quality and performance of the final component. Consistent and precise profiles are essential for accurate layering and material deposition in complex 3D structures. Various parameters, such as current, voltage, deposition rate, interpass temperature, and welding mode, impact deposit quality in WAAM. This study focuses on implementing a controlled heat input deposition approach, utilizing various welding modes: Control Weld (classic MIG/MAG), Speed Weld (voltage-controlled pulsed arc), Vari Weld (current-controlled pulsed arc), Rapid Weld (high-capacity spray arc), Root Weld (energy-reduced short arc), and Fine Weld (energy-reduced, current-controlled short arc). The study scrutinizes the impact of altering the welding mode on bead profile, bead quality, macroscopic morphology, microstructure, and mechanical properties in single-bead WAAM structures.
Gas metal arc welding-based metal printing is an effective tool to fabricate complex prototypes and tangibles products having enormous advantages such as low cost and minimum lead time for widespread engineering applications in the developed industry. Gas metal arc welding-based metal-deposition was implemented to build three dimensional specimens with varying cross-sections through different paths strategies, that is, spiral-in (circular and square) and raster (square, diagonal and circular). The given trajectory was followed by providing programmed inputs to the controller of the setup to deposit metal layer over the layer for producing a positive slope on the lower half and a negative slope on the upper half section of the deposited object. The fabricated setup can be used to produce sloped objects having 20° inclination. The mechanical properties such as tensile strength, bending strength and microhardness of the deposited 3D parts were investigated to observe the effect of different depositing strategies. Amongst the various deposition strategies adopted to build parts, the raster diagonal (square) and raster linear (circular) showed the maximum value of tensile and bending strength. The microstructural characterization of the deposited parts was also carried out using scanning electron microscopy (SEM).
This work investigates the deposition strategies with microstructural evolution and mechanical properties of SS308LSi overhanging disc produced by CMT-WAAM in horizontal position. The disc was deposited on a rotating cylindrical substrate where three primary geometrical abnormalities named sagging, start and end defect and humping were observed. The causes and remedial strategies were investigated to eliminate these abnormalities. Microstructure analysis of the layers cross section revealed a defect free layer depositions and columnar solidification with epitaxial grain growth. A very slightly coarser grains structure is observed in the middle layers of the disc compared to that of bottom and top regions. The microhardness at bottom, mid and top regions are in the range of 236 ± 9.2 HV, 227 ± 11.3 HV and 232 ± 6 HV, respectively. The microhardness values are consistent with the calculated SDAS along the build direction. Tensile tests were performed at room temperature and the samples failed with an average yield strength, ultimate tensile strength, and percentage of elongation of 391.4 ± 21 MPa, 616.8 ± 19.5 MPa and 45.6 ± 0.8% respectively. This work reveals that CMT-WAAM can successfully produce overhanging disc components of high-quality without using an industrial robot at a relatively low cost.
To improve the thermal-metallurgical-mechanical performance of the welded structure, the low-temperature water cooling is applied to assist welding Ti6Al4V alloy with filler wire. The behavior pattern of the thermal history is critically assessed with the aid of finite-element based heat transfer model. The shape of the simulated heat-affected zone is well agreed with experimentally measured values. The critical assessment on the performance of the weld joint is evaluated by metallographic analysis, energy dispersive spectrometer and micro-tensile. Increasing the flow rate and decreasing the cooling temperature can increase the cooling rate of the weld. As the rate of cooling increases, the cooling time is shortened by 15% and the concentration of oxygen in the weld area decreases from 10.84 to 6.98%. As the cooling rate increases, the effect of microstructure optimization of weld is enhanced. Blocky plate-shaped α′-martensite is apparent at a lower cooling rate, whereas the transformation of fine acicular α martensite is more complete at higher cooling rate. The dimensional variation of acicular α′ at the fusion zone has a significant influence on strength. The mechanical properties and hardness of welded joints are obviously improved with the temperature decrease.
The present study combines the Wire-based DED (W-DED) and Powder-based DED (P-DED) to achieve a high deposition rate and higher feature resolution, respectively, within the single component. The research puts forward a novel Wire-Power (WP) Hybrid DED process, which is realized by sequential deposition of feedstock in Wire and then in Powder form. Based on the deposition-extraction combination, three sample configurations, C1 (Y-X), C2 (X-X) and C3 (Y-Z), were fabricated and characterized for the mechanical properties and microstructural aspects. OM images revealed defect-free P-DED and W-DED interface, while the EBSD analysis showed grain size variations owing to differences in the cooling rates. The Ultimate Tensile Strength (UTS) values of C1 and C2 configurations are about 132.2 and 139.7 % higher in comparison to C3. Low cycle fatigue results showed that the C2 sustained a higher number of completely reversed cycles to failure in comparison to the other configurations. The impact energy absorbed by C3 is the highest, affirming the strong W-P interface.
Curved-generatrix-shell pyramid lattice structures (CPLSs) serve as critical components for hypersonic vehicle thermal protection systems. They can be used to improve thermal insulation performance and reduce the weight of the aircraft. Directed energy deposition-arc fabrication can be used as an effective method to fabricate CPLS. In this study, the effects of process parameters on droplet transfer, spreading, and rod formation accuracy were studied. With small current deposition, the droplet underwent a short-circuit transition, and the rod was well formed. When a large current was deposited, the droplet underwent spray transfer, and rod formation was poor. When the period interval time was 100 ms, a peak phenomenon appeared in the rod, and the formation accuracy of the rod was low. When the period interval time was 50 ms, the droplet at the top of the rod spread well, and the formation precision of the rod was high. The number of droplets and number of cycles affected the droplet deposition heat input and droplet volume. Finally, large size CPLS containing 20 rows and 90 columns with a single-layer-double-layer pyramid mixture was prepared. The overall size deviation was not greater than 0.8 mm and its relative error was < 7.2%.
The manufacturing of parts with medium complexity using wire-arc directed energy deposition (waDED) gets constantly improved by the development of tailored alloys and improvements in the generation of welding paths. In this study, both aspects are considered by proposing a novel aluminum alloy based on Al-Mg-Zn, which is then used for the waDED manufacturing of a car rim. The alloy was characterized in small-scale samples, in which no hot cracks and only a few gas porosities were found. In addition, the high quality of the alloy was verified by tensile tests of the heat-treated samples. The determined yield strength was >365 MPa, the ultimate tensile strength was >450 MPa, and the fracture strain was at least 3.9%. To put the new alloy to use, a standard aluminum car rim model was modified for the needs of waDED. Difficulties due to the steep overhang of the outer ring in the intersecting area with the spokes could be resolved by utilizing and adapting the collision avoidance of the path generation tool in the critical area. The optimization of the welding paths was simplified by first planning the paths using a section of the rim model. The rim geometry was manufactured successfully, and valuable findings regarding the waDED process of parts with medium complexity could be derived.
Wire arc additive manufacturing (WAAM) is presently growing as the major hub of research bodies throughout the universe. This is straightly noticeable in an enormous paper published recently pertaining to a myriad of distinct matters. Additive manufacturing is the quickest technique for the development of a product, and this is indicated by scientific industrial sections. It reinstated conventional ways in a few industrial circumstances by bringing down material utilisation. WAAM is much closer to welding in the process as it makes use of stratified deposition to design huge portions with less intricacy. Numerous experiments and estimates have evolved to ameliorate material properties concerning the remaining deformities like crackling and spattering. WAAM has acquired popularity as it has many benefits and very high efficiency. It increases the efficiency of the material and has a rate of deposition which is again very high and the lead time is shorter, the performance of the components is better, and the inventory cost is very low. This review is proposed to provide an appropriate summary of the field of WAAM. The inscribed matter in this review is embraced but not restricted to the materials. Various processes like monitoring, path planning, and modelling fall into the operations and techniques of WAAM. The alliance of detecting numerous authors into a consolidated form is the essence of this review. It is proposed to discover various fields in which the work is mislaid and in what ways the distinct topics can be manually integrated. A crucial estimation of introduced research along with welding research and a remarkable focus on additive manufacturing will accomplish this review.
The wire arc additive manufacturing process employing metal inert gas welding is a superior method for constructing large-scale components at a subsidized cost. This process has been experimented on Incoloy 825 for various industrial applications in large-scale industries like marine, chemical processing, and pressure vessel industries. This work mainly focuses on studying the microstructural properties and mechanical behavior of the wire arc additively manufactured (WAAMed) Incoloy 825 material. Microstructural analysis, x-ray diffraction analysis, Energy-Dispersive x-ray Spectroscopy, Electron Backscatter Diffraction analysis, hardness behavior, and tensile behavior of WAAMed Incoloy 825 were investigated. Titanium-rich secondary particles were observed using Energy-Dispersive x-ray Spectroscopy. In addition, location and orientation-based tensile strength and elongation behavior have been studied. Compared with wrought Incoloy 825, the WAAMed Incoloy 825 specimen inclined at 45° achieved nearly 86% ultimate tensile strength and 90% elongation. Fractography studies revealed that the WAAMed Incoloy 825 specimens exhibited a ductile fracture with large plastic deformation and brittle fracture in some areas.
Metal additive manufacturing (MAM) techniques are continously progressing since last decade and have marked a remarkable impact on the industry. Amongst the numerous MAM techniques, wire arc additive manufacturing (WAAM) exhibits high deposition rates, less production time, low raw material cost, flexibility with respect to the part size and high efficiency. WAAM is thus becoming one of the most promising AM techniques for metallic materials. Alloys of titanium, aluminium, nickel, steel and so on are predominantly utilized in WAAM and it has various applications in aerospace, marine and automotive industries. A lot of research has been put in and innovative practices have been developed to enhance the quality of the product by mitigating limitations such as corrosion, residual stresses, cracks, spatter, deformations, delamination, oxidation and porosity. In this review article, the effect of various process parameters and their optimization to counter the challenges in WAAM by using different methods of improvements like inter-pass cooling, heat treatment, inter-pass rolling, melt pool modifications and various optimization strategies are thoroughly discussed. Various trends and future aspects of WAAM are discussed to identify the challenges and research directions.
Fabricating fully dense and functional metallic components is one of the important challenges in Additive Manufacturing (AM). Additive Manufacturing is a technology in which functional components can be fabricated rapidly and efficiently from their CAD models. It is also referred as Layered Manufacturing (LM) as the object is created by slicing the CAD model into layers and realizing each layer at a time. These layers are thin and stacked or glued together to get the physical shape of the CAD model. However, realizing overhanging features is a difficult task due to deficiency of support mechanism for metals. A separate support structure has to be deposited to build overhanging structures. Although, use of a distinct support material is quite common in non-metallic AM processes, such as Fused Deposition Modelling (FDM), and the same for metals is not yet available. The various techniques in AM process for fabricating metal parts can be mainly classified as laser based, electron beam based and arc based processes. While some Additive Manufacturing processes like Selective Laser Sintering (SLS) employ easily-breakable-scaffolds made of same material to realize the overhanging features, the same approach cannot be extended to deposition processes like laser or arc based direct energy deposition processes. Even though it is possible to realize small overhangs by exploiting the inherent overhanging capability of the process or by blinding some small features like holes, the same cannot be extended for more complex geometries. A different approach to solve this problem is feature based slicing. Unlike uniform and adaptive slicing techniques, where the thickness of a given slice is constant, in feature based slicing inclined slicing; the thickness varies even within a given slice, based on its feature. The current work presents a novel approach for realizing complex overhanging features without the need of support structures. This can be possible by using higher axis kinematics or by adding extra degrees of mobility to the work piece or to the deposition system and suitably aligning the overhang with the deposition direction. Some Vital concepts required in realizing and depositing overhangs are feature based non-uniform slicing and non-uniform area-filling and the same are briefly discussed here. This research will summarize the issues and related approaches in the research, development, and integration. This includes understanding of the weld deposition process by establishing proper geometries, and automated process planning. This technique can be used to fabricate or repair fully dense and functional components for various engineering applications. Although this approach has been implemented for weld-deposition based system, the same can be extended to any other direct energy deposition processes also.
Copyright © 2015 by ASME Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature
Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
This paper presents an automated tool path planning for deposition of overhanging features using GMAW-based weld-deposition. Overhanging features, although possible to a certain extent in power-bed process like SLS, remain a challenge in deposition-based processes. Deposition processes like weld-deposition-based AM realised smaller overhangs by exploiting the inherent overhang capability of the weld bead; but the same cannot be applicable for complex geometries with large overhangs. This paper explains an efficient way of depositing the overhanging features through weld-deposition, without use of supports, based on inclined slicing and deposition. This approach uses higher order kinematics, that is, adding extra degrees of mobility to workpiece. The methodology used for realising these inclined slices based on an in-house MATLAB code has also been presented. While this concept is implemented in the context of weld-deposition, it can be extended for any other metallic deposition processes as well.
Depositing large components (>10kg) in titanium, aluminium, steel and other metals is possible by using Wire+Arc Additive Manufacturing (WAAM). This technology adopts arc-welding tools and wire as feedstock for Additive Manufacturing (AM) purposes. High deposition rates, low material and equipment costs, and good structural integrity make WAAM a suitable candidate for replacing the current method of manufacturing out of solid billets or large forgings, especially with regards to low to medium complexity parts. Amongst a variety of components, Ti-6Al-4V spars and landing gear assemblies, aluminium wing ribs, steel wing mockups and cones have been successfully manufactured. Strategies on how to manage residual stress, improve mechanical properties and eliminate defects such as porosity are suggested. Finally, the benefits of non-destructive testing, on-line monitoring and in situ machining are discussed.
Additive Layer Manufacture (ALM) is a technique whereby freeform structures are produced by building up material in layers. RUAM (Ready-to-Use Additive Layer Manufacturing) is an innovative concept for building large scale metal ready-to-use parts. The design for RUAM has several process steps: the geometric design of the parts taking the complex process behaviour of the arc welding process into account; FEM to predict temperature and stress distributions to minimise part distortions; and efficient robot tool path design. This paper covers these essential design steps from a technical as well as practical point of view. 1 INTRODUCTION New Additive Layer Manufacturing (ALM) technologies are currently subject of significant interest from industry. New wire and arc welding based technologies provide new routes to manufacture ready-to-use large metal parts. Producing large scale and high quality parts with very high deposition rates is the aim of the RUAM (Ready-to-Use Additive Manufacturing) machine currently being developed at Cranfield University. Aerospace industry estimates requirements of about 20 million tonnes of billet material over the next 20 years. With machining rates of ca. 90% and ever increasing material costs especially in titanium [1], conventional manufacturing strategies need reconsideration. The RUAM concept aims at reducing production costs by providing a new, sustainable, cost and time efficient manufacturing process which utilises well established as well as advanced cutting-edge technology. RUAM workpieces are produced by building up of material in layers (see Figure 1). New technologies such as CMT (Cold Metal Transfer) or Interpulse Welding allow for high deposition rates being more than 10 times faster than conventional powder based technologies.
Wire and arc additive manufacture enables us to build fully dense metallic parts by depositing material in layers using a welding process. Conventionally, in this process, the welding torch is always maintained in a vertical orientation, but this can cause accessibility problems and may require that the part is moved during the deposition process. The aim of the research presented in this article is to investigate the production of geometrical features using wire and arc additive manufacture with positional welding. Positional welding is particularly useful for building features with limited accessibility without having to manipulate the part. In the current work, inclined and horizontal wall features have been built using an inclined torch position. The knowledge obtained from these experiments has been further applied to build enclosed features. Additionally, a range of travel speeds has been investigated to better understand the effect of travel speed on part quality for angled walls. Factors that hinder the quality of the produced features have also been identified.
Hybrid layered manufacturing, an automatic layered manufacturing process for metallic objects, combines the best features of two well-known and economical processes, namely, weld-deposition and milling. A study of the mechanical properties like hardness and tensile strength of objects made through hybrid layered manufacturing is presented in this article. It was found that the interior matrix has negligible hardness variations in all directions. The tensile strength of the matrix displays negligible variations in the horizontal plane. However, the same for the vertical direction initially was found to be slightly lower, but this could be rectified by increasing the weld-deposition current. The ability of hybrid layered manufacturing to make composite material matrix with good material bonding has also been demonstrated. These studies help in understanding and controlling the anisotropic behavior of objects built using weld-deposition–based rapid prototyping and manufacturing techniques.
Additive Layer Manufacture (ALM) is a technique whereby freeform structures are produced by building up material in layers. RUAM (Ready-to-Use Additive Layer Manufacturing) is an innovative concept for building large scale metal ready-to-use parts. The design for RUAM has several process steps: the geometric design of the parts taking the complex process behaviour of the arc welding process into account; FEM to predict temperature and stress distributions to minimise part distortions; and efficient robot tool path design. This paper covers these essential design steps from a technical as well as practical point of view.
Three-dimensional welding has the ability to produce strong, fully dense metal parts in layers. Adaptation of a weld cladding technique has enabled the production of parts wider than normally possible from single beads. However, high heat inputs during welding could affect part quality. Simple temperature control techniques help improve surface finish. A number of parts were made incorporating temperature control. Results show that, although improvements have been made, corresponding time penalties can have a significant influence on build time. Descriptions of the welding system and temperature control technique are included as well as the surface measurement and residual stress assessment techniques used. Results of temperature versus time, surface finish versus temperature and temperature versus residual stress are presented and discussed.
Purpose
– This paper aims to develop build strategies for rapid manufacturing of components of varying complexity with the help of illustration.
Design/methodology/approach
– The build strategies are developed using a hybrid layered manufacturing (HLM) setup. HLM, an automatic layered manufacturing process for metallic objects, combines the best features of two well-known and economical processes, viz., arc weld-deposition and milling. Depending on the geometric complexity of the object, the deposition and/or finish machining may involve fixed (3-axis) or variable axis (5-axis) kinematics.
Findings
– Fixed axis (3-axis) kinematics is sufficient to produce components free of undercuts and overhanging features. Manufacture of components with undercuts can be categorized into three methods, viz., those that exploit the inherent overhanging ability, those that involve blinding of the undercuts in the material deposition stage and those that involve variable axis kinematics for aligning the overhang with the deposition direction.
Research limitations/implications
– Although developed using the HLM setup, these generic concepts can be used in a variety of metal deposition processes.
Originality/value
– This paper describes the methodology for realizing undercut features of varying complexity and also chalks out the procedure for their manufacture with the help of case studies for each approach.
Additive manufacturing based on gas metal arc welding (GMAW) is gaining increasing popularity as the process allows fabrication of fully dense parts with high material efficiencies and deposition rates. This paper aims at studying forming characteristics of multi-layer single-pass parts. Influences of arc current, deposit velocity, and heat input on layer formation were analyzed by using a passive vision sensor. Based on the results, the arc current has the greatest effect on the forming appearance, and a better understanding of the forming characteristics and process specification interval in multi-layer single-pass GMAW-based additive manufacturing can be obtained. Some newly improved GMAW methods were considered to improve deposition rates in multi-layer single-pass additive manufacturing process.
This paper presents a new deposition process for directly building cylindrical parts of the 5356 aluminium, alloy with variable polarity gas tungsten are welding (VPGTAW). The relationship between the geometric sizes of the deposited layer and the welding parameters is investigated. A machine vision sensor is used to monitor and control the are length that is a key welding parameter in the achievement of a uniform deposition. By optimizing the depositing speed and the thickness of the depositing layer, there is no need for a cooling system to cool the part. Three-dimensional parts with different wall thicknesses and different shapes are successfully obtained. The surfaces of the deposited parts are smooth and uniform.
Purpose
To fabricate fully dense components with low costs, a rapid prototyping (RP) system based on micro‐plasma arc welding (MPAW) was developed. The appropriate process parameters were investigated to build the parts with good mechanical properties and surface smoothness.
Design/methodology/approach
A simplified overlapping model between deposited tracks was established to investigate the relationships among the overlapping parameters, such as the ratio of width to height of the deposited track cross‐section ( λ ), scan spacing and overlapping ratio. Some ER308L stainless steel parts were built by different overlapping parameters, and the surface smoothness, tensile strength and elongation of the parts were tested.
Findings
The overlapped surface smoothness, tensile strength and elongation of the parts built with larger λ were better than those built with smaller λ . The longitudinal tensile strength and elongation of the parts were better than the transverse data.
Research limitations/implications
The scanning direction obviously affected the tensile strength and elongation of the parts, so the multi‐directional scanning mode should be used to get isotropic parts.
Originality/value
This MPAW‐based RP system provides a solution to build fully dense metal parts with relatively lower costs. The appropriate process parameters can be obtained with the developed overlapping model.
Superalloy integral impeller is a vital functional component of an aeroengine, but it is very difficult to manufacture if using the traditional five-axis NC machining method because of its complex free surfaces. Lamination deposition technology using high energy beams can overcome these difficulties and can be used to directly manufacture complex superalloy double helix integral impellers. However, subsequent re-machining should be required to guarantee adequate dimensional precision. In this paper, it is proposed to manufacture the superalloy double helix integral impeller using an approach of HPDM (hybrid plasma deposition and milling) which combines plasma deposition manufacturing as an additive technology and milling as a subtractive technique. Compared with the existing RP methods using high energy beams, HPDM solved the key problems of insufficient dimensional precision and surface quality caused by the step effect and lacking of supporting. To demonstrate the effectiveness of the proposed approach, an aeroengine superalloy double helix integral impeller with good performances of dimensional precision, microstructure and mechanics was rapidly manufactured by HPDM.
Subtractive manufacturing [computer numerical controlled (CNC) machining] has high quality geometric and material properties
but is slow, costly, and infeasible in some cases. On the contrary additive manufacturing (rapid prototyping) has total automation
but compromises quality. A hybrid layered manufacturing process presented in this study combines the best features of both
these approaches. It uses arc weld deposition for building near-net shapes, which are subsequently finish machined. Time and
cost savings of this process can be attributed to reduction in NC programming effort and elimination of rough machining. It
is envisioned as a low cost retrofitment to any existing CNC machine for making metallic objects without disturbing its original
functionalities. Near-net shape building and finish machining happening at the same station is the unique feature of this
process. A customized software generates the NC program for near-net shape building. The intricate details of integrating
arc welding unit with a CNC milling machine are presented in this paper.
KeywordsCNC machining-Rapid prototyping-Layered manufacturing-Hybrid processes-Retrofitment-Arc welding
A novel freeform fabrication method named 3D micro welding (3DMW) has been developed. It is a combined process of the freeform fabrication method with TIG (tungsten inert gas) welding. The titanium micro beads were investigated with respect to the diameter, height, and contact angle to the titanium substrate as functions of arc discharge current and two different shielding gases. The Ar-4% H2 gas was more effective in preventing oxidization of beads than Ar gas. Simple 3D titanium objects with arch, arabic numerals and pyramidal shapes were formed. Fine needle-like solidification structure of α-phase titanium were developed during bead formation due to the rapid cooling of the melt. The interfaces between a titanium bead and titanium substrate were jointed well without cracks or pores.
At the present time, the most widely used commercial rapid prototyping (RP) processes are based on polymeric materials, such as plastics or photocurable resins. While these prototype products adequately meet the requirements for “form” and “fit”, they are only very infrequently able to provide any “function” capability. This is especially true when considering metallic products. Laser sintering of metal powers has been studied and is currently being developed into a viable process. However, laser sintering requires expensive equipment and a high price form of starting material. A possibly more economical alternative is offered by the use of weld deposition processing.Research at the University of Kentucky has allowed the development of a dedicated control technology, including slicing/planning, system implementation and post-processing for RP using gas metal arc welding as the deposition process. The metal transfer control system is used to control the size and frequency of the droplets in order to improve the deposition accuracy. The component to be prototyped is specified by CAD surfaces or a solid model in standard IGES format. An integrated and user-friendly environment has been developed to slice the part, plan the deposition parameters, and control the deposition process. In this system, the deposition parameters, and control the deposition process. In this system, the deposition parameters, including the travel speed, touch angle, welding current, and arc voltage, are variably controlled to achieve the required density and three-dimensional geometry. This system, together with its operation, is destroyed and examples of several complex-shaped components produced are illustrated.
A process of combined additive and subtractive techniques for the direct freeform fabrication of metallic prototypes and tools is being developed by the authors. This hybrid process, called ‘3D welding and milling’, uses gas metal arc welding (GMAW) as an additive and conventional milling as a subtractive technique, thereby exploiting the advantages of both processes. In this paper, the results of the optimization of the deposition process using a statistical approach as well as the result of plastic injection molding with the inserts fabricated by this hybrid process are described. The result proves the applicability of the 3D welding and milling process for direct fabrication of metallic prototypes and tools.
This paper concentrates on the microstructural analysis of the three-dimensional (3D) parts built by rapid prototyping (RP) based on gas tungsten arc welding (GTAW). The material used for building 3D parts is AISI 1018. Two sets of experiments are carried out. From each experiment, samples are obtained by a standard metallographical procedure: cross sectioning, polishing, and etching. During the first experiment, the temperature at the locations with different heat-transfer conditions are monitored by thermocouples. The relationships between the geometry of the deposited beads and the welding parameters are developed. The microstructure analysis of fusion and the heat-affected zone is performed. Samples from the second experiment are examined on Vickers microhardness tests. The results showed that the deposited layers possess a maximum hardness at the top layer with a slight decrease towards the middle and bottom layers. The obtained results show that 3D parts built in this manner have a very uniform microstructure and are free of cracks and porosity.
Shaped metal deposition (SMD) is a relatively new technology of additive manufacturing, which creates near-net shaped components by additive manufacture utilizing tungsten inert gas welding.Especially for Ti alloys, which are difficult to shape by traditional methods and for which the loss of material during machining is also very costly, SMD has great advantages.In the case of Ti–6Al–4V the dense SMD components exhibit large, columnar prior β grains, with a Widmanstätten α/β microstructure. These prior β grains are slightly tilted in a direction following the temperature field resulting from the moving welding torch. The ultimate tensile strength is between 929 and 1014 MPa, depending on orientation and location of the tensile specimens. Tensile testing vertically to the deposition layers exhibits a strain at failure of 16 ± 3%, while testing parallel to the layers gives a lower value of about 9%.
Hybrid Layered Manufacturing is a Rapid Manufacturing process in which the metallic object is built in layers using weld deposition. Each layer built through overlapping beads is face milled to remove the scales and scallops and ensure Z-accuracy. The formations of single beads and overlapping multiple beads are modeled in this paper. While the individual bead’s geometry is influenced by the size of the filler wire and the speeds of the wire and torch, the step over increment between the consecutive beads additionally comes into the picture for the multiple bead deposition. These models were validated experimentally. They are useful not only to predict the bead’s shape but also to optimize the three process parameters.
Additive manufacturing of complex shapes through weld-deposition and feature based slicing
- J S Panchagnula
- S Simhambhatla
J.S. Panchagnula, S. Simhambhatla, "Additive manufacturing of complex shapes
through weld-deposition and feature based slicing, " vol. 2A, pp. V02AT02A004, Paper No. IMECE2015-51583, doi: 10.1115/IMECE2015-51583, 2015.