Hybrid Additive Manufacturing Research Articles

Hybrid additive manufacturing of ceramic/aluminum-titanium gradient composites via arc and laser cladding eutectic pools

ABSTRACT There is a great deal of interest in improving the efficiency of arc-directed energy deposition (Arc-DED) of aluminium matrix composites and the uniform introduction of reinforcing particles. In this work, ceramic/aluminum-titanium gradient composites were manufactured by hybrid additive manufacturing with arc and laser cladding eutectic pools. The results show that the laser cladding powder feed method can have a higher powder capture rate compared to bypass feeding. Coupling the laser and powder changed the pulsed base-arc characteristics and increased the peak arc length. After the addition of the powder mixture, the aluminium matrix formed an Al3Ti reinforced phase, which evolved from needles to rods as the amount of powder increased. As the content of ceramic particles and the Al3Ti phase increased, the average hardness of the AMC components increased from 55.5–126 HV0.1 and the wear rate decreased from 6.16 × 10−3–1.25 × 10.−3 mm3·N−1·m−1.

Enabling tailored microstructures by hybrid directed energy deposition processing of a nickel-based superalloy

The technological advances in additive manufacturing, particularly laser based directed energy deposition (DED), revolutionized the production of complex metal components. Despite this progress, the oriented heat flux and several reheating thermal cycles can induce a strongly textured microstructure, which induces an anisotropic mechanical behavior. In addition, considerable residual stresses typically require additional post-processing. Therefore, hybrid process chains for additive manufacturing (AM) are being developed, which aim at integrating conventional post-processing into the AM process. However, a detailed investigation of thermal and mechanical effects of such hybrid processes on the mechanical properties and their interrelation is lacking. In an experimental study, we explore the integration of thermal and mechanical processing steps within the DED process chain to locally tailor microstructures and mechanical properties. Through electron backscatter diffraction measurements, we demonstrate significant microstructural changes of DED-manufactured nickel-based superalloy samples using deep rolling and laser heat treatment. A mechanical surface deformation induces microstructural misorientation leading to an increase in hardness down to substantial depth of several hundred micrometers. Additionally, the targeted management of heat input during laser heat treatment results in different grain morphologies and sizes, affecting average microhardness within a significant depth. The results demonstrate the potential for microstructural tailoring using hybrid AM process chains, while a substantial sensitivity of the microstructure to thermal and mechanical load emphasizes the importance of a precise process control. This work provides an understanding of the process-microstructure-property relationship required for developing new process pathways in hybrid AM that integrate thermal and mechanical processes into DED manufacturing.

Grain refinement and mechanical properties improvement of additively manufactured Al-Cu alloy through pre-deformation in thermo-mechanical treatment

Inferior mechanical properties induced by porosity and coarse grains of wire-arc additively manufactured Al-Cu alloy restrict its industrial application. The inter-layer cold rolling, conventional heat treatment (T6) and thermo-mechanical heat treatment (T8) was applied to Al-Cu alloy, and the effect of pre-stretched strain in T8 treatment was investigated. The pre-stretched strain induces equal increments of hardness and YS for both the as-deposited and cold-rolled conditions before aging treatment, while the increments for cold-rolled samples are larger after aging treatment. The cold-rolled sample shows better tensile properties than the as-deposited sample with the same pre-stretched strain in T8 treatment, proving that T8 treatment further increased the strengths compared to the T6 treatment. It shows the best tensile properties with the pre-stretched strain of 5 %, exceeding the properties of 2219-T87 plate. With the increased pre-stretched strain, the density of the θ′ phases significantly increases; while further increase to 10 % pre-stretched strain induces severe coarsening of θ′ phases. Therefore, an optimized pre-stretched strain leads to high-density and tiny dispersed θ′ phases, thus resulting in the best tensile properties. Grain refinement induced by inter-layer cold rolling and uniformly precipitated phases resulted from proper pre-stretched strain both contribute to the strengths enhancement. The strengthening mechanism of hybrid additive manufacturing and inter-layer cold rolling followed by T8 treatment was discussed.

Hybrid additive manufacturing for Zn-Mg casting for biomedical application

Hybrid additive manufacturing for Zn-Mg casting for biomedical application

Biological response guided by hybrid additive manufacturing for Ti6Al4V titanium alloy

This research evaluates the cellular response from Ti6Al4V scaffolds fabricated by hybrid additive manufacturing (AM) with the goal of improving bone tissue growth and biocompatibility of titanium implants. Since cellular adhesion and viability are subject to microstructure, hybrid AM was sought to dictate biological response by creating a dispersed and gradient microstructure within implants. The objective was to evaluate the effect of gradient microstructures within Ti6Al4V scaffolds on cellular metabolic activity. Gradient microstructure was incorporated within scaffolds by hybrid AM coupling directed energy deposition (DED) with interlayer milling. The cellular response from the scaffolds was evaluated using cell viability assays in two stages: the Ti6Al4V powder used for DED was first evaluated, followed by the fabricated scaffolds. Cell viability on hybrid AM scaffolds was compared with as–printed, i.e., DED-fabricated and annealed Ti6Al4V scaffolds. The cell viability assays demonstrated that Ti6Al4V powder was non-toxic as cells cultured with powder exhibited metabolic activity similar to cells in growth media without powder. The cell viability study on scaffolds indicated, on average, cell adhesion on hybrid AM scaffolds outperformed as–printed and annealed scaffolds. This study provides preliminary data demonstrating the use of hybrid AM to dictate cell activity. A larger sample set would be required in future work to understand the effects of grain refinement through coldworking on biological response.

Effect of beam oscillating amplitude on forming quality, microstructure, and mechanical performance of Al-Mg-Sc alloy fabricated by laser-arc hybrid additive manufacturing

The oscillating laser-arc hybrid additive manufacturing was applied to fabricate Al-Mg-Sc alloy and the effect of beam oscillating amplitude on macro/micro-morphology and the mechanical properties were investigated in this study. With the oscillating amplitude increased from 0 to 6 mm, the stirring effect of laser beam on molten pool was firstly enhanced due to the expanded active region and then weakened because the laser spot located at the edge of pool. As a result, the improved forming quality, the reduced porosity and the refined microstructures were achieved when the amplitude reached 4 mm, and then negative effect occurred when the amplitude was 6 mm. Eventually, the optimal mechanical performance was achieved at the amplitude of 4 mm and the as-deposited tensile properties reached 353 MPa and 24 % for UTS, and EL in vertical direction, respectively, which were 13.5 % and 50 % higher than that of 0 mm.

Hybrid Additive Manufacturing for Site‐Specific Tensile Response in 316L Stainless Steel

Herein, an alternative way of achieving site‐specific mechanical properties is explored—the hybridization of a directed energy deposition technology with a secondary deformation process (hammer peening (HP)) which acts between deposited layers. By applying the peening in a selective manner, microstructure and hence mechanical properties can be locally varied. Microstructural characterization reveals recrystallization in the HP‐induced deformation zone. The columnar grains of as‐built regions with a grain size of ≈26 μm are transformed into a recrystallized zone with equiaxed grains having a size of ≈8 μm. There is also a highly strain‐hardened region below this recrystallized zone where the dislocation density is more than two times higher than in the as‐built condition. Subsequent tensile testing reveals that these microstructural zones corresponded to local enhancement in tensile strength normal to the build direction. The strengthening mechanisms are identified as Hall–Petch and dislocation (Taylor) strengthening, and their relative contributions are studied. The local strength enhancement comes at the expense of ductility in the build direction, which is studied via finite element modeling and attributed to strain localization into non‐strengthened areas. The results from this work show the possibility of achieving site‐specific properties via interlayer processing.

Influence of hybrid additive manufacturing processes on the microstructure and mechanical properties of maraging steel 1.2709 components with post-processing heat treatments

The microstructural analysis revealed that the hybrid manufacturing process, combining Powder Bed Fusion (PBF) and Directed Energy Deposition (DED), resulted in a refined grain structure with a uniform phase distribution in the Maraging Steel 1.2709 components. The post-processing heat treatments, specifically stress relief at 500 °C for 2 h and solution treatment at 850 °C for 2 h, significantly enhanced the material’s mechanical properties. The components exhibited increased hardness and improved tensile strength, attributed to the effective elimination of residual stresses and the promotion of desirable precipitate formation during heat treatment. Overall, the study demonstrated that the hybrid PBF-DED process, coupled with appropriate heat treatments, can produce maraging steel components with superior mechanical performance, making them suitable for high-stress applications in advanced manufacturing sectors.

Multilevel Printed Wearable Radio-Frequency Intelligent Identification Platform for Object Recognition.

As a noncontact target recognition technique, radio-frequency identification (RFID) technology demonstrates attractive potential in constructing human-machine interaction (HMI) systems. However, the current development of RFID technologies in HMI systems is hampered by critical challenges in manufacturing high-performance RFID readers with superior flexibility and wearing comfort. Hence, we propose a multilevel printing strategy to overcome the difficulties in manufacturing high-performance large-scale microwave systems. Compared to traditional processes, the RFID system fabricated by the hybrid additive manufacturing technique exhibits equivalent electromagnetic performance and has obvious advantages in terms of manufacturing cost and environmental friendliness. A printed reconfigurable antenna with intelligent radiation mode is seamlessly integrated with the reader circuit via a "one-step" printing technology. Additionally, through chemical doping and artificial intelligence (AI) prediction, we have developed a modified polydimethylsiloxane (PDMS) encapsulation to miniaturize the system volume and enhance reliability. Electromagnetic and mechanical measurements demonstrated that our flexible RFID platform offers superior reliability and stability during long-term daily use. The RFID platform possesses exceptional capabilities in target positioning and accurate identification, demonstrating unique potential in noncontact sensing and recognition, which are highly demanded by flexible and wearable HMI systems.

Fatigue and fracture in dual-material specimens of nickel-based alloys fabricated by hybrid additive manufacturing

The integration of additive manufacturing with traditional processes, termed hybrid additive manufacturing, has expanded its application domain, particularly in the repair of gas turbine blade tips. However, process-related defects in additively manufactured materials, interface formation, and material property mismatches in dual-material structures can significantly impact the fatigue performance of components. This investigation examines the low cycle fatigue and fatigue crack growth behaviors in dual-material specimens of nickel-based alloys, specifically the additively manufactured STAL15 and the cast alloy 247DS, at elevated temperatures. Low cycle fatigue experiments were conducted at temperatures of 950 °C and 1000 °C under a range of strain levels (0.3%–0.8%) and fatigue crack growth tests were conducted at 950 °C with stress ratios of 0.1 and −1. Fractographic and microscopic analyses were performed to comprehend fatigue crack initiation and crack growth mechanisms in the dual-material structure. The results consistently indicated crack initiation and fatigue fracture in the additively manufactured STAL15 material. Notably, fatigue crack growth retardation was observed near the interface when the crack extended from the additively manufactured STAL15 material to the perpendicularly positioned interface. This study highlights the importance of considering yield strength mismatch, as well as the potential effects of residual stresses and grain structure differences, in the interpretation of fatigue crack growth behavior at the interface.

Design optimization of lightweight automotive seatback through additive manufacturing compression overmolding of metal polymer composites

With the growing demand for enhanced automotive fuel efficiency and environmental sustainability, there is a need for lightweighting automotive components through innovative design and manufacturing processes. This study leverages a combination of numerical iterative design optimization and hybrid additive manufacturing–compression molding (AM-CM) technique for metal polymer composites to lightweight an automotive seatback. The AM-CM process enables robust mechanical interlocking between metals and composites, boasting high stiffness and strength with low overall density. Replacing metallic components with such metal polymer composites allows for comparable mechanical performance while significantly reducing the overall weight. First, the automotive seatback design space is reduced to critical load carrying regions using topology optimization and high stress concentration areas are identified using finite element analysis. Next, a lightweight metal polymer subcomponent is designed for a high stress concentration region. The full seatback frame with spatially heterogeneous material-specific design is then iteratively optimized to enable enhanced stiffness with minimal weight. Overall, the automotive seatback frame designed with location-specific metal, polymer, and metal polymer composite materials weighs 20% less than the metal-only design while exhibiting similar stiffness.

A Comparative Study of Artificial Neural Network and Regression Model for Hybrid Additive Manufacturing of Ti6Al4V Parts and Microstructural Analysis

A Comparative Study of Artificial Neural Network and Regression Model for Hybrid Additive Manufacturing of Ti6Al4V Parts and Microstructural Analysis

Surface engineering of carbon nanotube-carbon fiber networks for enhanced strength in additive manufacturing of nylon composites

This work quantifies the impact of chemical functionalization of carbon nanotubes and carbon fibres on the interfacial shear strength, tensile and interlaminar shear strength properties of additively manufactured nylon composites. The surface chemistry of functionalized carbon materials was evaluated through infrared spectroscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Single carbon fibre was dip-coated in a suspension of nanotubes and embedded into a nylon matrix. The fibres were pulled out to measure the interfacial shear strength, and the fibres with attached neat, carboxylated, and silanized nanotubes increased it by up to 67 %, 112 %, and 216 %, respectively. Composite samples were manufactured using a novel hybrid additive manufacturing method, which was able to deposit nylon layers and a suspension containing carbon reinforcement. The use of chemically functionalized nanotubes in the suspension led to carbon layers that improved tensile strength by 49 % and tensile modulus by 126 % over neat nylon. Functionalization of carbon reinforcement increased the interlaminar shear strength by up to 63 %. Overall, this paper demonstrates the importance of chemical modification in composite materials containing a large interface area of carbon materials.

Fabrication and control architecture of novel hybrid metal additive manufacturing incremental forming technology

Hybrid manufacturing processes redefine production dynamics by harnessing the synergistic interplay between process mechanisms, energy sources, and tools to impact manufacturing quality, productivity, and sustainability significantly. Accordingly, this article focuses on hybrid additive manufacturing incremental forming, where additive manufacturing and incremental forming are integrated in a unified setup, driven by a single power source. This integration opens avenues for innovative component and production design, capitalizing on the strengths of both methods while mitigating drawbacks. The fabrication of the hybrid additive manufacturing incremental forming setup involves crucial components like a hybrid extrusion forming unit, supporting plates, hopper-barrel assembly, band heaters, solenoid setup, and a comprehensive control architecture. Addressing challenges, particularly overheating in the hopper, and feeding zone, ensures effective material transformation with the hybrid extrusion forming unit. The subsequent section provides analytical analysis and validation of the hybrid extrusion unit. This technology enhances the entire process and addresses issues related to metal additive manufacturing, such as porosity and material shrinkage. The maximum tensile force sustained in hybrid additive manufacturing incremental forming before fracture demonstrates a notable enhancement of about 20% from 670 N in additive manufacturing to 805 N in hybrid additive manufacturing incremental forming. It also removes micro-cracks, and voids, and improves the inter-layer bonding, as observed through scanning electron microscopy. The results highlight hybrid additive manufacturing incremental forming's superior enhancement of mechanical properties and surface quality compared to traditional additive manufacturing approaches.

General Adaptable Design and Evaluation Using Markov Processes

Abstract Facing the challenges posed by increasingly complex, dynamic, and unforeseen requirements, the design process is grappling with the critical issue of ensuring sustained product satisfaction amid changing demands. This paper introduces an approach for evaluating design adaptability, considering potential future requirements. Entropy serves as a crucial indicator to quantify design effort and the Markov process is employed to simulate potential requirement changes. The information contents of design requirements and design solutions are defined based on information entropy theory, and the design adaptability of a design candidate is evaluated by calculating the extra design effort for satisfying the design requirements, which is the difference in information content between the design candidate and design requirements. Moreover, a simulation method for requirement evolution is proposed, which integrates information entropy theory and the Markov process to accommodate potential future requirements. The general design adaptability of design solutions is then calculated based on conditional entropy, taking into account the evolving design requirements. Finally, the effectiveness of the proposed approach is validated through a case study involving the design and evaluation of a hybrid additive manufacturing device.

A Microchannel Heat Exchanger Produced From a Metal Matrix Composite by Hybrid Laser Powder Bed Fusion and Inkjet Printing

Abstract This paper explores the production of an oxide dispersion strengthened (ODS) 304L stainless steel microchannel heat exchanger (HX) using a hybrid additive manufacturing process of laser powder bed fusion and inkjet printing. The study investigates the capabilities and economics of the hybrid inkjet-laser powder bed fusion (LPBF) process and evaluates the dimensional accuracy, functionality, and mechanical properties of the resulting ODS alloy. The effectiveness and pressure drop of the ODS heat exchangers produced by the hybrid LPBF tool are also determined. Results show that the inkjet-doped samples have a lower mean channel height with higher standard deviation than samples produced by LPBF alone. This is attributed to greater absorption of laser energy for the powder coated with the oxide precursor. The economic analysis shows that the hybrid process has a potential for reducing the unit cost of the heat exchanger based on cost modeling assumptions.

Improving the formability and quality of CMT additively manufactured aluminum thin-wall parts via laser stabilization effect

In the recent past, the deposition efficiency has been one of the most concerned problems in aluminum additive manufacturing. In this research, a comparative study on the formation quality, microstructures and mechanical properties of aluminum alloy thin-wall structures between the oscillating laser-arc hybrid additive manufacturing (O-LHAM) and wire-arc additive manufacturing (WAAM) at high deposition speed was performed. The formation quality of the additively manufactured thin-wall parts under O-LHAM was significantly improved compared with WAAM. The molten pool overflow was significantly eliminated due to the higher support force on the molten pool, thus the surface roughness Sa and the maximum surface height difference Sz of O-LHAM thin walls were reduced by 13% and 22%, respectively. Compared with thin wall manufactured via WAAM, the microstructure of O-LHAM mainly consisted of coarse columnar grains and showed anisotropic characteristics due to the increased heat accumulation. Moreover, owing to the higher porosity in the interlayer combination regions of WAAM sample, the elongation of thin walls manufactured via O-LHAM was higher than WAAM in both horizontal and vertical directions, reaching 36.8% and 32.5%, respectively. This work will provide more guidance on thin-wall additive manufacturing with high deposition efficiency.

Advancements in Hybrid Additive Manufacturing: Integrating SLM and LMD for High-Performance Applications

Additive manufacturing (AM) technologies enable near-net-shape designs and demand-oriented material usage, which significantly minimizes waste. This points to a substantial opportunity for further optimization in material savings and process design. The current study delves into the advancement of sustainable manufacturing practices in the automotive industry, emphasizing the crucial role of lightweight construction concepts and AM technologies in enhancing resource efficiency and reducing greenhouse gas emissions. By exploring the integration of novel AM techniques such as selective laser melting (SLM) and laser metal deposition (LMD), the study aims to overcome existing limitations like slow build-up rates and limited component resolution. The study’s core objective revolves around the development and validation of a continuous process chain that synergizes different AM routes. In the current study, the continuous process chain for DMG MORI Lasertec 65 3D’s LMD system and the DMG MORI Lasertec 30 3D’s was demonstrated using 316L and 1.2709 steel materials. This integrated approach is designed to significantly curtail process times and minimize component costs, thus suggesting an industry-oriented process chain for future manufacturing paradigms. Additionally, the research investigates the production and material behavior of components under varying manufacturing processes, material combinations, and boundary layer materials. The culmination of this study is the validation of the proposed process route through a technology demonstrator, assessing its scalability and setting a benchmark for resource-efficient manufacturing in the automotive sector.

Prediction of Geometric Dimensions of Deposited Layer Produced Using Laser-Arc Hybrid Additive Manufacturing.

Laser-arc hybrid additive manufacturing (LAHAM) holds substantial potential in industrial applications, yet ensuring dimensional accuracy remains a major challenge. Accurate prediction and effective control of the geometrical dimensions of the deposited layers are crucial for achieving this accuracy. The width and height of the deposited layers, key indicators of geometric dimensions, directly affect the forming precision. This study conducted experiments and in-depth analysis to investigate the influence of various process parameters on these dimensions and proposed a predictive model for accurate forecasting. It was found that the width of the deposited layers was positively correlated with laser power and arc current and negatively correlated with scanning speed, while the height was negatively correlated with laser power and scanning speed and positively with arc current. Quantitative analysis using the Taguchi method revealed that the arc current had the most significant impact on the dimensions of the deposited layers, followed by scanning speed, with laser power having the least effect. A predictive model based on extreme gradient boosting (XGBoost) was developed and optimized using particle swarm optimization (PSO) for tuning the number of leaf nodes, learning rate, and regularization coefficients, resulting in the PSO-XGBoost model. Compared to models enhanced with PSO-optimized support vector regression (SVR) and XGBoost, the PSO-XGBoost model exhibited higher accuracy, the smallest relative error, and performed better in terms of Mean Relative Error (MRE), Mean Square Error (MSE), and Coefficient of Determination R2 metrics. The high predictive accuracy and minimal error variability of the PSO-XGBoost model demonstrate its effectiveness in capturing the complex nonlinear relationships between process parameters and layer dimensions. This study provides valuable insights for controlling the geometric dimensions of the deposited layers in LAHAM.

Bifunctional nano-SiO2 additive for reinforcing the SiC/Al composites fabricated via a novel hybrid additive manufacturing

In this work, a novel hybrid additive manufacturing technique is used to prepare the SiC/Al composites. The effect of silica sol concentration on the microstructure and property of SiC preforms and SiC/Al composites were investigated. Silica sol infiltration proved to be an efficient strategy to address the troublesome issue of strength decrease for the SiC preforms after preoxidation. With an increase in silica sol concentration from 0 to 30 %, the strength of the pre-oxidised SiC preforms increased from 0 to 2.77 ± 0.21 MPa, which well satisfied the processing requirements of the subsequent vacuum-pressure infiltration process. Interestingly, the nano-SiO2 in the silica sol not only is favorable for the SiC–Al interface of SiC/Al composite, but also has a significant grain refinement effect on the aluminium matrix. As a result, the strength of the samples treated with preoxidation and silica sol infiltration reached a maximum value of 411.41 MPa, which was 88.38 % higher than 218.4 MPa of the control group. Meanwhile, a notable enhancement in fracture strain was observed from 0.125 to 0.156 % for the optimized SiC/Al composite. More importantly, the large-size and high-performance SiC/Al composite parts with complex structures have been successfully prepared by this hybrid additive manufacturing technique. The results of this work show that the hybrid additive manufacturing technology has great potential for application in aerospace, automotive industry and other fields.