High-speed imaging and process characterization of coaxial laser metal wire deposition

Motta, Maurizio; Demir, Ali Gökhan; Previtali, Barbara

doi:10.1016/j.addma.2018.05.043

Cited by 40 publications

(52 citation statements)

References 35 publications

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“…The DED process consisting of a powder feeding device and a laser is known as a laser additive manufacturing (LAM)-DED process [60]. The wire feeding type DED processes are classified into wire and arc additive manufacturing (WAAM), wire and laser additive manufacturing (WLAM), and wire and electron beam additive manufacturing (WEAM) processes according to used thermal energies [1,4,6,24,46,[58][59][60][61][62][63][64][65][66][67]. The DED process with off-axial feeding devices of the feedstock relative to the focused thermal energy is sensitive to feed orientations and deposition conditions [59].…”

Section: Principle and Classification Of Ded Processesmentioning

confidence: 99%

“…The WLAM process is one of the MAM processes to produce metallic parts without porosity using a laser, such as diode, disc, Nd:YAG, CO 2 , and fiber lasers, as a thermal energy source and an metallic wire [4,24,61,67,73,153,[185][186][187][188][189][190][191][192][193][194][195][196][197][198][199][200][201][202]. The WLAM process fundamentally uses the concept of laser cladding and welding, as shown in Table 1 [4,24,66,67].…”

Section: Characteristics and Principle Of Wlam Processesmentioning

confidence: 99%

“…Recently, the application of the WLAM process area was extended to the mBAAM for the manufacture of metallic parts with an extremely large volume due to characteristics of a high deposition rate [190,191]. Ti-based, Ni-based, Fe-based, and Al-based alloys are utilized as the material of the wire [24,61,[185][186][187][188][189][190][191]. Many researches focused on Ti-6Al-4V to develop applications of the WLAM process to the aerospace industry in recent years [24,153].…”

Section: Characteristics and Principle Of Wlam Processesmentioning

confidence: 99%

See 2 more Smart Citations

Directed Energy Deposition (DED) Process: State of the Art

Ahn

2021

Int. J. of Precis. Eng. and Manuf.-Green Tech.

373

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Metal additive manufacturing technologies, such as powder bed fusion process, directed energy deposition (DED) process, sheet lamination process, etc., are one of promising flexible manufacturing technologies due to direct fabrication characteristics of a metallic freeform with a three-dimensional shape from computer aided design data. DED processes can create an arbitrary shape on even and uneven substrates through line-by-line deposition of a metallic material. Theses DED processes can easily fabricate a heterogeneous material with desired properties and characteristics via successive and simultaneous depositions of different materials. In addition, a hybrid process combining DED with different manufacturing processes can be conveniently developed. Hence, researches on the DED processes have been steadily increased in recent years. This paper reviewed recent research trends of DED processes and their applications. Principles, key technologies and the state-of-the art related to the development of process and system, the optimization of deposition conditions and the application of DED process were discussed. Finally, future research issues and opportunities of the DED process were identified.

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Section: Principle and Classification Of Ded Processesmentioning

confidence: 99%

Section: Characteristics and Principle Of Wlam Processesmentioning

confidence: 99%

Section: Characteristics and Principle Of Wlam Processesmentioning

confidence: 99%

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Directed Energy Deposition (DED) Process: State of the Art

Ahn

2021

Int. J. of Precis. Eng. and Manuf.-Green Tech.

373

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“…Wu et al [15] presented an approach for achieving deposition direction independence in which the welding torch rotated according to the deposition direction in a process of wire arc additive manufacturing (WAAM). Some recently developed LMWD heads [16,17,18,19,20] solve the direction dependence issue by inserting the wire perpendicular to the substrate, so the laser beam is divided within the head and then refocused on the working plane. This introduces the additional complexity of accurately reconstructing the laser beam.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, while the defocusing effect is important in powder deposition [21], it is critical in the case of LMWD. Motta and Demir [17] described the issues concerning height deviation using a high-speed vision camera. Defects were observed such as stubbing when the working distance was too small and dripping when it was too large.…”

Section: Introductionmentioning

confidence: 99%

Development of an Intra-Layer Adaptive Toolpath Generation Control Procedure in the Laser Metal Wire Deposition Process

et al. 2019

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Recently developed concentric laser metal wire deposition (LMWD) heads allow metal addition processes which are independent of the deposition direction, thus enabling complex paths to be generated. The sensitivity of the process to height deviations has experimentally been observed to be greater with this type of head than with powder ones, therefore requiring more precise and local process control algorithms to be implemented. This work developed a methodology for measuring the part, layer by layer, using a 3D scanner based on structured laser light. Height corrections were applied to the mean and intra-layer height deviations by recalculating the deposition trajectories of the next layer to be deposited. Local height deviations were adjusted by varying the scanning speed, thus increasing the feed rate in the lower areas and decreasing it in the higher ones. Defects generated in the purpose, with height differences within the layer, were successfully corrected. A flat layer was re-established through the application of the control strategy. The internal integrity of the parts due to the scanning speed variation was analyzed, resulting in fully dense parts. The structured light measurement and height correction systems are found to be an affordable and time-efficient solution that can be integrated into an LMWD environment, thereby improving the process robustness.

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Closed-Loop Control by Laser Power Modulation in Direct Energy Deposition Additive Manufacturing

Baraldo

Vandone

Valente

et al. 2020

Lecture Notes in Mechanical Engineering

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Direct Energy Deposition is a metal additive manufacturing technique that has raised great interest in industry thanks to its potential to realize complex parts or repairing damaged ones, but the complexity of this process still requires much effort from practitioners to achieve functionally sound parts. One of the recurring flaws of such parts is the phenomenon of over-deposition, which may occur due to unpredicted local increases of energy density. The deposition of uniform metal tracks is critical in many practical cases, when parts are composed by a significant number of layers and/or when complex tool paths induce heat build-up, for example in thin structures. Therefore, detecting anomalies such as over-growth in real-time and dynamically correcting them is of paramount importance for achieving repeatable, first-time-right parts. This work studies the use of a closed-loop control system for Direct Energy Deposition, proposing to adjust on-line the power of the laser beam according to the feedback provided by the analysis of melt pool images. The images are acquired by a camera, mounted coaxially into the optical chain of the deposition head, which records images at 100 fps while the process is running. The proposed approach is explored experimentally by comparing the over-deposition measured on sample test geometries obtained with a traditional feed-forward approach with the over-deposition obtained through the developed closed-loop control laser deposition system.

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High-speed imaging and process characterization of coaxial laser metal wire deposition

Cited by 40 publications

References 35 publications

Directed Energy Deposition (DED) Process: State of the Art

Directed Energy Deposition (DED) Process: State of the Art

Development of an Intra-Layer Adaptive Toolpath Generation Control Procedure in the Laser Metal Wire Deposition Process

Closed-Loop Control by Laser Power Modulation in Direct Energy Deposition Additive Manufacturing

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