Fluctuation effects in Wire Arc Additive Manufacturing of aluminium analysed by high-speed imaging

Hauser, Tobias; Silva, Adrien Da; Reisch, Raven T.; Volpp, Jöerg; Kamps, Tobias; Kaplan, Alexander

doi:10.1016/j.jmapro.2020.05.030

Cited by 39 publications

(9 citation statements)

References 32 publications

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“…Most WAAM processes are based on gas metal arc welding (GMAW), and one of the most promising GMAW processes for WAAM is the cold metal transfer (CMT) process which enables a reduced energy input compared to other GMAW processes [2]. Due to the reduced energy input in the CMT process, it is easier to keep the process temperature within a specified temperature range, which enables a consistent part geometry [3]. In the CMT process, the wire is conveyed into the process zone through a push-pull movement [4].…”

Section: Directed Energy Deposition Processesmentioning

confidence: 99%

“…During manufacturing of larger parts, the AE could be influenced by process anomalies such as geometrical fluctuations, track deviations, or oxidation effects. Geometrical fluctuations often occur due to process temperatures that are too low or too high [3]. Oxidation effects can reduce the mechanical properties of the part and occur in particular in WAAM of aluminium due to the high affinity of aluminium with oxygen [18].…”

Section: Acoustic Emissions In Directed Energy Deposition Processesmentioning

confidence: 99%

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Acoustic emissions in directed energy deposition processes

Hauser

Reisch

Kamps

et al. 2022

Int J Adv Manuf Technol

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Acoustic emissions in directed energy deposition processes such as wire arc additive manufacturing and directed energy deposition with laser beam/metal are investigated within this work, as many insights about the process can be gained from this. In both processes, experienced operators can hear whether a process is running stable or not. Therefore, different experiments for stable and unstable processes with common process anomalies were carried out, and the acoustic emissions as well as process camera images were captured. Thereby, it was found that stable processes show a consistent mean intensity in the acoustic emissions for both processes. For wire arc additive manufacturing, it was found that by the Mel spectrum, a specific spectrum adapted to human hearing, the occurrence of different process anomalies can be detected. The main acoustic source in wire arc additive manufacturing is the plasma expansion of the arc. The acoustic emissions and the occurring process anomalies are mainly correlating with the size of the arc because that is essentially the ionized volume leading to the air pressure which causes the acoustic emissions. For directed energy deposition with laser beam/metal, it was found that by the Mel spectrum, the occurrence of an unstable process can also be detected. The main acoustic emissions are created by the interaction between the powder and the laser beam because the powder particles create an air pressure through the expansion of the particles from the solid state to the liquid state when these particles are melted. These findings can be used to achieve an in situ quality assurance by an in-process analysis of the acoustic emissions.

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Section: Directed Energy Deposition Processesmentioning

confidence: 99%

Section: Acoustic Emissions In Directed Energy Deposition Processesmentioning

confidence: 99%

Acoustic emissions in directed energy deposition processes

Hauser

Reisch

Kamps

et al. 2022

Int J Adv Manuf Technol

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“…It uses a solid metal wire as feedstock material and an electric arc as heat source to melt the wire. Potential application areas of parts manufactured by WAAM are aerospace, marine, railway, or healthcare [4,5]. However, the process still faces challenges in the industrialization [6,7].…”

Section: Introductionmentioning

confidence: 99%

“…1. Form deviations, e.g., due to improper heat management [4] or an oxidation [14], can propagate and result in gaps or wavy structures over several layers as shown in (a), (c), (d) and (e) in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

Context awareness in process monitoring of additive manufacturing using a digital twin

Reisch

Hauser

Lutz

et al. 2022

Int J Adv Manuf Technol

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Wire Arc Additive Manufacturing allows the cost-effective manufacturing of customized, large-scale metal parts. As the post-process quality assurance of large parts is costly and time-consuming, process monitoring is inevitable. In the present study, a context-aware monitoring solution was investigated by integrating machine, temporal, and spatial context in the data analysis. By analyzing the voltage patterns of each cycle in the oscillating cold metal transfer process with a deep neural network, temporal context was included. Spatial context awareness was enabled by building a digital twin of the manufactured part using an Octree as spatial indexing data structure. By means of the spatial context awareness, two quality metrics—the defect expansion and the local anomaly density—were introduced. The defect expansion was tracked in-process by assigning detected defects to the same defect cluster in case of spatial correlation. The local anomaly density was derived by defining a spherical region of interest which enabled the detection of aggregations of anomalies. By means of the context aware monitoring system, defects were detected in-process with a higher sensitivity as common defect detectors for welding applications, showing less false-positives and false-negatives. A quantitative evaluation of defect expansion and densities of various defect types such as pore nests was enabled.

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“…1–3 At present, WAAM has been applied in the production field of two, four, five, and six series aluminum alloys successfully, which plays an important role in aerospace and other fields. 4–7…”

Section: Introductionmentioning

confidence: 99%

Microstructure and mechanical properties of 7A48 aluminum alloy fabricated by the wire-arc additive manufacturing + micro forging hybrid process

Zhang¹,

Zhang²,

Xu³

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part L:

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Wire-arc additive manufacturing technology has been widely recognized as a suitable method for fabricating large-size, complex, and high-strength aluminum alloy components. Two components were obtained by adopting a self-made low Cu 7A48 wire under the deposition parameters (a voltage of 18 V, a current of 85 A, a welding speed of 9 mm/s, and an argon flow rate of 23 L/min). One was the wire-arc additive manufacturing component of Al–Zn–Mg–Cu alloy, and the other was obtained via WAAM + micro forging hybrid process with about a 35% forging reduction ratio. Compared to that of the single wire-arc additive manufacturing component, the porosity of the micro forging component was reduced by 78.6%, and the micro forging hybrid process averagely increased the ultimate tensile strength and elongation by 23.3% (360.6 MPa) and 209.8% (18.9%), respectively. Besides, both the fracture modes were ductile fractures. The microstructure of the wire-arc additive manufacturing component consisted of the coarse grain area and fine grain band. For the micro forging component, the grains were equiaxed and obviously refined, and the average grains size was reduced by 81.6%. After the micro forging hybrid process, the grain orientation tended to be unified from disorder, and the maximum texture index reduced from 5.69 to 4.08. In addition, the secondary T (Al2Mg3Zn3) phase in two components precipitated along the grain boundary.

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Fluctuation effects in Wire Arc Additive Manufacturing of aluminium analysed by high-speed imaging

Cited by 39 publications

References 32 publications

Acoustic emissions in directed energy deposition processes

Acoustic emissions in directed energy deposition processes

Context awareness in process monitoring of additive manufacturing using a digital twin

Microstructure and mechanical properties of 7A48 aluminum alloy fabricated by the wire-arc additive manufacturing + micro forging hybrid process

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