Introduction to the design rules for Metal Big Area Additive Manufacturing

Greer, Clayton; Nycz, Andrzej; Noakes, Mark W.; Richardson, Brad; Post, Brian; Kurfess, Thomas R.; Love, Lonnie J.

doi:10.1016/j.addma.2019.02.016

Cited by 78 publications

(41 citation statements)

References 11 publications

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“…It predominantly uses a laser beam as the heat source. Wire based DED processes provide a lower resolution as compared to laser-beam powder based processes, but have a higher deposition rate and the ability to build larger structures [14,15]. They generally use an electron-beam, plasma, or electric arc as the heat source.…”

Section: Introductionmentioning

confidence: 99%

“…Electric arc based DED melts the wire feed to deposit the layers. Emerging technology, like metal big area additive manufacturing (mBAAM) [14], takes advantage of the principle of electric arc welding to print big parts. Kinetic energy based DED systems, often referred to as Cold Spray, use a converging-diverging nozzle to accelerate micron sized particles to supersonic velocities [18].…”

Section: Introductionmentioning

confidence: 99%

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State of the Art in Directed Energy Deposition: From Additive Manufacturing to Materials Design

2019

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Additive manufacturing (AM) is a new paradigm for the design and production of high-performance components for aerospace, medical, energy, and automotive applications. This review will exclusively cover directed energy deposition (DED)-AM, with a focus on the deposition of powder-feed based metal and alloy systems. This paper provides a comprehensive review on the classification of DED systems, process variables, process physics, modelling efforts, common defects, mechanical properties of DED parts, and quality control methods. To provide a practical framework to print different materials using DED, a process map using the linear heat input and powder feed rate as variables is constructed. Based on the process map, three different areas that are not optimized for DED are identified. These areas correspond to the formation of a lack of fusion, keyholing, and mixed mode porosity in the printed parts. In the final part of the paper, emerging applications of DED from repairing damaged parts to bulk combinatorial alloys design are discussed. This paper concludes with recommendations for future research in order to transform the technology from “form” to “function,” which can provide significant potential benefits to different industries.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

State of the Art in Directed Energy Deposition: From Additive Manufacturing to Materials Design

2019

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“…The embossing resolution of the extra-toolpath geometry was dependent upon the melt pool size response time and the print speed. The ability of this technique to control local bead geometry has interesting implications, particularly for a large-scale AM process such as laser wire-based DED, which requires a different set of design rules than the majority of AM processes and has traditionally been limited to lower resolution of component details [13]. It is anticipated that the technique can be used in the near future for volumetric defect mitigation in toolpaths where local overlap of adjacent beads is inadequate.…”

Section: Discussionmentioning

confidence: 99%

Beyond the Toolpath: Site-Specific Melt Pool Size Control Enables Printing of Extra-Toolpath Geometry in Laser Wire-Based Directed Energy Deposition

et al. 2019

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Featured Application: This work applies to the production of large, complex, metallic preform structures in the aerospace and tool and die industries. In the aerospace industry, this technology has a potential role in the rapid production of custom, near-net shape preforms for machined Ti-6Al-4V components. Specifically, site-specific control enables localized control of bead geometry, which has enhanced defect mitigation capabilities and may enable local control of material properties.Abstract: A variety of techniques have been utilized in metal additive manufacturing (AM) for melt pool size management, including modeling and feed-forward approaches. In a few cases, closed-loop control has been demonstrated. In this research, closed-loop melt pool size control for large-scale, laser wire-based directed energy deposition is demonstrated with a novel modification, i.e., site-specific changes to the controller setpoint were commanded at trigger points, the locations of which were generated by the projection of a secondary geometry onto the primary three-dimensional (3D) printed component geometry. The present work shows that, through this technique, it is possible to print a specific geometry that occurs beyond the actual toolpath of the print head. This is denoted as extra-toolpath geometry and is fundamentally different from other methods of generating component features in metal AM. A proof-of-principle experiment is presented in which a complex oak leaf geometry was embossed on an otherwise ordinary double-bead wall made from Ti-6Al-4V. The process is introduced and characterized primarily from a controls perspective with reports on the performance of the control system, the melt pool size response, and the resulting geometry. The implications of this capability, which extend beyond localized control of bead geometry to the potential mitigations of defects and functional grading of component properties, are discussed. capability; this mode of control has been demonstrated by Hu et al. in laser cladding, Hu et al. and Hofmeister et al. in laser powder based DED, Zalameda et al. in electron beam freeform fabrication, and the present authors in laser wire-based DED [2 -6]. This mode of control effectually enables control of local bead geometry and management of interlayer energy density as heat accumulates in the component during construction [2]. The degree to which thermal gradients and heating and cooling rates are modified by this mode of control, and the subsequent impacts on solidification dynamics, microstructure, and material properties, is the subject of continuing investigation, largely on a machineand material-specific basis.The literature indicates that, in the research demonstrated to date, the common goal of efforts to control the melt pool size in DED has been to maintain a consistent melt pool size with a constant controller setpoint. This type of control has the effect of maintaining nominal bead geometry both on an intralayer basis and throughout the printing of components, yielding global geomet...

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“…The embossing resolution of the extra-toolpath geometry was dependent upon the melt pool size response time and the print speed. The ability of this technique to control local bead geometry has interesting implications, particularly for a large-scale AM process like laser-wire DED, which requires a different set of design rules than the majority of AM processes and has traditionally been limited to lower resolution of component details [13,14]. It is anticipated that the technique can be used in the near future for volumetric defect mitigation in toolpaths where local overlap of adjacent beads is inadequate.The capability to emboss specific, secondary geometry means that part identification features, such as a serial number or QR code, could be permanently added to components during the printing process.…”

Section: Discussionmentioning

confidence: 99%

Beyond the Toolpath: Site-Specific Melt Pool Size Control Enables Printing of Extra-Toolpath Geometry in Laser-Wire Directed Energy Deposition

Gibson¹,

Richardson²,

Sundermann³

et al. 2019

Preprint

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A variety of techniques have been utilized in metal additive manufacturing (AM) for melt pool size management, including modeling and feed-forward approaches. In a few cases, closed-loop control has been demonstrated. In this research, closed-loop melt pool size control for large-scale, laser-wire based Directed Energy Deposition is demonstrated with a novel modification: site-specific changes to the controller set-point were commanded at trigger points, the locations of which were generated by the projection of a secondary geometry onto the primary 3D-printed component geometry. The present work shows that, through this technique, it is possible to print a specific geometry that occurs beyond the actual toolpath of the print head. This is denoted as an extra-toolpath geometry and is fundamentally different from other methods of generating component features in metal AM. A proof-of-principle experiment is presented in which a complex oak leaf geometry was embossed on an otherwise ordinary double-bead wall made from Ti-6Al-4V. The process is introduced and characterized primarily from a controls perspective with reports on the performance of the control system, the melt pool size response, and the resulting geometry. The implications of this capability, which extend beyond localized control of bead geometry to the potential mitigations of defects and functional grading of component properties, are discussed.

show abstract

Introduction to the design rules for Metal Big Area Additive Manufacturing

Cited by 78 publications

References 11 publications

State of the Art in Directed Energy Deposition: From Additive Manufacturing to Materials Design

State of the Art in Directed Energy Deposition: From Additive Manufacturing to Materials Design

Beyond the Toolpath: Site-Specific Melt Pool Size Control Enables Printing of Extra-Toolpath Geometry in Laser Wire-Based Directed Energy Deposition

Beyond the Toolpath: Site-Specific Melt Pool Size Control Enables Printing of Extra-Toolpath Geometry in Laser-Wire Directed Energy Deposition

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