| 1. |
- Kaplan, Alexander, et al.
(författare)
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CYCLAM : Recycling by a Laser-driven Drop Jet from Waste that Feeds AM
- 2017
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Ingår i: Physics Procedia. - : Elsevier. - 1875-3892. ; 89, s. 187-196
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Tidskriftsartikel (refereegranskat)abstract
- Additive manufacturing of metal parts is supplied by powder or wire. Manufacturing of this raw material causes additional costs and environmental impact. A new technique is proposed where the feeding directly originates from a metal sheet, which can even be waste. When cutting is done by laser-induced boiling, melt is continuously ejected downwards underneath the sheet. The ejected melt is deposited as a track on a substrate, enabling additive manufacturing by substrate movement along a desired path. The melt first flows downwards as a column and after a few millimeters separates into drops, here about 500 micrometer in diameter, as observed by high speed imaging. The drops incorporate sequentially and calmly into a long melt pool on the substrate. While steel drops formed regular tracks on steel and aluminium substrates, on copper substrate periodic drops solidified instead. For this new technique, called CYCLAM, the laser beam acts indirectly while the drop jet becomes the main tool. From imaging, properties like the width or fluctuations of the drop jet can be statistically evaluated. Despite oscillation of the liquid column, the divergence of the drop jet remained small, improving the precision and robustness. The melt leaves the cut sheet as a liquid column, 1 to 4 mm in length, which periodically separates drops that are transferred as a liquid jet to the substrate. For very short distance of 2 to 3 mm between the two sheets this liquid column can transfer the melt continuously as a liquid bridge. This phenomenon was observed, as a variant of the technique, but the duration of the bridge was limited by fluid mechanic instabilities.
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| 2. |
- Samarjy, Ramiz S. M., 1965-, et al.
(författare)
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Additive manufacturing and recycling by a laser-induced drop jet from a sheet edge
- 2018
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Ingår i: Journal of laser applications. - Melville (NY) : American Institute of Physics (AIP). - 1042-346X .- 1938-1387. ; 30:4
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Tidskriftsartikel (refereegranskat)abstract
- A new technique for additive manufacturing was recently presented by depositing droplets as a continuous track on a substrate, where the droplets were ejected from laser remote fusion cutting of a metal sheet. For the here presented approach, the droplets are instead ejected from the sheet edge, termed the machining mode, which is compared to cutting. Here, the transmitted part of the laser beam does not hit and interact with the deposited track because of lateral dislocation. High speed imaging has shown that laser-induced boiling, which drives the melt downwards, causes asymmetric conditions in the machining mode by lateral pushing of the generated drop jet under the sheet, where the melt can even attach. Compared to machining, the cutting mode keeps less deviation of the drop trajectories, higher precision, and a smoother surface finish. It was demonstrated that the edge conditions after machining are sufficient to repeat the process. This enables additional technique opportunities, including recycling of a whole sheet of waste metal. By the aid of high speed imaging from two different perspectives, the melt flow behavior, the drop jet precision, and process trends with respect to parameters, drop ejection, and deposition were studied.
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