Studies on Thin and Thick-Walled SS316L Overhanging Specimens Manufactured Using Powder-Fed Laser-Based Directed Energy




Belchou, Alexander P.
Jacob, Ashish
Joshi, Sanjay
Reutzel, E.W.
Coutts, Peter

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Effective Design for Additive Manufacturing (DfAM) requires accurate knowledge of a machine’s capabilities and limitations. One important factor is the machine’s ability to deposit unsupported overhanging features. A general method was devised to characterize the ability of a powder-fed Laser-Based Directed Energy Deposition (LB-DED) system to deposit overhanging features with various overhang angles, wall thicknesses, and scan strategies, which was then investigated on a DMG Mori LASERTEC 65 3D Hybrid LB-DED system using 3-axis toolpaths. To assess the accuracy of the manufactured overhang angle, for each specimen the angle of the downward facing surface and upward facing surface were measured and compared to the target overhang angle. It was observed that for the longitudinal scan strategy, overhang accuracy substantially degraded as wall thickness increased. For the transverse and cross hatch patterns there is no observable trend between the achievable overhang angle and the wall thickness. In addition, it was observed that in general increasing the target overhang angle degrades the accuracy of the manufactured overhang angle. The most accurate overhang angles overall were achieved for the longitudinal 1 bead thick specimens. These results will help inform future DfAM and path planning strategies. This research fills a gap in the literature by providing a general method to assess overhang capabilities for LB-DED systems.



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