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UK Researchers Examine Particle Dynamics in Powder Bed Fusion https://ift.tt/2BQ07YQ In ‘Fluid and particle dynamics in laser powder bed fusion,’ authors P. Bidare, I. Bitharas, R.M. Ward, M.M. Attallah, and A.J. Moore examine laser bed and powder bed interaction. In this study, the team was able to study and create images of areas where powder was removed during single line and island scans. Research gave the scientists further insight into the PBF process, making it obvious that it is more dynamic than previously realized, and includes substantial movement (driven by the laser-induced plume of metal vapor and plasma above the melt pool) between power and agglomerates both in and above the powder bed. Previously, images have been recorded through a Renishaw AM250 3D printer, but laser and powder particles ‘could not be resolved.’ Other image sequences, however, were used to discover powder areas overheating, and then defects. The scientists used an open architecture PBF system for in situ measurements, offering automated build of fully dense components. The computer offers:
The system offers high resolution imaging plus the ability to melt single tracks in the powder bed and during builds using multiple layers.
Direct imaging was allowed through the top viewing window, with an infra-red absorbing window offering the side views. The team inserted the camera onto a tilt stage, transforming the powder bed area, and meaning that several areas could be both scanned and imaged. They then moved forward in imitating gas and plasma dynamics during PBF thermal effects. For process thermodynamics, an energy balance was used to account for all types of heat transfer from conductive to convective to radiative. Temperature increases build plasma density and powder agglomerates forming when scanning islands.
Laser plume was directed in a forward motion for the first time from the melt pool, and other studies have remarked on this happening because of droplet detachment. The team also believes the forward motion is specific to PBF.
What do you think of this news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard.com. [Source / Images: Fluid and particle dynamics in laser powder bed fusion] Printing via 3DPrint.com | The Voice of 3D Printing / Additive Manufacturing https://3dprint.com February 25, 2019 at 02:39AM
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