AMUG 2023

Metal AM: an Overview from Plasma Atomized Powders to Quality L-PBF Parts

Metal Additive Manufacturing (AM) has attracted great interest in fabricating parts for medical and aerospace applications due to its capacity to produce complex and lightweight geometries. The primary feedstock materials for AM are metal powders and their quality has a great impact on the final performance of a printed part.

The first part of this paper describes a radio frequency (RF) plasma technology used to manufacture highly spherical powders with controlled interstitial elements. Primary characteristics of powders including particle size distribution, oxygen content, and morphology are discussed. The impact of the primary powder characteristics on the secondary characteristics including flowability and density are then explained.

The second part of the paper discusses recoater technology used in Laser Powder Bed Fusion to spread fine and medium size powders. In addition, a powder handling system Autonomous Powder Module (APM) that can implement different powder reuse schemas as per ASTM standards will be discussed. Finally, some of the physical and mechanical properties of the parts produced by laser powder bed fusion in conjunction with roller spreading technology will be explained.

Rethinking the Production Line with 3D-Printed Extrusion Dies

Molds, Dies, and tooling are good fits for metal additive manufacturing due to their smaller production volumes and lack of a rigorous qualification system. For many of their projects, the tooling sector does not have to answer to a strict regulatory body like the medical and aerospace industries do. The tooling sector also lacks the investment focused on Design for Additive Manufacturing that is seen elsewhere. One partner saw an opportunity use Powder Bed Fusion for an extrusion die to make one of their products. Yearly production volumes of roughly 100 dies coupled with a clear integration plan made additive a promising choice. While the original goal was strictly increased wear performance, they were able to improve throughput because of their redesign efforts.

The key to success in this project was the willingness to challenge every aspect of the existing mold design and tweak the settings of the production line. Past dies were machined out of Aluminum, but are now printed in Inconel 718. Inconel has better wear properties, but is difficult to machine and has poorer thermal conductivity. With manufacturing via Powder Bed Fusion, machining is no longer necessary. The decrease in conductivity is tackled by improved conformal cooling channels in a new design that results in a lower working temperature. These changes lead to a 25% increase in productivity by ramping up the extrusion speed of the final product made with the new molds. Even at faster speeds, the molds last six times as long before wearing out.