Design and Test of a Desktop Metal Additive Manufacturing System

Abstract

Laser powder bed fusion (L-PBF) is a process for the additive manufacturing of metal parts in which layer after layer of powder is fused together, thereby constructing a three-dimensional part. L-PBF's ability to produce complex geometries with few wasted materials makes it a sustainable, potentially cost-effective choice for fabricating high-performance aerospace components such as valve housings and combustion chambers. Currently, L-PBF is a costly and rather inaccessible process due in part to its susceptibility to manufacturing defects, which can cause entire parts to be scrapped. Professor Arnold's group has been investigating the use of a dual-laser scan system to better control the strong temperature gradients encountered during the L-PBF process, which has the potential to quell defect formation. Prior to this project, the dual-laser study was limited to a single layer of powder. The goal of this project was therefore to automate the powder deposition and layer advancement process so that exploration of the dual-laser system can be efficiently and safely performed in full 3D. Following a brief literature review of the L-PBF process, analytical and numerical modeling was performed to get a sense of the physics at play. Then, building upon the work of Nina Arcot '20, the design of a custom L-PBF machine was improved and realized, resulting in a final product that adequately addresses all aspects of metal 3D-printing through L-PBF: laser scanning, build plate advancement, powder deposition, powder loading, gas flow, and electronics & control. A series of test prints were then conducted to determine optimal processing parameters for a single laser, eventually demonstrating the machine's capacity to produce a partially solid 3D structure. Due to having only a single semester of laboratory time as a result of the pandemic, experiments were not able to proceed to the point of producing full-solid parts and dual-laser exploration. Finally, samples produced from the single-laser experiments were characterized using confocal and SEM microscopy, and recommendations were made for future research.