Rapid Qualification of Additively Manufactured Parts

Over the past twenty years, laser powder-bed fusion (L-PBF), a process in which a laser beam selectively fuses successive regions of a powder bed, has evolved from a method used to prototype metal products to a well-established process for manufacturing parts. One of the issues hindering its use in highly regulated industries, such as commercial aviation and medical device manufacturing, is the time it takes to certify that parts produced by L-PBF will perform as well as parts manufactured using conventional processes. To overcome this issue, researchers in the Materials and Manufacturing Group at ARI are developing techniques for rapid qualification and certification of additively manufactured parts.  

The first step in this process involves utilizing a pseudo-analytical model to create process maps that correlate the melt pool geometry and solidification microstructure. To validate these calculations, we conduct experiments to study the impact of various L-PBF process parameters, such as laser power and travel speed, on the resulting microstructure. During these experiments, the team utilizes a high-speed infrared (IR) camera to measure the melt pool signature (temperature and size). By correlating the process parameters, process signatures, and resultant microstructure, the team can build two types of controllers: a multi-input, multi-output (MIMO) fuzzy logic controller and an active disturbance rejection-based feedback control (ADRC) system. Finally, to validate the controller performance and qualify the process, they use these controllers to build actual parts, which they use to perform mechanical property testing and characterize the microstructure. 

In addition to shortening the time required to qualify and certify L-PBF parts, this approach will allow small and medium-sized manufacturers (SMMs), who may not have the expertise to build physics-based models of the process, to qualify the parts they produce, which will also expand the domestic supply chain for critical sectors, such as defense.  

The figure above explains the process for creating digital twins for powder bed laser fusion.