Behind the doors of the Lawrence Livermore National Laboratory (LLNL), there is always something innovative going on. From the development of a new volumetric 3D printing process to the creation of new metamaterials. Recently, a team from the lab revealed it had achieved a breakthrough in the development of the first research-grade, open-architecture multi-beam metal 3D printer.
The project, which is backed by the Air Force Research Laboratory, is aimed at better understanding the multi-beam additive process and finding ways to optimize it for faster and larger build rates. The research-grade multi-beam 3D printer created at the lab will give LLNL scientists the tool to pursue this investigation.
In the additive manufacturing industry, metal 3D printer developers have increasingly started to integrate multiple laser beams into the machines to speed up the build process and produce larger parts. Despite these machines being sold and used, however, there is still a way to go until multi-beam 3D printing is truly optimized.
That is, in short, the goal of LLNL’s 18-month project, which launched last spring. The research-grade 3D printer developed by the LLNL team (led by materials scientist Aiden Martin) consists of a single-beam Fraunhofer-Aconity3D system fitted with a custom two-beam unit. The upgraded machine is being used to study how lasers work together to build a single part and if there are any defects or risks that come with a multi-laser approach.
“We’ve identified experiments that can fundamentally characterize how the two lasers indirectly interact with each other through various physical phenomena such as vapor plume and plasma generation at the surface (of the build),” Martin said. “We’re really looking at the fundamental limitations of the multi-beam process, expanding the capabilities of the software and on optimization of the process.”
So far, the team has printed a number of objects using the multi-beam system and has started to characterize the parts. This next stage will involve establishing diagnostic techniques, such as high-speed optical imaging and beam profiling, which will provide more insight into how defects are caused and how to improve the process.
GE Global Research collaboration
The LLNL team is also working in collaboration with GE Global Research to develop a commercial-grade, open-architecture multi-beam 3D printing platform. This initiative, part of a larger America Makes project, also involves the development of software by LLNL and GE to support multi-beam printing.
GE reportedly reached out to LLNL to conduct experiments on the multi-beam process in order to better understand the physics behind the laser printing process, expanding on research conduced by LLNL physicist Ibo Matthews. In Matthews’ research, the physicist said that, in theory, a multi-beam approach should reduce print rates. If for instance, two lasers are used, the print speed should be twice as fast. In practice, however, this has not yet been achieved.
“The way that the multi-beam commercial systems came about was similar to how the whole technology came about, in that there wasn’t a lot of forethought in optimizing the system—it was really just slap on the laser and go,” Matthews explained. “There are basic questions that no one really has an answer to. The most important is that the origin of defects in these systems isn’t well characterized. So, we’re definitely going after that and the larger questions regarding the ideal way is to operate multi-beam systems.
“The kind of measurements that [Martin] and his team are doing are going to clarify the interaction of two lasers with a metal surface as they scan around. It’s just not studied yet at the depths we plan to go into.”
In other words, the investigation into the multi-beam additive process being carried out at LLNL will hopefully lead to improved build rates and sizes for metal 3D printing.