Infrared benchmarking 3D printing

Advanced vision systems could ensure high-quality, reproducible parts from 3D printers. Researchers at the U.S. Department of Energy’s (DOE) Argonne National Laboratory in Chicago have added an infrared camera to the high-energy X-ray source at Argonne’s Advanced Photon Source to allow researchers to measure thermal signatures across surfaces in real-time. The camera was funded through a Laboratory Directed Research and Development (LDRD) program as part of Argonne’s Manufacturing Science and Engineering Program.

“This camera brings our work close to the applied science realm, establishing those early links between the basic science work we do with the beamline and real-world additive manufacturing (AM) systems,” says Aaron Greco, a principal materials scientist at Argonne and project co-leader for Argonne’s AM effort.

Argonne was the first U.S. national laboratory to integrate a metal 3D printing apparatus into a beamline, or photon path, for X-ray diagnostics. It is also the only national laboratory that can view the metal powder melting within the melt pool in less than a nanosecond. Adding the high-speed infrared camera to a synchrotron beamline enables researchers to more closely replicate the deposition processes that occur on the manufacturing floor.

The combined diagnosis tools let researchers capture X-ray images at 1 million frames per second (fps) and thermal images at 100,000fps during 3D printing, creating movies of defect formation caused by melt pool instability, powder spatter ejection, and inappropriate scan strategy.

Used side-by-side with X-ray microscopy, high-speed thermal imaging can deliver insights into how much and how fast different regions in the part heat and cool during the build, which involves millions of laser line scans. These insights can be used to reduce variations in part design and improve the efficiency of AM.

“Infrared and X-ray imaging complement each other,” says Argonne physicist Tao Sun. “From one side you have the X-rays penetrating the sample to help you see the microstructures without any thermal information, while on the other you have the infrared camera capturing many thermal signatures associated.”

The infrared camera augments X-ray imaging by helping visualize the formation of vaporized powder plumes as the laser hits and moves across the powder. These plumes, high in heat, can disrupt laser performance. The plumes cannot be seen using X-rays alone, due to the particles’ vaporized state, but are captured by infrared light. Alongside measurements taken by X-rays, parameters including heating and cooling rates can feed into models of 3D printing to improve their accuracy and speed.

By correlating X-ray and infrared imaging with defect formation, users could determine when defects were forming based on a given signature and take preemptive measures to mitigate or fix the problem.

Argonne National Laboratory
https://www.anl.gov

The U.S. Department of Energy’s Office of Science
https://science.energy.gov