January_February_2022_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | J A N U A R Y / F E B R U A R Y 2 0 2 2 1 1 DIAGNOSTICS FOR 3D PRINTING Diagnostics currently used to ensure high-quality liquid metal jetting (LMJ) prints rely on high-speed videog- raphy, which requires expensive equip- ment and generates large amounts of data. While adequate for evaluating a few seconds of a test printing, it isn’t a feasible solution for longer builds. Researchers at Lawrence Livermore National Laboratory (LLNL), Calif., are looking to address the challenge with a new diagnostic tool that can deter- mine the quality of metal droplets and monitor LMJ prints in real time. The approach uses low frequency, electro- magnetic near-field detection to cap- ture metal droplet dynamics that, when combined with simulation, provide information on droplet features based on signal amplitude and phase alone. Researchers say the ability to character- ize the droplets using just one param- eter significantly reduces the amount of necessary data, making processing and feedback of longer-term LMJ prints possible. With the new tech- nique, they discovered large-scale trends such as print variation and anom- alies at the nozzle, as well as micro-level attributes of the droplets, including size, position, and dynamics. The result is a compact and non-invasive diagnostic able to distinguish droplets in LMJ machines at higher print rates than possible before, as well as the capa- bility to detect additional features of the print system, research- ers say. In the future, signal processing techniques could be used to correlate optical and millimeter-wave measure- ments and predict droplet properties based onmillimeter-wave results alone. llnl.gov. Liquid metal jetting is one of the newer methods of 3D printing. Courtesy of CC0 Public Domain.