ADDITIVE MANUFACTURING is the magazine devoted to industrial applications of 3D printing and digital layering technology. We cover the promise and the challenges of this technology for making functional tooling and end-use production parts.
Issue link: https://am.epubxp.com/i/894355
AM / Taking Shape additivemanufacturing.media 49 maximum temperature. At a feed rate of 0.35 mm/rev. and a cutting speed of 2 m/min. on an artificial bone, the drill without cooling did not exceed the critical temperature of 50°C, while the use of internal cooling kept the temperature at a maximum of 35°C (95°F) with a cooling agent temperature of 20°C (68°F) and at a maximum of 25°C (77°F) with a cooling agent temperature of 1°C (33.8°F). Then, when the feed rate was decreased to 0.07 mm/rev., the test showed the same re- sults for the internally cooled drill, but caused temperatures to rise above 50°C in less than 100 seconds for the conventional drill. In other words, thanks to the internal cooling system, low feed rates no longer lead to higher temperatures and the risk of bone dam- age. This means that the technology could also be beneficial in other areas, such as the manufacture of surgical saws, Toolcraft says. The bone drill is connected to a coolant reservoir so that water flows into and out of the drill without exiting into the patient's body. Real-Time, High-Res Monitoring of Structural Defects in Metal AM By Brent Donaldson One of the challenges and one of the significant areas of unknown that is slowing the advance of metal additive manufacturing relates to understanding and controlling the formation of the metal and the microstructure that results. But imagine if you had a front-row seat to see these thermal dynamics at play in real time. What if you could peer inside metal and alloy powder beds at a microscopic level during a laser powder-bed fusion process, just as the laser makes contact, and witness how it melts and shapes the powder—not just at the surface, but below the melt pool? And what if you could use those observations to quantify the formation of defects with unprecedented resolution? Enter the U.S. Department of Energy's Argonne National Laboratory, which, with assistance from Carnegie Mellon University and Missouri University of Science and Technology, has accomplished precisely that. Using a synchro- tron beamline—one of only three in the entire world—a team was able to record the laser- metal interaction with a high-speed X-ray instrument located at the Advanced Photon Source, a DOE Office of Science user facility located at Argonne. The resulting video resolution, captured at an astounding 50,000 frames per second, allows the scientists to study the formation of a given material's microstructure—including pores and other defects—frame by meticulous frame. Dr. Tao Sun, lead author of the published research about the work and a physicist with the imaging group in the X-ray science division at Argonne, says that without this kind of granular understanding, we'll never be able to realize metal AM's full potential. Fig. 1: In this still X-ray image, the laser power is set to 340 W and the laser beam size is ~220 microns (1/e 2 ). The numbers indicate the time nodes. The raw data were taken with a frame rate of 50 kHz. The exposure time for each individual image is 350 ns. All the scale bars are 200 microns. Coolant Circulation Coolant Circulation Coolant Reservoir