Acoustic sensing for overbuild-recoater blade collision detection in laser powder bed fusion additive manufacturing

Laser powder bed fusion (LPBF) additive manufacturing is widely used to fabricate geometrically complex metal components. In LPBF, a layer of metal powder is swept onto the build surface by a recoater blade and then melted with a laser; this process is repeated to build a part layer-by-layer. A common flaw in LPBF processes is overbuilding, where some region of a layer is built higher than the desired layer height. Collisions between the overbuild and the recoater blade on subsequent sweeps can lead to a persistent defect in the part or damage to the recoater blade. In this research, acoustic emission sensors mounted to the recoater blade subassembly of an EOS M290 machine are used to detect collisions with the recoater blade. This work presents the sensor configurations for and results of preliminary experiments conducted during powder sweeps only and during fabrication of small test coupons. [Work supported by NASA Space Technology Graduate Research Opportunities (Grant No. 80NSSC23K1213)]