62 Evaluating the Potential Exposure to Metal Fine and Nano Particles Generated During Wire and Powder Laser Metal Deposition

This study aims to evaluate the release of fine and nano particles during Additive Manufacturing with wire and powder Laser Metal Deposition where the layers of metal feedstock are deposited and contemporaneously melted by a high-energy beam during the building phase. We analysed an experimental set-up in a research laboratory equipped with two different nozzles: one operates by jetting powder while the second by depositing a metal wire. The campaign included environmental and personal monitoring during whole processes adopting AISI-316L as feedstock. Fine particles are assessed by the optical counter Lighthouse3016-IAQ, allowing to detect six size classes (0.3-10 µm). DiSCmini was used for measuring number and average diameter of nanoparticles (10-300 nm). A significant release of nanoparticles occurred with both nozzles during the building phase and, although the peaks were higher when using the powder nozzle (2.9 x 106 n/cm3), the average values were around five times higher with the wire nozzle (6.5 x 105 n/cm3, 75 nm). Adopting the wire nozzle reduced the particle emissions during initialization and cleaning phase, avoiding handling powders. Considering the state of the art and industrial practice, the relevant novelty of the work lays in the detection of nanoparticles even for wire laser metal deposition due to the melting and partial vaporisation phenomena induced by the high-power density of the laser beam. The results highlight the importance of adopting proper working procedures and personal protective equipment for the operators entering the box when interrupting the building phase with both powder and wire nozzles.