Multi-physics based methodology for evaluating powder feeding quality for Laser Metal Deposition

Abstract

Powder based Laser Metal Deposition (LMD) is an additive manufacturing technology that offers great advantages to the production of high added value products, like the possibility to manufacture in one whole piece parts with very complex geometries, or to repair existing ones. One of the critical elements of this technology is the powder feeding system, which, depending on its specific design, can provide powder flows that are more or less stable, thus heavily affecting the homogeneity of deposited tracks and, ultimately, of final part quality.In this work, we propose a methodology for assessing the fitness of a powder feeder for a LMD system. The assessment is based on deposition quality maps, which provide a reference for predicting the waviness of a deposited track in function of powder flow oscillation frequency and amplitude. Such maps are generated by performing multi-physics simulations of straight deposition tracks and evaluating their level of regularity. The simulation model is calibrated by a preliminary experimental campaign and can be used further on to assess the effects that any flow frequency-amplitude couple has on deposition quality, without the need to perform new deposition experiments for assessing a new powder feeder. The methodology is demonstrated by calibrating the simulation model for a commercial LMD machine loaded with Inconel 718 powders.