Laser droplet generation from a metal foil

Metal droplets are used in various droplet based innovative technologies, especially in joining of temperature sensitive components where the amount of applied energy and its spatial distribution are important. Laser light has already been proved to be a suitable energy source for metal droplet generation, since it enables high spatial and temporal control of the energy input. In this contribution, a novel process of laser droplet generation (LDG) from a metal foil is presented, which could provide increased flexibility of the generated droplet parameters compared to the existing LDG processes. In the novel LDG process, a horizontally placed foil is irradiated by a laser beam from above and the melted part of the foil is detached by shielding gas overpressure above the foil. The results of presented preliminary experimental study show that droplet formation from metal foil is possible by means of an annular laser beam. In addition to this, the space of process parameters is explored, showing influences of temporal intensity distributions of the annular laser beam, shielding gas overpressure, and foil thickness and material on the process outcome. (C) 2014 Published by Elsevier B.V.