Laser rapid manufacturing on vertical surfaces: Analytical and experimental studies

Analytical and experimental studies on geometrical aspects of the deposited tracks were carried out at different processing parameters for laser rapid manufacturing (LRM) in vertical surface configuration using AISI type 304 stainless steel powder on the substrate of the same material. The vertical downward shift of the deposited track and its peak due to the gravity flow of the melt were found to follow quadratic dependence on the track height. The downward rounded bulging was found to be quite significant for the scan speeds lesser than 200 mm/min, while this was insignificant for the scan speeds more than 400 mm/min. A set of consolidated processing parameters for continuous material deposition was identified. The threshold value of laser energy and powder fed, both per unit traverse length for the continuous deposition were found to be ~ 96 J/mm and ~ 0.006 g/mm respectively. The maximum powder catchment efficiency was ~ 42% for stand-off distances in the range of 15-18 mm. The surface waviness factor was found to decrease from ~ 0.95 to ~ 0.05 when the overlap index was increased from 30% to 80%. The study provides a deeper insight into the ensuing geometrical aspects of the tracks using LRM in vertical configuration.