In-Situ Laser Control Method for Polymer Selective Laser Sintering (SLS)
Selective laser sintering (SLS) of Nylon is a significant portion of the Additive Manufacturing (AM) market for structurally sensitive applications. To achieve high performance in these laser melted parts, one would like to see consistent melting of the powder over the part region in each layer of the build. Current research methods into improving this consistency focus on the use of IR sensing to adjust heating elements in attempt to gain even temperature distributions over the pre-laser melted powder layer with the expectation that the laser at constant power, speed, spot size, and spacing will deliver constant melting properties. In this paper we examine a complimentary method of gaining even melted properties by sensing the pre-lased powder along the laser track, and adjusting the laser power to achieve a common post melted temperature everywhere on the part. We describe the feedback based laser control method that varies the laser power in to account for the pre-sintering temperature profile across the part bed. Various tests have been performed, and a method for employing this strategy throughout a build is presented.