Dr. David L. Bourell is the Temple Foundation Professor Emeritus at The University of Texas at Austin. He is a leading expert in advanced materials for Laser Sintering, having worked in this area since 1988. Dave was the lead author on the original materials patent for LS technology. Issuing in 1990, this patent has been cited by 315 other patents. He holds 10 primary patents and has published 290 papers. He was recently the recipient of the 2023 ASTM Advanced Manufacturing Lifetime Achievement Award.

Topic title: Mechanical Property Reliability for Polyamide Processed using Powder Bed Fusion

Abstract:

One of the historic obstacles to widespread application of PBF polymers in structural applications is the reliability, consistency and repeatability of part service properties between builds.  This will be discussed in the context of data from a service bureau for which over 100,000 ASTM D638 tension tests have been performed on commercial builds of AM laser sintered polyamide.  It is shown that the usual method for relating process parameters to part properties, the macro-volume energy density, is valid when considering the part service strength but is not adequate when considering part ductility.  A solution approach for improving part reliability will be presented based on thermal modeling during the build process.  Results show that part service properties arise from an accumulation of time above the crystallization temperature. Therefore, the cooling characteristics of the parts as dictated by their location in the build volume are important variables affecting part quality. A model is presented which has predictive ability for acceptable part ductility.