Performance limitations in polymer laser sintering

Commercial laser sintering (LS) machines have been used for years in a variety of rapid prototyping applications. Emphasis in the LS research community has moved towards rapid manufacturing: the creation of engineered structural components. However, the mechanical properties of LS parts are often inconsistent compared to their molded counterparts. This is due to a variety of factors including feedstock uniformity, microstructure evolution due to LS processing, and the overall ability of commercial LS machines to reliably form structural parts without thermal degradation of the feedstock powder. This paper will review the current state of the art of commercial LS machines, and discuss the resulting implications for rapid manufacturing. Particular focus will be paid to the role of part bed temperature variations due to non-uniform heating, unsteady cooling due to natural convection currents in the part chamber, and how these and other phenomena may impact the design of laser control systems. (C) 2014 Published by Elsevier B.V.