Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Selective Laser Sintering: Coalescence Phenomena and the Effects of Process Parameters on Part Performance" By Teal F. Dowd Purdue MSE Preliminary Exam Advisor: Professor Jan-Anders Mansson ABSTRACT Selective Laser Sintering (SLS) is a free-form three dimensional additive manufacturing process, capable of producing functional graded parts. The fundamental driving force for polymer SLS is coalescence of powder particles through reduction in Gibbs free energy once sufficient laser energy has been provided. The powder particles combine and densify through diffusion until a mostly dense part is created. Coalescence rate and quality are increased through smaller particles with high packing efficiency (optimized through binary size distributions), and using polymers with high mobility (low molecular weight and low viscosity). Part strength is highly dependent on correct build parameters. Research suggests that increased energy density (a function of laser power, scan spacing, and scan speed) is highly correlated with increased part modulus, density, and elongation at break, with the ceiling at the point of material degradation. Other major build considerations are build orientation, powder refresh rate, preheat temperature, base polymer crystallinity, and particle chemistry. Date: Tuesday, December 17, 2019 Time: 12:30 P.M. Place: IMI 127