Efforts to reduce part bed thermal gradients during laser sintering processing

Part bed surface thermal gradients (x-y plane) are usually present in laser sintering (LS) fabricators. The purpose of this study was to investigate various means to reduce these thermal gradients. Several experiments were conducted using a FLIR™ infrared camera to examine the thermal profile of the part bed during the LS operation. Experiments included thermal profile characterization of the part bed with different nitrogen shielding gas flow rates, assessment of the proper experimental settings, and a temperature profile record of the part bed from the warm-up to the cool-down stage. A series of experiments were conducted using the laser as a heat source to preheat part bed surface cold spots to decrease the thermal gradients, which effect was limited by the natural low thermal conductivity of nylon 12 powder and large heat convection. Moreover, manifolds were mounted below the piston to provide warm nitrogen down draft flow during the LS operation.