Characterization of Selective Laser Sintering™ Materials to Determine Process Stability

The Selective Laser Sintering (SLS) process has proved to be an excellent method for prototyping functional parts out of engineering thermoplastics such as polyamides. However, the material undergoes physical and chemical changes due to repeated heating cycles in the SLS equipment. This causes variations in powder characteristics and performance in the SLS process. With the increased utilization of SLS for direct manufacturing it is necessary to develop a characterization and testing system that can determine powder fitness to ensure process stability and part quality. Current powder recycling methodologies use an average virgin-to-used powder mixture. In a new approach, a testing mechanism to deliver a numerical, measurable material characterization will be discussed. Experimental results of repeated reuse of material and its resulting physical effects on mechanical properties, shrinkage, and chemical tests will be presented. A definitive testing and measurement process control will be shown to improve process stability and thus part quality and consistency.