Thermal History Correlation with Mechanical Properties for Polymer Selective Laser Sintering (SLS)

This study investigates the in-situ monitoring of the Selective Laser Sintering (SLS) process by focusing on finding correlations between tensile strength, elongation to break, and fracture location to the observed thermal history of manufactured parts. It compared the monitoring ability of a stationary reference mid-wave infrared and a bore-sighted mid-wave infrared camera. ZYX tensile bars were built to leverage the high dependence of tensile strength on interlayer bonding, which is generally assumed to be related to layerwise thermal conditions. Various thermal history analysis methods, for example: cold subregion temperature, average layer temperature, and outline average temperature were tested. Additionally, several smoothing techniques that reduced noise over time were assessed for their ability to improve the correlation for each individual method. Overall, cold subregions observed over four layers in a tensile bar’s thermal history had the best correlation with fracture location and mechanical strength.