Novel real-time structured light 3D scanning technique for powder bed state and recoater wear analysis in powder bed fusion

In Powder Bed Fusion, recoater streaking caused by blade wear has a negative impact on the product quality. Thus, continuous monitoring of the state of the powder bed and the presence of recoater streaking is essential for evaluating the wear condition of the recoater. This study proposes a 1-bit image design for the creation of phase-shifted stripes in a structured light system, which overcomes equipment limitations and enhances the speed and accuracy of the measurement system. The time available for scanning during the powder spreading and scraping action is around 0.64 s. The proposed method completes a single scan in 0.43 s, thereby ensuring that the scanning process does not interfere with the normal operation of the machine. Furthermore, the measurement accuracy reaches 8.4 μm and thus enables the powder bed surface morphology to be accurately reconstructed. A method is developed for evaluating the dimensions of the recoater streaking marks through an analysis of the point cloud data acquired by the structured light system. The insights obtained through this analysis provides a quantitative understanding of the wear condition of the recoater blade and thus allow for the timely replacement of the blade in order to preserve the quality of the printed parts.