In-situ process monitoring and statistical quantification of powder bed forming and build processes in laser powder bed fusion additive manufacturing

Abstract

Abstract Additive manufacturing is an essential technology in digital manufacturing and has been widely applied in various fields. However, because the intrinsic properties of laser powder bed fusion (PBF-LB) lead to the generation of defects, the development of an in-process monitoring and feedback control technology is necessary to assure the final product quality and process repeatability. In this study, an in-situ process monitoring system capable of simultaneously measuring the surface texture of the powder bed and solidified part and the melt pool behavior was developed. The surface texture of the powder bed and solidified part was quantified by introducing a parameter of 2σ. As a result, since it was difficult to directly correlate the 2σ value with the density of the specimen, the correlation between the surface texture and the density was investigated by introducing the areal surface texture parameter Sal. Consequently, it was revealed that the Sal is one of the effective factors to investigate the correlation with the density of the specimen. Moreover, it was revealed that the unevenness of the solidified part surface impacts the melt pool morphology and the spattering behavior via the in-situ monitoring system. Furthermore, it was elucidated that the shape of the melt pool during multi-track scanning was asymmetric in the scanning direction, and spattering occurs excessively toward the solidified part side because the vapor plume direction turns to the solidified part side due to the asymmetric melt pool via the melt pool monitoring module. Thus, the systematic understanding of the PBF process through the quantification of the surface texture of the solidified part in consideration of melt pool behavior can support the development of a monitoring and feedback control system for PBF machines in the near future.