Browsing by Author "du Rand, Francois"
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- ItemDevelopment of a quality management framework for powder-based additive manufacturing systems(Stellenbosch : Stellenbosch University, 2023-12) du Rand, Francois; van der Merwe, Andre Francois; van Tonder, Petrus Jacobus Malan; Stellenbosch University. Faculty of Engineering. Dept. of Industrial Engineering. Engineering Management (MEM).ENGLISH ABSTRACT: With the rise of the fourth industrial revolution, powder-bed-based Additive Manufacturing (AM) technologies have been rising alongside conventional manufacturing technologies in regulated industries such as aerospace and medicine. In recent years, the global drive has been to guarantee the quality of parts manufactured using these AM technologies to the same level as conventional technologies. While a significant portion of research was conducted on verifying part quality as part of the postprocessing process, this can usually only be done using non-destructive testing (NDT) methods. However, these processes are often expensive and time-consuming; thus, a requirement was identified for the in-situ monitoring of the part manufacturing process. There have been several studies that have attempted to address this requirement. Still, most of these studies have only focused on detecting defects that may occur during the build process and, in some cases, the classification of defects according to the defect type. The aim of this study was focused on developing a monitoring system that can be used to monitor the quality of the powder bed surface and, in the future, provide closed-loop feedback to the machine control system about the state of the powder bed surface. For the development of such a closed-loop feedback system, it is necessary to classify defects based on their type, severity, and position on the powder bed surface. This type of closed-loop feedback system is not yet implementable due to the proprietary nature of the machine control systems and manufacturer hesitance toward un-validated autonomous feedback systems. However, it is envisioned that with the correct frameworks in place, this may soon become a reality. Based upon these requirements, the first half of this study was primarily focused on developing a framework that can be used to classify defects according to the defect's type, severity, and position on the powder bed surface. The study also focused on how the framework could possibly be used in the future to implement an autonomous closed-loop feedback system that can apply corrective actions to the defects on the powder bed surface. The second half of this study was focused on the physical development of a monitoring system that could be used to monitor the powder bed surface. This monitoring system had the capability to autonomously detect and classify the defects present on the powder bed and then further process these defects according to the developed framework. This physical implementation of the monitoring system was then used to process images that were captured of real-world build jobs. The results recorded using this monitoring system were then evaluated, and it was proven that the proposed framework could be used to successfully classify these powder bed surface defects and provide feedback to the machine operator. These results demonstrated that the proposed framework could be used to create the foundation for further developing a closed-loop feedback system for powder-bedbased AM technologie