Entwicklung und Systemintegration eines Recoaters mit drahtloser Kraftsensorik zur Detektion von Pulverbettstörungen im PBF-LB/M-Prozess

Powder Bed Fusion using a laser beam (PBF-LB/M) is an additive manufacturing process based on the layer-wise deposition and selective melting of metal powder. In current PBF-LB/M systems, recoaters with silicone blades are predominantly used; however, they are susceptible to damage caused by wear and recoater collisions, which can result in defects in the powder bed. As such defects are often detected at a late stage, they lead to increased scrap rates and process interruptions.
The objective of this diploma thesis is the development of a recoater system capable of reliably detecting recoater collisions while simultaneously offering enhanced robustness against wear and collision-related damage. For this purpose, the state of the art in sensor systems for powder bed process monitoring is first reviewed. Based on this analysis, a wireless sensor system is developed to measure the forces acting on the recoater and to warn the user in the event of a collision. In addition, a novel roller recoater with a silicone coating is designed, providing improved resistance to wear and collisions compared to conventional recoater designs.
The developed system is evaluated through printing and collision experiments and benchmarked against the state of the art. The printing experiments demonstrate an increase in powder bed density of 2.23 % ± 0.01 % and a reduction in part porosity of 50 % when using the roller recoater. In collision tests, the roller recoater withstands part protrusions of up to 1000 µm without significant damage, whereas the OEM recoater exhibits severe damage at protrusions of 900 µm. Throughout all experiments, the sensor system reliably detects recoater collisions and provides user warnings. The developed overall system achieves Technology Readiness Level 7.