Laser Powder Bed Fusion Process Feedback Control Based on In-Situ Powder Layer Thickness

Abstract Laser Powder Bed Fusion (LPBF) is a widely used additive manufacturing (AM) technique for producing complex metal parts. However, achieving consistent part quality remains challenging due to variations in powder spreading, layer thickness, and thermal conditions. This study investigates the real-time measurement of powder layer thickness using a laser 3D scanner to monitor surface profiles before and after powder spreading. While a feedback control method is proposed for adjusting scan strategies based on in-situ measurements, the experimental work is limited to layer-wise analysis rather than real-time process control. Through 118-layer experiments, we provide valuable insights into powder layer evolution, showing that the actual layer thickness stabilizes around 100 μm—significantly higher than the programmed 40 μm thickness—while volume shrinkage after laser exposure measures approximately 60 μm. Additionally, recoater-induced defects such as waviness, scratches, and overhang bending are identified as key contributors to build inconsistencies. Although this work does not demonstrate direct quality improvements, the findings offer critical data for future optimization of LPBF processes. The insights gained highlight the importance of integrating real-time feedback control to enhance build quality and process reliability in metal additive manufacturing.