Process monitoring of laser powder bed fusion

The layerwise production paradigm entailed by the Laser Powder Bed Fusion process makes potentially available a large amount of information on a layer-by-layer basis, to determine the stability of the process and anticipate quality inspections of the part while it is being produced. Such information can be gathered through a variety of sensors used in-situ and in-line, ranging from pyrometers to high spatial and/or temporal resolution cameras or acoustic emission sensors. This Chapter provides an overview of the quantities that can be acquired as signatures of the process and proxies of the final quality of the part, the methods suitable to make sense of acquired signals to detect anomalies, and process control solutions for defect mitigation, correction or avoidance. The Chapter also provides an up-to-date perspective on the current open issues for a wider industrial adoption of these techniques and most promising future research directions.