First-time right manufacturing in laser-based powder bed fusion of polymers by in-situ process monitoring and spectral x-ray dark-field imaging

Laser-based powder bed fusion of plastics (PBF-LB/P) is an additive manufacturing technology, which is up to now well established in the production environment due to its high maturity level. However, if a production process fails or is successful is evaluated subsequent to the PBF-LB/P process. This drawback of the otherwise mature technology is caused by the missing link between process information or rather a process signature and resulting part properties since there is no established process monitoring approach available. As soon as the porosity reaches a specific value the mechanical properties decrease due to the porosity-driven failure mechanism, which is why understanding the resulting mechanism for pore formation during processing is needed. On a part level, the residual porosity depends on the feature size and geometry. For real-world components away from simple test coupons the porosity distribution is unknown. Thus the project is underpinned by two technical innovations (i) an in-situ measurement system for PBF-LB/P, that is capable of predicting component properties during processing, and (ii) an X-ray inspection method based on a combination of spectral detection and dark-field imaging, that can quantify porosity in bulk materials below the resolution limit of the imaging system.