Abstract
The interaction of the fast moving laser beam and the metal powder during Laser Powder Bed Fusion (LPBF) can result in strong process fluctuations leading to the formation of weld defects, which significantly reduce the quality of the generated parts.
In order to analyse these process fluctuations during the LPBF-process a model arrangement was set up, which allowed the simultaneous use of different monitoring tools for the observation of the interaction of the laser beam and the powder bed as well as the surrounding area. High-speed imaging in the visible wavelength range with high magnification and framerates of up to
10,000 fps was used to observe the interaction of the laser beam and the powder bed. High-speed imaging in the infrared wavelength range with up to
1,500 fps was used to analyse the temperature distribution and the solidification of the melt pool and the previous vectors. Additionally, off-axis Pyrometers and several on-axial diodes were used and the information obtained from the different sensors was compared.
The results of the high-speed online process monitoring will be presented and discussed for each monitoring tool. Furthermore, it will be shown that the use of a closed-loop control system may be advantageous to achieve high part qualities.
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