In situ measurement of particle flow during fiber laser additive manufacturing with powder feeding

In situ measurement of particle flow is a promising tool to visualize how the particles affect the power feeding laser additive manufacturing (PFLAM). A simple and robust platform based on optical feedback interferometry (OFI) was implemented in this study. The diameters of particles, the change of particle density, and the agglomeration behavior of particles in the powder stream generated by the powder feeder can be measured through in situ measurements based on the OFI. Signal detection and data processing became more difficult when the particle diameter was much larger or much smaller than the detection laser wavelength. The distribution of particles in fiber laser-induced plume with a diameter ranging from 0.3 μm to 4 μm can be measured using the OFI in laser additive manufacturing with powder feeding. The percentage of particles with a diameter of about 0.65 μm in plume decreased significantly with the increase of laser power.