Combining laser aided ablation and polishing to minimize surface roughness of additively manufactured aluminium components

“The surface roughness of additively manufactured parts is much higher than the acceptable range for most applications, thus post-processing is needed to qualify these parts for use. Laser polishing can be used to bring the surface roughness in an admissible range, but if the initial roughness is very high then the energy density for the polishing process needs to be very high to achieve a significant reduction in roughness. This high energy density can produce many process defects. Also, laser polishing alone cannot get rid of high wavelength asperities. Any waviness in the part can be linked with initial waviness in the as-built part and to the high energy density used during laser polishing. Waviness makes it harder to achieve dimensional accuracy. In this study, we propose a solution to extensively reduce surface roughness while also mitigating surface waviness, using a combination of laser ablation/machining, laser macro-polishing and laser micro-polishing. Surface roughness (Ra value) of 1.11 μm in one direction and 1.60 μm in another was achieved, which was more than 93% reduction in Ra compared to the as-built part. At the end, a process to achieve dimensional accuracy using pulsed laser ablation/machining is illustrated”--Abstract, page iv.