How does increasing laser power in SLS printing influence the surface finish of the printed part?

Increasing laser power in SLS (Selective Laser Sintering) printing can have a complex influence on the surface finish of the printed part. While it can initially improve sintering and fusion between powder particles, potentially leading to a smoother surface, excessive laser power typically degrades surface finish. Higher laser power increases the energy input into the powder bed, causing greater localized heating and more pronounced melting. This can lead to several negative effects on the surface: increased surface roughness due to the formation of larger, more irregular sintered particles; powder sticking or "caking" to the surface because of over-sintering; and increased thermal distortion, which can create warping and unevenness on the part surface. Therefore, finding the optimal laser power is critical. Too little power results in incomplete sintering and a weak, porous surface, while too much power leads to the aforementioned surface defects. Achieving a smooth surface finish in SLS often involves a balance of laser power, scanning speed, and powder bed temperature, tailored to the specific material being used.