The roughness of a surface depends on a variety of factors, including the design of the part, the manufacturing process used to create it and the manufacturer. Even if you select a 3D printing technology with a supposedly great surface finish, the parts might still present some stepping marks or have a slightly curved surface, causing a decreased surface roughness quality.

You can keep in mind that the MJF process produces a less porous surface compared to SLS, and has a smoother texture. And as you said, a near-perfect poreless surface can be achieved in both MJF and SLS thanks to post-processing operations like vapour smoothing and bead blasting.

We conducted experiments in-house with SLS and MJF 3D prints and we actually have some concrete data to share. We measured the surface roughness of SLS prints with different surface finishes: PA12 raw part (approximately 8 µm), PA12 bead blasted (4.5 µm) vs PA12 vapour polished + dyed black (2.5 µm). And we did the same for MJF prints and 5 other 3D printing technologies. I would recommend you to check our article on this topic: https://xometry.pro/en-eu/articles/3d-printing-surface-roughness/

• This reply was modified 1 year, 10 months ago by Nikolaus Mroncz.