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Interesting - why does this happen? And is it possible to make a printer that overcomes this? Or are there post-printing techniques that can be used?
I read that SpaceX is printing their rockets engines.
Howard-
Interesting - why does this happen? And is it possible to make a printer that overcomes this? Or are there post-printing techniques that can be used?
SLS printers work by melting a powder. unfortunately theres always gaps between the powder particles (like balls in a ball pit). some of the gaps disappear (surface tension of the liquid steel pulls it in to the gaps i think?).
considering this, and the surface finish that Screwball brought up, check out the manufacturers example finish, no gaps, pretty darn smooth:
Personally, ive never achieved something like this, so i guess they are heat treating the parts afterwards. when ever i print something it looks like like very fine sandpaper. heat treating isnt off the cards, but i dont actually know anyone at work who does it.
Isotropic
Yep, precisely that.
Air in the build chamber is removed/replaced with an inert gas before the laser starts its work (steel uses nitrogen, titanium requires argon), but while a forged billet part is 100% 'solid' (or so you'd hope), a 3d-printed part is not.