Oh c'mon it ain't as bad as all that. Yeah - it's gonna have all the properties of a casting, or worse properties than a casting if you're sticking with the laser sinter. Which is going to make it jaw-droppingly expensive so let's assume it's a casting. But that means you destructively test one in a hundred or one in fifty and move on. Waste to usable material ratio? If you're casting it, it's got the waste of a casting. If you're sintering it, it's got effectively none - you're fusing powder and the unfused powder goes back in the hopper. Let's presume we're rollin' HDPE. It's going to cast utterly without drama. Our material costs are entirely related to waste so the less we use the happier we are; we have no dross 'cuz it all goes back in the bin. Let's presume we're rollin' aluminum. Yeah that casting is going to be a bit of a nightmare but we can adjust for that. Either way we're in a much better regime than if we have to 5-axis the bitch or weld it up. Ductile iron? I can heat treat it and shot-peen it. It'll magnaflux like anything else. Heat sinks on Microsoft Surface Book 2s are laser-sintered 3d-printed aluminum. I know. Crazytown. But they make 'em about 300 at a time in a printing process that takes about 5 hours so... it works.
If you're sintering it, it's got effectively none - you're fusing powder and the unfused powder goes back in the hopper. That was the original thought... but turns out the powder thats was near the laser gets affected by the heat and if you pour it back in you get all sorts of additional material oddities in the next part. So you get get material properties for the first part but the scatter kills you on part #2. Idk why you would make 3D printed heat sinks... probably because you have too much money but ok it works fine in any application where you dont need structural material properties. So if you want to turn a 10c heat sink into a $5 one you can or if you need some sort of fancy decorative shape for a trim price, great but the technology is decades out for practical and cost effective structural applications. You will see this stuff pop up here and there as peoples pet projects or to show how cutting edge some company is but its just not ready for prime time, and may never be. I should caveat that all by saying that 3d printed parts like this should be great for fluid systems applications. Any time you need weird mixer geometries with internal cavities, probe holes, flow reducers and mixers 3D printed parts like this will work great.
This is news to me. Not doubting you - curious. Can you show me some links on that? I suspect so they can iterate quickly. They're complex shapes; more like exhaust vents than sinks and they're curved in two directions. They'd be problematic to cast. I agree with you largely. but turns out the powder thats was near the laser gets affected by the heat and if you pour it back in you get all sorts of additional material oddities in the next part.
Idk why you would make 3D printed heat sinks... probably because you have too much money but ok it works fine in any application where you dont need structural material properties.
Here is a decent one talking about the decreased tensile strength of products made from recycled polyamides. Though I'd like to hear HGL's input as well. Going to a different setting and hoping it's a good analogy, It seems to make sense from the organic synthesis standpoint. Once you allow it to happen, runaway polymerization is one of the easiest ways to obliterate your product (e.g. decarboxylation of salicylic acid to phenol). All you need is heat and impurities that act akin to nucleation sites for growing crystals.
That paper is about polymers, though, and the whole fun of SLS is powdered metal. I have no doubts that getting a polymer melty-adjacent makes the remelt janky. If you're talking about steel, aluminum or titanium, though, you're at basic-bitch cast level anyway.