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Comment by chroem- | Hacker News Reader

It's like the brogrammer world just discovered powder metallurgy.

This exact technology has existed for decades but hasn't seen widespread use because it has serious problems. I don't see any evidence that Desktop Metal solved these issues either. The resulting parts have high shrinkage, poor dimensional tolerance, and poor mechanical properties. The sintering process leaves voids inside the material that serve as stress concentrations, causing the material to fail well below its rated strength. Also sintered parts tend to fail catastrophically rather than yielding since the adhesion between particles is much weaker than the yield strength of the metal.

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"brogrammer"

https://www.desktopmetal.com/company/about/

I see a bunch of PhDs with backgrounds in material science (among other things). It's just possible they might have a clue.

I'm referring to the hyperbolic headlines talking about a "metal printing revolution," not the actual company. There are already off the shelf solutions to do nearly the exact same thing that everyone here is getting all worked up about. What's more, you could have purchased those solutions before the internet was even a thing.

What does that have to do with brogrammers?

I think OP is referring to the software-oriented HN crowd who have highly upvoted this article despite little evidence that desktopmetal is doing anything revolutionary.

How has it not seen widespread use? Buy just about any consumer-grade power tool today, and inside will likely be some powdered metal components. They're in some of the high-end tools, too, and can provide excellent quality with decent design.

I have no clue whether these prototyping machines will produce parts of that quality, but the important observation is that 'good enough' is the key threshold. Many times you don't need the full strength of a machined steel part, just something a bit better than plastics can provide.

Those parts are produced via Metal Injection Molding (MIM). MIM parts have similar issues to printed (laser sintered) parts but injection molding is a far more efficient process for mass production.

I thought the gears are done via a simpler sintering process: https://www.youtube.com/watch?v=-K6_wbBnXmc

Is that still considered MIM?

I'm reserving judgment until I get my hands on parts - which aren't yet publicly available. I've heard that their parts have passed rigorous materials testing, but until I get make some, machine them, and physically test, will I start to believe.

With $200M+ they better be doing something new! So far, we know they are very good fundraisers and marketers, but I do think it could be different this time (i.e. maybe they'll crack it).

Yeah. That is a bit scary. People got used to think that plastic and wood are pretty weak and fragile materials (compared to metals). But people believe that metals have much more strength (even if in reality they don't - in case of some metals and alloys), so I wonder if they start using printed metal parts in their cars (or similar), because it is much cheaper (but "it is made of metal, so must be strong enough!").

Will this cause more accidents?

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