UncleRice on July 28, 2017, 10:38:15 am
I love this stuff. Now I want one. They are effectively tempering the parts as part of the printing parts, so the structural integrity of the material shouldn't be terrible. I'm not ready to print out engine parts or a firearm with it, but I'm sure they are getting better.
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Sean Roach on August 02, 2017, 01:29:25 pm
I think I'd still rather have a mSLS machine and accompaning hot isostatic press.
I figure a decent nitrogen concentrator could be used for both a passable shield gas for both the sintering, and the isostatic press.

Where I think the solution is, is to use a bigger laser, and project it into an image over the whole surface, in much the way that DLP stereolithographic systems work.

I'd rather not have those binders in my alloy, unless I know that they improve the properties of the final product.

Of course, for high-end production, nitrogen is probably likely to be as big a problem as anything that might be in those binders. For that, I'd want to be able to switch over to neon or argon for a shield gas. Both in the mSLS, and the isostatic press.

UncleRice on August 03, 2017, 06:53:15 am
Would enclosing it all in a vacuum be beneficial?
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Sean Roach on August 03, 2017, 10:42:08 pm
Would enclosing it all in a vacuum be beneficial?

Probably very. It'd reduce impurities, and probably help with porosity, too. The higher the vacuum, the fewer impurities.
On the flip side, it'd also significantly change the heat dissipation of whatever you're making. You'd have to re-engineer around whatever you're working on staying hot for a longer period. Small features could potentially melt off, if you tried to make them too fast.
One possible solution would be a Peltier probe, to quickly cool the areas that are done. Touch the area with a cold-stick. This introduces further complexity, of course.
Another, simpler, solution, might be to cool the roller/blade that spreads each successive layer. Or, if not cool, per se, manage the temperature so the whole working piece stays the ideal temperature from the first layer to the last.

Bear in mind, however, that an SLS, including an mSLS, has two tanks. One for what you're making, and one for the powder you're making it out of. The first tank is filled as the second one is emptied. Your envelope, whether it's an inert gas or vacuum, has to enclose both.

Also, I remember that moon dust has a consistency similar to damp beach sand. I don't know why. Potentially, I could see metal powder reacting similarly, under vacuum. If so, your roller or squeegie will have to thinly spread a substance that wants to stick together. I can see how it could be done, but it wouldn't be as straight forward as using the same squeegie or roller from a standard atmospheric pressure unit.
Probably something more like a hopper, positively feeding the material into another layer, rather than just raking the next layer over from the other tank.

Probably inert gas ones are simpler to engineer.

 

anything