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[deleted] t1_j8mu1es wrote

[deleted]

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asshatnowhere t1_j8nsj26 wrote

Funny, at my last job I was literally developing and building a pseudo printer that would be used to determine a process for testing this very thing. In a nutshell, this device would function similarly to a metal 3d printer but it would very accurately weigh every single layer to calculate bulk density of the powder and through laser scanning methods look for potential voids in each layer. The idea is that it would be used as a metric for honing in on 'best practices' for optimal printing.

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BeardySi t1_j8ntzg1 wrote

Interesting, any details available?

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asshatnowhere t1_j8obyck wrote

In short, it functions like a DMLS printer where you have a build plate that descends and a moving blade to deposite the layer. The idea is figuring out a way to completely decouple the build plate after a layer is deposited so that it can be weighed, the area of the layer is known, and then the build plate is returned to its original position. The challenge is the tolerances involved. We're talking fractions of a milligram, and the build plate needs to be returned to the same position with thousands of an inch (mixing units, fight me). The other challenge was not losing a single bit of powder during the decoupling and not disturbing the layer. Then you also had to purge the seal in a pure nitrogen and dry environment.

I left the project fairly early though as I had changed jobs. But the prototype was showing promise although never fully tested.

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Jumpbase t1_j8odw1r wrote

The Company Phase3D is doing something similiar but only with a heigthmap of the spreaded and/or melted powder, at the company im working in we're currently in the planning stage to build somehting like this in our Ceramic 3D Printer

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Confused-Engineer18 t1_j8qm7c3 wrote

That kinda genius, I wonder if a cruder method could be used with fdm printing via using load sensors in the print bed.

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CW3_OR_BUST t1_j8mzhgk wrote

Sometimes a chunk of metal is easier to get than a how many barrels of such a fine powder, too. Powdered metal isn't exactly straightforward. There's a lot of ways that the process can go wrong, and leave contamination in the powder from tooling and transportation. On the other hand, a billet of most alloys is easy to make any size, and a lot cheaper in most cases, and can give much more repeatable crystal structure.

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cjameshuff t1_j8naiwr wrote

> Sometimes a chunk of metal is easier to get

Sometimes it's the only way to get a particular material. You're not getting single-crystal structures out of a powder bed, for example. And processes such as forging bulk materials can have desirable effects on its microscopic structure.

And yes, there are also things you can do with additive methods that you can't with casting and machining. Different manufacturing approaches have different tradeoffs. Ultimately, you'll make most effective use of these techniques by applying them where they're most effective, rather than, oh, trying to print an entire rocket or something.

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nsa_reddit_monitor t1_j8nl1f1 wrote

I want them to print an entire rocket because then I can take those designs and print a really tiny rocket at home.

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DaoFerret t1_j8o64km wrote

Knock knock knock

This is the department of homeland security! Your neighbor said you were building rockets in your garage!

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erinaceus_ t1_j8odyk7 wrote

Yes, and it really worked! I was over the moon when I found that out!

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shadowmage666 t1_j8nrdas wrote

There is a company called fabrisonic that uses sound waves to essentially weave different metals together but they also have a process which is almost reverse 3d printing by removing parts of the metal. They said in a documentary that they also produce metal parts for nasa where they need liquid or gas channels inside of a sealed object, by using their method of creating the objects as one piece they can make objects that will be more able to handle strong environmental shifts in pressure and temperature however they do not have the reduced weight capacity that some of those other semi hollow devices and these new meta shapes have , however they can create objects which normally wouldn’t be able to exist.

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Barrrrrrnd t1_j8obtkq wrote

Man I love living in the future. I wonder how they are able to account for possible issues with micro-cracks at the edge of the channels inside the closed object. Just normal x-ray?

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shadowmage666 t1_j8on1df wrote

Good question; not really sure how their QA process works but they probably have some type of intrusive scanning

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dblink t1_j8uwmgt wrote

Ultrasonic testing is probably the most common method of non intrusive/destructive scanning.

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ackermann t1_j8o8ok0 wrote

Relativity Space, who are trying to 3d print an entire rocket, must be putting a lot of work into these problems…

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Sniflix t1_j8p4gmp wrote

They are supposed to launch this year. Even NASA and the Chinese are heavy into 3D printing rockets. Rocket Lab has been launching 3D printed rocket engines with success. There are dozens of other companies trying to make the engines the same way.

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thomascardin t1_j91gvad wrote

And they are naming their components based on Starcraft. Spot the nerd!

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Shimada_Tiddy_Twist t1_j8ofc2j wrote

Quality can not be made by testing, it can only be achieved by working on the process.

  • some japanese dude probably
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Boostedbird23 t1_j8os4zu wrote

Voids are expected in castings, especially steel castings. We do our best to design the tooling to minimize it. However, we also factor those expected defects into the (derating fatigue, for example) material properties when we do our FEA analysis. It seems like these 3D printed designs would be no different.

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bohemica_ t1_j8qvr5t wrote

Glad we have FEA, additive manufacturing really wouldn’t be easy to implement without it. I say this because AM is still a rather under-standardised field and will probably remain that way for a while, at least process-wise. Of course you have a general idea of what happens when you change parameters or object geometry, but without simulating things on a case by case basis, no way you would be able to produce a reliable part.

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monchota t1_j8nw9qm wrote

All of that can easily seen and detected. This is high end manufacturing, not someones at home printer.

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FluffyGarbage23 t1_j8ouhyx wrote

But the cost of ink and the cost of producing a rocket is almost the same!

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cat_prophecy t1_j8odj1e wrote

What's the difference in QC testing these parts vs. QC testing literally any other Aerospace part? When I worked in GA, the people doing welding needed to have their welds all x-rayed, magnafluxed, or whatever. Certainly there are ways of finding and addressing porosity or voids in a 3d printed part.

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dtroy15 t1_j8qna8p wrote

I work in medical. Implants are cycled to test their long term durability. 3D printed implants often have this problem - one implant will survive 300k cycles, another only 5k. Same material, same design, made by the same manufacturer on the same equipment at the same time.

Metal printing has a long way to go before it can approach the durability of machined parts.

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tequilamockingbrb t1_j8o2cfi wrote

This paragraph and the resultant comments made me join your sub. That's some brilliant info!

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Mateorabi t1_j8qhs2r wrote

I wonder if a 3d printed lost-"wax" process would work better. 3d print it, pack it in sand, pour in molten alloy that melts the 3d printed object. Get the same shape but with cast material.

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Cumupin420 t1_j8q3e1f wrote

I work at a medical manufacturing plant that has these printers. They can do anything they want and can control everything. If there is a void they can program it to not happen, takes a lot of time but it gets done.

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