Question about making parts using 3D printing

[4RG.I.'S]

Larger parts are possible, the USMC has experimented with 3D printed concrete buildings!

https://www.marinecorpstimes.com/news/y ... -40-hours/

That being said, precision parts are a bit of a different story, possible and cost effective may conflict with each other.

[chainfeed]

I'm a manufacturing engineer by trade and while 3D printing has come a long way it still has a ways to go especially for making replacement parts for aircraft. What does this part look like exactly?

[bdk]

The technology for metals is problematic because the strength of materials is different using additive Manufacturing compared to traditional plate and forged materials. Titanium is probably easier that aluminum. You might have trouble finding a chamber larger than about 24" long in any direction. You are also competing with high-end aerospace, so very expensive.

[Eddie]

So - there are definitely 3d printed (or additively manufactured) components going into aerospace applications. The thing is, the material properties are probably closest to those of a casting (I.e. risk of porosity, no favourable grain alignment etc.) vs. those of a part machined from stock or forged. It’s a great tool, but it’s definitely worth recognising that it’s just another tool in the toolkit.

[CAPFlyer]

I agree with Eddie. Most of the additive metal printing done to date is more aligned with cast parts, you "print" the part and then machine to final dimensions. It does help with saving waste since you're casting something that is close to the final dimensions, but a rough printed part will still need finishing work. It does allow for lower-rate production to be cost effective since you don't need tooling, but if it's something that needs to be forged or machined from stock directly for strength, then printing it won't work. The PBY nose ring would probably work if printed in sections (due to the limits of the print size), but the center section probably wouldn't since you need the strength.

Currently most of the additive metal printing in aerospace has been focused on rocket engines and engine parts where you can use it to make complex shapes that would otherwise require massive amounts of machining. In these cases, they need pressure strength to handle the pressures of feeding fuels and the combustion process, but it's not a "weight bearing" structure, so the needs are different and you can use a cast or cast-like metal and still have sufficient strength.

[Ken]

How about composite materials for static, indoor Museum aircraft?

Seems like craftsmen could spend weeks making an exact replica of a part (and in a Smithsonian-like environment that may be necessary) but a 3D printed replacement might be the most effective route.

Can anyone recommend companies currently doing this type of work, particularly ones who can laser scan an original and then print the replica?

Ken

[DoraNineFan]

How about composite materials for static, indoor Museum aircraft?

Seems like craftsmen could spend weeks making an exact replica of a part (and in a Smithsonian-like environment that may be necessary) but a 3D printed replacement might be the most effective route.

Can anyone recommend companies currently doing this type of work, particularly ones who can laser scan an original and then print the replica?

Ken

Someone has been doing that for his own static Merlin for a while. He has access to a larger 3D printer and spare materials that would have been discarded.

https://www.flickr.com/photos/130143587 ... 0467086187

I'm hoping this leads to 1/4 scale or 1/3 Merlin or DB engine kits for the hobbyist to build for display.

[bdk]

How about composite materials for static, indoor Museum aircraft?

I've seen full size plastic exhaust stubs for an Allison static display. Being done on hobbyist equipment though, not really for commercial consumption.

Keep in mind that the surface finish of Fused Deposition Modeling, the most common process at the moment, often looks very stringy and would require a lot of surface finishing. Selective Laser Sintering gives a better surface finish, but the equipment is generally beyond what a hobbyist can afford.

[4RG.I.'S]

How about composite materials for static, indoor Museum aircraft?

I've seen full size plastic exhaust stubs for an Allison static display. Being done on hobbyist equipment though, not really for commercial consumption.

Keep in mind that the surface finish of Fused Deposition Modeling, the most common process at the moment, often looks very stringy and would require a lot of surface finishing. Selective Laser Sintering gives a better surface finish, but the equipment is generally beyond what a hobbyist can afford.

These merlin stacks look pretty interesting:

https://www.engineering.com/AdvancedMan ... lying.aspx

[airnutz]

I'm glad some industry folks stepped in on this subject. I took some foundry in high school and kinda kept up with the technology over the years. I did learn and use welding and other metal fabrication in work and hobbies. As for Col. Rohr's last question, you can use the 3D method for patterns(plastic would be cheapest) if you find a machine large enough but cost and time could be the kicker. It would probably be cheaper and more efficient to go old-school using the wooden pattern and sand cast method and weld the pieces together if the size made it more efficient to do it in pieces. Since it's non-operational there should be no big deal.
EDIT

Last edited by airnutz on Tue Oct 22, 2019 2:34 pm, edited 1 time in total.

[Dan Jones]

Knowing very little about it I'd guess a simpler or cheaper way to go might be to make the master for the ring as a 3D printed part (out of plastic or whatever) and then use that plastic part to make the mold, then use the traditional technology from there.

[Deuelly]

For small runs, 3D printed sand molds are actually fast and fairly cost effective.

https://hoosierpattern.com/additive-manufacturing/3d-sand-printing

Brandon

[GarryW]

Okay let me ask it this way can we use 3d printing to make the molds for say the turret rings for PBY nose gun and other parts that mold have been lost over the years. The one thing I was told by the guys who own the PBY in Sanford Maine was that they can basically make everything for the nose turret except the nose ring.

I know the blueprints exist for the construction of the nose turret both for a -5 and -6 which had two different types of nose turrets,

From the hobbyist side, this is quite common place. Using a 3D printed model to create a mold is used extensively when you need something that is stronger than plastic filament. I see no reason why this wouldn't scale. Basically the same process that was used "back in the day" except utilizing technology rather than a die modeler.

[kennsmithf2g]

There is at least one company that uses robotic welders to "print" rather large parts. Post processing machining is used for the final shape.

[airnutz]

It occurred to me this morning that I've seen some rather large rings formed from a ring roller on an industrial scale. If we're talking about the ring the turret or cupola rides on that's smaller, say 2" thick around 30-36" diameter which is relatively small to what's possible and pretty low tech. I dunno, whut do the engineers think?