3D printing
3D printing
(OP)
Did anybody tried to install a spare part which has been manufactured with 3D printing. If the answer is yes, how did you managed to certify the material for printing. I'm not speaking about SR item.
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RE: 3D printing
Granted, 3D Printing and such has come a long way in ~20 years, but I still think of it as mostly for 'dog and pony shows'.
Just my opinion.
Note that we have a 3D Printing forum:
3D Printers and Materials Forum
(663 members)
forum1536: 3D Printers and Materials
Ask your question there. Better, browse it a bit, and judge for yourself if any of the subject technologies are ready for prime time, much less certification.
Mike Halloran
Pembroke Pines, FL, USA
RE: 3D printing
But, if it's not a safety-related (SR) item, why would you need to qualify the material? You can use whatever you want, including stuff from the local hardware store. It doesn't affect the nuclear side of the house. That's the whole meaning of SR versus nonSR.
(Mike there's a lot in a nuclear plant that doesn't affect the nuclear part ... everything from routine plumbing and lights up to the turbine generator. I really wouldn't care if someone used a 3d printer to replace a part in the locker room.)
Patricia Lougheed
A FAQ for you to consider: FAQ731-376: Eng-Tips.com Forum Policies
Translation assistance: forum1529: Translation Assistance for Engineers
RE: 3D printing
Then the sintering and forming of the piece starts to actually "forge" the powder into continuous grains. And, sometimes, traditional forging and machining follows to get finishes and surface in tolerance. So, even after 3D "assembly" for parts, you'd have to qualify the forming/forging follow-on processes for SR items. A traditional cast part needs qualification for voids, overflows, mold failures and internal flow blockages or bad grain structure. It's just that the nuke industry grew up with traditional casting and forging methods, so its QA "thought" and laws are old - but their intent is valid for 3D printed material.
You could even consider the coated powder fuel inside their coatings and the cooling paths inside the original Navy core plates as the original 3D assembly process.
RE: 3D printing
• Certificate of material powder for 3D printing,
• NDE inspection (UT, RT, VT, PT)
• Destructive test in accordance with ASTM standards
• Print additional sample of item and cut it and inspect
Thank for any idea
Peter Lovrencic
NEK
Vrbina 12
8270 Krsko
Slovenia
Peter.lovrencic@nek.si
RE: 3D printing
Surface NDE may, or may not, be the same: For example, a dye penetrant inspection might have been required for a forged and welded assembly because it was welded. The forging might have needed a mag particle exam because it was forged and the assembly needed to be checked for casting flaws. An assembly might have been xrayed because that was the only way (at that time) to assure some inspector that clearances or internal passageways were not blocked by mold residue or sand or grit from the molding process.
On the other hand, a 3D printed part may be questioned about gran structure and total strength BECAUSE it has been assembled in 3D and then sintered, but not rammed by a 35 ton press to squish the hot grain structure according to 1950's accepted metal-working practice. (That "Well, we always used to do it that way!" does NOT always mean "that way" was the best way or the only way or even the "needed-to-be-done" way. It DOES MEAN, however, "that way" has been written up and accepted - and it might be "the only way" as well. So you WILL have to justify differences from the old way.
Destructive testing of at least the first 3D product will almost certainly be "expected" even if it is not "written" because of the industry's and the regulator's proper and natural caution. BUT! A destructive test may not need final intrinsic exact machining of all surfaces and shapes. If the strength test does not stress parts of the unit that are intrinsically and elaborately machined, destructively test the "casting" of the 3D part. Do a leak check on the machined part.
Document what you proposed doing, get an independent opinion, perhaps of your other customers who may later buy your parts, and submit the package. Be conservative, but be real.
Expect closer scrutiny (as is proper!) when the new part has an ultimate strength close to requirements. For example, assume some actuator after all safety factors and "what if" scenrios and margins and estimates is required to survive (not fail) at 850 lbs on the actuator pin. You make a 3D part, sinter it, forge it (if required), heat treat heat, machine it, assemble it, and test it. If it fails at 1250 lbs on the actuator pin, people will accept the result. (The original part geometry was obviously overbuilt, over-designed.) But it is "passed" the destructive test at only 910 lbs force, you's probably should test a second part. The failure was very close to the required level. That -retest evaluation should be a part of your package as well. It shows you are addressing manufacturing variations and assembly variations in the 3D "assembly" and printing.
It is possible the 3D printing community has protocols for this conservatism, but probably not. Aero? More likely - they've been approaching 1.0 safety factors in rocketry since the V-2's first blew up on the launch pad.
RE: 3D printing
As for NDT, if it is a fatigue critical part then CT is the only way to go. The CT will cost a lot more than the part.
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P.E. Metallurgy, Plymouth Tube
RE: 3D printing
RE: 3D printing
I have seen AM parts (scanning laser, Ebeam, and a few others) that were post HIPed and they still have very non-homogeneous properties.
Nothing that flys is built with less than 1.75, and a lot of the parts are 3.5.
If you can find parts that were built with SF of >10 and you want to reduce that to 6, then you might have some candidates. But building and testing three of four parts so that you can install one does not sound worth it.
One of the real problems is that none of the systems runs closed loop. That is to say that if the part building process has a variation in it (power, temp, pool size, powder feed...) does it correct, and does it record where that happened? Today those are both No.
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P.E. Metallurgy, Plymouth Tube
RE: 3D printing
Patricia Lougheed
A FAQ for you to consider: FAQ731-376: Eng-Tips.com Forum Policies
Translation assistance: forum1529: Translation Assistance for Engineers
RE: 3D printing
RE: 3D printing
RE: 3D printing
pxp, what material are they working in? They should plan on printing test coupons in the various orientations matching sections of the impeller for destructive testing.
So far I have not seen reported fatigue values for metal AM parts that reliably match those of castings.
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P.E. Metallurgy, Plymouth Tube
RE: 3D printing
RE: 3D printing
But larger 3D modeling of complex parts IS going to be a growth industry as old cast parts wear out and corrode and get worn down. Turbines, pump impellers, engine and coolant castings. The forges and machine tool castings themselves that are no longer made.
So, keep to your goal. but yes, you are trying to break into the hardest part of the hardest, most strict industry with due cause to "feel" that it MUST BE conservative and not accept new technology - and the QA risks of small flaws in that technology.
"It ain't what you don't know that is the problem.
It ain't what you know you do not know that is the problem.
It's what you don't know you don't know that is the source of the problem."
RE: 3D printing
RE: 3D printing
Are they planning to HIP these in order to get full density?
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P.E. Metallurgy, Plymouth Tube