AM_F2019_06

That long discussion but it still applies to additive manufacturing parts as well. But unless Boeing is certifying them — which in this case with Digital Alloys, Boeing is going to certify the parts under the STC, supplemental type certificate that they hold. If Boeing certifies to the FAA that these titanium additive manufacturing parts are good, the FAA is going to say fine, you're responsible, you're taking the risk, okay. If the plane comes down because of it, you're gonna take the heat. And guess what's happening on 737 Max? The FAA is not taking the heat, well they've taken a little heat, but mostly it's Boeing right, because they approved it.

But you can get around the manufacturer through the PMA process, and you can either design a brand new aircraft component yourself and have the FAA approve it, or you can prove equivalency to the design standards. But the FAA cannot release what the design standards are to you. They have them, but it's proprietary information. Boeing gave them that information, they can't release it. But if you supply information, you know, a sack of documents like this, they can say yes, this meets the same criteria that Boeing gave us, or no it doesn't. But it's not as if you can go through and ask what doesn't it meet, okay. They don't have to tell you, they can't tell you that because they'd be violating the — they might be violating the confidentiality. So it's a sort of cat-and-mouse game.

Student: [question about FAA equivalency processes, inaudible]

Right, in the FAA — I think most of the equivalencies to the FAA work very closely with the FAA, because well yes and no. The European Union of course has Airbus and their lab will give Airbus a little benefit of the doubt, like we'll give Boeing a little bit of benefit of the doubt. But if you go to South America, they have their aviation authorities, and when they have a problem, it's not that they're not independent, but they're gonna go ask the FAA what they think. And the FAA will send people in to do part of the accident investigation, because they want to know what happened. They're charged with promoting safety. And even if the 737 Max went down in Indonesia, whereas the other one Ethiopia or somewhere, yeah there's FAA, you know there's Americans on site, okay. And they were probably the ones who came back and merged the data from the Indonesian or Ethiopian. Of course the Indonesians, the Ethiopians are also dealing with — we probably have more expertise in our FAA than Ethiopia or Indonesia. So they actually work very closely. They have to, because none of them have enough staff to do it all.

And they rely a great deal on the manufacturers. When there's a failure, you'll hear that the National Transportation Safety Board went in there the next day. Pipeline explosion, NTSB is there. A ferry sinks, NTSB is there. A railroad derailment, anything where there's transportation involved, we have a National Transportation Safety Board. They're charged with going in and doing the investigation. They don't have all the expertise to do that. They will invite in people from the railroads or the manufacturer of the railroad equipment, and they will come in and they'll ask them questions, and they have subpoena power. If you don't answer the questions, they'll get it, okay. They'll go to the judge and they'll force you to give it. So there's sort of a cooperative mode here. Is it completely cooperative? No, okay. But I mean, the companies aren't going to say oh well we screwed up, okay. But these guys, the US engineers at NTSB are not all stupid, okay.

And now we have a Chemical Safety Board which modeled after the NTSB. NTSB's been around for fifty years. There's a big explosion in a chemical plant in Texas, CSB's in there, right. Big hundred-page reports on why it happened. It's sort of like ocean investigations of an industrial accident. Sometimes they're pretty good and sometimes they're pretty bad. It just depends on the quality of the government investigator writing the report, okay.

Other questions? That answer your question? So see, I actually think learning about these investigations and how it really works is interesting. But it's not as scientific and technical, it's more political, okay. But it's real, okay. No other questions then, okay.

Let me — I passed hopefully the sign-in sheets. Good. Most of you have attended enough classes that's not going to be an issue. If we look at — you might as well run it if you haven't seen it. So they're not going to make just simple parts, they're going to make some part. This is the Digital Alloys, this is from their blog site, and they actually have taken a Boeing part. And Boeing has actually — Boeing's done this analysis, and if this is to make a five kilogram titanium buy-to-fly — remember buy-to-fly ratio — five kilogram part, that's a fly part, that's five kilograms. Five kilograms is probably going to fit within the size of a soccer ball or something. And making a hundred parts, not just one part but a hundred parts, you know, you're not making one-of-a-kind unless you're a spacecraft.

And what we've got here is for additive [versus] machining. Yeah, you can set up your CNC machine to do this, and this is just to do rough machining — forty days, okay. Remember you're going to machine away probably ninety or ninety-five percent of the five kilogram, so you're gonna make 500 kilograms of parts, but you're going to multiply that by twenty, you've got 10,000 kilograms — or is that right, anyway you can figure the math if I did it wrong. But you've got a lot of chips, titanium chips at the end, and it takes time to do that, many days. This is for Joule printing, but if you could do it by binder burnout or something else, you would also get something similar, seventeen days. Well forty days versus seventeen days, and you start doing the math on all that on the cost, and you're gonna find that the heat, the energy in CNC machining for a single part is not very much energy. I don't think the energy thing is all that interesting.

But if you get into the actual — well I guess the real thing here is the time savings, okay. You're gonna find that additive manufacturing of these parts is a lot cheaper than manufacturing the old-fashioned way, where they just hog out of a big hunk of titanium and make a little bitty part, okay. Remember the Aladdin movie, you know, great tremendous power, little bitty house to live in for Aladdin. You have to have brackets, maybe.

Okay, so then he went on. Part eight is about powder bed fusion, which is something like laying down a layer of powder, coming along with a laser, electron beam or an arc or something. And now we get part size. So their process will do things that could be as big as the soccer ball, which is your five kilogram part. Some of these things like binder jetting, where you actually squirt powders and fuse them together and building something up, okay, you can make a golf ball, okay, or a tennis ball, or something. If you want to make something that's, you know, substantial in size, a meter, you're gonna have to be into directed-energy deposition, and he'll show you something on that in a little bit.

Here's an example from the General Electric area, an aerospace fuel nozzle, very complex part. Yeah it's a structural material but it's a functional material. Remember I told you the other day, when you're doing pixel-by-pixel, you've got to have a functional advantage. Just strength, you know tensile strength, yield strength and elongation are not going to cut it. You can usually make those things other ways. But when you need all these little holes and bosses and things, previously made from twenty different parts, and so there's a tremendous cost savings there.

If you go to directed-energy deposition, there's powder and wire deposition. Well this is — my technical community where I got my tenure was welding. Of course you wouldn't necessarily know that, so of course, but this is the types of stuff that I would do and do research on and look at heat transfer and whatnot. But you basically have a wire, you're feeding in like a welding wire, you've got an arc — this is a gas tungsten arc — and you basically just put down a little drop, some metal about the size of a weld pool. So you can make something a meter in diameter, okay, if you keep going. I want to keep going, let's see, probably have to tell it stop. This is laser, this is on their blog, I just stole these right off the blog. So you've got a laser, you're feeding powders in, and you're making a cylinder out of powders, okay, so far as that goes. And that's probably about — those both, well the wire EDM was slowed down — for real speed, this is probably about real speed, okay.

Now what do you get if you look at deposition width in millimeters versus print speed in kilograms per hour? If you have nice small pixels less than a millimeter in size, you're not going to put down a lot of kilograms an hour, in fact you're gonna be talking ounces per hour, okay. If you have some big weld pool and you're gonna be making something the size of a meter, yeah, you've got ten kilograms an hour. And you know what, that's about the fastest anyone, any welder can weld. If you go through and figure out the economics of a welder doing things on a website, you look at how many pounds per hour or kilograms per hour a welder can put down, it's a few for gas tungsten arc, it's around seven pounds an hour is a max. Look for other processes, you might get fifteen or twenty pounds an hour, okay. Well there it is, okay. It's not any faster than just laying it up as weld beads, and we've been doing that — additive manufacturing for years.

In fact that's why I brought this, and that's why I drew this picture. You might recognize this. [Tom indicates a turbine engine diagram and a shroud piece.] It's a turbine engine, okay. You've got a center shaft, you've got some compressor blades, and you've got some combustors where you add the fuel and the compressed air. And then those go past the turbine blades. Those turbine blades spin this whole thing. As they spin this whole thing, the compressor blades compress the air by about a factor of thirty in volume, but it's going up in temperature, so you get to like thousand psi pressures. But you've got a problem. You don't want any blowback. When you've got high pressure here and atmospheric pressure out here, if you don't have a good seal between the shroud and the blade, you're going to be losing efficiency as the air goes the other way.

So what do they do? Well the first thing we do is we make a honeycomb. [Tom holds up a piece of shroud.] This is a shroud, actually a piece of a real shroud that had been in service. And this is not the blade with it, but the blade's going to be spinning at twelve, twenty thousand — twelve thousand, twenty thousand rpm, it's going pretty fast. And it's going to be going past this thing. And we actually make it a nice soft compliant honeycomb structure that will wear away as the blade creeps. It's working at higher temperatures and it gets longer over time, over thirty thousand hours of operation it gets longer. And as it gets longer it just cuts into the shroud and it keeps a good seal.

What do we do — well these tips wear out and we want to recondition these blades. Not this one, but some of the fancier blades could cost two or three thousand dollars a piece, okay. So what do we — we go along with these little directed energy deposition. We never called it that before, the advanced additive manufacturing, but they actually called it laser [LASER] welding. The Air Force went to Tulsa, I think Tulsa Oklahoma, maybe Oklahoma City, they have a big repair facility for their engines, and they would just put on little carbide composite coatings on the tip so that it intentionally cuts into the surface as it's spinning at high speed. We've been doing that for fifty years, okay. That's additive manufacturing folks. It's done on the original parts, it's done on the repair parts. We do all kinds of additive manufacturing because we're saving a two thousand dollar blade and letting it go for another thirty thousand hours. There's a lot of value in that, okay. So that's another place of additive manufacturing, is repair and maintenance and things like that.

And then they go through binder jetting and we won't go through that now. This came up the other day, is how big are these parts and do they shrink. If you start out with a powder compact this fifty percent voids, when you just glue powders together, well once you heat it and sinter it, something this diameter or this diameter shrinks down to this. These are not huge parts, but this is a compressor blade or vane or whatever. And it really doesn't have great geometry control. I mean it looks good, but balancing this — because it's gonna spin at 30,000 rpm, okay, for something that diameter it's gotta be balanced folks, okay, it's not gonna be easy. Typically we cast these things, but anyway, we don't do it by additive manufacturing. This I think is a demo, I'd be surprised if that's in production, okay.

And then the last thing that Alex hooked up — put together — is surface roughness. All kinds of different surface roughnesses. This is wire directed energy deposition, these are just a bunch of overlapping weld beads. This is the Joule printing, which is pretty rough, you've seen that, pass it around. Binder jetting can be pretty fine. Powder bed, which is sort of like the Desktop Metals, is better — a lot better than Joule printing. But — and here's the sizes, or these guys are not dimensions, but he's got another graph that I haven't really studied, but basically it shows that the surface roughness in microns goes from a hundred microns for that weld bead down to five microns or less for the different processes. So different attributes for different processes. And here's an example that he had in there, another type, I think it's probably titanium, it could be stainless steel, part done by a directed energy deposition process on a plate. The plate actually becomes part of the final machined part. There's lots of machining, but it cuts down your machining so far as that goes. And that's sort of the end. Yes.

Student: [question about shrinkage from sintering, inaudible]

Yep, from the sintering process you're talking about. It's one of my problems with the sintering process, okay. If I come to the conclusion that aerospace manufacturing is a sweet spot and I need ultra precision for the aerospace market, I don't think — I don't think the powder shrink as a sintering process is any good for that. They think they're heading towards the automotive market, I think they're kidding themselves, okay. But you know, maybe they're gonna — they're gonna have an IPO and they're gonna be faculty members of this department walking away with five or ten million dollars in their pocket. I don't have that, so maybe they're not smarter than I am. But your grandmothers are gonna end up with a lot less in their pension fund ten years from now, okay. Because someone's going to take and buy some of that IPO, put it in the pension, and over time you're going to see it just drop down, in my opinion. That's my opinion, okay, it's just an opinion.

But you can make your own choice right now. You now know enough, and in fact — okay so we spent six hours talking about — actually not even that, because of had tangents — but on additive manufacturing. Whether it's additive manufacturing of metals, or whether it's high-temperature superconductors, you're MIT students, you should be able to study the technology on your own for two hours and know more about it than the person who wrote the article in the Wall Street Journal that says it's a wonderful thing, new technology, okay. I guarantee you, two hours of intense study. And I would have loved to have given you papers to write where you could, you know, take a topic, but I found it's easier just to let you pick a topic that you like and you'll study it, okay. But you've become an expert with two hours on a topic that you're interested.

Well if someone is trying to — let's say your grandfather left you $100,000 to invest in some new startup at MIT, hopefully you wouldn't just go to the first one that's walking down the infinite corridor, right? You're gonna do some study and hopefully you'll spend two hours studying the technology, maybe rejecting it. Then you've got to go study another one, took two hours. In the end maybe you'll spend ten hours to select one out of five, okay. But you ought to be able in two hours to learn quite a bit and do critical thinking, if you know some of the principles.

One of the principles I taught you in the beginning: the value of a pound saved in an automobile is $2 over the life of the vehicle. In aerospace it's $200. As I always say, they have vice presidents at American Airlines figuring out how many magazines they're gonna put on that aircraft, because magazines are heavy, okay. And at $200 a pound just to carry around something people aren't gonna read, okay, that's a lot of money. On aerospace — our space technology, you know, Elon Musk, he wants to die on Mars. But he wants to — he wants to die on Mars but he doesn't — "do I want to do it on landing," that's one of his quotes. I think we should send him to Mars, okay. It'd be — nevermind I won't say any more, okay.

First of all, it's a — one — it's a what, a one-year trip one way, okay. And the $20,000 — the people who are going to colonize the moon, let's not go to Mars, they're gonna colonize the moon at twenty thousand dollars a pound. Well let's say the original Space Shuttle was supposed to reduce the price of a pound in orbit — that was in 1970 dollars — from $10,000 a pound to $1,000 a pound. Let's say we can do it for a thousand dollars a pound, okay. SpaceX or whatever is going to get payload in orbit for a thousand dollars a pound. You know what it's gonna cost for me to buy a ticket? I would be — I would be incentivized to lose some weight, okay. A thousand a pound, okay.

And once you get to the moon, you might need some other things there to live off of, right? Which is why NASA is looking at, well can we dig up moon rocks and process them to make ore, you know, in order to make metals. And how — where we're gonna get the energy out there, okay. Well we've got solar energy, yeah, okay fine. You start looking at all the things you have to do. And you were at NASA Langley, and they've got hundreds of people looking at how they're gonna do this, right? How they're gonna weld things in space, you know, and how they're gonna process things in space, how they're gonna repair things, you know.

And I heard a faculty member — I was at an alumni thing in Philadelphia once, and I was talking about whatever I was talking about. We had a young faculty member, she's not so young anymore, but this was twenty-five years ago I think. She was close to tenure and she has tenure now, and so a very distinguished career. And she was talking about the mission to Mars, okay. And she was saying, you know, and we can afford this, we spend as much money on potato chips each year as we do on a program of — which would be about two to three billion dollars a year she was claiming, to go to Mars over the next twenty years, okay, forty billion dollars. Well first of all I don't think it'll be two billion a year, I think it would be twenty billion a year, you know, it'd be four hundred billion. But you know let's take her two billion. And I leaned over to the person next to me, I said if you did a poll of all the people in America, would they be willing to give up their potato chips for a trip to Mars? I think I know how that vote would come out, okay. I think it comes out every day in the grocery store, okay.

I — there's a lot of other things we need in this country that we could spend 400 billion dollars on, in my opinion, for a social good, than to send Elon Musk or Mark to Mars [Mark Zuckerberg?], okay. I'm sure he's enjoying it and he could pay for it. Anyway, so I have my opinions about some of these things, which I think — I just gored an ox, or there are arcs anyway — they probably could defend themselves and talk about why it's useful and stuff. And you can look back at the putting a man on the moon, that brought us gallium arsenide, which is one of the great materials advances. I admitted that, okay, in LEDs and all those other things, GPS, and a lot of things come out of that. But you could also spend that money in other ways and develop sustainable, environmentally friendly technologies. Maybe we would have had solar power thirty years ago if we had invested some money in solar power thirty years ago, okay. Anyway there's lots of choices and they're often made for political reasons.

Any questions? So let me just say that this actually is — the next lecture without — Alex hooked up next Thursday will be the sixth lecture. And we're supposed to meet on Wednesday but I have to go to a trial in Houston, and I never know when I'll get off the stand. So let's cancel class next Wednesday, let's do Alex Huck step next Thursday. We have Jerry, put this on Stellar. And if we need another class after that, we'll schedule a class in October, okay. But I'd rather do that than be sitting there on Tuesday evening trying to get the word to you that we do or don't have class on Wednesday. I think it's just easier. And if I am here on Wednesday morning, well I'll find something to do and you can find something to do on Wednesday morning.

Now what I'd like to do on Thursday with Alex is let you ask whatever questions because he's live, this — okay, he put these blogs together I think they're excellent and balanced presentations of what the advantages are on different types of additive manufacturing. He of course is in the business and so he's going to be — he is promoting his, but a lot of his stuff came from real data. In this case you can see all the Boeing interest and you're getting Boeing's data on the parts.

But I'd like you to think about, if you had an additive manufacturing idea and you were doing a startup, what would your strategy be? What industry would you go after? What material would you go after? Why did we not talk about aluminum? Because aluminum has got an oxide and it's hard enough to weld. Try to take little particles of it and join them together is gonna be extremely difficult. Titanium doesn't have a surface active oxide that's hard to get rid of, so titanium is nice. Stainless steel is not bad from that point of view. Why haven't we talked about copper alloys? You could do copper alloys or brasses, but what's the volume there? Okay, the volume is in steel. Or if you're going to aerospace, you're looking at aluminum or titanium. Or you might get out of metals and you might get into composites. So you might talk about plastics additive manufacturing, which probably has a number of applications in the aerospace industry to make excellent composite structures. Or maybe you've got an even better idea, if you can figure out how to repair those composite structures, because that's one of the big Achilles heels for composites in aerospace. We can make them, but we sure don't know how to repair them very well, and they do get dinged up every now and then. Look at the Space Shuttle, okay.

So I'd like you to think about — do some critical thinking, as if you were going to invest, or you have a startup, what types of materials, processes, industries would you go after? If you don't know where you're going, any road will take you there, and it probably won't be profitable, okay. Any questions? So there's my soapbox.