On-Demand, High-Rate Additive Manufacturing for Ship/Maritime Repair

KEVIN HAMILTON: My name is Kevin Hamilton. I'm a technical consultant at Autodesk. And I want to speak to you a little bit with a colleague of ours from-- his name is Wei Ya. He's from RAMLAB-- about on-demand spare parts repair for marine industry. The class is supposed to be easy. I don't know what easy is, because that could be anything from advanced materials to something like CNC, for instance.

So we're going to cover lots. But if it's a bit too much, let me know. You can always ask your questions afterwards. We're going to go a little bit slowly, hopefully, to get you guys through it. It's a collection of different things from the last year. Some of it is super new. You might be the first ones to actually see it, which is always a good thing. So-- yeah, let's get started.

So we're going to go through five main topics. The first is an introduction to additive manufacturing DED, which is Directed Energy Deposition. We'll look at different techniques in in that process, and how we work with them. We're going to look at digital workflow-- actually going from CAD to a finished part, and then see how that workflow can be achieved. We're going to focus a little bit on one special DED process called WAAM, and then, from there, we're going to look at some of the material science. That part is a little bit advanced, and for sure, it will be. Even for me, it is. But we'll go as slowly as we can for you. And then we're going to look a little bit at one case study, which should be a first for most of you guys. OK? We have an hour. So we're going to finish roughly around 45 minutes, and we'll have some time for questions.

So what is additive manufacturing and AM 3D printing? Or DED is one type of additive manufacturing-- it's Directed Energy Deposition. OK? You would have no doubt seen something about 3D printing in the last several years. A lot of noise on 3D printing-- mostly consumer goods. Things you can buy-- like, you know, shavers, limbs, these metal components. So they've been around. But actually, through all the noise, there's maybe one process you would have never heard of. At least, I hope you haven't. And if you haven't, hopefully, today you can at least learn about it, and then it'll become a household additive process.

So there are seven additive manufacturing classes, or family. Most of them, you probably are familiar with. There's SLA, which is your lights lithography. There's FDM, which is more deposited in toothpaste, I guess. Put it that way, You've got SLS, which is your plastic powder bed, and you got SLM, which is the metal powder bed. The one which you probably would have never seen is that last one, there-- DED. It's an odd one. But I'll tell you what it is as we go through. It does have a few characteristics. It's mostly for metal. It using a high energy power source to melt some kind of metal. Generally speaking, it's large scale, and I'll show you what "large scale" actually means.

We've got maybe a little bit of a debate between the powder bed guys, who you're probably familiar with, and DED-- who's better? That's always been a bit of a fight. It's usually high rate, meaning you are depositing a lot of material at a time compared to other processes. OK? It's usually on a robotic system or gantry, whatever the platform happens to be. So the size is not really limited. It just depends how big your machine happens to be. Where, say, for instance, powder bed, you're limited to a particular volume of the machine size. OK? And we are always making near net shapes, so it's never finished component. It's usually something has to be done to it afterwards. It's usually used for repair, or new parts production. And if I were to bet on something, repair is the future. Just you watch. It's going to happen. OK?

So there are four types of DED. The reason why they're different is the energy source is different. The first is electron beam with wires. So you've got your power sources is an electron beam. And usually it's in the vacuum environments, otherwise you wouldn't be able to form the electron beam. You fire electron beam through, and it melts some wire. You can see the video, there, in the bottom-- bottom left, for you. OK? This one, there are only going to be one or two companies that are actually doing this, because it's very specialized. It's very, very difficult. Probably the biggest and the fastest additive process is this one. So if you look at deposition rates, this is the fastest one, by far. It's usually doing about 20 pounds an hour at its top end-- which, you could argue if that's good or bad. But it's pretty fast compared to other processes. OK?

We've got a second one called arc welding and wire. This is probably the most common one that most of you would be familiar with, although we give it different names. It's just MIG welding. But, because we like to be fancy, it's called Wire Arc Additive Manufacturing-- WAAM. Wire and electric arc. OK? So that one is used to just weld and build bigger parts.

And we've got laser and wire. This is probably, of the DED classes, the slowest one. So the laser, itself, is usually five kilowatts. If you're doing anything with this sort of slow power lasers melting wire. Generally speaking, when you finish, the surface looks better than anything else than you can actually produce with DED. So it's quite an interesting process. You can get really, really close to net shape components with this process. But it's slow. OK? You can see it there, on the bottom.

And the last one is probably one of my favorites, only because it's been around for probably the longest, that we are mostly familiar with-- it's powder with laser. So effectively, you funnel powder through a nozzle, and you melt it with laser. Sounds very simple. But it's annoying, let's say. Because, you know, gravity can be a pain. Your powder tends to be a bit of a pain. Generally speaking, you've got the machines-- this can usually go on a milling machine, for instance. Your typical CNC platforms or robotic platforms. OK?

Speed OK, so far? Cool. Let's do it.

So what do I mean by "large scale?" So that box is a 250 by 250 by 250 millimeter volume. That's the size of what you typically get in the most general powder bed systems. That's typical. That next box, which we'll see, is the biggest possible powder bed today. It's about a meter, or so. But that is a three meter by three meter box, or a six meter by three meter by two meter box. That's sort of the size that you get with big systems-- so big robotic systems, big gadget systems. So when I say, "large scale," it's that little box, there. That's what people talk with additive. But that's tiny. It's silly. It's too funny, in fact. But you can fit a car in these platforms, they're so big. Of course, being so big, you have other issues that come with it. But let's ignore that for a second. OK?

There are a few systems that are available. Some of them are commercial, some of them are not. And there's a few sort of handmade, bolted together platforms. So on top, there is a platform from Cincinnati-- the [INAUDIBLE]. It's usually been used for plastics, but you could use it for metal, I'm sure, in the future.

We've got this robotic-- so the one in the middle is from Sciaky. It's the electron beam system. It's a three by three by three block. It's in a vacuum, making lighter titanium components, usually, or usually reactive materials. And you've got a robotic system from [INAUDIBLE] or Panasonic, and this is just a normal welding robot on a track. So it's quite basic. It's off the shelf components, mostly. We're going to talk about this one a lot, today.

On the bottom left, we've got a powder laser process. It's probably the biggest platform that I'm aware of. Making the components-- that thing that you can see in there is about 2 meters. That one-- which is quite big. It's about-- I think about 400 hours to build that component. And of course, we've got just normal welding kits we can just buy and use for welding. You stick a torch on the end of it, and you're done. Easy. OK?

What can you build with DED? So there's a few things we can actually build. Some of them are small, or big. It depends. You can sort of see what is possible. You can see the quality of what's been produced, and how it ranges from different components. So this is a part that we produced, one of our first parts that we produced a few years ago. It's part of the landing gear rib. So it's a very critical component, a very structural component. A class one component. So a structural fail safe component. And we've been testing different methods of depositing it, and of course, using CNC machining to see how we can actually finish it.

So obviously, this is a pretty off part. All right? We've got extra material, there, which we don't need. We have to remove it, somehow. When you do the CNC, it's back to your finished component. So in the end, that shape, again-- your final part is achieved by milling. Excuse me.

OK. We've got-- this is a titanium component. It's an engine mount pylon. So it's a very critical component, which we built maybe a year and a half, two years ago. This is probably one of my favorite parts, because of how difficult it was to produce this a couple years ago. I think now, it's a bit easier. We can try it. But it's been fun. This has been pushed by aerospace because it is a very-- titanium is expensive. And when you buy a big block of this, you throw away 90% of it. It's just wasted. So this way, you buy a small plate, you weld what you need to weld, and then you machine-- back-- done. The business case is very, very strong for these sort of components. OK?

We have a few examples from different people in industry who are doing this. We've got Norsk Titanium and Cranfield University, who are also building aerospace parts. Typically just ribs. Because they're going to be easy, but most airplanes are made of these components. So it's pretty common. And they lend themselves very, very well to DED. So it's actually pretty perfect.

We've got a big part from Sciaky. This is the one that's the vacuum machine. So they're building again large components. As I mentioned, it's the fastest, but it's also the roughest. So you can sort of see the surface finish is not so great. That-- your bead size is about 8 millimeters, 10 millimeters bead size. So your smallest feature you can ever make is, let's say, six millimeter, seven millimeter, in that volume. OK? So you have to remove a bit of excess. OK?

So that's sort of a bit of background on DED, and different platforms that are available. And it's always good to ask why do you do any of this stuff in the first place? OK? For me, the question of using AM is never for AM. No one wants to just do additive manufacturing. No one wants to just build stuff. It's usually for components, for an end reason. And we often forget that piece, actually. It's funny how often we forget that piece.

So there's a few things I want to just share with you of why additive manufacturing is a thing that you would use, and the sort of reasons that's behind why you would use it. I thought we can do the four rough lifecycle of a part, so from design, production, use, and end use. And then we can see what's in those four. OK? I've chosen four examples at random. These two we built ourselves, and that one is from MX3D in Amsterdam. And that's Vulcan parts from GKN. OK?

So on the design side, this one is a bit easy to understand, I think, because we can make components that you could not manufacture in any other way. So you almost have to say additive. But that's too easy. It's too easy. Why else would you use additive manufacturing? A lot of ways to reduce your part count, for instance. Complexity-- you can reduce complexity. You can have high quality. You can tell your manufacturing as you need to. You only deposit what you need to deposit. Not excess.

You can of course, customize a lot. So it's not just-- you could actually do the mass customization could be possible with this. There are some limits, of course. But it could be possible. So this bridge has been designed, and is going to be built. You've probably never seen a bridge like this before. Because otherwise, it would be a pain to make. Why would you even make it to begin with? But still, that we can actually do it. This is about a half finished now.

On the production side, why would you ever think about additive manufacturing on the production side? There's a few reasons. And most of it has to do with logistics. That word is difficult for me to say. So typically, you've got small lead times. You can actually produce large parts in a short amount of time, because you don't have to wait for billets or large castings or large forges. So you can make a big part in a week or two, without having to wait a half a year for forging, for instance. OK? That's really the big reason for doing it.

You can make small batch parts. I can make one part, or 10. I wouldn't want to make 100 or 1,000, because there's some limits as to how fast the process can be. And if you're going to make 1,000, probably your best not to use AM. Because it's never going to be cheap. It's not going to be as good as you can make it with casting. In some cases, depending on what you're making, the material is actually better than casting. So it depends on what your application happens to be. OK?

So the idea is that you can actually have a smaller footprint for production. You can do a lot of stuff in a small platform, low energy use, let's say, compared to, say, a big foundry, for instance. But there are some debates about what's possible. So my colleague [INAUDIBLE] can tell you a lot about casting-- which I'm also a big fan of, by the way. So you have to tell us what you are going to use additive for basic application. OK?

So this is an example of a ship hull. It's a small piece that goes in the bow of the ship. This is a difficult part to actually produce. It's a lot of-- it's a time consuming process to actually make. Because you have some guy who is trying to reach eight meters into the ship, and try to weld that thing. It's almost impossible. And they spend so much time doing that. And we were able to produce this in a couple of days. Actually, two at a time, because it's easier to produce two than to produce one. So in that case, like, why wouldn't you do it? So it just made so much sense. OK?

And then, the last on the use side-- this is apart from GKN, where they effectively just used a laser wire process to deposit these structural ribs. Imagine if you're going to mill that, or if you're going to fabricate that somehow, by welding different components together. This is a massive part. It's about 50 kilos of deposition, which is pretty huge for this process. And they're able to reduce mass of the entire thing, compared to what they could do before. The lifetime of the components could be improved depending on how you are working with the process, and how far you're thinking ahead, which is also possible. And ultimately, we have a lot less environmental impact. That's the idea. It's about sort of what we think, we believe. It's yet to be proven, because we have not really studied how much energy we're using. But if you compare to, say, casting for a one-off, or 10 components, it's a massive base you need to be able to do that kind of parts. Unless it's a bit less frequent.

And the last one is on spare parts. This is the reason why we're actually here, today, because this is an area where we're focusing a lot of energy. Because the business case for reducing your spare part count is enormous. We typically spend a lot of money keeping parts, not using them. About 30% of all spare parts never get ever used or seen, which is kind of a waste. And you have a space for keeping these. So this is a process which can actually help you minimize your warehousing costs and your spare part count. So this is a really important topic.

This is a propeller we built. It's hollow. And you'd need to design to replace some other propeller that could be damaged. You can do this in a few days, for instance. OK?

So I'm going to go quickly through the workflow of this from CAD to finished part. I'm going to go fast on this one, because it's a lot of material. So if you have any questions, make some notes, and ask me afterwards. OK? So the workflow is typically six big steps. So you got, at the top, your part you want to have in your hand after it's all finished. We always have to make a part beforehand, we're actually going to build-- your preform. That's an important topic. How do you want to build the parts? Do you build all of it? Do you build layer by layer? That kind of stuff. Your physical machine-- when does your power source go on and off? When does the material move and not move? Your tool paths-- how does the machine actually physically move? Your sequencing-- what do you do first? Do you go left to right, or right to left, for instance? And, of course, you have verification of the whole process chain. OK?

So the first one is the same workflow, again, just in pictures. So I start with my actual part that I want to have in my hand, ultimately. I do my preform, which is slightly bigger than what I want to actually produce. I put it on the machine. I have a physical setup. I have to think about how the machine actually behaves. I've got my tool paths, which I'll make. I have to embed some-- this should work. Yeah. I have to embed some knowledge about the process on the tool path to be able to produce them. So things like welding parameter, occurrence, laser power, for instance. Your material flow. And ultimately, you have to then produce that, somehow. So either build a few layers, machine, cool, heat-- whatever you have to do. That's your sequencing, there. And of course, then simulate the whole thing to see how your part will behave, and other material will also behave.

Why do we do this? The process is a bit rough. So this is some of the worse things I could find from our own shop. So this is things that we've personally produced. And I like them because they tell the story which you never see. People always show you the thing that's the final part. The finished product. It's always beautiful. But it's these shitty actually-- that's supposed to be a vase. It's supposed to be nice. But look at it. It's so rough. It's terrible. So why do we get this, and how do we fix it?

So that's the reason why we need to think about the final part. Of course. But also, what you want to produce, first of all. What you want to build. That is a 10 centimeter deflection of the part. So imagine you're making a part, and it just sort of bends that much. It's crazy. It's possible. There's so much heat and stress, that happens. So we have to think of all this stuff when we program the parts-- when we actually go and build them. And some of the issues that you can sort of see is your welds are too far apart. They don't even bond. Which can happen. It's kind of a pain. And you've got cracking, you've got distortion, of course. Those are possible.

So typically, your part comes from a drawing. You have a drawing which says what tolerance it needs to meet, what specification the part must be able to achieve. We can never build that thing. It's got holes everywhere. We cannot build holes. It's just not possible. So we have to do something else, beforehand. So we start with our final part, and we work backwards. We sort of simplify and decompose that piece to something we can actually make. So we remove all the holes, remove all the fine features, which we'll put in afterwards. We'll say, for instance, milling. We add in a base plate, because we have to build onto something. We cannot build in open air. It's impossible-- for now.

We might simplify. For instance, we might move and say, actually, I don't want to build those sharp corners. You can never see a sharp corner. It might be also a stress point. So let's simplify-- with some fillets, for instance. OK? So that's-- it's a lot of work to do this. An experience. But we're used to doing it for casting. So for instance, you never cast final form. You always have a casting model that you actually build. But you never see this, because the foundry will do it for you. But in AM, all of a sudden, you have to do it. So it's a whole different field, a whole different ballgame of what you need to know to be able to produce these sort of components. OK?

And I'll just list a few steps. This, you can take a photo of you can have afterwards-- sort of a different step-by-step that we normally go through to produce the final preform. So we start with the actual part we want to have in the end. We remove some features-- some geometries which we cannot actually build. We think about actually where do you put the base plate? But, as I said, no one really can tell you what's optimal. But we have experience, of course.

You might want to add some stock. Maybe you're going to do some [INAUDIBLE] afterwards, for instance. You have to oversize some features. And then you do some additional geometries for things like distortion, or cracking, for example. And now, you have a model, which is this-- which is idealized. But obviously, when you're finished, you have that thing. That's different from that thing. It is. So how do we make this go close to this? In my mind, I normally make a model that's halfway in between. It's never perfect. But the closer we can make this to the real thing, the better your idea will be. And we can get some tools, like simulation tools, to help us define how that should look. Because obviously, it's difficult to imagine this.

You're building-- how do you build? Do you build left to right? Right to left? How do stresses occur? How do we deal with heat? All the stuff we are trying to figure out. No one knows what the answer is. We usually use simulation to help us understand this. So for now, there's a lot of things which we do manually to help you define how your parts is to be built.

The process. I've shown here three of the processes. These are events. So your laser goes on, it goes off. That's an event. Your gas goes on, it goes off. So when does those things happen? That's a very specific timing. So if you have CNC background, you're milling. You put your spindle on at the start, and it stays on. You're done. Wherever it comes on, it doesn't matter, as long as it stays on before you start to cut. Whereas this, when you are cutting, your laser must be on, your gas must be on. So those timings are really, really critical.

And of course, your tool paths. Tool paths is what people usually go to first. But it's my sort of-- I push it a little far, because it's too easy, let's say. It's too obvious. So of course, the different tool paths are possible based on your feature you want to make. So 2.5D, sort of prismatic things, your features on a rotary shaft or on a arbitrary surface. And they are tools for this, which we've been able to produce in the last several months, to help people build this part.

This is my favorite slide. It's awkward, I know. So let's say I have a meter long tool path. I could cut it. I could wear it. I could glue it. I could sand it. How do we tell the process what I'm doing in that line? How do we embed knowledge on the tool path, for instance? This is what this slide shows. So for every point, we can describe what the processes is. What my power, what my speed should be, to help you control the process very, very finely. Otherwise, this is just a path you can use to cut, for instance. It's possible. OK?

So you've got very detailed control. And the question, of course, now, is, how do I know when to change something? This is a question that no one really has an answer to yet, but we're trying to find this out, as well. Sequencing-- so this is the example which I like to use, because it's easy to show propellers being built. It's difficult to build them, but nice to show. So if I'm going to build a propeller, I'm never going to build that one blade fully. I might build a layer of it, go to the next blade, next blade, next blade. So that's the sequencing which you're going to see there. So I'll start with my first layer, deposit it. Now, I might want to wait to cool it. I might want to do some active cooling or active heating, depending on how your process is developing. OK?

This is a really critical step, which we can also get some tools to help you do. And of course, you can do some simulation of the machine moving, to see how the machine is going to move. If you have any collisions, that symptom of it beforehand. If I'm milling, I can see the simulation of how the material is being removed. And if I'm doing additive, I can then see how material is also being added. It's a bit slow, but it should come up in second. There you go. And obviously, I want to be able to verify that with my machine tool. So if it's a robot or milling machine, we can then verify what we've produced, and make sure actually it's good enough to be to be built. OK? So for us, we don't really care if it's a milling machine or robot. It's the same thing, really, for us.

So I want to introduce PowerMill additive. You're probably the first group out of the company to see this live, let's say. There's a software-- we have a software called PowerMill, which is a platform for machine control, for milling, for polishing, for grinding, whatever. And we use it also for additive. So far large scale additive, this is how it looks. Not very exciting. But we've got some tools that can help you define your part you want to produce, your tool paths, edit them, simulate them, visualize them, and then go to the machine. So if you're curious about this, if you're doing any work with DED, come find us. We can assess this process. OK?

So did the survey, maybe about a year ago, about what kind of parts we want to be able to produce. This is only for information. We said, OK, what are people wanting to produce? So if you see additive parts, you have some nice, fancy, difficult parts that are not really functional. Which is pretty much these things, over here, that everyone wants to produce. But why do you want to produce them? What's the use? Is there any value to them? And so we said, actually, we're going to only help you do these first five, because it's common to do those. And it's the ones that are usually difficult, that you're going to be using a lot more often. So that's what the tools are.

And I think I'm going to shut up now, for a little while, and let my colleague Mr. Wei Ya jump in and tell you a bit more about what WAAM, specifically, and how we've been using it to be able to produce, in this case, a modern propeller. OK? Thank you. I'll come back for questions afterwards.

WEI YA: OK. Thank you for the introductions. I am Wei Ya from China. I work in Holland. I studied welding and material science in the past 11 years. So actually, we use the technology available to do innovative stuff. So a very typical welding set up-- the additive manufacturing with the WAAM arc. You can use the MIG or TIG-- both can be done. And then you have a typical robot that you drive and define tool paths, you additive tool on the top. And you have your material supply as a [INAUDIBLE], normally 200 to 250 kilos behind. And you have a CNC control for the robot, and then you have your shielding gas. Normally it's the helium or argon. Then you put it in a option. OK. Let's go down one.

So what's so special about our equipment we use over there is that we have a cold metal transform, which is similar to the furnace concept, but we can have a better control in feeding of your wires, how to control it. And the interactive process, you can have different angles, which is not be able to control with the normal welding systems.

So in traditional welding, you make a deposition, and you have base plates help you take out your heat. You can constrain your base plates so you can constrain the deformation. And then you, on the surface, let's say a 2D case, you would have like a surface coating, you can study them, which I did my PhD study on it. And then you can really simulate how the heat is flowing, how the geometry build up. You can do the simulation. There's three group in the world working on this at this moment. Then you have to understand how the materials will respond to your process. It doesn't matter if you use the laser or electron beam, or the arc-- the important is to understand how the heat reactions, and that you are able to manage stress build up.

So the additive manufacturing concept is somebody give you a part, ask you to build it, but there's no basis for that. You probably have the base plates to take out of the heat. But what happens after you build it up? So during the process, you need to define how many layers that you want to build up. Because it's very critical if you build up too big or too small, will your machine able to reach the bonding between them. If the bonding is weak, it doesn't make sense to build them. Then, after that, you have to define how you want to weld the pattern-- that's the tool path. Because when you do the rotation, or you don't do rotation, in the materials and the stress and the temperature that will have different impact.

Afterwards, you have to really put into the digital format with each slice layer, and make a deposition. And then you will have a near net shape, and you need to do the final post-processing to get your final component. So all the concept-- all the series that we learn in school-- ideally, you can achieve anything. But in reality, they are all difficulties. So that's why the RAMLAB was funded in Holland, in the Netherlands-- to look into these areas. And for us, we have focused on marine industry, for the starter. And there you can see the propeller, under the ship-- it's symbolic for the marine industry. That's the focus of last year's work.

So for propellers, they can have a different shape, different design based on the size of the ship and based on the purpose of your ship. For us, when we started, it's a journey that let's say we want look into what additive manufacturing can bring to this component-- what can we use for it. So we tried different designs in the process. So this one is an example for the first blades that we deposited with a hollow propeller. In 1985, people already study it, but the hollow structures are normally difficult to cast. They can break, because there's sharp corners. So we test it on a 2D form. And we use the single bead pass to make all the connections. Then we realize that, yes, we can make a hollow propeller.

Then we say, this is very simple. It's a 2.5D cases. We need a little bit more challenge. So we have the next design, let's say we've put a little bit crazy, when you need to use different access. Put more blades on. Let's see how the materials respond, how the heat goes. So we built also half into size propeller. And as you can see, we use a different strategy from left to right, from the base to your shaft, and the way that you build up during the process to control. I think this was done with a furnace setup of Autodesk in the UK.

And once you are able to control your bead shape, you can generate really nice features. And then we finish the challenge of the hollow propeller. And we took a next step. OK. For current marine industry, they're not happy with that if you put a hollow propeller. Everything-- standards, certifications, everything has to be checked. So they want you to go a step back, a little bit. To start from a solid propeller. So we are thinking about, OK, then we make a propeller that's close to the current state of the word. Make it a solid.

So we use the long bead design. I think it's the four bead parallel with each other, with different rotations. And it's about one meter size of the propeller. Then after that, we deposited it. It takes me, I think, three weeks to make this. Each blade has 20 kilos. And during the deposition, we find out there are some distortions. And you have to compensate during the building how to manage this materials flow. And when you want to build a solid piece, which parts you need to take more care of.

And then we come to see, OK, now we want to do near net shape. We don't want to put so many materials over there, but we want to put as less as possible, and make it better. So we set our journey for another exploration of the new design. And then we made a very, very tiny propeller. This is-- I think the diameter is 0.3 three meter. What's the difference from this and from that is the large one, it's very easy when you have a big curvature surface, you deposit your materials. Then you can consider the curvature as flat. But this one, because the diameter of the shaft is only 50 millimeter, the curvature is very sharp. Interiors, the previous welding parameter that we have, it does not work on this. So we have to make a few tries and find out why and how to do it.

Why this is very important? This is very small scale, but we want to do a huge propeller. So next step, everything in the real life for the big propeller we make, we follow this strategy. So these are just for design explanation. We can have more features, like, if you want to composite the flow dynamic, make the propeller more efficient, you need to design based on the physics of the fluid dynamic. Then you will add the features on top. This cannot be realized by casting-- the traditional way of making propellers.

And with that, we can explore how fast you can do it-- the prototyping, that lead time-- all kinds of new studies can be added in that regions. So to summarize the before designs, there's a sequence of how you preform your parts that you want to add on the top, and then you have to simulate to see your parts, and then drive with your machine everything's working, if it's properly or not. And during the depositions, if you have able to extract the heat information, late one can use for simulation, how the heat distribute. Then, in future, you can use the model just to predict if there's going to be deformation, or not, where you need to manage your welding parameter differently. Afterwards, you can do a milling to check the surface qualities. And always near net shape for this resolution of technique.

For this one, it's about half a millimeter-- less than half a millimeter you can achieve. About 400 micron. For a normal pulse bed laser, it depends on the particle size. You can go between 20 micron to 100 micron. Even better one, SLM. It's because they have a refined particle, so they can reach about 20 micron.

So the post-processing can do either manually or use the CNC milling. And for marine industry, the guy who's doing manual grinding are really expert. You will see later on. So for the materials aspect, when we set out to study the propeller, the next question is, what materials do you use for the propeller? You can have aluminum, stainless steel, but the common one is a nickel aluminum bronze. Why we use it? They are stronger than the steel, but lighter, because you have aluminum inside. If you take just copper, it's heavier than iron. And then super corrosion resistance. So this is the actual part that really attract people. So you have the propeller with a couple meters. You can use these materials for piping-- valve. And that is for submarine propellers.

So for this, the cast materials. Normally, you have the alpha phase as the matrix, then you have the precipitates of this. Isn't that the beta phase. Compared to the alpha phase, is brittle. And these intermetallics-- some helps to strengthen your materials, some weak your materials. So you would like prefer some of copper-3 type of the precipitate. But in general, they are all intermetallics. And the intermetallics, especially the iron and aluminum, they are not the preferable in your materials. So they can appear in a different shape, as you can see. Go through the slide.

Then, in a traditional cast materials, you will see a lot of this intermetallic. When you're put in a sea environment, they become a selected corrosion location, which you don't want. But after you process with WAAM, these intermetallic, you can suppress them. But we still want to keep the strength. Then you play with your cooling rate, get to refine the grid structure. Then you will still have the strength, and avoid the corrosion resistance reductions.

So for propeller, where it is important is the connection between the hub and the blade. To simulate the mechanical property of this materials, because of why we need to check the mechanical properties is the traditional way of making propellers, how they test the strength of the propellers is with a separate batch of materials cast in a small case, and make the tensile impact test, and then get the value. Which is not symbolic to the micro structure inside of the propeller. For us, for the first time to do it, we work with a certification agency. So we propose that we make the component, which can simulate the heat micro structure happen in the materials. That's why we design these two type of testing. It's the T shape and bonding test. And later on, actually, the bonding test sample, we don't even need to consider it, because we built the hub, also.

So that's another story. So you can see, we used about two kilo per hours of deposition rate. We made the T-shap and bonding strength samples. And then we machine the sample out of these materials. So then we perform the actual ISO standard tensile test. And then you can see, with the tensile strength, materials start to have plastic deformation. Here we have the necking, and then eventually break. Then you get the results of your strength.

So if you plot it, you will see if the materials stay in this region, you will coming back to the elastic region. So everything safe, and it will go through different shear dislocation movement stages. Up until the ultimate tensile strength, and then you know how much elongation you will have. So what we find out is compared to the cost of the materials, we have a superior materials property. For the yield strength and tensile strength, we are more or less above the level-- I think 50 pascals. But what you saw, the impact is about four times higher. What does that mean? It's because the propeller, in the water, normally they are damaged by the impact. And you need the high ductilities to absorb the impact. When you warm materials has a high ductility, you absorb more impact. And the propeller will be safe after impact as long as it's not past the breaking point.

So as my colleague Kevin already said, to be able to finish the whole digital manufacturing process, you have to get your original design put in 3D models, and then you define how you want to build this propeller. You have to check how you want to deposit the sequence, the tool paths. Eventually put in a simulation, to see if everything's working properly. So after the deposition, we work with the accompanying [INAUDIBLE] for scanning to see if we have any huge deformations from a similar point of view. So we did a 3D scan at a different stage to check if propeller keep the shape. So it turns out that it's not that bad. It's about-- according to my estimation before, it will have about 8% of deformations. But because we have to stop in between-- two times I'll finish the propeller. So we have roughly about 15% of deformation. I think it can be managed to be less than that.

So, as you can see, we-- yeah. As a team, we used banana as a scale to see how big the things you can make. Yeah. So it's about 1.4 meter in diameter of this propeller. And then we have weight about 400 kilo. For this one, because we are first time to build it, so it's a little bit over designed. Russian in design. The new one is about half of the weight. And this one takes about 300 hours to make. The other is only 156 hours, with some posting time-- so I would just say 180 hours.