Powder bed fusion I: Electron beam melting

- Hi, welcome back. In this segment, we're going to look at a powder bed fusion process called electron beam melting. We're lucky to have Amy join us here to talk about both the applications, and the advantages and disadvantages of this process. It's important to recognize that this is a powder bed fusion process, in which we're taking metal powder, like this, and we're applying an energy source to sinter, or melt it into a solid object. Now, in order to illustrate the process, we're going to take a look at the production of a turbine blade for an aircraft engine. Now, it's important to recognize that the electron beam process is significant in this application, because producing this turbine blade out of the particular alloy they use is very difficult using traditional means, and there's a lot of waste using traditional processes. So, here we see the turbine blade being input in a CAD model, into the system. It's being sliced up into many, many different slices so that the machine can produce it. This is an electron beam melting machine. We're loading hoppers with titanium powder, and then we're sealing the machine. Electron beam melting produces in a vacuum so that you have full density. That is no port, no porosity, no gaps inside the metal object. We're preheating the metal, and we're applying the electron beam one layer at a time. When that beam hits that powder, it melts it into a solid mass, and we repeat over, and over, and over, and over again. Building that product up one layer at a time until we have the finished object. Now, it's important to note that when the object comes out of the machine, it doesn't look like what you just saw. In fact, it's embedded in a block of powder to look something like this. So, there is some processing that we have to do in order to knock that powder off so that we have our finished object, which looks like this. And I want to note that when we're cleaning that part up, we're using the same material that we use to manufacture the part, so that in the end, we can recycle it all into the next process, less wastage. Now Amy, can you help us understand what some of the big application areas for this technology actually are? - One of the biggest application areas is actually medical. So in medical, we need custom parts. Everybody's body is different. So a great example of that is this hip replacement. So this is an actual hip replacement, and this would go into a femur. This can be tailored to the size of your femur, and the shape. And we can also incorporate this special porosity here on the surface. And this is actually what bone likes to go to. They figured out what porosity bone likes to go to, and they've incorporated it into this design. They've also incorporated that same bone porosity into this hip cup. So, this is kind of how this would go together. So we can actually tailor objects for surgery, for surgical implants. - So, we take some sort of a scan of a person's body, and then we design it in CAD, and then we produce it using electron beam melting? - Exactly. - Interesting. - Another great application for this technology is actually anything that requires intricate structures. Because we are centering, and we don't have the same thermal gradients as with SLS, we can do intricate structures without the need for what they call thermal support, which is anchoring each part down to the build plate. So we can do intricate structures like this here. We can see we have hydraulic lines already plumbed into the structure. We can also do these mesh structures. This is really great for heat transfer applications, and also applications where you might want very lightweight materials, but very strong. So we can make sandwich panels out of this kind of geometry. - Terrific. Any big disadvantages that we need to know about? - I would say the number one disadvantage is probably the cost of this technology. It's a very expensive technology. And as you buy a machine, you also have to buy a person to operate it. So, it's an intense process, and you do have to have some knowledge to operate the machine. - What can you tell us about surface finish? This seems pretty rough. - For all added manufacturing metal processes, you are going to get this rough surface. That's kind of unavoidable at this point. So any surface that you need to be smooth, you will have to machine. So any of those surfaces that have to be exact with very, very, very tight tolerances, you will have to machine. - Okay. So overall, we've got electron beam melting. It's a powder bed process. Very high end. Big applications in aerospace. Big applications in the medical field. Little cleanup. Few issues on the surface finish, but very high quality metal parts when we're done.