Directed energy deposition: Laser metal deposition

- Hi, welcome back. In this segment we're going to look at a process technology called Directed Energy Deposition. We're happy to have Amy here with us who's going to help us understand some of the applications for this technology as well as some of the advantages and disadvantages. Now, I think that this is an interesting technology because in contrast to other processes where we've seen the laying down of a layer of material, in this case metals, and then the application of an energy source, for directed energy deposition what we do is we apply the energy source and then we inject the material, either in a powder form or in a wire form, into the energy source in order to create the object. Now we've got a great video from our friends at the at Oak Ridge National Lab that's going to illustrate this process for us. So we've got an open air system here, no vacuum. In this case, it's a two material system. So we're going to fill one reservoir material here with powder, not wire. Could just as well be wire. And then a second reservoir with a second material. - [Amy] So this is great if you wanted two different materials in your finished product. - [Mark] And we're going to prepare the field for the build. - [Amy] So you see we have a start plate there that we're going to be building on top of. - [Mark] So we're going to have, in the end this is going to be attached to the build plate and we're going to have to cut it off somehow. - [Amy] Exactly. - [Mark] So we begin injecting the material and then there goes the laser, and we notice that the material's actually being injected into the field created by the energy source. - [Amy] Right, and so we're going to have powder going everywhere at this point. So it is important that this process happens in a glove box. - [Mark] Okay, and we begin to build our internal geometries layer by layer, building it up from the bottom. - [Amy] You can see we can do some voids within the part as well. - [Mark] So we're going to add a second material around the first material to complete a finished object. Amy, can you help us understand what some of the key applications of this technology are? - Right, so, the number one application for this technology is actually tool repair. So we spend a lot of money making these very large metal tools and if something breaks or it gets worn down or it's not done correctly, we can actually add that metal back to the part and then machine down to where the part should be. Another great application is any application where we want two or more materials. So we can actually create objects with metal alloys where we're alloying two different metals together, or we can create gradients between two different metals. - So I could start with, for example 100% of material one and then slowly but surely add in more and more material two until I've transitioned all the way over a period of space into material two. - Right, so you can get the perfect gradients between two materials. Another application is large objects. Because we're not printing in a vacuum, we're not building in an inert environment, we don't have to deal with a large powder bed, we can actually scale this technology very easily to build large parts. - And in fact, for example, aerospace, they're building full parts. It's not just about repair. It's actually building the entire metal part. - Right, and a big part of that is because they can do those large parts with this technology. One drawback about it though, is that you don't get as high accuracy and precision with this technology. Because we're spraying powder or maybe injecting a wire, we don't have as much control over where that material goes. So we're not going to get sharp corners or very well defined features. - So I should expect they have to do some machining in order to get the final precise shape that I want out of this. - Exactly. - What about supports, support structures? - Right, so if you wanted to do features that have overhangs or any geometry that requires a support you will have to do a lot of planning ahead for that because this technology does not lend itself well to that. With powder bed systems, we automatically have support in that powder. So, we can do overhangs and we can do things that require support. We just have to plan ahead for them. - Okay. Cost and speed? - So actually, the speed of this technology is pretty good. If you don't care about accuracy or precision, you just want to lay down a lot of metal really quickly, you can actually do that. - [Mark] And that could actually work if I'm resolved to machining it to the final shape. - Right, absolutely. And then the cost, it's not extremely expensive because again, we're using a laser and then we're not inverting or operating in a vacuum. - Terrific, so, directed energy deposition. We've got a process that differentiates itself from powder beds because we're actually injecting the material, whether it's powder or wire, into the energy source instead of the other way around. Really, really good for tooling repair or a large part repair. But we're also, especially in aerospace, we're building large parts out of the thing. So the advantage is that I can move fast, lay down that material, right? Disadvantage, I got to be careful about supports, I got to plan ahead, and I have to expect that I'm going to need to do some machining by the time I'm done.