"About 35 years from now, every medium-large metal component will be 3D printed,” says Steven Camilleri, the co-founder and CTO of metal 3D printer maker Spee3D. “There still may be foundries using the metal technology we’ve been relying on for the past 12,000 years, but everything from spare parts for mining equipment and combine harvesters to components for military and maritime vehicles will be made by some sort of additive process.”
Camilleri sat down with All3DP to go more in-depth about large-scale metal 3D printing: its vast potential to disrupt forging and casting; the mounting demand for faster, cheaper large metal parts; why his company is taking on large-scale metal 3D printing; and what the new TitanSpee3D machine is capable of.
Last week, Spee3D launched a large version of its metal 3D printer, which uses a technology called cold spray. It was years in the making and, according to Camilleri, addresses a need that “small-scale” metal 3D printing is not able to fill.
The TitanSpee3D 3D printer from Spee3D is essentially the company’s existing technology in a large form with a few changes to the way it operates. For example, to better account for the weight of the large metal parts, it is not the deposition head that’s stationary, but rather the part is stationary and the cold spray nozzle works around it on a robot arm. Most of the new technology in the Titan is in its software and control systems that enable planning and remediating the various stages of the part build as it’s printing.
Not only are the physics and technology requirements of large-scale metal additive manufacturing different than small-scale, such as metal binder jetting or metal laser powder bed fusion, but the materials, processes, workflow, and market are completely unique, according to Camilleri. In this Q&A discussion, he sets out a fascinating perspective on the next size up in metal additive manufacturing.
Why do you say large-scale metal 3D printing is a completely different industry from small-scale?
“It’s very easy to think that large-form metal additive manufacturing is just small additive made larger. But it’s actually a different field entirely, one quite distinct and quite different. The optimals and outputs are different, the problems to solve are different. In fact, the entire market is different once you move from small-scale metal to large-scale metal.
“That small metal part market is developing and there are good use cases and millions of parts have been made. Yet people are still playing and learning about the technology. They’re implementing it cautiously and it’s all slowly emerging. Large scale metal parts, on the other hand, are vastly more expensive and never made by accident. You never make a toy large scale metal part.
“Every time you make a large-scale metal part it has to work the very first time and meet all the requirements.
“Demand for these parts are high from the construction market, such as for spare parts for excavators and in agriculture, for spare parts for combine harvesters. There’s the maritime market where large metal parts are constantly failing due to corrosion, and the defense market, of course, loves big parts for vehicles, as well as the mining, oil & gas market, and energy market. They all need low quantities of large metal parts made to very high specifications.”
Why has scaling up powder bed and wire-based metal 3D printing been a challenge?
“One of the reasons small-scale metal technologies fail on large parts is the weight of the parts, which makes build rate — the rate at which you put down material — critically important.
“Take a look at laser metal powder bed fusion, a very common process in smaller scale printers, for example. It simply doesn’t scale. You can’t just make the printer bigger and have it still continue to work. The powder beds themselves are fraught with random defects that can happen as a result of imperfect spreading of the powder or having the layers weld together imperfectly.
“As parts get bigger, quality becomes much, much more important. The idea of the metal powder bed fusion process being reliable enough to make a large part becomes practically impossible to achieve as you go to large scale.
“It’s actually quite a different philosophy when it comes to large format metal 3D printing. For small metal parts, you design it, and press a button, and make the part. But with large scale, you have to think of it more like constructing a building. You’ve got to have a team of people building in stages, and looking at the quality as they go. You’ve got to identify quality issues, then stop, remediate, and continue. So a very large metal part might still take a month to print. Laser powder bed fusion doesn’t enable this. You have one shot when you hit print and every perimeter has to be perfect and perfectly executed within the machine over the course of days.
“So the analogy would be telling a team of builders, you’ve got to build this 10-story skyscraper and nothing is allowed to go wrong. But that’s not efficient. What you want to do is live with affordable levels of quality, and then build in stages. Large metal part building is difficult by any process, even casting.
“I was recently at a company called Sheffield Forgemasters in the UK that was casting with the prow of a new American icebreaker with molten steel. It was a 270-ton part and there was months of effort setting up the mold cavity for that part. I saw the giant crucibles of 90 tons each of molten steel and felt the danger that was involved in doing that work. Then after pouring, it takes months for the part to even solidify. So if you’re in the defense industry, or mining or construction, you may have a two-year lead time to get your project scheduled at a large-scale metal fabricator and then hope that the quality is fine.”
What are the advantages of cold spray vs. other metal 3D printing technologies when it comes to large-scale?
“Cold spray is definitely an emerging form of additive manufacturing, but it’s got big advantages. For example, we can make high quality metal parts without melting the feedstock. This is important when you go back to what we talked about speed. It takes time, when you’re building a part layer wise with wire arc additive manufacturing, for example, to change metal wire from a solid to a liquid. Then you can apply that layer and then wait for that layer to cool down a bit before you can apply the next layer. There are few ways to speed up this process.
“With cold spray, there’s no speed limit. We shoot the material in a solid state into the part and we build it up that way. And as a result, we’re really not constrained at all on build rate, it comes down to how much energy we can throw into the process. The resolution is also much finer than WAAM and the parts can be used naturally without any machining.
“Because we’re not heating the material, we don’t have a problem with parts changing volume and changing shape as it changes temperature, such as with powder bed technologies. When you’re making very large parts with a powder bed over a long period of time where temperatures could vary by 200 degrees, it’s actually quite difficult to end up with the right shape. And they wind up with this problem called residual stress, where the part is trying to fly apart the moment you start cutting into it.
“Another advantage of cold spray technology is the cost of materials. We don’t need especially fancy powders. We can use powders that are typically 10% of the cost of a powder bed fusion powder.”
Who will purchase large 3D printed parts and printers?
“Ideally, the people who are making these large parts now, will be the ones most interested in acquiring this technology and producing parts with it. The people most familiar with the older processes are the perfect people to be adopting this new technology. However, when we say that, we’re usually referring to foundries. These companies understand very intrinsically what the parts need to do, how they should be quality controlled and tested, and how to ship them. They have the skills and the workforce to handle these large parts. Yet, foundries have become an offshored commodity industry with little appetite for innovation.
“Instead, we’ll see print bureaus emerging. Right now, there are only a couple that specialize in large part additive manufacturing, but I suspect that’s going to be a growth industry because the demand is there, and people need the parts.
“Most people who talk to us want parts, but we’re not set up to make these giant parts, do quality control, and ship them all around the world; we’re a technology company. So the beta program that we’re doing now is aimed at testing the market, learning who the players are that are interested in this technology, and what kind of problems need to be solved to smooth the path.
“We’re responding to an enormous amount of demand from a range of different industries because people are having trouble with casting. They want more detail, more sophisticated materials, shorter lead times, better quality, and lower costs, which casting really can’t deliver.
“The foundry of the future might have some good casting folks and some digital support for them. It would have equipment like ours, but also wire arc AM, other technologies and all the machining, heat treatment, validation, testing, and metrology required. And then, at that point, that’s quite an interesting business that can provide parts to a wide range of market verticals.”
Source: www.all3dp.com