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As displayed at the ExOne HQ
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ExOne 3D printer
Rise in demand for 3D printing machines has boosted ExOne's Q4 figures.
Binder jetting champion of the 3D printing sector and leader in metal additive manufacturing solutions ExOne was the obvious choice for a feature on what drives new material development in this increasingly crucial arena.
TCT Magazine spoke to Chief Technology Officer of the NASDAQ-listed company Rick Lucas, an expert in next-generation material development and member of America Makes, about the drivers behind new materials and instances where they have been put to excellent use, saving customers time and money without compromising on quality.
"When it comes to case studies," Lucas said, "stainless steel infiltrated with bronze is the best candidate. We print a stainless steel and what you end up with about 60 per cent powder packing in the green state, and what we do is centre that with the metal and infiltrate with a bronze, then you get a near-full density part that is durable."
Lucas went on to explain matrix materials, where the material is composed of at least two parts - one being metal. "This means the skeleton is made up of one material and we incorporate a lower melting metal into it to fill up the porosity. Full density materials present us with the most opportunities, so single alloy or alloys that are familiar to industry, but getting those alloys to full density from a nickel alloy like Inconel 625 is something we've been working on.
"Our goal is to print a part at full density. Customers want full density products and what's driving that is the development of materials people are familiar with."
"Leading the industry"
ExOne's extensive research and development looks into both new materials and more established compounds.
"On the R&D Side we have been working on new materials that can form full density parts. Historically the major materials we've made are matrix materials, like 430 stainless steel infiltrated with bronze. Our customers are pushing us towards full density alloys people are accustomed to using in specific applications," Lucas said.
"ExOne is leading the industry. When it comes to 3D printing binder jetting techniques, which is essentially gluing powders together with a binder, it's really powder metallurgy. Instead of compacting it, we’re binding it and so in terms of that particular technology, ExOne is the world leader by far. We're really the only company that does binder jetting that I'm aware of, other than universities and other experimental folks."
Lucas believes this 3D printing technique is truly better than other methods of fusing metal powders and indeed additive manufacturing in general. He stated - while reiterating that his expertise is with tech, not marketing - that binder jetting offers the best total value to the customer across the widest range of industries with the broadest range of materials.
"There's processes out there like powder injection moulding where they compact these powders with a binder and have a separate process to get the product to full density. What we're saying is instead of sintering the powder as we print it, let's just use a binder and glue it together really fast in really large pieces, so in terms of speed and size, this technique is the best technology for making large pieces within this timeframe."
ExOne's 420 stainless steel infiltrated with bronze has been put to numerous uses. Lucas raised the prosthetic hand case study as a good example of where 3D printing has made the same product more quickly and cheaply than using traditional methods.
Cost and speed
One of the main reasons the client approached ExOne was cost. They needed to produce these components faster and cheaper than conventional subtractive machining methods like casting, or something faster and cheaper than that. They were paying $250-$1,500 "depending on the complexity" and on average, it would take a couple of months to get the part.
Lucas said: "We actually printed this in the 420 stainless infiltrated with bronze and the cost to them was $25-$100, so basically ten-times savings and of course we were able to produce these and ship them off in two-to-three weeks.
"The speed at which you can make parts is obviously a major advantage to 3D printing technology."
Another example Lucas used was mud pump rotors. In the case study he gave, the customer was looking for a manufacturing technology that could offer the necessary precision, along with faster production times and cost savings.
"These parts are used for down hole drilling equipment and they were paying anything from $400-$500 per unit. They were made in China with long lead times and they did have significant wear and basically they wore out really quickly. So, we began printing a matrix material that can work very effectively in erosion-type applications, so we used a stainless steel bronze matrix and charged then $75-$100 per unit. So again, about four or five-times savings over what they were paying originally and we were able to ship them in around 15-20 days getting three or four times the wear resistance."
Lucas explained that being able to offer customers these 3D printing solutions makes it a very easy decision for the client, particularly with matrix materials that have certain properties making the material cheaper and quick to print, as well as offering excellent performance in certain environments.
"Our goal as a company with the binder jetting technology is to increase the number of materials available to out customers, particularly with materials they are familiar with. So in terms of different metals, stainless steels 316 and 174, Inconel 625 and 718, titanium, CP titanium and there's a number of tool steels, M2, E2, E13 - these are all things that would be familiar to people making parts. We provide those materials at full density and configurations they want so in terms of parts that are generally complex or need fast lead times, this technology is very well suited." Lucas stated.
"There's a number of techniques out there of powder metallurgy," he continued. "In terms of post-processing and getting parts to full density, what we do is instead of compacting that initial preform, we actually print it.
"What's nice about this is a lot of the knowledge base that already exists out there in terms of processing powder materials is well understood and so for us obviously we've been working on different binders and printers that can print other materials and this is actually the easy part for us. It's a case of matching our printing technology and techniques with conventional powder metallurgy and pulling those two together to create a much better solution."
"You are no longer limited"
Lucas explained that this technology is ideal for numerous industries but particularly those where speed is of great importance. Additionally, the usual suspects of aerospace, medical, oil and gas, and of course industrial are sectors ExOne's clients work within, as well as mining and government initiatives which typically look for "fast turnaround and quick delivery".
It can be used in any industry," he said. "Really in terms of what 3D printing does for you, any complex shape you can draw in digital space, you are no longer limited when you think 'how do I make this'?"
Lucas continued: "Look at some of the laser techniques like EBM and there's been a lot of materials being introduced there. Well, we’ve been working on - I don't know the exact number - but it's greater than 15 alloys and materials for binder jetting and it really isn't limited. That's the beautiful thing about it. And it's not just metals, it's ceramics and other materials a laser would struggle with. On the metals side, we're just using conventional metallurgy to densify those materials - it's really a technology that doesn't limit us in any way.
"We have high expectations this year in terms of a large number of materials to be released to the market. Publically we've stated we wish to release a new class of materials every six months, but obviously we're going to try and do even better than that."
ExOne is nine years old and in that time has gathered expertise and experience by the armful, using this group knowledge to problem solve and bring about new advancements in material developments and what its machines are capable of doing.
"We use that knowledge to speed up that part of the process," Lucas said.
"We really believe if you’re making large parts inexpensively, this is the way to go. The other technologies, even though you are getting full density parts, there's so much residual stresses in those materials that they still have to be put through thermal treatment to get the densities they need, so the question is why even do that? Why melt the powder if you're going to use these post-processes anyway? All you're doing is adding cost.
"I really think if you look in terms of total value to the customer, the speed and size of making parts and the material options that you have with this technology, if you're looking for one technology that applies across the largest number of industries it's going to be binder jetting."