3DMT Partners MIM and 3-D Printing for an Efficient Approach to Medical Device Production

Deland, Fla.-based ARC Group Worldwide, which operates three injection molding facilities (ARC MIM), now has two 3-D printing operations in the United States operating under the name 3D Material Technologies (3DMT) in Florida and Colorado.

Engineering Manager Drew Roberts runs the 3DMT facility in Longmont, Colo. He sat down with ODT to discuss 3-D printing and its role in the medical device industry:

“3DMT sparked out of a larger corporation that is largely focused in metal injection molding (MIM). We have 25 years experience in sintering metal and now we’ve branched off into our own 3-D printing side,” Roberts told ODT. “Because we’re part of this larger organization, we’ve been able to purchase seven metal printers and six plastic printers in the last couple months. The metal printers run between $500,000 and $700,000. It’s a pretty big investment.

“Some of our MIM customers are in medical world. We were working with one company on knee replacement parts, and we do quite a few different medical and surgical applications. A lot of those customers will be some of our first 3-D printing customers because we’re providing prototypes long before our mold is even ready so they can test out the functionality of that part.

“We also 3-D print finished products in low run production. In the very beginning stages of MIM, there’s not much you can do until you have a tool, a mold, and you can be months and almost $50,000 to $100,000 deep before you ever get a chance to try out that part. So 3DMT is producing the early stages of 5-10 parts, maybe 100-1000 parts, and then once they’re ready to go into larger quantities we can roll them over into MIM side and they take it to 10,000-1 million parts a year. If a customer only wants a 1,000 parts, it doesn’t make sense to spend $50,000 on a tool. We could print up 1,000 parts in a couple weeks and lower the cost quite a bit.”

ODT: What materials do you work with at 3DMT?

Roberts: Plastic materials range quite a bit. One of the major ones we work with is called ABS (acrylonitrile butadiene styrene). Every company has its own proprietary name for its blend. Most of them are actually liquid resins. They may not necessarily call is ABS, so they would call it ABS-like. One of the new machines we’re working with does PCs (polycarbonates), ABS, nylon, the whole range. On the metal side, currently in Colorado I run in 17-4 stainless steel. In our Florida operations they’re using cobalt chrome, and we’re unrolling titanium, aluminum, inconel, the whole wide range of metals as well as plastics.

ODT: Are there limits on the types of materials you use?

Roberts: It depends on the project. Right now we’re feeling out what kind of projects are coming in. There are materials we don’t use currently, but we are unrolling according to demand.

For the medical market, there’s been a big push to 17-4 for the medical market. Titanium is an interesting one they really want to unroll. Clean machines that have just touched titanium is something we’re getting into.

The medical industry is very concerned with contamination, so with a machine that has run cobalt chrome for instance, and then switched to titanium, regulatory authorities are concerned with the seal still having a little bit of that cobalt chrome, or some of the different components being contaminated. So one of the things 3DMT is unrolling is that one of the new machines we’re going to be getting down the road is going to be tested, proven and calibrated with titanium and shipped to us with nothing but titanium ever touching it. It’s something we really want to get into—having a strictly titanium, non-contaminated machine.

ODT: What are the size parameters of 3-D printing at 3DMT?

Roberts: Our build tank is 9.8 x 9.8 x 12.8 inches in Colorado. In Florida, the printers are inch shorter in height. The way direct metal laser sintering (DMLS) works is you have a metal build platform, and you have a scraper or roller that lays down powder on top of that platform. Every time the platform drops, the roller drops more powder on top of it. The the laser fuses just where you want. So if you were building a ring, it would just be small circles as it goes, and layer after layer you can change the geometry and change what you’re sintering, so you can make endless geometries. The downfall is that you’re introducing heat, so if you were to make a part that was the full 9.8 x 9.8 inches, and built it up quite a few inches, there’s a lot of heat going on there. You have some trouble with issues such as warping. So what we’d need to do is go through the design and maybe add some lattice structure or shell it out so we can get away from a full solid block that may have differential shrinkage, so we can build quite a large project, but it wouldn’t be completely solid. It wouldn’t necessarily be limited to a couple inches here and there, but we want to make sure the heat can dissipate and the part can build correctly. We do have the capability to build quite large objects.

ODT: Patents on 3-D printing processes are in the process of expiring. How will this expiring affect the industry?

Roberts: We’re not actually getting into the production of the printers, so we’re not involved in the patent wars. However, we’ve brought in three of the major competing 3-D printers on the metal side—EOS, Phoenix Systems [bought by 3D Systems last year], and Concept Laser—and all three of them are battling for patents now. We’re on the positive side of things because they’re all fighting each other to improve on technologies and improve on patents, so now they’re unrolling these highly capable machines. Since we’re not biased towards one company or the other, we’re able to roll in all these different technologies that come out of this.

It’s going to be very interesting in the next couple of years. A stereolithography (SLA) patent just ran out this year [patents around SLA have been expiring over the past decade]; The selective laser sintering patent will expire next year, and the DMLS behind that, but Once all these patents run out [such as patents around stereolithography (SLA), selective laser sintering (SLS), and DMLS) it’s going to be an arms race to see who can unleash the better, bigger, stronger machine.

ODT: Where do you see 3-D printing going in the future?

Roberts: That’s another major consideration we’ve thought about, being that we’re such a big MIM facility, we’re looking at the trends. Maybe five, 10, or 20 years down the road, MIM is going to be seriously threatened by 3-D printing. So getting into it at this point where everything’s really opening up and getting more capable, we’re only going to be establishing a positive position on the market. So I think in the next maybe 10 years, 3-D printing is going to take over some of those upwards of 10,000-part production runs, but it will not replace the MIM side until we can get prices down, build tanks up, and take materials to another level.

My father owned a plastic injection molding company and back in the late 1990s, when I was about 13 or 14 years old, he had an SLS machine. So I’ve seen this technology since I was a teenager, and it definitely excited me then. Being able to now be involved in this type of company and this type of technology, it’s extremely motivating to push what I can do.

ODT: What are some of the limitations of MIM?

Roberts: MIM is limited by the shape you can actually open in the tool. There are two large pieces of steel that have to close together; you shoot the mold; and then they have to come apart. You can’t get away with overhanging angles or undercuts, so the tools get extremely complex. You’ll have moving slides along each of those steel plates, and now you’re upwards of $100,000, and there are some geometries you just couldn’t do for MIM.

I actually used to work as a machinist, so I definitely know the limitations and capabilities of having to use a physical end mill. You have to use a straight piece of steel to cut away your material. So you’re definitely limited in what they call that traditional subtractive manufacturing. But in additive manufacturing with the DMLS or SLS process, we add layer by layer, so undercuts don’t mean anything as long as their angles don’t hit 45 degrees or we can support it. So now we can do geometries with endless limitations of cavities, lattice structures, internal features that you could never get in the injection molding side. You can do inner lined cooling channels that flow in a circular fashion right around the part so you get optimized cooling channels and optimized process time. And there are some case studies where they’re dropping 50 percent of their molding time just by printing different cavities with inner line cooling channels that make it 10 times more efficient, so you’re able to pump out a lot more product. This gives the ability to do away with subtractive manufacturing where your actually starting with more material and taking it away, we’re starting with no material and adding only where we need. So there are endless limitations on the ability of these machines.

ODT: What are some of the limitations of 3-D printing?

Roberts: The major limitations to metal 3d printing, and this goes across the board with all technologies, is supports. If you have a 45-degree angle, you can get away with building that angle. But once you go under that threshold, you have to now support the angle or support that piece. The way you support it is with the metal itself. You sinter thin, lattice-type structures and it builds up to that area so it won’t fall back into the powder. The Phoenix Systems we have in Florida have an easier time with this because they pack their bed down so they’re able to get away with greater angles, so they can un-support themselves as they grow. Another limitation is surface finish. DMLS is a little bit rough. The process inherits itself to have a little bit of a grainy surface finish, but the material is finishable, polishable, and chromable so you can actually design into the part maybe a quarter percent shrinkage in the larger area so you can actually polish it down to a mirror-like finish. The limitations are minor.