Are the Seven Families Still Valid for Describing 3D Printing Processes? AM Radio #21B

A set of widely accepted categories for classifying 3D printing processes includes binder jetting, directed energy deposition, material extrusion, material jetting, powder bed fusion, sheet lamination and vat polymerization. In this segment from the latest episode of our AM Radio podcast, Stephanie Hendrixson and I examine these categories. Do they still make sense? In the more than 10 years since these categories were imagined, AM processes have advanced, and new processes have appeared that fit these categories awkwardly. In the course of this conversation, we ask for the listener’s help: What do you think some better categories might be?

         

  

Transcript

Peter Zelinski 
Additive manufacturing includes a lot of processes, so many of them I’m not sure Stephanie and I can keep track of them all. We’re going to try to stump each other on this episode of AM Radio.

Stephanie Hendrixson 

The AM Radio podcast is brought to you by the Additive Manufacturing Conference at IMTS, the leading industry event focused on 3D printing for production. Learn more at AdditiveConference.com. Welcome to AM Radio. I’m Stephanie Hendrixson. I’m here in the studio today with Pete Zelinski. Hi, Pete.

Peter Zelinski 

Hi, Stephanie.

Stephanie Hendrixson 

So, the tagline for this podcast is the show where we tune in to what’s really going on in additive manufacturing. And that’s kind of a big goal that we have. And it sort of extends beyond this podcast. It’s a big goal because this space is just constantly in flux. There are always these new developments coming out in the printing hardware, in the materials, in the software. There are lots of new players coming into the space, lots of different companies coming in as suppliers, lots of new companies coming in as adopters or inventors and creator type people that are starting businesses by virtue of 3D printing. And it’s kind of a lot to keep track of. But it’s also challenging because additive manufacturing, we talk about all the time how it contains more than just 3D printing, like you have to think about design, you have to think about postprocessing, you have to think about different ways that your business works. But just that 3D printing step actually contains a lot. So when we say 3D printing, it’s not the same as saying turning or injection molding. It’s not just one way of making parts. It can be any number of different ways of building something in layers. And some of those methods are really weird, even the common ones that we see all the time start to look weird when you really take a close look at them. Would you agree?

Peter Zelinski 

I would. I think I hear where you’re going with this, that additive manufacturing is a huge category. But just the term 3D printing by itself describes a whole lot, a broader term than than any other manufacturing process category you could name because, like, what material is not somehow touched by 3D printing at this point? It covers the range of metals, the range of polymers, as well as ceramics and other materials. But in addition to that, it complements and or challenges almost every other manufacturing operation: casting, machining, molding assembly. And the commonality, as you say, is building discrete parts in layers, building discrete parts, according to an entirely digital process. That is a common element shared by a whole lot of, kind of, as you said, at the end there, like weird processes.

Stephanie Hendrixson 

Yeah, and, like, it’s not uncommon for us to go to a trade show and come back having seen something that we’ve never seen before, like some way of doing that layering of building those discrete parts.

Peter Zelinski 

It is my favorite thing about getting to cover additive manufacturing, you’re getting to be a witness to what’s happening in manufacturing right now. The technology is still changing, and it is changing fast. Every couple of years or so, it’s still true that the hand is dealt new. There’s, there’s some big new process or element or way to go about additive that has joined the mix of what’s possible.

Stephanie Hendrixson 

So, what I want to do in the first half of the show today is just, let’s test each other a little bit, because there have been so many new processes introduced in the last few years. And there are some that we just don’t encounter that much. And so, I asked both of us to bring a list of three sort of weird, unusual processes. And we’re going to challenge each other to see if we can explain what they are and how they work. Are you game for this?

Peter Zelinski 

I’m game for this. Yeah, there are so many processes that even, it’s sort of our job to keep track of it all, and it’s, there’s too much of it to keep track of.

Stephanie Hendrixson 

Yeah, so this will be kind of a friendly competition, but also, I’m hoping we’ll maybe get to a better understanding of some of the processes that are out there. All right. So, here’s my first one, and I’m gonna go easy on you. This is one that you definitely know because it’s one that we encounter a lot. But it’s one of those cases where if you really stop and think about how it works, like, it is sort of a strange and unusual process. Pete, can you explain Multi Jet Fusion?

Peter Zelinski 

I’m, I believe I can, I’m pretty sure I can, but it’s a good starting point. It’s a good starting point for this, this exercise because it is a weird process. It has become a super mainstream process like how many, how many episodes of The Cool Parts Show have involved parts made of Multi Jet Fusion?

Stephanie Hendrixson 

Many.

Peter Zelinski 

Yeah. So, this is a very widely accepted method of of production, polymer additive manufacturing, but it is also a process option that arrived after the definitions of what the additive processes are had started to take hold and this one arguably doesn’t, like, fit the definitions all that well for as widely used as it is. So, how does Multi Jet Fusion work? Multi Jet Fusion — the, the polymer additive process offered by HP — so it’s a powder bed process, polymer in a powder form. There is a binding agent that is applied using ink jets. Basically, HP, the 2D printer maker, is using precision ink jetting technology for 3D printing. So, within this bed of powder polymer, binding agent is jetted in just the right shape, layer by layer by layer, to cause that that polymer to adhere together as part of the same cycle and the same sort of stroke of the machine. That layer is heated, it causes the layer of polymer to fuse together and the part is built up that way, gluing and fusing, gluing and fusing, gluing and fusing. And then at the end of it, you get usually not just one part. Usually, a volume of parts is sort of nested three dimensionally within the whole, the whole cubic shaped bed of the, of the Multi Jet Fusion machine. But at the end of it, you sort of get, like, this brick of powder that you get the parts out of it, take the loose powder away, get the parts out — oh, it has to cool first, it has to cool first — but then you sort of you, you vacuum the powder away, you remove the powder, and then you pull finished parts out of it.

Stephanie Hendrixson 

So, I’m going to be just a little bit nitpicky. And this is a detail that I had to remind myself of is that the agent that’s being dropped is not literally like a glue, like we would think of, they call it a fusing agent. There’s something, like, sort of chemically happening. The fusing agent kind of causes that powder that’s affected to absorb heat more readily. And so, when that fusing step happens, it’s like the powder that has been sort of pre-treated in that way is what’s going to fuse together.

Peter Zelinski 

You’re totally right. Now that you say that, you’re totally right. Yes, correction noted.

Stephanie Hendrixson 

The other weird thing about this process that I only just recently learned is that there’s another agent being jetted at the same time. HP calls it the detailing agent. And so, that’s kind of what you would use around the boundaries of each layer, like around particular features. And actually, when those parts come out of the powder bed after they go through that whole depowdering process, they have sort of that grayish look, but if you were to cut one open, it would be probably black inside because they use a lot of nylon, and that gray that you see on the surface is actually the result of the detailing agents. So, the parts are actually black on the inside, but they, they look gray because of that.

Peter Zelinski 

Got it? Yeah.

Stephanie Hendrixson

All right. What do you have for me?

Peter Zelinski 

Okay, this one also, I think my first one might be easy for you, because I think you’re going to be able to do this one. But 3D printing process, additive process in metal, describe to me the MELD manufacturing 3D printing process.

Stephanie Hendrixson 

Okay, so MELD manufacturing, they use a process, I believe it’s called friction stir welding. And this is a way of 3D printing with metal where you don’t melt the metal, which is sort of strange as as metal 3D printing processes go. And I believe the way that it works is they can take a solid piece of metal, like just, like off the shelf bar stock. And they spin it really fast and sort of press it down against the build plate or against the workpiece. And just like the friction from that is enough to again, not melt, but kind of, like, deform the material and make it stick to itself or make it stick to whatever they’re trying to build onto. And there are some benefits with this, that you’re using a solid piece of metal, you’re not having to deal with powder. If it’s not a reactive metal, like, you probably don’t need any sort of atmosphere around it. And I think they were even experimenting with using some other types of feedstocks like machining chips. Like, you can easily recycle other materials into this process.

Peter Zelinski 

Yeah, I don’t think I have a correction to that. I think, I think that the way you phrased it is basically right, I think. So the technical term would be the yield strength of the metal, the combination of force and friction allows a solid piece of metal being fed against the part to exceed its yield strength and therefore plasticize. And that plasticization is enough to apply the material in the absence of any kind of state change.

Stephanie Hendrixson 

Alright, for this next one, I’m going to give you the company name, and also the process name, just because this one again is, like, one of those that I only recently learned about, and it’s a little bit more obscure than certainly, like, Multi Jet Fusion, but the company name is Grid Logic and the process that they’ve developed for 3D printing is called multimaterial powder bed technology. And I’ll give you a hint here, it is not powder bed fusion — it is powder bed technology.

Peter Zelinski 

Yeah, so Grid Logic, their process, it’s like, it’s like they use sand as the support in process to build a metal part. And so layer by layer, both sand and metal are being deposited — boy, yes, this is, this is a really good one. This is a really good example of what you’re saying because we have been to Grid Logic recently. And I’m realizing that you’re, like, catching me unaware, I’m drawing a blank a little bit on the process. Like, I don’t remember having the sand sort of built up as sort of, kind of, like the loose temporary tooling that supports the part. It allows them to accomplish a lot of things, like there’s, there’s some freedom from support structures that happens there. And what I’m drawing a blank on is what technically adheres the metal powder. There’s a sintering step afterwards, it goes to a furnace, but exactly what that agent is, that is within the metal powder, I don’t recall.

Stephanie Hendrixson 

So, to my understanding, there is none. Everything in this process is, is loose. And so, it looks kind of weird, because they’re using, like, the angle of repose on the sand to hold everything in. And so when you watch one of these parts being built, these powdered materials are going into just, like, sort of a metal box, and it builds up and there’s sort of a gap all the way around the build area. And they fill that with sand before they move the box just to hold everything in place. And then that whole thing goes into the sintering furnace, so, so it’s all loose up until that point. And then once you’ve done the sintering, once your parts are solid, you can just lift them out of that sand and the sand can be reused infinitely. So it’s sort of like what we’ve seen, like, with people printing sand tools for casting except that you’re depositing the sand and the metal at the same time. And you’re not gluing them together kind of temporarily.

Peter Zelinski 

Yeah, and there’s no, there’s no binder as you’re describing and there’s no pressure either, it’s, I remember, it’s like when you said angle of repose, it all came back to me because that was the fascinating aspect of the process. As we were there watching it, it’s basically, the sand holds it all together just long enough to get it into the furnace and the sintering step makes it solid.

Stephanie Hendrixson 

Yeah, and this process has a couple of advantages over maybe laser powder bed fusion because you’re not dealing with a laser, so it opens up these opportunities for things like copper and refractory metals, like things that are kind of difficult to do with laser powder bed fusion. And I believe they can also use just kind of standard metal powder off the shelf, like it’s not specially formulated for 3D printing. It’s a little bit more affordable, it’s a little bit more accessible.

Peter Zelinski 

Yeah. My next one is one that, like, I know you’ve encountered, and you have covered it, but it’s also, it is one of the iconic weird 3D printing processes. So, can you explain Fabrisonic’s approach to additive manufacturing?

Stephanie Hendrixson 

Okay, yeah, let me try. So Fabrisonic, they use a process that’s called ultrasonic additive manufacturing. UAM. And I think if you were to look at, like, the literal categories of 3D printing, this is sheet lamination. So they’re taking, like, really thin sheets of metal and vibrating them together. And if I’m remembering this right, the vibration removes a layer, I think it’s an oxide layer on the material and, like, that causes the metal to stick together. And so there is some heat generated in the process, but not a lot. And so you can do things with these parts, like embed sensors, and put motors and electronics and stuff inside of them as long as they can withstand, like, that little bit of heat as the layers are coming together.

Peter Zelinski 

Yeah, the oxide layer is the weird kind of counterintuitive aspect of this process. But it, like materials want to join together with like materials. It’s just that in our everyday macro world, they’re covered with a layer of stuff that prevents that from happening. And ultrasonic welding is a well-established process. And this is basically just using that ultrasonic welding. It gets the barrier out of the way just long enough for the, the material to glom together.

Stephanie Hendrixson 

That’s the technical term. Yeah. All right, then the next one that I have for you. Also, this is a process that I only became aware of in the last six months to a year. It’s from a company called MASSIVit. I believe they are based in Israel, and the name of their process is Gel Dispensing Printing.

Peter Zelinski 

Okay. I have not spent enough time with MASSIVit, but Gel Dispensing Printing. So I’m, I’m imagining a gel being dispensed. So, like, I’m gonna say it’s an extrusion process and the gel perhaps is a carrier for a different material, and so I’m going to guess that it’s, like, it’s an, it’s an FDM-ish process that temporarily uses a gel to, to distribute the material it’s carrying, and then in a later heating process, the gel goes away and the powder within it fuses together.

Stephanie Hendrixson 

So, it is an extrusion process. MASSIVit, they make really big printers. So, like, maybe not BAAM size, but, like, medium to large size printers, and they are extruding a gel. But the gel is not a carrier for a powder or anything else like you’re imagining, but it is a thermoset polymer. So most of the time when we see extrusion printers, they are printing with thermoplastics, which is like, you know, the solid filament or the, the solid pellets. And just by heating and cooling, there’s, they’re sticking together and they’re, they’re fusing with the thermoset that they are using, it comes out as, yeah, a gel-like liquid resin. And then the printhead has a UV light that cures the material as it’s being deposited.

Peter Zelinski 

And so the, the part is done at the end of the build.

Stephanie Hendrixson 

Yeah, so the part can be done at the end of the build. They’ve got a couple of different variations on this. They do offer water-soluble support materials, like you can do things like build really complicated geometries that need supports, and then wash it away afterwards. They use this to build composite tooling and jigs and other things like that. But yeah, because you can cure that material, right as it’s being put down, you can pull completed prints right out of the printer.

Peter Zelinski 

All right, cool. Next opportunity I have next show we’re at, I gotta check out MASSIVit. Alright, here’s, I think, our last one. So Stephanie, just like you did, I’ll give you the company name and the name of the process, the company is Tritone, and the process is Moldjet.

Stephanie Hendrixson 

So, I’m going to be so honest here, I have not heard of either of these things. If I was going to take a guess, Tritone makes me think of two different things like the tri makes me imagine, like, sort of like, one of those delta style printers that has the three points and, and the head sort of moves between them. But I don’t feel like that’s where this is going. But Tritone makes me feel like there are maybe multiple materials involved. So I think my best guess would be that this is somehow a way of, like, printing a mold and then depositing material inside it at the same time or something like that.

Peter Zelinski 

Yeah, that’s right. Yeah, that’s right, as far as it goes. So Moldjet, it is, well it is jetting to build a mold. There is a polymer mold that is built up in layers with material deposited into that mold as it’s being built, metal that is applied as kind of a paste, and it hardens within the mold as that mold is being built and to see the Tritone machine that does this process, it’s like a carousel. And there’s different stations around the carousel. So, there’s apply the mold, apply the paste, heat it and then, at the end of this whole process, when you pull the mold with the part out, the mold dissolves during the heating process. There is sintering and the, the completed metal part results from that.

Stephanie Hendrixson 

Wow. So okay, the audience can’t see my face, but I am so surprised I was anywhere close on that one. The thing I wasn’t expecting was for this to be a metal process, but good branding, like good naming because I sort of got it even without knowing anything about it.

Peter Zelinski

Yeah, yeah, Moldjet gets you there.

Stephanie Hendrixson

Well, so Pete, thanks for playing. This is kind of a silly exercise. But I learned something. I hope you did too.

Peter Zelinski 

I absolutely did. Additive includes a lot of processes, including maybe some weird ones. But like this last example, Tritone and you said, “Oh, you didn’t even know it was metal.” Like, I guess that reminds me of a conversation I had with Ben Arnold of Tritone. He’s, like, their, their business development guy. And so the Tritone process, the Moldjet process, it sort of falls in the same category as binder jet, say, as a way of making metal parts. And, like, this conversation we’re having, even the premise of the conversation we’re having like sort of weird processes, strange processes. Why are there, they weird? It’s because, like, there’s this set of categories that sort of frame the way we think about what the additive processes are, but the processes keep changing. And is there an extent to which those categories are being challenged now and maybe the categorization was a little premature?

Stephanie Hendrixson 

I think we should talk about that after the break. The AM Radio podcast is brought to you by the Additive Manufacturing Conference at IMTS. The leading industry event focused on 3D printing for production. Co-located with North America’s largest trade show dedicated to manufacturing equipment, the AMC takes place September 14 and 15 at Chicago’s McCormick Place. The Conference takes a practical applications-based look at the machines materials and methodologies being used to 3D print functional components, including both tooling and US production parts. The event is designed for owners, executives and engineers as well as OEMs involved in durable goods manufacturing. Join the Additive Manufacturing team in Chicago for a day and a half of conference sessions and networking opportunities. Find more information and register at AdditiveConference.com.

Peter Zelinski 

Hey, welcome back. So, before the break, we were talking about some unusual 3D printing processes, and Stephanie and I were sort of shaming one another with our lack of fluency in, in different obscure additive processes, but it touches on a point that I’ve thought about from time to time, which is, we have a set of widely accepted industry categorizations for different 3D printing processes. But as 3D printing technology continues to advance and new processes are developed, I’m feeling those categories straining, and they seem less and less useful for containing and defining all of the options that are out there. And maybe we could explore and talk about that a little bit.

Stephanie Hendrixson 

Yeah, I mean, I think some of the processes that we discussed in the first half of the show, they come across as strange because they’re sort of like straddling a couple of these categories. But maybe just as, as a baseline here, the things that we’re talking about, this is the Seven Families of Additive Manufacturing. It was developed by an ASTM committee, the Committee on Additive Manufacturing Technologies, and they published it in 2010. So, it is 12 years old at this point. But basically, what they’ve done is created seven process classifications for additive manufacturing. And those processes are binder jetting, directed energy deposition, material extrusion, material jetting, powder bed fusion, sheet lamination and VAT photopolymerization. And for each of these, there’s sort of a description provided. There’s some, some strengths listed, some typical materials. But as we’ve been talking about, these seven categories don’t quite stand up to every potential 3D printing process we might throw at them.

Peter Zelinski 

Right. And for a categorization system, sure, there can be exceptions, and there can be a miscellaneous bucket. But if your exceptions and your miscellany gets to be too large, then you have to question whether the categorization is still working. And we maybe saw hints of that in the processes we were talking about in the first half of the show. Like, let’s go back to them for a moment and see if we can get them to land in categories. The one you started with, for example, Multi Jet Fusion — you asked me to describe that. So sure, that is a powder bed fusion process. And I think most people would place it as, as powder bed fusion, but the thing of it is, so that process appeared and was adopted after this categorization system was written. And when almost anybody who’s in the additive manufacturing space thinks about powder bed fusion, like they’re not thinking about Multi Jet Fusion, like it’s not what comes to mind right away, in part, because, like, this is a little bit of a stretch, maybe, but you could make the argument that binder jetting is also a category that Multi Jet Fusion could land in. So it’s not a clean fit with either category. And so that sort of, like, speaks to a challenge of this system.

Stephanie Hendrixson 

Yeah, and the other weirdness, like, just sticking with Multi Jet Fusion and putting it maybe in the powder bed fusion category right now, that category is also strange because it includes both polymers and metals. So, is Multi Jet Fusion the same as electron beam melting or the same as selective laser melting, both of which are metal processes that use either an electron beam or a laser to sinter point by point or melt, melt the powder point by point?

Peter Zelinski 

Right. I think we’re going to circle back to that. There’s a lot going on, potentially, in a powder bed machine. And so just saying powder bed, is that really a descriptive enough category to draw all these processes together?

Stephanie Hendrixson 

But it’s limiting at the same time because as we talked about with Grid Logic, they call their process a powder bed technology, but it’s not powder bed fusion because the fusion happens later in the sintering oven.

Peter Zelinski 

Right? Okay, so what is Grid Logic? Like, how would you, how would you place it in these categories?

Stephanie Hendrixson 

Like, it’s more like binder jetting, but there is no binder to jet, so it’s, it’s binder-less jetting.

Peter Zelinski 

Okay, so yeah, like, Grid Logic doesn’t land well within, within these categories. MELD’s process, friction stir welding, like, like, where does that go? I could get semantic about it. Like, is it material extrusion if you’ve got bar stock that’s being fed down onto the workpiece? Like, that’s, that’s not really extrusion. And is it directed energy deposition? Well, I mean, there’s, there is energy involved in applying force and friction to the workpiece to the material, but that’s really not the kind of directed energy we’re thinking of when we think of that process. So it’s, like, you’re looking for the best wording to fit even though whichever category it goes in, it doesnt, like, fit the other things in that category all that well.

Stephanie Hendrixson 

Yeah. So for whatever reason, like directed energy deposition, we expect to, like, see a spark visibly, kind of see the energy happening. And with MELD, you don’t really get that visual — like you see the layers building up, but it doesn’t look the same as other DED processes,, and there are lots of other things that, sort of, I guess you would have to throw in that category that maybe don’t belong there either. I’m thinking of, like, some of the cold spray processes like Speed 3D, where the metal is building up, but the energy is just, like, really fast air and it’s not causing a spark. It’s not, ‘Oh cool, it’s melting’ in the same way that some of these other processes are.

Peter Zelinski 

Yeah, yeah, the thing you said at the beginning there, how you like, you expect a spark. And so that sort of gets at these seven family categories are semantic word sets. But then there’s this other thing, which is our intuitive sense of what processes kind of go together. And there’s this growing mismatch between the intuitive clumpings that we talk about, and these kinds of long-standing, now, categories.

Stephanie Hendrixson 

And so, are the categories still useful?

Peter Zelinski 

They are because as we sort of got to in the, in the first half of the show, the range of process possibilities continues to expand, and new processes are coming. And when we’re in motion in this space, we have to explain them to one another, and these well-established families at least offer a reference point for defining processes and comparing them to one another. So like, like VAT polymerization is getting stretched a bit because there are a couple or a few different options now for what looks like VAT polymerization, except there’s no VAT involved, or at least the part is not growing in a vat, but we can at least say like, “Well, yeah, it’s VAT polymerization, except without the VAT.” Like, there’s a way to talk about it, thanks to these terms.

Stephanie Hendrixson 

Yeah. So, like, MASSIVit falls into that category. And some of the other processes that we’ve seen recently, like BCN3D, fall into that VAT-less photopolymerization sort of thing. And so maybe there’s a way to sort of like broaden the categories like, could we just call it photopolymerization and drop the VAT conception?

Peter Zelinski 

Yeah. So that’s, that’s an easier one. Like, you asked if the categories are still useful, I guess one of the challenges of the established categories, and maybe one thing that’s a little unfair about them is, and this was sort of Ben Arnold’s point with Tritone. And, and again, he’s, he wants to advance Tritone’s technology. He’s selling Tritone machines, so but his point is kind of like, why should this process be weird, but binder jet feels more mainstream? And part of that is just because, yeah, binder jet’s been around longer. But also, theres the fact that binder jet is one of these terms in the seven families, that is sort of an arbitrary choice that may or may not be representative of how these technologies will ultimately, when everything is mature, be accepted and be thought of.

Stephanie Hendrixson 

So, longevity played a role here because not everything that we’re talking about today existed in 2010. And it makes sense that some of the categories that were established here are getting stretched now with new information and new, new developments.

Peter Zelinski 

So yeah, longevity is for real, and processes that have already been proven and been accepted, certainly deserve to be understood that way and have their place as references for what comes next. But is it useful to lock in these processes established only fairly recently as sort of the structural defining points for the ways we organize additive going forward? Like you mentioned, powder bed fusion, and it both includes a whole lot that maybe doesn’t go together and is also limiting in terms of what it implies? Or what it leaves out? Are there different clumps we could find as a thought exercise that might describe alternative ways to group these technologies?

Stephanie Hendrixson 

Yeah, I mean, I think there are. I think they would have to be maybe, again, maybe a little bit broader than what is presented here. Or maybe you need more categories, and they need to get narrower. So, like, does Grid Logic become part of a powder bed category instead of powder bed fusion? Or do you create subcategories where powder bed fusion is for things that use lasers and electron beams and there are other ways of using powder that become their own category maybe?

Peter Zelinski 

That’s a good point. Take the fusion out of it, and let’s make the powder bed the commonality. So, I wonder if rather than the powder bed being the commonality, are there other commonalities we could find? What if we said laser base processes, and that would bring in laser powder bed fusion, but also deposition processes that use lasers. And if you clumped it that way that would leave out, for example, electron beam processes, which are a different form of powder bed fusion that addresses different kinds of parts. The categories now have powder bed as the commonality. We could have the type of energy source as the commonality and segregate the processes that way.

Stephanie Hendrixson

Sure.

Peter Zelinski

Another clump concept: processes that needs sintering like metal part processes that either need an oven or don’t need an oven at the end of the build.

Stephanie Hendrixson 

Well, I would, I would expand that because you’d have to put ceramics in there too. There are a lot of ceramic printing processes where you’re using a slurry or something, and the part is not going to be done coming off the printer. It also needs that sintering step.

Peter Zelinski 

Yeah. So noted. Noted. So processes in need of sintering. Like that’s, that’s binder jet. Absolutely. It’s the Tritone MoldJet process we mentioned, but it’s also FDM processes, FFF processes that deliver metal powder and produce a metal part that also needs sintering to complete it. So you’re thinking things like rip Vidya, or the, the Markforged Metal X process or the way Desktop Metal does its studio system. So they’re process-bound metal deposition — it’s, it’s fused filament fabrication, using polymer to deliver metal powder make the part that then needs to be sintered.

Stephanie Hendrixson 

Yeah, so that’s one of those things that did not exist to my knowledge in 2010. But we’re seeing several different ways of doing metal FFF by extruding a filament of some sort that contains metal powder, and then sintering it after the fact — whether that’s a dedicated system, or I think BASF has a material for this you can use on like an Ultimaker, or other types of desktop printers. And yeah, like, the question of where to put that, and does that belong with the other extrusion processes? If you think about it instead, as these are all things that need sintering, it kind of has a home that it maybe doesn’t have right now.

Peter Zelinski 

Yeah, that’s right. That’s another example. So these, these processes delivering metal with a polymer agent. So yeah, it is fused filament fabrication. And so the specific category it would land in is material extrusion. But the extrusion doesn’t tell the whole story. Yeah. Okay. So here’s one more of these, I've been thinking about solid state versus non solid state processes.

Stephanie Hendrixson 

Okay, so this is a place to put things like MELD and maybe the Fabrisonic ultrasonic additive manufacturing, where the material is not melting. It gets to be in the solid state category, and the processes where there’s, like, a laser or there’s an electron beam, or heat is being applied. Like, that would go into the not solid state category.

Peter Zelinski 

Yeah, 3D printing. Ultimately, this is a materials engineering technology every bit as much as it’s a geometry creation technology. And these categories focus on how the geometry is created. But yeah, that distinction, does the metal need to melt or not? That has, obviously, like, tremendous implications for the material properties and the microstructure coming out of the process.

Stephanie Hendrixson 

Okay, so these are some compelling arguments and some interesting potential categories. I agree with what you said earlier that the categories are useful in that they allow us to kind of talk about these different processes and sort of understand them. Like, if you came to me and started explaining something and said, “Well, it’s kind of like binder jetting,” like I would get that. And I would understand it more quickly because I have that framework already. But I would kind of argue that these categories are sort of artificial in the sense that I don’t think people coming into additive manufacturing, like those manufacturers we write about that are experimenting with 3D printing and pursuing business opportunities through 3D printing, I don’t think they’re thinking about it in these terms, at least in my experience. The stories that we’ve heard, it seems like people approach this more from, like. a material standpoint, or size standpoint, like they have something specific in mind. And they need to find the right material and the right build volume that can do it. And they’re not thinking about it in terms of, ‘Well, I want to buy a directed energy deposition machine, which one should I choose?’ It’s, ‘I need this type of aluminum. And I need to be able to build it this big.’ And that’s what’s going to decide the ultimate technology purchase that they make.

Peter Zelinski 

That’s well said, like I, what I hear you saying is these seven families say that is a way of thinking about this that’s useful for discussion within the additive manufacturing community at large. It’s really not a useful interface for process selection when you’ve really got a job to do or a part to make. You’ve got other decision factors that you’re thinking about. It guides you to a process and that process, like, lands well within the seven families or doesn’t land well within those families. But that’s something you might discover or think about later. And it really is not relevant to how these processes get adopted.

Stephanie Hendrixson 

Things that we think of as weird because we’re familiar with these categories. And we see that the process doesn’t quite fit into the category. Someone who’s going to use that and find good use cases for it, they don’t necessarily, they care what category it fits in. They might discover it later and think, well, okay, this is sort of strange. And maybe not everyone is doing what I’m doing. But if it works, if it does what you need it to do, it sort of doesn’t matter.

Peter Zelinski 

Oh, totally right. But that brings us right back to where we began. Multi Jet Fusion, like, it was weird when it was introduced. And it clearly won adoption, like the weirdness did not stand in the way.

Stephanie Hendrixson

Yeah, yeah, for sure.

Peter Zelinski

Let’s pause this conversation for now. This isn’t a really interesting topic that connects to a lot, and we’d love to hear from you about this. We’d love to hear from listeners. What thoughts do you have about the ways to categorize, organize, define the ever-expanding palette of additive manufacturing processes? You can find us anywhere. Stephanie Hendrixson, Peter Zelinski — you can find us on social media. The Additive Manufacturing Media brand — you can find it on social media. Reach out to us through any of those channels. We’d love to hear your thoughts on this.

Stephanie Hendrixson 

And if you enjoyed this episode of the show, you want to hear more AM Radio, make sure to subscribe. You can find us on iTunes, on Spotify, anywhere that you get your podcasts. Thanks for listening.

AM Radio is recorded with help from Austin Grogan and Seth Cooper. The show is edited by Alex Lytle and me, Stephanie Hendrixson. Our artwork is by Kate Bilberry. AM Radio and Additive Manufacturing Media are products of Gardner Business Media located in the Queen City, Cincinnati, Ohio. I’m Stephanie Hendrixson. Thanks for listening.