Additive Manufacturing

In 1996, doctors in Wilford Hall, Texas, looked at a set of x-rays, their hopes sinking. What they saw was an image of a set of conjoined twins. The x-ray showed that the upper bone of the leg that the little girl shared was simply not big enough for both of them. The parents would now have to make an impossible decision. Which of their daughters would be able to walk? and which would not. But the doctors weren't ready to give up, yet. They had one last idea.

It was a long shot, but they were willing to try anything if it meant sparing the parents an impossible choice. They turned to an unlikely new technology for a solution. 3D printing. otherwise known as additive manufacturing. If you've seen a 3D printer working, there are many different kinds. They will generally build up a 3D object through many repetitions of a lower dimensional unit process. Like, for example, we're squeezing molten plastic through a nozzle.

And so you're really only depositing one point in the object at a given time. This new technology provided answers that the x-ray could not. The physicians were able to 3D print a model of the leg bone that the twins shared. This artificial replica made their analysis of the bone much easier and more accurate. In the end, they realized that the bone was big enough for both of them.

Instead of making a choice between the two girls, the doctors were able to separate them successfully. Both girls were able to walk. Asking what if changed the course of two lives that day. Looking at the problem from a different angle, literally, allowed the doctors to solve a problem that appeared unsolvable. More than 20 years later, researchers in additive manufacturing are still asking that question.

And they are still finding surprising answers. Welcome to the Big Ideas Lab, your weekly exploration inside Lawrence Livermore National Laboratory. Hear untold stories, meet boundary-pushing pioneers, and get unparalleled access inside the gates. From national security challenges to computing revolutions, discover the innovations that are shaping tomorrow, today.

I keep telling my students they need to build a Lego printer because you can imagine the power of being able to design and produce your own custom Lego bricks. My sons would definitely be demanding such a printer post haste. Hayden Taylor is an Associate Professor of Mechanical Engineering at the University of California, Berkeley. He teaches his students every day about the endless possibilities of additive manufacturing.

Additive manufacturing is the process of building a component from the bottom up by adding material. This is contrary to typical manufacturing methods where materials are removed. It's often known as 3D printing. And it's a way of manufacturing objects by adding material onto the object rather than, for example, taking it away from a larger block of material, which would be called subtractive manufacturing. That's what lathes and milling machines do.

or indeed forming material. So objects that are injection molded, you melt material, you force it into a mold. That's a forming process where you start with the same volume of material that you finish with. But an additive process... doesn't need a mold. It doesn't need special tooling for a specific object. It allows you great geometric freedom by enabling you to put material exactly where you want it. Are you hungry? Uh-huh.

What would you like? Maybe some chicken soup. Additive manufacturing as a concept has been prevalent in sci-fi stories since the 1940s. But it wasn't until the 1980s that it actually started to become less fiction and more science. This boom started with a man named Charles Hull. Charles is credited with inventing the first real iteration of 3D printing. In the 1980s, he was working for a company that used UV light to create the tough, waterproof coatings on tables.

As he worked, a question started to nag at him. What if I could use this UV light to solidify liquid plastic layer by layer? In his spare time, he started building what is now known as the first ever 3D printer. Years later, in 1984, he patented the process known as stereolithography, or SLA. the process of using a laser to cure liquid resin into plastic in a layer-by-layer process. His work laid the foundation for modern 3D printing.

In the late 2000s, scientists at Lawrence Livermore National Laboratory began focused development on 3D printing. Chris Spaticini is the Materials Engineering Division Leader in the Engineering Directorate at Lawrence Livermore National Laboratory, one of the researchers leading the charge on additive manufacturing.

we started to think about how do we make small-scale systems like microchips, but mechanical systems that are three-dimensional? How do you make them 3D? This was probably 12 to 15 years ago. Our idea was to work with a professor at the University of Illinois on something he had been developing called projection microstereolithography, which is a big long word. And all it really means is we use light and...

light sensitive liquids to create solid components. You shine light on the liquid, the chemistry is tuned to convert to a solid when it gets hit by light. Now we can do that and focus the light down very small. and build a structure up in three dimensions, thereby giving us that 3D microsystem. Lo and behold, this was the first additive manufacturing project at the laboratory.

Chris's work with light-sensitive liquids revolutionized how tiny intricate structures could be created, turning liquid into solid with just the right wavelength of light. This technique laid the groundwork for many of the additive manufacturing platforms in use today, each tailored to specific materials and applications. Caitlin Krikorian-Cook is a polymer engineer at Lawrence Livermore Labs. One of the roles in my part in developing or designing some of these materials.

was to be able to characterize how fast this liquid can turn into a solid. It's called an induction period. So you can shine light on the liquid. for a short period of time without it changing at all. And then all of a sudden it'll start curing almost instantaneously. And so that gives us a little bit more control over the resolution.

Additive manufacturing is an exciting new technology for several reasons. One of which is the ability to completely customize the output. Traditional manufacturing techniques, while efficient for mass production are designed to produce large quantities of identical parts. Changing a single element in the production line often requires retooling, creating new molds, and significant downtime, all of which are costly and time consuming. In contrast,

Additive manufacturing excels in customization. Each item can be individually tailored without altering the overall production setup. From dental implants and prosthetic limbs to proprietary aerospace hardware, This flexibility allows for precise adjustments in design. For example, creating a unique part with specific dimensions or features in additive manufacturing only requires a change in the digital file, not the physical machinery.

The promise of additive is that every structure can be different. You don't have to make the same structure twice. That's Maxime Shustef, a group leader in the materials engineering division at Lawrence Livermore National Laboratory. There is more to this promise than just making customized products. Additive manufacturing allows for products that are stronger or lighter than those made using traditional manufacturing methods.

What additive manufacturing gets you is a high level of geometric complexity. You can make incredibly complex components that you could not have made any other way. So we often say that additive manufacturing or 3D printing is most valuable or most useful for very high value, low volume, complex components. If you want to make 10 million ball bearings.

additive manufacturing is not the way to do it. We often get asked the question by those who aren't too familiar with additive manufacturing and 3D printing. I have this component. If I make it with 3D printing, is it going to be faster, cheaper, and better? A lot of times the answer is no. So why would you use it? The answer is what you should do is redesign your component to be much more complex and have much more functionality. It becomes something new, but there's no other way to make it.

An additional advantage to the additive manufacturing process is that for newer products, it can accelerate the design build test loop. Normally, if you want to make a component, you have to have a human design it, you bring it to a machine shop.

cut away the metal, which can also be wasteful. They make the product, they give it back to you, you test it, it breaks, and you think about it a little more and you redesign it and you go do it all over again. With additive manufacturing, you can change your design very quickly. upload the file to the printing machine and make a new component fairly quickly. So it allows that iterative design cycle to be much faster.

So it's really good for development as well. By accelerating the design and prototyping process, additive manufacturing brings incredible flexibility to development. Different additive manufacturing platforms allow for this adaptability. And each platform, from volumetric additive manufacturing to direct ink extrusion, uses specific techniques to turn ideas into physical forms. One of the most exciting advancements her team is working on is VAM or Volumetric Additive Manufacturing.

Unlike traditional layer-by-layer approaches, VAM allows for complex shapes to form all at once, expanding both the possibilities and speed of material creation. If we're talking about volumetric atom manufacturing or VAM platform, so that's going to be photosensitive resins, right? Those are resins that go from a liquid to a solid when exposed with a specific wavelength of light.

But when we think about things like direct ink right, that's going to be a sheer thinning type of material. So this process is where you extrude a material through a nozzle. Think of it kind of like toothpaste. So it has specific. rheology. So when you shear it through a nozzle, it reduces viscosity until it exits the nozzle. It maintains its shape. And that's a way to be able to then print complex shapes within that platform.

While these additive platforms allow for intricate designs and unique material properties, they're not without limitations. subtractive manufacturing, though less flexible, offers a level of consistency and reliability that additive methods still strive to match. Still, there are benefits to subtractive manufacturing, even with the new innovations in the additive space.

Subtractive manufacturing is tried and true whereas additive manufacturing brings in completely different variables that add in additional layers of complexity. Addering manufacturing still produces a lot of defects in your component. When you think about machining, you buy a big block of material like aluminum or steel, and it's a solid block of material, and you could inspect it, but you know there are no...

major defects in it and then you start shaving things away. With additive manufacturing you don't start with a block of material. You start with a liquid or a powder or a wire as your feedstock. That's where material science and engineering and manufacturing really become one. It blurs that line.

So with additive, you're melting something, you're converting it from a liquid to a solid, you're doing something to it to turn it into the final material and component simultaneously. You can have material defects because of that. There's a lot of deep science and engineering that goes into understanding that, and that's what we try to really do here at the lab. The answer, it seems, lies in a blending of the two methods, offering unique advantages in complexity and customization.

We bring up things like injection molding. Maybe you want a really complex mold. You only need five of them. You build them with additive. Then you start filling the mold and you make 5,000. This blend of techniques highlights the versatility of additive approaches. It's all really hybrid and integrated, but additive is really good, again, at high complexity, high value, lower volume. I will say there are some companies out there doing medium to high volume with additive manufacturing.

which can range from producing intricate molds for small runs to high volume production in aerospace. For example, there are some aerospace companies that make aircraft engines. And they now make some of the metal components in the engine with additive manufacturing. And they make up to 40,000, 50,000 of these a year. They have an entire factory set up with metal additive manufacturing machines. They're all set up exactly the same way.

And they just make that component over and over and over again. But what exactly are the methods involved in additive manufacturing? There's a wide array of techniques, each with its own strengths and applications. Photopolymerization is one method. It means you have a big bucket of liquid and you shine light on it and there are different ways to shine light.

You can do it with really tiny lights and make small parts. You can do it with big lights and make big parts. Anything where you use light and a liquid is typically called VAT photopolymerization. A second category we'll call extrusion based. What does that mean? Those 3D printers you can buy at Home Depot and have at home or that maybe you had at your school, those are typically extrusion-based printers. It looks like a pen, and a little filament comes out of it.

What those typically are doing, the most common process, is fused deposition modeling or FDM. The third category is called laser powder bed fusion or selective laser melting. And these are typically the methods that are used to do things like metal materials. So the most common way to do metallic materials like stainless steel or titanium or something like that, you need a high energy source.

and typically you're melting and reforming the material. The other one, I refer to it as something called binder jetting. And what it does is it typically spreads out of powder. It could be a metal, it could be a ceramic, it could be a plastic. And it has like an inkjet printhead, almost like a printer where you print out your documents. And that inkjet printhead is squirting out little droplets of what's called binder. For lack of a better term, I'll call it glue.

So very fine droplets of glue into the powder. And now you've glued that powder together. Spread a new layer of powder over the top and do it again and build your part up. And as the methods in additive manufacturing continue to evolve, they open up new possibilities, not only in design, but also in the types of materials that can be used.

Caitlin Krikorian-Cook's team looks at additive manufacturing materials, new technologies that offer flexibility, durability, and even responsiveness, enabling applications far beyond traditional manufacturing. My background is a polymer engineer. And so typically, I'm sitting in different meetings, leading different teams in order to develop new materials for our various different additive manufacturing platforms.

Caitlin's expertise as a polymer engineer pushes the boundaries of what materials can achieve in additive manufacturing. And while all of these different methods and materials are groundbreaking in their own way, there is one that is a little different. One that stands apart. And this piece of tech is unlike any that have come before.

My name is Hayden Taylor. I'm an associate professor of mechanical engineering at the University of California, Berkeley. My research group has been working with the additive manufacturing team at Livermore for... almost 10 years at this point. And we've interacted on a number of topics, most notably the development of computed axial lithography. Computed axial lithography, or CAL.

is different from the other types of additive manufacturing. And just like with Charles Hall back in 1984, this breakthrough started with Hayden Taylor and PhD student Brett Kelly asking the very important question, what if? One day, I remember it back in 2016, Bress and I were standing here in my office musing about how we might be able to reduce an arbitrary geometry in a single process step.

Achieving arbitrary geometry in manufacturing means being able to create shapes and structures without any limitations on their complexity or form. This capability allows for the production of unique designs that were highly impractical or even impossible with traditional subtractive manufacturing methods. As discussed, many types of additive manufacturing techniques can achieve intricate geometries.

But what Hayden and the team at Lawrence Livermore National Laboratory wanted to explore is what kind of geometries could be made if they were able to make an item in a single step. So if you've heard of a CT scan... Computed tomography, as we call it. Typically what you do, whether it's a human or a component, you take that thing and you slowly rotate it. And usually you shoot an x-ray at it.

and you have a detector on the other side. And those x-rays, that energy goes through the component. And some of it gets attenuated and goes slower, and you have higher intensity in certain areas. There's a time component to it when it actually gets to the detector. You take all that information and you use what are called tomographic algorithms to calculate the shape. And then you have a 3D model of it in the computer. That's how a CT works at a very high level.

The idea came to me to say, well, yeah, let's basically do a CT scan in reverse, which is you're relying on rotation and you're bringing in energy from thousands of different angles over the course of the process. And the more... angles, the more freedom you have to control the final geometry. Imagine you have a block of clay and you want to sculpt a detailed statue.

Traditional 3D printing would be like adding thin layers of clay one at a time until you build up the whole statue, which can be slow and leave visible lines. Computed axial lithography is like having a magical sculptor who can shape the entire block of clay from every direction simultaneously, instantly creating the statue with perfect detail and smoothness.

all at once. So what if you do it backwards? Take a 3D CAD model. In the computer, do similar mathematics so that you create essentially virtual x-rays throughout the component. And then you take a projector or a laser. And you shoot the light like a movie as a sequence of those images into a vial of liquid, a vat, filled with photopolymer that's slowly rotating. You're hitting it with x-ray images as it rotates.

And that's causing the liquid to turn to solid as it rotates. And the part just starts to appear everywhere. This technology opens up entirely new possibilities for additive manufacturing. With this new process, printing is faster because it eliminates the hydrodynamic stresses otherwise put on the print volume.

It also is a more stable way of printing, because the object is being printed all at once instead of layer by layer, reducing material imperfections from the printing process. And those advantages are just the start.

It allows us to print materials that are very low in stiffness inherently. Things like hydrogels, which are water-infused polymers that are very low in stiffness. Because we are... not using layers to print the object, we can get... relatively smooth surfaces on the printed part we don't get what's sometimes referred to as the stair stepping effect where you have a transition from one layer to the next and a jagged edge so that's attractive if you want to print things like

optical components, lenses, ophthalmic components. The fourth advantage is what we refer to as overprinting. And this is an analogy to something that is done very often in injection molding. where you will take some metallic component and then injection mold plastic around it, if you think about the handle on a screwdriver.

That's sometimes called insert molding as well, or over molding if you think about the rubberized handle on a toothbrush. The last advantage is particularly exciting because it could take the customization of a product to a whole new level. I think that opens up some interesting possibilities in consumer electronics, for example, customizing the fit of earbuds or hearing aids, or think about the potential of smart...

contact lenses that have electronics embedded in them. Those sorts of applications where you have some metallic or electronics component that needs to be coupled with a plastic.

casing or protective layer. I think that might be a good set of use cases. And that's just the start of what Cal is capable of. Cal is relying on Expertise from several different disciplines, i.e. optics, mechanical design, precision engineering, photochemistry, computational imaging. No one person can provide all of that expertise, of course, or do a good job of it. So it can only work if the people involved instinctively look to collaborate with others and are good at it.

information sharing and articulating what the requirements are for a successful process. If it sounds like Cal is multifaceted, that's part of the magic of additive manufacturing and has been from the start. There's no one way to utilize this technology. The what if question remains. And what if is a lot closer than we think. 3D printing isn't just about making things.

These processes, from stereolithography to computed axial lithography, are all about trying to understand more about our world. Additive manufacturing is allowing us to study the world in new ways. Advancements in biology are at our doorstep. One area that I spend a lot of time working in and that I am quite excited about is biological materials because nature knows how to build with them and we're not very good at it.

But additive manufacturing lets us start making inroads into that. This approach is opening new avenues in medicine, environmental science, and beyond. And it's interesting because as we go, we learn that we're still rank novices compared to nature. It's had billions of years of evolution to get good at it. And we've had maybe a couple of decades.

Despite many advancements, we are still learning from nature's time-tested designs. The lab's work is a humbling reminder of how much we have yet to master. But it's also a testament to how far we've come in just a few decades. But for volumetric additive manufacturing in particular, because what we're trying to do there is create an entire structure in one step. there's a lot less movement of the material so that

approach in general is very good for these soft materials that are relevant in biology and in life sciences. It's a hugely interesting area for generating artificial organs, for generating testbed systems, for being able to do drug testing without using animals.

and then potentially even trying to do hybrid organic-inorganic materials where you can take some of the best properties of what life and life science has to offer and some of the best properties of what we can do with engineered non-living materials. Imagine custom-built tissues that heal wounds or replace damaged organs, all tailored to the specific needs of individual patients.

or materials that not only mimic the strength and flexibility of spider silk, but can also self-repair when damaged. These innovations are just the beginning of what we can achieve by combining life sciences with advanced engineering. Every researcher in this field has different ideas about how to implement the technology. And that is one of the strengths of the teams at the lab. The teams are multidisciplinary by design and questioning norms is seen as a strength.

We also need our teams to be able to work together. So everyone that we hire, we really value a collaborative mindset and openness and a generosity. with their technical knowledge. So folks who like to have their door open and who enjoy having their colleagues come and ask them a question.

say, hey, you know, I don't understand this part of the problem. Can you help me understand this? Or where do I go to look for understanding the material science or the chemistry of this? Because I'm really having a hard time getting this material to behave the way I want it to, or it doesn't respond to my lights the way I want it to.

The guy over there down the hall knows the optics, so we bring him in for a conversation. Collaboration is key, and so is resilience. Additive manufacturing is an industry of trial and error, so failure is to be expected. Learning to overcome it. is one of the keys to keeping the pursuit of new breakthroughs alive. I think getting buy-in to trying the idea was a key threshold, but then what happens after that is really important. So you need people who are not going to...

give up when they get the first negative outcome. I think an ability to believe in something and just keep trying different tacks until something happens is really valuable. Pure brilliance is overrated, I think. The opportunities are endless and will continue to be as long as people keep asking that question. Which you really cannot do without is curiosity. It's almost a given with folks who are scientists and engineers because they tend to come with that mindset.

You've got to be interested in the many different parts of the problem and other areas of technology, other technical fields. And I think that's how everyone here grows. The next three years, we're trying to realize what we're calling sentient materials. But these are materials that can actually lock or program themselves along the way. So if you have two discrete bounds of, let's say, energy absorption or stiffness, the materials can actually lock in between these different states.

and hold that state until it experiences another stimuli to be able to then revert back or learn that state and decide how it should be able to change its stiffness on the fly. So kind of like a synthetic living type of material. The minds behind advancements in additive manufacturing are constantly looking for new problems to solve, whether through the creation of small-scale microchips or bioengineered organic tissue.

As long as the scientists at Livermore stay curious, there's no doubt they'll keep finding new ways to help. Thank you for tuning in to Big Ideas Lab. If you loved what you heard, please let us know by leaving a rating and review. And if you haven't already, don't forget to hit the follow or subscribe button in your podcast to keep up with our latest episode. Thanks for listening.