Adhesion Matters - Fraunhofer IFAM

Episode Date: August 3, 2025

In today's episode, the focus is on the Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM), which is a leading independent research institute in Europe, specializing in Adhesive Bonding Technology, Surfaces, Shaping, and Functional Materials. Founded in 1968 and part of the Fraunhofer-Gesellschaft since 1974, IFAM boasts over 730 employees across seven German locations. Their core competencies, including metallic and polymeric materials, surface technology, adhesive bonding, shaping, energy storage, and automation/robotics, are fundamental to addressing future-relevant industries like Mobility, Energy, Aviation, Maritime Technologies, Medical Technology, and Life Sciences. Fraunhofer IFAM emphasizes a holistic approach, covering the entire value chain from material development to industrial manufacturing, including quality assurance and personnel qualification.

Think about, you know, your everyday experience with adhesives. Maybe a strip of masking cape you peel off a freshly painted wall. Right. Or maybe a dab of super glue that, well, permanently fixes a broken mug. Yeah. We usually want our glues to stick and stick really hard. And generally the goal. Yes. Strength and durability. But what if that incredible strength actually becomes a problem later on?

What if the ability to make a strong bond wasn't the only goal, but also maybe crucially, the ability to undo it? to make something let go cleanly on demand. That's precisely the revolutionary concept we're diving into today. Debonding on demand. It's a big shift in advanced adhesive technology. Debonding on demand. Okay. And our sources for this deep dive, they come primarily from the Fronhofer Institute

for Manufacturing Technology and Advanced Materials IFAM. They're a globally leading research institution really at the forefront of this whole field. Franhofer IFAM, got it. So our mission for you, the listener, is to explain. how these high-performance adhesives are quietly revolutionizing various industries. How this groundbreaking idea of debonding on demand is a real game changer for sustainability and repair and maybe what surprising innovations and critical safety measures are involved in this cutting-edge science.

Exactly. There's a lot to unpack. Okay, let's unpack this then. When we think about adhesives, our minds might not immediately jump to like high-tech manufacturing. It seems maybe a bit niche. It might seem that way initially. But what exactly makes adhesive bonding, as you say, such a pioneering joining process of the 21st century? That's quite a statement. It is, but it's justified. It's an excellent question. Because it's importance, it really goes far beyond just sticking things together. Adhesive bonding

is absolutely essential for advancing multi-material lightweight construction. Okay. Yeah, it enables the reliable bonding of not only identical materials, but crucially dissimilar materials think metal to plastic or composites to glass, things that are hard to join otherwise. Right, things you can't just weld together. Precisely. And unlike traditional methods like welding or riveting, adhesive barns don't weaken the mechanical properties of the parts themselves.

They don't introduce stress concentrations, no heat distortion. So it's not just about holding things together without messing them up. It's actually about making the whole structure potentially better. In many ways, yes, because beyond sheer strength, these bonds are often designed to perform other sophisticated functions. Like what? Well, they can be formulated to conduct heat or electrically insulate or seal against liquids or gases or even bridge tolerances, you know, small gaps in complex assemblies.

Okay, that's versatile. Where are you seeing these advanced capabilities really shining? What industries? Oh, they're kind of a hidden backbone in so many sectors. In transportation, for example, we see it in automotive, body and white bonding. That's the core structure of a car before painting. Right, the mainframe. Exactly. And in rail and aviation, like for windscreen bonding or sandwiched bonding, where you join multiple layers of different materials for strength and lightness,

very common there. It's incredible to think about the breadth of applications. I mean, beyond these big scale uses, where else are advanced adhesives popping up? Maybe in surprising ways. Well, the precision demanded by microbonding in electronics, that presents a completely different set of challenges, tiny component specific properties needed. Yeah, totally different scale. Then you have highly specialized applications. Medical technology, for instance, where adhesives must resist harsh sterilization methods like auto-claving, and of course, they have to be biocompatible.

Can't have them reacting with the body. Absolutely not. Or think about aerospace adhesives. There need to withstand extremely high and low temperatures, huge swings. Wow. Even civil engineering, you know, in load-bearing structures like windows, facade, Timber construction, even heavy steel construction, relies on specialized adhesives. Even heavy steel, you wouldn't think.

Yes. And even the packaging industry, where manufacturing costs and speed are absolutely critical, uses advanced adhesives. What's really insightful here is that institutions like Fronhofer IFEM with their, what, half century of focused research? Yeah, 50 years you mentioned. And over 200 employees working just on this. They haven't just become experts.

They've actually watched and shaped how adhesive technology evolved from, you know, simple glues to precision engineering. That gives them an unparalleled perspective on where this is all going. Okay, that sets the stage perfectly. But here's where it gets really interesting for me. If adhesives are so good, so crucial for holding complex structures together, doesn't that create a new challenge down the line? How so? Well, what happens when you actually need to take something apart, you know, for repair or recycling or maybe you? even just temporary assembly during manufacturing, and the bond is just too strong.

That's exactly the problem debonding on demand, or DOD, was created to solve. It's about giving adhesive specific debonding properties for a controlled and ideally residue-free release of the bonded joint. Dr. Matthias Popp from Fronhofer IFAM notes that this represents a really significant shift in focus. It's almost the opposite, he says, of the past emphasis on just pure durability. Right. Designing it to come apart as well as stay together. Precisely. We're now designing for deconstruction as much as for construction. And the environmental benefits, the sustainability side. That seems pretty compelling. Oh, absolutely. This technology makes a vital contribution to the circular economy.

How specifically? But enabling the separation of recyclable materials and allowing their reutilization. For you, the listener, think about something like the footwear industry. They have a huge interest in separating and reusing polyurethane soles from shoes. Which must be really tough with normal glue. Incredibly difficult, yes. Traditional adhesives make that almost impossible without destroying the materials.

DoD could change that. Beyond recycling, it's also incredibly useful for, say, temporal fixation. Emperal fixation. It's holding something temporarily, like holding a workpiece firmly in place for precision machining, and then letting it go cleanly afterwards

without any damage or residue. Ah, okay. Like a temporary clamp, but an adhesive. one. Sort of, yes. But this raises an important question, doesn't it? How do you make sure the adhesive doesn't just spontaneously debonded during its normal working life? Yeah, that would be bad. Exactly. That's the primary technological challenge. The debonding process must only be triggered under controlled conditions at a time the user specifies, and it has to comply with safety and environmental regulations. So how do they control it? Yeah. How do they make it let go

only when intended? Well, Dr. Popp suggests that future developments will likely focus less on changing the fundamental adhesive chemistry itself and more on adding tiny particles to the adhesive mix. Cardicles? Yes, particles that can be activated by some kind of external trigger like microwaves or UV light or maybe ultrasound. So you zap it with something and the particles react weakening the bond. That's the core idea, using external triggers rather than inherent instability. That sounds incredibly clever. Does Fraunhofer, IFAM, have a specific method they've developed that shows this in action? They do.

Their innovative method involves applying an electrical DC voltage, nothing too high, maybe 48 volts, for example. Okay, relatively low voltage. Yes, but simultaneously with a moderate temperature increase, say, around 65 degrees Celsius. So voltage and heat? Exactly. And the crucial safety measure here is that both conditions must act together. That prevents accidentally bonding.

You can't just apply heat or just apply voltage. It needs the dual key. Right, a built-in fail-safe. Yeah. Make sense. And what kind of results are they seeing with this dual truther approach? Does it work well? The results are quite remarkable, actually.

After these dual triggers are applied, the adhesive strength is greatly weakened. How weak are we talking? Well, they've measured residual strengths of only 0.1 newtons per square millimeter in tensile shear tests on aluminum. 0.1 n millimeter. Okay, I need context. Is that a lot? It's practically nothing. A tensile shear test measures the force needed to pull two bonded overlapping plates apart. point one end millimeter means it takes almost no force to separate them. The bond

essentially gives way. Wow. Okay, so it really does debond on demand. Yes, and it leads to what's called an adhesive fracture, meaning the brake occurs cleanly right at the interface between the adhesive and the material. And the cling-up. Is it messy? That's another key benefit. Crucially, the adhesive can then be removed as a closed film, like peeling off a sticker almost. It leaves no stubborn residues on the joined parts. Which means they can be easily reused or recycled. Precisely. And what's even more impressive is the versatility.

This method isn't just her aluminum. It can be applied to diverse substrates, other metals like seal, silicon, conductive surfaces like coated glass, even CFR-key, carbon fiber reinforced plastics, and also carbon black-celled plastics. And importantly, it's compatible with common surface pre-treatment processes that are already used in industry. That compatibility is huge for adoption, I imagine. Definitely lowers the barrier.

So what does this all mean for the bigger picture? Beyond this incredible leap in debonding on demand, what other cutting-edge innovations are making adheses, you know, smarter or stronger, maybe even more sustainable overall? Well, the focus certainly extends beyond just debonding. There are broader development goals on the sustainability front, for example. There's a lot of intensive work going into using renewable and toxicologically safe raw materials in reactive polymer systems. Reactive polymer systems. Those are the ones that cure chemically. Yes, exactly.

And the goal isn't just simple substitution, like finding a bio-based equivalent. It's about developing solutions that are actually superior in performance to the traditional petrochemical products. Really? Better performance from bio-based. That's the aim, and they're achieving it. A great example is bio-based Steinhall adhesives for corrugated board. They're now developing versions without the toxicologically concerning chemical borax, and aiming for equal or better performance. That's a significant step forward for greener manufacturing,

especially in something as common as cardboard boxes. It really is. And when we think about the incredible demands of high-tech industries, how are adhesives evolving to meet those super-specialized needs? Right, like the aerospace or medical examples. Exactly. We're seeing a lot of innovation there, too. For instance, there are things called PAA, pre-applicable structural adhesives.

These can be applied to parts like bolts or steel. sheets beforehand, maybe for local reinforcement, and then cured later during assembly. Then there are adhesives specifically designed for medical tech resistant to special sterilization methods, we mentioned, or potting compounds, you know, the materials used to encapsulate and protect electronic components. Right, keeps them safe. These are being designed with adapted coefficients of thermal expansion, meaning they expand and contract at the same rate as the electronics they protect, which prevents

stress buildup, and they can also have conductive properties if needed. Tailored to the specific electronic application. Precisely. And looking at really innovative materials, there's work on something called benzoxazine vitrimers. Benzoxazine vitrimers, that's a mouthful. It is. But they're fascinating. They're being developed for repairing fiber composite components. Think airplane parts, wind turbine blades. Okay, important stuff. What's special about them?

Well, these are a new class of polymers that can actually be reshaped and repaired multiple times. Their key advantages are. They're storage stable at room temperature, so no expensive refrigeration needed. They're non-meltable in the traditional sense, non-sticky, before activation. Easier to handle, then. Much safer and easier to handle than typical liquid reactive resin systems, yes. Adhesion is generated via pressure and thermally induced chemical exchange reactions within the material itself. That sounds like a real leap in material science.

And it's not just the adhesives themselves, is it? It's also about how they fit into complex manufacturing. How are engineers combining these advanced bonding methods with other ways of joining things? Ah, you're touching on hybrid joining. That's a big area. It combines adhesive bonding with mechanical joining processes. Think riveting, hemming, or clinching. So glue and rivets, basically.

Why do both? Well, if we connect this to the bigger picture, it allows you to combine the best of both worlds. You get the high crash energy absorption and stiffness that bonded joints offer. Right, the strength. with the fast process speed, and, importantly, the peel strength you get from mechanical joining. Adhesives aren't always great under peeling forces. Rivets handle that well. Uh, complementary strengths. Exactly. And research is even optimizing how you combine them.

For example, looking at the spacing of the mechanical joining points, they found that increasing the distance between rivets, say from 50 millimeters to over 150 millimeter, actually improved the quality of the overall bonded joint in some cases. It shows a more efficient synergy. Interesting. So it's not just slapping them together. It's optimizing the whole system. It has to be optimized.

And with such complex processes, materials, applications, quality control must be absolutely paramount. How do you guarantee consistent high-quality bonds across all these different industries and applications? You're absolutely right. Quality assurance is critical. Process simulation plays a huge role now simulating everything from the dosing and application of the adhesive to the curing process. To catch problems before they happen. Exactly. To minimize sources of error and ensure consistent quality.

This requires really comprehensive quality assurance procedures throughout the entire adhesive bonding process chain. And adherence to international standards is key. Standards like. Ike ISO-21368 or EN1-1-460. These used to be known under different names like DIA standards in Germany, but they are crucial frameworks for ensuring high quality, safe, adhesive bonds, especially in safety-critical fields like rail vehicle manufacturing or aerospace.

Makes sense. You need that rigor. Yeah. And all this advanced tech sounds fantastic, but ultimately it's people who have to design with apply and inspect these adhesives, right? Right. How crucial is the human element here? Oh, absolutely crucial. You can have the best adhesive in the world, but if it's not applied correctly by trained personnel... It won't perform as expected.

Exactly. That's why the training aspect is so important. Franhofer IPM, for instance, offers extensive recognized training programs, things like the European adhesive bonder, the European adhesive specialists, and the European adhesive engineer courses. E-A-B-E-A-E-A-E. These qualifications are vital for ensuring that professionals really understand the complexities of modern bonding techniques, from surface preparation to application and quality control.

And keeping that knowledge current must be ongoing. Definitely. That's where events come in, like the Bremen bonding days, the next one scheduled for October 2930, 2025. These events bring together industry and science to share the latest developments, troubleshoot problems, and ensure continuous updating of knowledge for everyone working in the field. It's about building and maintaining that whole ecosystem of knowledge and expertise. It really paints a picture of a rapidly evolving field.

So we've come a long way in this deep dive, understanding adhesives from, you know, simple everyday glues to these incredibly high-tech bonds that can be super strong, and then crucially be triggered to let go when the, It's clear how these intelligent high-performance materials are really set to profoundly impact sustainability, repair capabilities, and advanced manufacturing across just countless industries. And what's truly fascinating, I think, is that this shift towards debonding on demand signals a really fundamental change in how we approach design and product life cycles. How so? It moves us much closer towards a truly circular economy. We're starting to design products where the end of life disassembly is considered,

just as carefully as the initial assembly and performance. It's about designing for that graceful disassembly from the outset. That's a powerful idea, designing for the end as much as the beginning. Okay, let's leave our listeners with a final thought. You're right. Consider the concept of permanence in the products

all around you. What if everything from our electronics, our phones, our computers, to maybe even our infrastructure, could be designed not just to last, but to gracefully disassemble. Opening up entirely new possibilities for resource reuse and What seemingly permanent aspects of your own life might benefit from a little debonding on demand.