Adhesion Matters - Surfacing Film for Lightning Strikes (Henkel)

Episode Date: August 3, 2025

The global aerospace lightning strike protection (LSP) market is poised for significant growth, projected at a Compound Annual Growth Rate (CAGR) of 7.2% from 2024 to 2030. This expansion is primarily driven by the increasing adoption of composites in aircraft manufacturing, a rise in global aircraft deliveries, and the critical need for enhanced aircraft safety and performance. Henkel, a key player in this market, offers advanced solutions like its LOCTITE® EA surfacing film, which integrates lightweight expanded copper foil within an epoxy-based composite film to provide superior lightning strike protection, weight savings, and improved manufacturing efficiency. The effective distribution of these temperature-sensitive materials, which require cold chain logistics, is crucial to maintaining product integrity and meeting global demand.

Welcome to the Deep Dive. Today, we're tackling something pretty mind-bending when you think about it. How do modern planes, you know, the ones increasingly made of non-metal stuff, composites, how did they just fly through a lightning strike? Seems like it should cause massive problems, right? It's a great question. And, yeah, it really gets to the heart of what we call aerospace lightning strike protection. It's this critical part of aircraft safety, often totally unseen.

And it's a field that's moving incredibly fast, lots of material science, engineering, It's fascinating, really. Absolutely fascinating. And definitely something most people probably never consider. So our mission today for this deep dive is to unpack all that. We want to explore the materials, the tech, the surprisingly complex logistics, and what it all means for the future of flying. We're drawing on all the material you shared with us. Okay, so let's unpack this.

To start, planes getting hit by lightning, it happens more often than we think. Oh, much more often. Yeah, it makes robust protection just non-negotiable. And the core problem, like you said, is composites. They're fantastic materials, lightweight, strong. But they don't conduct electricity like aluminum does. So that massive energy from a strike, it needs somewhere to go safely. Right.

It can't just dissipate naturally through the skin like on an older metal plane. Exactly. Without good protection systems, you're looking at serious damage. Structural integrity issues, safety risks, flight delays. It all adds up. And that's why the market for these LSP systems is booming. We're seeing a global CAGR that's a compound annual growth rate of about 7.2% predicted between 2024 and 2030. Wow, 7.2%. That's pretty significant growth.

It is. And it's driven by a few things. More composites and planes, obviously. Just more planes being built and delivered overall. And also really stringent safety rules from regulators about lightning protection. And this demand, it's worldwide, you mentioned. Absolutely global. Europe's actually expect to see the highest growth rate, partly because they're aerospace-based composites industry is so strong. But then you look at Asia Pacific. They're projected to take about 40% of all global aircraft deliveries, thinking back to the period between 2015 and 2035. So, yeah, massive demand coming from there too. Okay, let's talk materials then. How did we get from, I don't know, just basic conductive

paint to where we are now? Well, the solutions have evolved quite a bit. You still see conductive coatings like copper or aluminum paints or layers, conductive fibers woven in. sometimes special composite materials themselves. Carbon vibers can be somewhat conductive. And then they're these specialized lightning protection films. It's all about protecting the structure, keeping the plane safe. And the cost for this stuff. I imagine it varies.

It does. For, say, basic coatings or films, you might be looking at maybe $10 to $50 per square meter, roughly. But the really advanced solutions, the integrated ones offering top peer protection, yeah, they're priced higher, as you'd expect. Okay, and this is where it gets really interesting for me. this move away from doing things in multiple steps. Like, you used to put down glue, then carefully lay down a separate metal mesh. Right.

Often copper or aluminum mesh. Yeah. Very fiddly, time-consuming work, lots of potential for error or waste. And now, there's a single-step solution. Exactly. That's where innovations like Henkel's ontite EA 9845 LC-E-E-O come into play. A type of surfacing film. What's clever is it integrates a really lightweight, expanded,

copper foil directly into the epoxy film itself. Expandant copper foil, so it's not a woven mesh. Correct. It's made differently, which has some advantages we can touch on. But the point is, you apply this one film to composite parts, especially those with a honeycomb core, I think fuselages, wings, engine

to cells. And it cures to form this highly conductive layer right on the surface. So the lightning hits that layer first. Precisely. It spreads the current out rapidly across that conductive surface, prevents it from concentrating and blasting through the underlying composite structure. It acts like a sacrificial shield, basically.

That makes sense. And you mentioned Textron Aviation using this early on. What were the big wins for them for the manufacturers? Yeah, they were an early adopter. The benefits are pretty clear. Huge reduction in production time. You eliminate that whole separate mesh application step. Less waste, too. No more trimming and handling delicate mesh, which often led to scrap. And ultimately, lower overall costs. Sounds great. But with any new process, Were there hurdles, getting production lines changed over training? Oh, absolutely. Implementing any new material system into a complex manufacturing environment always has challenges.

You need process validation, quality control adjustments, retraining staff. It's a significant undertaking. But the performance benefits here were just so compelling. Let's take performance then. How well does this integrated film actually handle a strike? Very well. That expanded copper foil is key. Yeah.

Its high conductivity spreads the energy out fast over a wider area. that reduces the localized stress on the impact point. In the really tough lab tests, the zone 1A test. Right, the worst case direct strike zones. Exactly. In those tests, the damage on the outside was typically contained to about a 15 centimeter, maybe six inch diameter circle. Penetration was minimal, maybe a couple of inches deep into the film,

and the very top layer of composite. And crucially, no damage seen on the backside of the test panels. So the damage stays shallow, repairable? That's the idea. superficial, manageable damage. Plus, there are other wins. Up to 30% weight saving compared to some older film and mesh methods. That's huge in aerospace.

30%. Wow. Yeah. And it's also UV resistant, which means less sanding or surface prep needed before you paint the aircraft. Gives you a smoother, higher quality surface right out of the mold, essentially. You mentioned the expanded copper foil being different from woven mesh. Can you elaborate on that conductive element? Sure.

So many of Henkel's products use this non-examination. unwoven metallic mesh. It's produced directly from a solid foil. This lets them use almost pure copper, maximizing electrical conductivity. Most woven mesheses have to be alloy mixed with other metals just to give them the strengths to be woven. And allowing reduces conductivity. Significantly, sometimes by up to 50% compared to pure copper. Another benefit is the film adhesive itself protects that copper layer. Bare copper mesh is really fragile and easy to distort. The film makes it much easier to handle, position accurately during manufacturing, and It holds its shape.

Okay, so you've got this amazing high-tech film. It's manufactured. Then what? How does it get to the aircraft factory? Seems straightforward, right? Ah, well, here's probably the most surprising twist in the whole story. These materials are incredibly temperature sensitive. Like, among the most perishable chemicals used in manufacturing.

Perishable, you mean like food? Almost. They need strict refrigerated storage. We're talking zero degrees Fahrenheit, which is minus 18 Celsius or even colder. and they have a limited shelf life, typically a 12-month warranty if kept perfectly cold. Minus 18C, that's serious deep freeze. It is. Think about the logistics. You make this film in, say, California.

It needs to get to an aircraft parts factory in Japan or Germany or wherever. Right. It has to travel packed and dry ice with constant temperature monitoring the whole way, even for just an overnight shipment. Wow. An entire global cold chain just for this surfacing film. Exactly. Distributors like Bodo-Muller-Chemi, Boeing distributors, services, they specialize in this. It's a huge logistical challenge. The precision required is

intense. Billions of dollars of aircraft safety depends on that temperature staying constant. That is truly remarkable. So what happens if that cold chain breaks, even briefly? Is the material ruined? Potentially, yes. Any significant temperature fluctuation, what they call an excursion, could compromise its properties. The ability to cure properly, its conductivity, it might shorten the shelf life or just make it unusable. There are very strict. protocols. Okay, so assuming it arrives perfectly frozen at the factory, what's the next step? How do they actually use it? Right. So first, you have to take it out of the freezer, but you can't open the sealed bag right away. You have to let the whole roll slowly warm up to room temperature first. That

prevents condensation from forming on the cold film, which could cause problems. Ah, makes sense, like a cold drink can on a humid day. Exactly. Once it's a room temp, you open the bag, position the film, usually fabric side down onto the prepreg. That's the uncured composite material. Then it all gets cured together under heat and pressure co-cured. And just to mention, there are other similar films, like Loctite EA 9837.1A.0, another epoxy-based one. Improved surface finish. Works with lightning strike foils, too. Such a meticulous process from start to finish.

Looking ahead now, what are the sort of cutting-edge trends shaping the future of LSP? Where is the research heading? Well, there's ongoing work on even more advanced materials, things like conductive polymers aiming for better performance. maybe even lighter weight. There's also a big push towards integrated systems. So instead of just LSP, can the system also provide, say, electromagnetic interference shielding, EMI shielding, or help the thermal management? Combining functions into one layer. Right.

Streamlines the design. Saves weight, saves space. Very attractive for engineers. There's also research into what you might call smart materials. Things like piezoelectric materials, which generate a voltage under stress or electrostrictive ones that change shape. with an electric field. The idea there is maybe developing active protection systems, ones that could detect a lightning strike starting and react in real time. Still very much research, though. Active protection. Wow. And the regulators, FAA, EASA, they're keeping pace.

They are. Standards are constantly being updated as technology evolves and we learn more. That pushes innovation too. And like everywhere else, there's a growing focus on sustainability, greener manufacturing processes, materials with less environmental impact. So, pulling back to the bigger picture, all these advancements, where else are they making a difference besides the big commercial jets we usually fly on? Oh, the impact is much broader. Military aviation is a huge area. Stealth aircraft. UAVs, drones.

They rely heavily on composites and need advanced, tailored LSP, business aviation to private jets. Customized solutions are needed there. And then there's the whole emerging urban air mobility sector, UAM. You mean the air taxis, the EVTILs. Exactly. Electric vertical takeoff and landing aircraft. They're often smaller or very composite heavy, flight at lower altitudes, perhaps. Their LSP needs are quite unique and absolutely critical for safety certification. These advanced films are vital enablers for them.

Even commercial space. Spacecraft, launch vehicles, satellites, they face electrical discharge risks too, including lightning during launch or reentry. Robust protection is increasingly important there as well. It really is foundational technology for so much future flight. But despite all this progress, what are the main roadblocks? What challenges still make this a tough market? Yeah, it's definitely not without its hurdles.

Cost is always a factor. Developing and integrating these advanced materials and systems is expensive. R&D is costly. Certification is costly. Technical complexity is another one. Getting these systems perfectly incorporated into intricate aircraft's designs isn't simple. Especially retrofitting older designs, I imagine. That can be particularly challenging, yes.

And just ensuring consistent performance. These materials have to work flawlessly under a huge range of conditions, temperature extremes, humidity, vibration, for years and years. Proving that reliably is tough. And finally, navigating the different evolving regulations across the globe. That remains a constant compliance challenge for manufacturers. Well, this has been a truly illuminating deep dive. It's clear the specialized world of lightning strike protection isn't just about safety. It's really driving innovation in materials, in manufacturing efficiency, and even helping with environmental

mental goals by making planes lighter. That's a great way to put it. It really shows how these innovations that seem quite niche like a special surfacing film and its incredibly complex cold chain, how they actually have these profound ripple effects across the entire aerospace industry. They enable lighter planes, which means less fuel burn, lower emissions, and they're making entirely new forms of air travel like UAM, even conceivable. So here's a final thought to leave you with.

We've talked about these incredibly vital yet extremely temperate, yet extremely temperate, sensitive, almost perishable materials, and the unbelievable global logistics needed to handle them perfectly. How might that level of precision, that kind of intense material management, maybe reshape other high-tech fields? Industries that also need extreme safety and performance, could we see similar approaches pop up in places we aren't even thinking about yet?