Hey, let’s cut to the chase—if you’re a designer, maintenance guy, or parts hoarder who’s ever used a wave spring, you’ve probably dealt with that annoying “settling” thing where it feels like your spring just stops holding pressure like it’s supposed to. Today I’m breaking down exactly why that happens (we call it relaxation, for the nerds) and why it matters so much for anyone who sources wave springs. I’m not here to feed you textbook jargon or make this sound like a college lecture—this is straight from the trenches, being a wave spring supplier for over a decade. Wave Spring
First, let’s define what a wave spring even is for the new folks reading. It’s that flat, thin spring, usually made of stainless steel, that has those little wavy curves pressed into it instead of the tight coils of a traditional helical spring. They’re designed to save space—like, a ton of space. You can slide one into a groove that’s half the height of a regular coil spring, and it still packs a punch. But here’s the catch: their whole shape is super dependent on that initial pressure you apply when you install it. That’s where relaxation comes in.
Relaxation, in spring terms, is when a spring loses its ability to exert consistent force over time, even if it’s being held at a fixed deflection (meaning it’s squashed to a set height, like it would be bolted into place in an engine or gearbox). It’s not “breaking” like a bent paper towel—this is a slow, permanent (but not always catastrophic) shift in the spring’s curve shape that makes it weaker. Let me explain it simply. When you first stamp that wave spring from a strip of steel, it’s got that peak-and-valley shape, right? When you compress it, those peaks push in, and it stores energy like any other spring. But over time—hours, years, whatever—those peaks start to flatten out a little. That’s relaxation. The material is just rearranging itself under constant stress.
Wait, but not all wave springs relax the same way, right? That’s what I tell every customer who calls me panicking because a batch of springs they bought last year suddenly isn’t working. Let’s talk about the factors that play into this, because if you know these, you can actually mitigate it instead of fighting it.
First up: material choice. This is huge. I’ve had customers use cheap carbon steel wave springs for applications that run hot, and they come back saying the springs died in 6 months. Carbon steel is cheaper, but it’s way more prone to relaxation under prolonged stress, especially at temperatures over 150°C. Stainless steel? Grade 301 is a workhorse for us—it’s got high tensile strength and holds shape way better. We also do 17-7 PH for super high-stress or high-temp environments (up to 400°C). Yeah, it’s a little more expensive, but I’d rather you pay a few extra bucks for a spring that doesn’t fail mid-production than replace a whole machine because your cheap springs relaxed and let a gear shift out of place.
Next, load and deflection. This is the actual amount you’re squishing the wave spring. If you compress a wave spring past its designed limit—like, way more than the engineers specified—you’re cramming those peaks so tight that the steel’s yield point gets breached. That’s when you get plastic deformation, which is basically permanent bending, not just relaxation. Relaxation is elastic deformation slowly turning plastic. So if you install a wave spring with a deflection that’s 20% over what it’s rated for, you’re asking for trouble. I see this all the time in assembly lines where workers just cram parts together without checking the specs. We always tell customers: run the numbers on your deflection, and don’t guess. We can even help with that, by the way—we have engineers on staff who’ll run load-deflection curves for free for any new project.
Environmental conditions, too. If your wave spring is sitting in a wet, corrosive environment? Not only does it rust, but corrosion eats away at the peak points, making them weaker and more prone to flattening. If it’s exposed to chemicals, that can break down the steel’s molecular structure over time, accelerating relaxation. And temperature—we already touched on that, but it’s worth repeating. Every material has a “relaxation temperature threshold.” Go above that, and relaxation happens exponentially faster. A wave spring that might only lose 5% of its force in 10 years at room temp could lose 20% in the same time at 200°C. That’s a big difference.
Wait, but is relaxation always a bad thing? Let’s be real—sometimes it’s actually a feature. Think about a clutch or a brake assembly, where parts wear over time. A little relaxation in the wave spring can compensate for that wear, so you don’t have to adjust the clutch every few months. But too much relaxation is a problem. If it’s in a precision application, like a bearing preload in a CNC machine spindle, even a 10% force drop can throw off the alignment so bad you’re making parts that are out of spec. That’s when downtime costs way more than buying better springs from the start.
Now, let’s talk about how we as a supplier address this, because I’m not just here to rant about problems—I’m here to give solutions. First, we do material testing on every batch of wave springs we make. We run stress-relief processes during manufacturing to lock in the shape. Wait, what’s stress-relief? It’s heating the spring just below its melting point to get rid of the internal stresses from stamping and forming. That makes the final product way more resistant to relaxation. We also give every customer a load-life curve that shows exactly how much force a spring will retain over time, under their specific operating conditions. No guessing, no vague claims—hard numbers.
Another thing: wave spring design. Not all wave springs are made equal. There’s single-turn, multi-turn, nested (two or more springs stacked together), and even beveled wave springs. Nested springs, for example, distribute the load more evenly across the peaks, so each individual peak doesn’t take as much stress. That means less relaxation over time. I had a customer last year who was using a single-turn spring in a heavy-duty gearbox, and it was relaxing in 2 years. Switched to a nested pair, and they haven’t had a single issue in 5 years. That’s a no-brainer, but most design engineers don’t think about that until it’s too late. I make it a point to ask every new customer about their application load and operating conditions, not just the size and part number. That way, I can recommend the best design to minimize relaxation.
Wait, let’s bust a myth here. A lot of people think “wave springs are less reliable than coil springs because of relaxation.” No, that’s not true. If you spec them correctly, they’re actually more reliable in many cases, because you can get consistent preload without taking up a ton of space. Coil springs have gaps between coils, so over time, those coils can shift, but wave springs are a solid ring of peaks, so the load is distributed more evenly. The only time relaxation becomes a problem is when you spec the wrong material, wrong design, or wrong deflection. I see so many customers cut corners on material to save a buck, and that’s where the relaxation issues pop up.
Let me give you a real example. A medical device client reached out to me last year, panicking. They were using wave springs in a surgical robot joint, and the springs were losing 15% of their force within 18 months. That’s a disaster—you can’t have a surgical robot that drifts because the spring holding the joint tight relaxed. Turns out, they were using 301 stainless steel, but at their operating temperature of 180°C, 301’s relaxation rate is higher than they thought. We switched them to 17-7 PH, ran a proper stress-relief process, and adjusted the deflection to be within their rated limit. Now, those same springs are still holding 98% of their force after 3 years. That’s the difference between knowing your stuff and guessing.
So, what can you do to avoid relaxation issues with your wave springs? First, work with a supplier that cares about your application, not just selling you a standard part. Second, don’t over-compress the spring—stick to the rated deflection. Third, match the material to your operating temp and environment. Fourth, consider nested or multi-turn designs if you’re under high load.
At the end of the day, relaxation isn’t a flaw of wave springs—it’s a characteristic of how they work, and it’s totally manageable if you do it right. I’ve been in this game for 12 years, and I can’t count how many times I’ve fixed a customer’s wave spring problems by going back to basics, adjusting the material or design, and avoiding the common pitfalls.
Torsion Spring If you’re dealing with wave springs that are relaxing too fast, or if you’re working on a new project and want to spec springs that will stand the test of time, don’t hesitate to reach out. We’ll walk through your application, run the numbers, and make sure you get the right spring for the job—no jargon, no hidden fees, just straight talk from someone who’s been there.
References
- Shigley, J. E., & Mischke, C. R. (2001). Standard Handbook of Machine Design (3rd ed.). McGraw-Hill.
- Spring Manufacturers Institute. (2018). Spring Design Manual (6th ed.). Spring Manufacturers Institute.
3.ASM International. (2019). Metals Handbook: Volume 3: Alloy Phase Diagrams (10th ed.). ASM International.
Shengzhou Deyuxiang Hardware Accessories Co., Ltd.
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