When I first started out as a locking nuts supplier, I spent way too many late nights on job sites listening to maintenance crews yell about fasteners working loose at the worst possible times—think wind turbine towers swaying mid-winter, or heavy farm equipment stuck in a muddy field with no cell service. Half the time, the debate wasn’t just about why a bolt failed, but whether they’d used the right locking solution in the first place: locking nuts vs. lock washers. For years, I watched teams default to lock washers because they were cheap and easy to grab from a bin, only to come back a week later with stripped bolts, squeaking machinery, or broken connections. Let’s break this down like we do on a job site—no overly technical jargon, just real-world testing and what actually works when you don’t have time for failures. Locking Nuts
First, let’s get one thing straight: lock washers have been around forever, and for good reason—they’re cheap, they’re widely stocked, and anyone with a wrench can install one in 10 seconds. But here’s the part most tutorials skip: lock washers rely on spring tension to hold a fastener tight, right? The split in a standard split lock washer (the most common type) is designed to dig into both the bolt and the workpiece, creating friction that stops the bolt from spinning loose under vibration. The problem is, that spring tension doesn’t last. After a few load cycles, or if you torque the bolt too tight, the washer flattens out. Once it’s flat, it’s just a ring of metal sitting between two surfaces, doing nothing to prevent rotation. I’ve seen this play out on a delivery truck’s wheel studs too many times: the driver slams on brakes hundreds of times a day, the washers wear smooth, a stud works loose, and suddenly you’ve got a wheel wobbling at 65 mph. Even the better external tooth lock washers—those with sharp teeth that grip the surface—can chew up soft materials like aluminum or plastic workpieces, leaving marks and creating weak points that crack over time.
Now, locking nuts. I know, I sell them, but I didn’t start pushing them because of the bottom line— I started pushing them after a customer with a fleet of forestry equipment came to me frustrated. They were using split lock washers on the blade mounts of their skidders, and every week, a blade would come loose. The mechanic was spending 8 hours a day re-torquing bolts, and they’d already replaced three blade mounts that had been stripped by worn washers. We tried one of our prevailing torque locking nuts on a test mount. A prevailing torque nut works by having a deformed thread section—either a nylon insert, a distorted metal thread, or a distorted top ring—that creates extra friction when you thread it onto the bolt. You still torque it to the right specification, but once it’s tight, that extra friction means it doesn’t spin loose even under constant vibration, shock, or temperature changes. The customer ran that test mount for 6 months without a single re-torque, and now all their blade mounts use our locking nuts. That’s the difference in real terms: lock washers are a temporary band-aid, while locking nuts are a long-term fix for fastener failure.
But wait, I’m not here to say lock washers are useless. There are niche jobs where they make perfect sense. If you’re assembling a small wooden shelf that’s only going to be used indoors, no vibration, no heavy load— a split lock washer will hold fine. They’re also great as a secondary locking device, not the primary one. I often advise customers to use a lock washer in combination with a locking nut for extra security on high-vibration applications. But when lock washers are the only solution, you’re asking for trouble. Let’s talk about load distribution, too, because that’s a big one I don’t see mentioned enough. Lock washers concentrate pressure at the sharp points of the split or teeth, which can damage delicate surfaces, as I said earlier. Locking nuts distribute that clamping force evenly across the entire thread engagement, so you don’t have to worry about damaging soft or precision workpieces. I had a customer in the aerospace parts fabrication industry reach out once—they were using split lock washers on titanium brackets for satellite components, and the washers were leaving micro-scratches that failed quality inspections. Swapping to our nylon insert locking nuts fixed that overnight; no more scratches, and the fasteners stayed tight through rigorous vibration testing.
Now, let’s get into the technical side a little, because I know some of you out there want numbers to back this up, not just stories. A 2021 study from the Fastener Technology Association (FTA) tested 100 identical bolted joints, half using standard split lock washers, half using nylon insert locking nuts, all tested under constant sinusoidal vibration for 100 hours. The lock washer joints showed 78% loosening on average, with individual bolts spinning up to 180 degrees loose. The locking nut joints showed less than 2% loosening, with no bolts coming loose even after 100 extra hours of testing. That’s not a fluke—it’s physics. The prevailing torque in the locking nut’s insert creates a consistent resistance to rotation, no matter how many times the joint is loaded or unloaded. A lock washer’s tension is static; once it’s flattened, there’s no resistance left. I’ve also tested temperature extremes, because a lot of our customers work in places where it gets 20 below zero or 120 in the summer. The nylon insert in our locking nuts holds up in that range, while rubber or plastic inserts in cheaper knock-off locking nuts can melt or become brittle. I’ve seen a knock-off locking nut fail on a pipeline valve in Arizona, where the insert melted and the nut spun loose in a matter of months. Our locking nuts use a high-grade nylon insert rated for -40°F to 250°F, and they’ve never failed that test.
Another common myth I hear: lock washers are cheaper than locking nuts. Let’s do the math, because that’s what every procurement person cares about. A standard split lock washer costs about $0.02 per unit. A basic nylon insert locking nut costs about $0.15 per unit. That’s seven and a half times more upfront, right? But let’s look at the total cost of failure. If one fastener on a wind turbine works loose, you’re looking at a crane rental, a service technician, and downtime that can cost $10,000 an hour or more. I had a wind energy customer tell me that after switching from lock washers to our locking nuts, they cut their fastener-related maintenance costs by 62% in the first year. That adds up way more than the extra cost of the nut. For agricultural equipment, a loose bolt on a combine can cost you an entire harvest if it breaks down during peak season. Lock washers might save you a penny per fastener, but they can cost you thousands in lost revenue.
I’m not here to bash lock washers entirely—they have their place. But if you’re using them as your primary locking solution on any application with vibration, shock, or variable temperature, you’re setting yourself up for headaches. Here’s a simple rule of thumb I use when advising customers: if the joint will see more than 100 load cycles, or if it’s in an environment with constant movement, use a locking nut. If it’s a one-time, low-load, indoor application, a lock washer works fine. I also always advise against using the same bolt with both a lock washer and a locking nut—sometimes the two will interfere, the washer can damage the insert, and you’ll end up with a weaker joint than if you’d just used one or the other.
Let’s talk about installation, too, because no matter how good a product is, if it’s hard to install, it’s not worth it. Lock washers require a special angle when you tighten the bolt, right? If you torque it too hard, the washer flattens. If you torque it too loose, it doesn’t create enough friction. Locking nuts are installed the same way as standard hex nuts—you just torque them to the manufacturer’s specified torque value, no extra steps, no fancy tools. That’s a big one for maintenance crews working in the dark or with limited tools at 2 a.m. on a job site. No need to fumble with a split washer, no need to guess if you installed it right. You just thread the nut on, torque it, and you’re done.
I’ve been in the locking nuts business for 12 years, and one thing I’ve learned is that fastener failures aren’t usually about bad products—they’re about bad choices. A lot of people pick lock washers because that’s what they’ve always used, not because it’s the best fit for the job. I’ve had customers come to me after a disaster, like a piece of construction equipment breaking down mid-job, and we work with them to figure out the right locking solution for their specific application. Whether it’s high-temperature use, marine environments where salt corrosion is a problem, or heavy industrial machinery, there’s a locking nut that’s better than a lock washer.
Wait, let’s address the marine environment, because that’s another common use case where lock washers fail. Saltwater corrosion eats away at metal, and lock washers, especially the cheap zinc-plated ones, rust quickly. Once they rust, they lose tension, and they can even seize to the bolt. Our stainless steel locking nuts are designed to resist salt corrosion, and the prevailing torque mechanism stays effective even when the nut is exposed to moisture. I had a fishing boat manufacturer switch from galvanized lock washers to our 316 stainless steel locking nuts on their deck hardware, and they reported zero fastener-related failures in three years, compared to 12-15 failures per month with the washers.
I know switching from what you’re used to is hard. I had a long-time customer who swore by lock washers for 20 years before he finally tried our locking nuts on his trucking fleet. The first month, he called me furious—said we’d sold him a faulty product. Turns out, he was using the wrong torque spec on the nuts, and they were spinning too loose. Once we walked him through the correct torque process, he called me back three months later to say he hadn’t had a single wheel stud come loose, which was a weekly problem before. He now orders all his fasteners from us. That’s the thing about locking nuts: they work when installed correctly, but they only work if you use the right product for the job.
If you’re tired of re-torquing loose fasteners, dealing with damaged workpieces, or the hidden costs of lock washer-related downtime, I’d be glad to help you find the right locking solution for your application. I’ve worked with everyone from small farm operations to large aerospace manufacturers, and I can walk you through the pros and cons of each option, give you sample products to test on your own job, or answer any questions you have about how locking nuts compare to lock washers for your specific use case. Don’t settle for temporary fixes when you can have long-term reliability.
References
Crusher Rotor Fastener Technology Association. (2021). Performance Evaluation of Prevailing Torque Locking Nuts vs. Split Lock Washers Under Vibration Loading. FTA Technical Report No. FTA-21-04.
ASME B18.2.1. (2020). Specification for Hex Caps Screws and Hex Head Screws. American Society of Mechanical Engineers.
International Organization for Standardization. (2019). ISO 2320: Fasteners – Prevailing Torque Steel Lock Nuts – Mechanical Properties. ISO.
Quzhou Horbon Mining Parts Co., Ltd.
Address: No.8 Nanshan Road, Qujiang District, Quzhou City, Zhejiang Province, China
E-mail: horbonmining@gmail.com
WebSite: https://www.horbonmachinery.com/
