Author: Scott Bredemann
Updated: 12/8/2025 | Read Time: 6mins
Lock washers (also known as locking washers) are small components, but they play an important role in keeping bolted joints from loosening under load. They’re used anywhere vibration, movement, or changing forces can cause a standard nut and bolt to back off over time. At their core, lock washers work by adding tension or friction to the joint so the fastener stays in place once tightened. Different designs achieve this in different ways—some rely on spring-like compression, while others bite into the mating surfaces to resist rotation.
What Are Locking Washers?
Lock washers are specialized fastener components designed to keep nuts, bolts, and screws from loosening after installation. Unlike flat washers, which primarily spread load and protect surfaces, lock washers are shaped—or intentionally deformed—to create resistance within the joint. This resistance helps maintain clamp force when the assembly is exposed to vibration, shifting loads, or temperature changes.
How Do Locking Washers Work?
Lock washers function by altering the way a bolted joint behaves once it’s tightened. Their geometry—whether split, curved, conical, or serrated—changes the interaction between the fastener and the surfaces it clamps, adding forces that counteract loosening.
For spring-style designs, the washer is slightly compressed during tightening. This compression creates a stored mechanical load that pushes back against the nut or bolt head. When vibration or movement occurs, the washer helps maintain contact pressure so the joint doesn’t lose clamping force as easily.
Tooth-style washers work differently. Their serrations grip into the mating surfaces as the fastener is tightened. This creates small points of interference that make it harder for the nut or bolt to rotate once in place. Instead of relying on stored tension, these washers use increased friction and surface engagement to resist loosening.
Common Types of Locking Washers
Lock washers are produced in several forms, each built around a different mechanical principle and suited to specific applications. The four types most frequently used in mechanical and industrial assemblies include spring, wedge, tooth, and split designs.
Spring Lock Washers
These washers are shaped to provide controlled flexibility. Their curved or conical profiles allow them to deflect slightly when tightened, which helps them adapt to minor shifts in the joint. They are often used where assemblies experience intermittent loads or where maintaining steady contact pressure is important.
Wedge Lock Washers
Wedge lock systems consist of paired washers with interlocking wedge-shaped ramps on one side and serrations on the other. When the bolt attempts to loosen, the wedge action increases the separation between the washers, producing a counteracting force that resists rotation. They are commonly chosen for high-vibration environments or connections where reliability is critical.
Tooth Lock Washers
Tooth-style washers feature internal or external serrations that create multiple points of contact around the fastener. These teeth embed lightly into the adjoining surfaces during installation, increasing resistance to turning. They are useful in applications where materials allow for slight surface penetration and where friction-based locking is appropriate.
Split Lock Washers
Sometimes referred to as helical spring washers, these have a single split and a slight twist that creates uneven ends. When tightened, the washer flattens and its edges exert opposing forces on the nut and the joint surface. This shape provides a simple mechanical barrier to rotation and is one of the more recognizable and widely used lock washer types.
Parting Thoughts
MISUMI USA carries a wide range of lock washers, including – split lock washers, wedge lock washers, spring lock washers, and more. If you have any questions about fastening concerns for your next project or fix, please feel free to contact our product experts, and engineers. For more insights about lock washers, and other manufacturing related articles be sure to check out our blog, and articles like – Best Lock Washer by Application, Thread Per Inch Chart, Socket Size Chart, and more.
Disclaimer:
The content on this webpage is for informational purposes only. MISUMI makes no guarantees, expressed or implied, regarding the accuracy, completeness, or validity of the information. Performance parameters, tolerances, designs, materials, or processes should not be assumed to reflect third-party suppliers’ or manufacturers’ deliverables within MISUMI’s network. Buyers are responsible for specifying their part requirements.