Tab Lock Washers

Tab lock washers are mechanical locking washers designed with one or more projecting tabs (or lugs) along their outer edge. Once the fastener is tightened, one tab is bent upward against a flat on the nut or bolt head, while another tab is bent against the edge of the mating part or into a corresponding slot or hole. This mechanical interlock physically prevents the fastener from rotating loose, offering a highly reliable, positive locking method that does not rely on spring tension or friction alone.

Because they provide a true mechanical lock rather than relying on tension or friction, tab lock washers are especially valued in applications subject to heavy vibration, shock loading, or safety-critical assemblies—such as automotive steering and suspension components, industrial machinery, structural fastening, and heavy equipment—where fastener loosening could lead to serious failure.

Within this category, Lily Bearing offers tab lock washers to match both major fastener standards:

• Inch Tab Lock Washers – Sized to imperial fastener standards, designed for use with inch-sized bolts and nuts in machinery and equipment built to US/imperial specifications.
• Metric Tab Lock Washers – Sized to metric fastener standards, suited for globally manufactured equipment and metric bolt/nut assemblies.

Each type is available in multiple sizes and material finishes to accommodate a wide range of fastener diameters and application environments.

Frequently Asked Questions

How Do Tab Lock Washers Work?

Tab lock washers feature bendable tabs along their outer edge. After the fastener is tightened, one tab is bent flush against a flat face of the nut or bolt head, and another is bent against an adjacent surface or into a slot, mechanically preventing the fastener from rotating and loosening.

How Are Tab Lock Washers Different From Split or Tooth Lock Washers?

Split and tooth lock washers rely on spring tension or biting teeth to resist loosening, and their locking force can diminish over time or under extreme vibration. Tab lock washers provide a true mechanical interlock by physically bending tabs against the fastener and mating surface, offering a more positive and permanent locking solution.

Can Tab Lock Washers Be Reused?

Tab lock washers are generally intended for single use. Once the tabs have been bent to lock the fastener, straightening and reusing the washer can weaken the tab material and compromise locking reliability. It's recommended to install a new tab lock washer with each assembly.

How Do I Choose Between Inch and Metric Tab Lock Washers?

The choice depends on the fastener standard used in your application. Inch tab lock washers are sized for imperial bolts and nuts, while metric tab lock washers are sized for metric fasteners. Be sure to match the washer to your fastener's measurement system and diameter.

What Applications Benefit Most From Tab Lock Washers?

Tab lock washers are ideal for applications where fastener loosening could lead to critical failure, such as automotive suspension and steering systems, heavy machinery, structural assemblies, and other safety-critical joints subject to continuous vibration or dynamic loads.

Do Tab Lock Washers Require Special Installation Tools?

Installation typically requires basic tools to bend the tabs, such as pliers or a hammer and punch, depending on the tab size and washer material. No specialized equipment is generally needed, though proper technique is important to ensure the tabs seat securely against the fastener flats.