Washers

Flat washers, lock washers, spring washers, and specialty washers for load distribution and vibration resistance.

Flat Washer

Standard round washers that distribute load and protect surfaces from bolt or nut damage. Most common washer type for general fastening.

steelstainless-steelzinc-plated flat type

Split Lock Washer

Helical spring washers with a split that creates tension to resist loosening. Common anti-vibration solution for bolted joints.

steelstainless-steelzinc-plated lock type

Fender Washer

Large-diameter flat washers with small inner holes. Originally for auto body work, now used wherever large load distribution is needed.

steelstainless-steelzinc-plated flat type

Belleville Washer

Conical disc springs that provide high spring load in compact space. Used where consistent preload or vibration dampening is critical.

steelstainless-steel spring type

Star Washer (Internal Tooth)

Washers with internal teeth that bite into bearing surfaces to prevent rotation. Better grip than split lock washers on hardened surfaces.

steelstainless-steelzinc-plated lock type

External Tooth Lock Washer

Washers with external teeth that bite into mating surfaces. Greater holding power than internal tooth versions, visible when installed.

steelstainless-steelzinc-plated lock type

Wave Washer

Wavy spring washers that provide light spring pressure in a thin package. Used for preload, cushioning, and axial play compensation.

steelstainless-steelberyllium-copper spring type

Finishing Washer

Countersunk washers that accept flat-head screws flush with the surface. Creates a smooth, finished appearance.

steelstainless-steelbrass countersunk type

Shoulder Washer

Stepped washers with a raised center that insulates bolts from surrounding material. Common in electrical applications for isolation.

nylonPTFEphenolic insulating type

Sealing Washer

Washers with bonded rubber or neoprene sealing ring for watertight connections. Essential for outdoor and plumbing applications.

steelstainless-steelaluminum sealing type

Dock Washer

Extra-thick heavy-duty washers designed for marine and outdoor structural applications. Provides maximum load distribution.

steelstainless-steelgalvanized flat type

Nord-Lock Washer

Wedge-locking washer pairs with serrated faces that prevent loosening through wedge effect. Superior vibration resistance.

steelstainless-steel lock type

Frequently Asked Questions

Do I always need a washer with a bolt?
Not always, but washers are recommended in most applications. They distribute the clamping load over a larger area, prevent surface damage, and provide a consistent bearing surface for the nut or bolt head. Washers are especially important on soft materials (wood, aluminum, plastic) where the fastener head could pull through or crush the surface.
What is the difference between a flat washer and a fender washer?
Fender washers have a much larger outer diameter relative to the hole size compared to standard flat washers. This extra surface area spreads the load over a wider area, making them ideal for thin or soft materials where a standard washer might pull through. They are commonly used in automotive body panels, sheet metal, and drywall applications.
Do lock washers actually prevent loosening?
Split lock washers (helical spring washers) are the most common type, but testing by the Junker vibration test shows they provide minimal anti-loosening benefit compared to a properly torqued plain washer. For reliable vibration resistance, Nord-Lock wedge-locking washers, thread-locking adhesive, or prevailing torque nuts are more effective solutions.
What size washer do I need for a given bolt?
Washer sizing is based on the bolt diameter. The washer's inner diameter should be slightly larger than the bolt shank — typically 1/16" larger for imperial sizes. For example, a 1/2" bolt uses a washer with a 9/16" inner diameter. Standard washer outer diameters and thicknesses are defined by SAE (narrow) and USS (wide) specifications for imperial, and ISO 7089/7093 for metric.
When should I use a Belleville washer?
Belleville washers (conical spring washers) maintain tension in a bolted joint by acting as a spring. They compensate for thermal expansion, settling, and relaxation of the clamped materials. Use them in applications requiring consistent clamping force over time — such as flanged pipe connections, electrical connections, and high-temperature assemblies where differential expansion occurs.