FF-W-100 Tooth Lock Washers — Internal & External
The specification for FF-W-100 tooth lock washers covers highly engineered flat washers with sharp, twisted teeth stamped around the internal or external edge. These teeth bite into the mating surfaces to resist loosening under dynamic loads. Maintained under FF-W-100 revision C (January 29, 1969), this document remains fully active with no superseding standard identified.
At a Glance
FF-W-100 Tooth Lock Washers Overview
FF-W-100 tooth lock washers are specialized Federal Specification fasteners used in assemblies with bolts, studs, and machine screws. As the fastener is tightened, the twisted teeth flex and bite into both the fastener head or nut face and the joined material. This robust mechanical engagement resists rotation and helps maintain clamp load under intense vibration.
Unlike standard helical spring lock washers (FF-W-84), which rely primarily on axial spring tension, tooth lock washers work through direct mechanical embedment with the mating surfaces. They are actively procured for military and infrastructure builds today, with status checks and documentation readily available on the Defense Logistics Agency (DLA) ASSIST portal.
Mechanical and Electrical Applications
Because of their biting action, internal tooth washers and external tooth washers provide dual benefits. Mechanically, they prevent unwanted backing off in low-torque joints. Electrically, they are a dominant choice for grounding connections. The sharp teeth cut directly through surface oxides, paint, or other non-conductive coatings to establish a highly reliable, low-resistance electrical bond. They are milled from carbon steel, corrosion-resistant steel (CRES), brass, and bronze depending on the electrical and environmental requirements of the application.
Tooth Configuration Reference
For helical spring lock washers instead of tooth-style locking devices, see FF-W-84. For plain (non-locking) flat washers, see FF-W-92.
Frequently Asked Questions
How does a tooth lock washer differ from a spring lock washer?
A tooth lock washer resists loosening through direct mechanical engagement — its twisted teeth physically bite into both mating surfaces. A spring (helical) lock washer instead relies primarily on axial spring tension from its coiled, split cross-section.
Why are they common in electrical work?
The sharp teeth cut through surface oxide, paint, or other non-conductive coatings on the mating parts, helping establish a reliable low-resistance electrical bond in addition to their mechanical locking function.
Need FF-W-100 Tooth Lock Washers to Print?
Ananka Fasteners manufactures compliant tooth lock washers in internal, external, and internal-external configurations with full material traceability.
Prefer email? sales@anankafasteners.com
