Serrated Shake Proof Washers
Shakeproof washers are an anti-vibration type of locking washer. The surface of the washer features special teeth that lock when tightened, making them resistant to vibration. They are sometimes referred to as lock tooth washers.
On an internal shakeproof washer the teeth are found on the internal rim of the washer. Conversely, on an external shakeproof washer the serrations are on the outer rim. Selection of either depends upon where in the application the washer needs to grip.
Shakeproof washers are most commonly used in the electrical industry.