Locking Washers
Star and tooth washers feature twisted serrated teeth that physically bite into mating surfaces to create a mechanical barrier against vibration-induced rotation. Available in internal, external, or combination tooth designs, they maximize friction and holding power on relatively soft substrates like aluminum or plastic. Additionally, the teeth pierce through surface coatings to establish secure metal-to-metal electrical grounding paths in electronic and automotive applications.
Tooth washers, interchangeably referred to as star washers or serrated lock washers, are specialized fastening components designed to deliver aggressive locking action and vibration resistance. Unlike standard flat washers that rely solely on friction, tooth washers feature twisted, serrated prongs that physically bite into the bearing surface and the underside of the fastener. This physical interference establishes a mechanical barrier that actively resists rotation and loosening caused by dynamic forces. Furthermore, the sharp teeth are highly effective at cutting through surface finishes—such as paint, rust, or oxidation—to guarantee secure metal-to-metal contact, a critical requirement for electrical grounding.
To achieve the necessary biting action without fracturing under load, tooth washers are forged from materials that balance hardness with ductility. High-tension Spring Steel and Carbon steel are the most common, providing the necessary bite. Stainless Steel variants in A2 and A4 grades offer superior longevity in corrosive environments, while Brass is selected specifically for specialized electrical applications.
The environmental resilience of tooth washers is augmented by a vast selection of surface treatments. Standard options include Self-Color (Plain), Zinc Plated, and Black Oxide. For harsher conditions or specific industry requirements, advanced finishes are available, including Hot-Dip Galvanized, Nickel Plating, Copper Plating, Brass Plating, Chrome Plating, Cadmium Plating, and high-performance Zinc-Aluminium Flake Coating.
Tooth washers are classified by the orientation of their teeth, ensuring compatibility with varying fastener heads and assembly geometries. The primary Forms include:
Manufacturing is standardized under rigorous specifications:
These standards ensure the washers consistently deliver vital Mechanical Properties such as Spring Tension, High Spring Force, Biting Action, and Anti-Rotation.
Tooth washers are indispensable in industries where machinery is subjected to constant vibration, thermal cycling, or shock. In the automotive and heavy machinery sectors, they prevent critical engine and chassis bolts from backing out. The electronics and electrical engineering fields rely heavily on tooth washers to bite through chassis coatings, ensuring low-resistance grounding paths that are essential for safety and signal integrity. They are particularly effective when used on softer metal substrates or plastics, where their teeth can embed deeply and securely.
Tooth washers are highly effective, reliable locking devices that bridge the gap between mechanical security and electrical continuity. By leveraging standardized forms (Internal, External, Conical) and a diverse array of materials and coatings, they offer engineers a proven solution for preventing fastener failure in vibration-heavy and grounding-critical environments.
Our tooth washers are available in a range of sizes, materials, and standards. Contact us for a detailed specifications sheet and competitive bulk pricing.
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