Lock Washers

Lock washers resist loosening from vibration and load cycling by applying spring tension or biting into the bearing surfaces. They are a simple, economical way to keep threaded joints tight in machinery, vehicles, and equipment subject to movement. We stock split and tooth lock washers across every common material and size.

Split (Helical) Lock Washers

The most common type — a single coil of spring steel that flattens under clamp load, providing tension and a slight bite from its sharp cut ends. Split lock washers work well in general machine assembly and are stocked in regular and heavy sections.

Tooth (Star) Lock Washers

External tooth: teeth around the outer edge bite into the bearing surfaces, providing strong anti-rotation grip and good electrical bonding — ideal under bolt heads on larger fasteners. Internal tooth: teeth on the inner edge are hidden under the head for a cleaner appearance, common on smaller screws. Internal-external combines both for maximum grip.

Materials and Finishes

Spring steel with zinc plating: the economical standard. 18-8 stainless: corrosion resistance for general use. 316 stainless: marine and chemical environments. Match the washer material to the fastener to avoid galvanic corrosion.

Dimensional Standards

Split lock washers follow DIN 127 / DIN 7980 (metric); tooth lock washers follow DIN 6797 / DIN 6798. Inch sizes follow standard SAE/USS patterns.

Selecting the Right Lock Washer

Choose split lock washers for general vibration resistance, external tooth for maximum grip and electrical bonding, internal tooth for a clean look on smaller fasteners. Match the bore to the bolt and the material to the fastener. Note that for critical high-vibration joints, prevailing-torque lock nuts or thread-locking compound often outperform lock washers.

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