DIN 9250 S Safety Lock Washers

DIN 9250 S Safety Lock Washers are conical spring washers with radial serrations formed on both bearing faces. The washer has a dished profile rather than a flat geometry, allowing it to develop elastic spring action when compressed in a bolted joint. The serrated surfaces create mechanical resistance against rotation between the washer, bolt or nut, and mating component.

The product is commonly identified in the fastener market as DIN 9250 (S), DIN 9250 S safety washer, or S-type safety lock washer. The S designation is associated with the standard form of this washer design. The same product family is also commonly described using terms such as Schnorr-type safety washer, serrated conical washer, or ribbed safety washer. The term “Schnorr-type” describes the product design and should not be interpreted as indicating an original SCHNORR® product.

The combination of a conical spring profile and serrated bearing surfaces distinguishes this washer from conventional flat washers and simple split lock washers. Under bolt preload, the conical section is compressed while the serrations engage the contact surfaces. This arrangement helps maintain joint resistance to loosening where vibration, cyclic loading, or other dynamic forces could reduce clamp stability. Original SCHNORR safety washers use the same general design principle of a disc spring with serrations on both sides.

DIN 9250 S safety lock washers are commonly used with screws, bolts, and nuts in mechanical assemblies where resistance to self-loosening is required. Typical applications include machinery, automotive components, industrial equipment, electrical equipment, and general mechanical fastening. Selection should consider the fastener size, mating surface condition, required preload, and compatibility between the washer material and the joint components.