ISO 10673 specifies the requirements for Plain Washers intended for use in screw and washer assemblies (commonly known as Sems bolts). Unlike standard washers, ISO 10673 washers are engineered to be pre-assembled onto a screw blank before the threads are rolled, ensuring the washer remains permanently captured on the fastener.

This standard provides three types of washer series—Small (S), Normal (N), and Large (L)—to accommodate different load distribution needs in high-speed automated assembly environments, particularly in the automotive and electronics sectors.

The primary engineering focus of ISO 10673 is assembly efficiency and retention. Because the washer is captured by the screw's thread crest after rolling, the hole diameter of an ISO 10673 washer is specifically sized to clear the screw's shank but remain smaller than the major diameter of the finished thread. This eliminates the risk of missing washers on the production line and ensures consistent torque-tension relationships in the final joint.