Spring washers are normally made out of spring steel and are hardened to HV 430 to 530 and are used along with almost every externally threaded fastener. Due to their Spring action, they give a locking effect to the tightened fastener, when fastened with Spring washer.

Plain washers A flat washer with a particularly large outer diameter in proportion to its central hole. These are commonly used to spread the load on thin sheet metal, and are named after their use on automobile fenders. They can also be used to make a connection to a hole that has been enlarged by rust or wear.

A washer is a thin plate (typically disk-shaped, but sometimes square) with a hole (typically in the middle) that is normally used to distribute the load of a threaded fastener, such as a bolt or nut. ... Washers often have an outer diameter (OD) about twice their inner diameter (ID), but this can vary quite widely.

H.S.F.G Washer. Coronet load indicating washers are used in the structural industry to provided evidence that the required tension has been achieved. The raised protrusions will crush in relation to the load applied, providing a permanent observation that required tension was achieved.

DTI Washers. load cells that are manufactured with raised dimples that are used to indicate when the proper tension level has been achieved during tightening, since tension is what we are after NOT TORQUE. DTI's are manufactured to the F959 specification.