Washers are parts used for fasteners such as bolts, screws or nuts. They are usually located between the fastener and the nut to protect the surface of the workpiece, disperse the pressure and prevent the fastener from loosening.

Washers play an important role in mechanical connections. They protect the surface of the connected parts by providing additional contact area to avoid surface damage caused by direct contact with the nut or bolt head. At the same time, the use of washers can disperse the pressure of the fastener on the connected parts, thereby reducing the pressure per unit area and preventing soft materials from being crushed.

Washers are divided into flat washers, spring washers, locking washers, stop washers, and special-purpose washers