Flat Washers, Plain Washers, Fender Washers

A flat washer, or plain washer, is a flat annulus or ring, often of metal, used to spread the load of a screwed fastening. Additionally, a plain washer may be used when the hole is a larger diameter than the fixing nut. The normal standard flat washers are DIN125, DIN9021, ANSI B18.22.1. The common metals are carbon steel, stainless steel, alloy steels.

A fender washer is also a flat washer with a particularly large outer diameter in proportion to its central hole. They 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. DIN440 is one of the fender washers.

  • DIN125 Flat Washer
  • DIN9021 Flat Washers
  • DIN440 Fender Washer
  • ANSIB18.22.1 Washers


There are more type of flat washer, made of non-metals, e.g. rubber, EPDM, aluminium, brass, plastic, etc. Those are special usages, like for sealing or insulation purpose, widely used in electronics and tele-comunication accessories.

.A penny washer is a flat washer with a large outer diameter, in the UK. The name originally comes from the size of the old British penny. In the UK, most industries refer to all large OD washers as penny washers, even when the OD is as much as twice the size of the old penny. They are used in the same applications as fender washers.

A spherical washer is part of a self-aligning nut; it is a washer with one radiused surface, which is designed to be used in conjunction with a mating nut in order to correct for up to several degrees of misalignment between parts.