Washers are disks of metal or non-metallic material placed beneath a nut, an axle bearing, or a joint, to relieve friction, prevents leakage, isolate, prevent loosening or distribute pressure. There are many different types of washers and washer type products for a variety of applications.  Common types include flat washers, beveled, C-washers, D-shaped washers, countersunk or finishing washers, fender washers, lock washers, SAE washers, sealing washers, spherical washers, square washers, tab washers, torque washers, shoulder washers, and spring washers.  Flat washers are thin, flat, and circular general-purpose washers, with a centrally located hole.  Beveled washers have a tapered bearing surface. C-washers have a slot cut from the center to the perimeter.  Typically the slot is the same width as the "center hole."  D-shape washers have a flat edge cut away on the parameter.  Countersunk washers come in a number of shapes: 90 degree countersunk, angle countersunk, flanged, unflanged, rolled flange, etc. Most people are familiar with the finishing type used for cosmetic purposes on many consumer products.  Fender washers have a large outside diameter in comparison to the inside diameter.  External tooth lockwashers have teeth around the outer perimeter of the washer.  Helical spring lockwashers are split rings of metal or steel that when tightened, resist loosening.  Internal tooth lockwashers have teeth around the internal perimeter.  SAE washers are approved by the Society of Automotive Engineers.  Sealing washers seal around a bolt or fastener. Spherical washers have a cross-section in the form of a half or partial sphere.  Square washers can have a rectangle shaped inside or outside profile.  Tab washers have a tab(s) that may be bent for the purpose of locking. Tab washers are made in an almost infinite variety of configurations with internal and/or external notches and/or tabs, single or multiple, formed or flat.  Torque washers have sharp prongs formed to sink into the mating surface.  These washers are used for anti-rotation between washer and mating surface.  Shoulder washers have a sleeve with the same inner diameter as washer hole.

Washers can be specified in ANSI nominal sizes or ANSI metric sizes.  Important size dimensions to consider when specifying washers include inside diameter, outside diameter, thickness or working height, and rated or working load.  Metallic materials of construction available for washers include aluminum, brass, copper base alloy or bronze, copper, nickel base alloy, spring steel, steel, hardened steel, stainless steel, and titanium.  Non-metallic materials of construction include ABS, acetal, asbestos, felt, leather, nylon, polyester, polycarbonate, polyethylene, PVC, polypropylene, PTFE, and rubber.  Common finishes for washers include anodize, black oxide, phosphate, galvanized, nickel plated, tin plated, zinc plated, and zinc chromate.

Washers are disks of metal or non-metallic material placed beneath a nut, an axle bearing, or a joint, to relieve friction, prevents leakage, isolate, prevent loosening or distribute pressure. There are many different types of washers and washer type products for a variety of applications.  Common types include flat washers, beveled, C-washers, D-shaped washers, countersunk or finishing washers, fender washers, lock washers, SAE washers, sealing washers, spherical washers, square washers, tab washers, torque washers, shoulder washers, and spring washers.  Flat washers are thin, flat, and circular general-purpose washers, with a centrally located hole.  Beveled washers have a tapered bearing surface. C-washers have a slot cut from the center to the perimeter.  Typically the slot is the same width as the "center hole."  D-shape washers have a flat edge cut away on the parameter.  Countersunk washers come in a number of shapes: 90 degree countersunk, angle countersunk, flanged, unflanged, rolled flange, etc. Most people are familiar with the finishing type used for cosmetic purposes on many consumer products.  Fender washers have a large outside diameter in comparison to the inside diameter.  External tooth lockwashers have teeth around the outer perimeter of the washer.  Helical spring lockwashers are split rings of metal or steel that when tightened, resist loosening.  Internal tooth lockwashers have teeth around the internal perimeter.  SAE washers are approved by the Society of Automotive Engineers.  Sealing washers seal around a bolt or fastener. Spherical washers have a cross-section in the form of a half or partial sphere.  Square washers can have a rectangle shaped inside or outside profile.  Tab washers have a tab(s) that may be bent for the purpose of locking. Tab washers are made in an almost infinite variety of configurations with internal and/or external notches and/or tabs, single or multiple, formed or flat.  Torque washers have sharp prongs formed to sink into the mating surface.  These washers are used for anti-rotation between washer and mating surface.  Shoulder washers have a sleeve with the same inner diameter as washer hole.

Washers can be specified in ANSI nominal sizes or ANSI metric sizes.  Important size dimensions to consider when specifying washers include inside diameter, outside diameter, thickness or working height, and rated or working load.  Metallic materials of construction available for washers include aluminum, brass, copper base alloy or bronze, copper, nickel base alloy, spring steel, steel, hardened steel, stainless steel, and titanium.  Non-metallic materials of construction include ABS, acetal, asbestos, felt, leather, nylon, polyester, polycarbonate, polyethylene, PVC, polypropylene, PTFE, and rubber.  Common finishes for washers include anodize, black oxide, phosphate, galvanized, nickel plated, tin plated, zinc plated, and zinc chromate.