AFT offers a wide selection of flat washers available in many sizes, specifications and materials. Flat washers are generally used under the head of a bolt or nut to distribute the fastener load over a larger surface area. They also help to prevent corrosion between a steel screw and an aluminum surface.
SAE Flat Washers
SAE flat washers are specified by the Society of Automotive Engineers to meet the requirements of automotive manufacturers. They have a smaller diameter and thinner thickness then their counterpart bolt sizes of USS flat washers. Standard SAE flat washers can be made from a low carbon steel or stainless steel and plated with zinc, HDG, or black oxide. SAE through-hardened flat washers are made with a higher grade of steel (SAE 1035 – 1050 steel) and heat-treated. They are designed to perform the same functions as low carbon SAE flat washers, but for use specifically with high-strength hardened steel bolts. Product standards require all through-hardened washers 1/4” diameter and larger to bear the insignia identifying its manufacturer.
USS Flat Washers
USS flat washers, or United States Standard washers, were designed to meet engineering requirements for the majority of industrial applications for manufacturing and maintenance and repair (MRO). The outside diameters, inside diameters, and thickness specifications were developed to meet the largest range of applications. Standard USS flat washers are made from low carbon steel whereas USS through-hardened flat washers are made from a higher grade steel (SAE 1035 – 1050 steel) and heat-treated. They perform the same function as USS plain washers, but for use specifically with high-strength hardened steel bolts. Product standards require all through-hardened washers 1/4” diameter and larger to bear the insignia identifying its manufacturer.
Structural Flat Washers
ASTM F436 round structural washers have dimensions comparable to the USS plain washer, but with a smaller outside diameter, and manufactured with a higher grade of heat-treated steel. They are designed to be used with A325 and A490 structural bolts, but can also be used for general applications. Structural washers are most commonly supplied plain or with a galvanized finish. ASTM F436m is the standard specification for hardened steel metric structural washers.
As a flat washer supplier, AFT offers additional types of flat washers and MIL-Spec flat washers, including narrow flat washers, L9 thick flat washers, SAE tension flat washers, HDG flat washers and more. Our in-house plating shop and manufacturing facilities can also assist if your application requires custom washers or specialty plated washers, such as Xylan, silver or e-nickel. Shop our selection or contact our experienced sales team today for assistance.