In general, washers are used to increase the bearing surface of a nut or fastener's head, provide a smooth mating surface or protect the surface from damage when the nut or head is rotated, compensate for oversized or irregular shaped holes, space or shim parts, or to resist loosening.
Washer size refers to its nominal hole size and is based on screw size. Its outside diameter (OD) is always larger.
Hardened and high strength alloy washers are used with graded fasteners, such as ASTM A325 and SAE Grades 5 and 8
Depending on the washer type, common materials include stainless steel and steel. Finishes include nickel for brass and steel, and hot dip galvanizing and zinc plating for steel. Unplated and uncoated steel washers—referred to as plain finish—may also be available and are susceptible to rust. Not all washer types are available in all materials and finishes.
Washer size refers to its nominal hole size and is based on screw size. Its outside diameter (OD) is always larger.
Hardened and high strength alloy washers are used with graded fasteners, such as ASTM A325 and SAE Grades 5 and 8
Depending on the washer type, common materials include stainless steel and steel. Finishes include nickel for brass and steel, and hot dip galvanizing and zinc plating for steel. Unplated and uncoated steel washers—referred to as plain finish—may also be available and are susceptible to rust. Not all washer types are available in all materials and finishes.
