Washers are another critical member of the wide world of fasteners. They’re certainly not sexy and can be overlooked at times. However, they play a crucial role in the function and longevity of the majority of products using mechanical fasteners. Like most fasteners, there are many different types and sub-types, with the application ultimately driving the appropriate selection.
According to Engineering360, washers are, “… disks of metal or non-metallic material placed beneath a nut, an axle bearing, or a joint, to relieve friction, prevent leakage, isolate, prevent loosening, or distribute pressure.”
Most people are likely familiar with the typical “Type A plain washer,” otherwise known as a flat washer. These are considered general-purpose washers and are used in myriad applications.
SAE washers are similar to Type A plain washers but are thinner and approved by the Society of Automotive Engineers for use with fine thread bolts and nuts. Other major categories of washers include Spring or Disc washers (of which there are many styles), Lock washers, Torque washers, and more. We’ll break down down the different types of washers and their applications in more detail in future posts. Today’s entry will focus on the common attributes of each washer.
While very important, the basics of common washer attributes break down quite simply into size, thickness, material.
Washers are available in both imperial and metric sizes. It’s important to know by which standards the washer is measured to guarantee you get the correct size.
American National Standards Institute (ANSI) nominal sizes specify the washer based on the size of the fastener with which it is to be used. However, nominal washer sizes as determined by SAE, USS (United States Standard), and JIS (Japanese Industrial Standards) call out the inner and outer diameters as well as the thickness.
Washer thickness is an important factor. The thickness measurement of most washers refers to the axial cross-section of the washer. However, in the case of a spring washer, the thickness is more likely to describe the unloaded working height.
The materials of your end product, as well as the load a washer will need to endure, are the determining factors as to the material washer you should select. When a washer is subjected to higher levels of cycle loading, spring steel or high alloy steel should be specified. When being joined to a soft surface, or limited load bearing is required, a softer material may be used.
Metal washers can be composed of aluminum, brass, bronze, copper, carbon steel, hardened steel, spring steel, stainless steel, titanium, and other alloy based materials.
For applications in which a non-metal washer is preferable, materials include ABS, felt, nylon, polyester, polycarbonate, polyethylene, PVC, polypropylene, rubber, and more.
Austin Hardware® has a large selection of washers to complement most fasteners and applications. Contact your Austin customer service representative or your nearest location for assistance. If you know your part number, you can search the Washers pages on our website and place an order. If you need just a little help finding the right size or style, consult the charts starting on page 1448 of our hard copy catalog or the online flipbook pages of the catalog.