What is the difference between flat washers, spring washers and stop washers?

Washers are typically used to secure bolts. They are mechanical components that keep a bolt or screw from loosening or aid in distributing loads from a nut or bolt head over a large surface area. More than that, they protect the area from damage during installation by providing a wedge between the fastener and the mating surface. Skipping out on these useful devices can reduce the service life of the system or product you are working on. As such, this blog will cover three of the most common washers: flat, spring, and stop washers.

Flat Washers

Flat washers, or plain washers, are generally made of a variety of materials including aluminum, brass, nylon, silicon bronze, stainless steel, and steel. They have a circular shape to them with a hole in the center. Their role is to increase the contact area between the screw and the machine. Moreover, they distribute the fastener’s load while successfully reducing heat and friction during the tightening process. As there are several types of flat washers, the next section will cover a few of the most widely used.

One such type is called a fender washer which has a larger outside diameter as compared to the inside diameter. You can find these washers in automobiles, plumbing, sheet metal, panels, and more. Next, shoulder washers are used to insulate screws, wire, or other components within an assembly. This type of washer is available in fiber-glass, phenolic, nylon, PCTFE, PTFE, and other various metals.

Spring Washers

A Spring washers have axial flexibility and are utilized to prevent fastening or loosening due to vibrations. They consist of a split in the washer section that, when secured, each side of the split bites into the nut and the mounting surface. Additionally, they can be used in the bearing and non-bearing structures of most mechanical products. They distinguish themselves from other washers in their cost-effectiveness, easy installation, and suitability for systems that require frequent assembly and disassembly. The one drawback of using this type of washer is that it may loosen over time. Moreover, there are square and rectangular spring washer designs.

One type of spring washer is called a curved spring washer, and it is able to support small loads. In addition, it provides a uniform spring rate over the deflection range and has linear load-deflection qualities. Next, finger spring washers are utilized to mitigate noise, excess wear, vibrations, and skidding wear on rotating elements.

Stop Washers

A stop washer is often used to prevent a nut from loosening. This type of washer can be subdivided into a retaining washer for a round nut, an outer tongue retaining washer, a double-ear retaining washer, and a single-ear retaining washer. The retaining washer for a round nut is beneficial for when the nut is locked, while the latter three are used in the case of locking with a general nut.