All You Need to Know About Washers: Types, Material Options, and Size Guide

Various Types Of Washers

Manufacturers use different types of washers to create and join parts. Each type of washer has subcategories, but there are main types you should know about.

Plain Washers

Plain washers are the most common type used. They distribute the fastener’s load while minimizing heat and friction during tightening. They can also serve as spacers, typical in industrial and domestic applications. Plain washers include:

Flat washer

Flat washers, also known as flat nut washers, provide complete insulation and protection against abrasion and serve as spacers. Flat washers are disc-shaped with a hole in the center. They are ideal for small-headed screws, as they distribute weight over a larger surface area.

Fender washer

Fender washers are larger than flat washers and feature a small hole in the center. They are designed to distribute loads over a wider area, making them useful in various applications. In addition to their role in construction, fender washers are important in the plumbing sector and sheet metal fabrication.

Torque Washer

These washers are principally used in the woodworking industry. When a nut is tightened, the washers’ outside prongs feature square holes that prevent the accompanying bolt from spinning.

Countersunk washer

Countersunk washers in this category create a flush finish when secured with a flat-head countersunk screw. This capability to accommodate countersunk fasteners is due to its recessed top.

C-Shaped washer

A C-shaped washer is similar to a standard flat washer but features a hole cut from its center, creating a C-shape. One key advantage of this type of washer is that it allows for adjustments, removal, or modifications without needing to remove the fastener.

Shoulder washer

Shoulder washers, made from nonconductive materials such as nylon, are used as bushings to insulate fasteners or shafts.

Spring Washers

Spring washers are a specific type of lock washer that provides axial load to fasteners, helping to limit movement caused by vibration or thermal expansion. They are ideal for applications that need a certain degree of flexibility, so they are commonly used in airplane actuators, such as flight controls and landing gear. Spring washers in this category include:

Dome spring washer

These washers help manage large load capacities with minimal deflection. They also absorb significant vibrations and ensure a flat surface.

Belleville washer

These conical spring washers maintain tension during assemblies’ thermal expansion and contraction. They can support significant weights while only deflecting slightly.

Wave spring washer

Wave spring washers curve in two directions and are commonly used as cushions or spacers. They can support moderate weight and help prevent excessive wear on surfaces.

Crescent spring washer

The crescent spring washer, also known as a curved spring washer, features a curved design that helps maintain flexibility. It can also withstand very light loads.

Finger spring washer

Finger spring steel washers are carbon steel and feature three curved flanges. These washers reduce vibration, minimize skidding wear, and diminish noise on rotating components.

Carbon steel is frequently used for manufacturing finger spring washers because it combines the fixed load points of wave washers with the flexibility of casing washers.

Lock Washers

Lock washers are designed to prevent screws and nuts from rotating and loosening. They help maintain the integrity of these fasteners even during intense vibrations caused by machine or equipment operation. Lock washers keep fasteners securely in place, counteracting any loosening due to friction. There are several different types of lock washers, including:

Helical washer

A helical washer is designed to secure fasteners. These washers are made from non-continuous rings bent inward and outward in opposing directions. When a fastener is used to secure the washer, both ends of the bent washer flatten out and grip into the mating surface.

Internal toothlock washer

This washer has numerous teeth in its inner diameter, ensuring the bolt head remains secure. Additionally, it helps reduce shock and noise while locking various types of fasteners in place.

External toothlock washer

External tooth lock washers use a toothed design to prevent nuts or screw heads from loosening. They are most effective with screws that have larger heads. The many teeth on the outer diameter grip the surface, providing excellent compression resistance and ensuring high torsional resistance.

Other Washers

Keyed washers

Keyed washers are commonly used between bolts to prevent them from spinning, particularly in the automotive industry. These washers feature an internal tab that stops the automobile shaft from rotating. They are also used in various applications, such as chassis components and cylinder heads.

O-rings

O-rings, commonly called gaskets, are made of rubber and come in various shapes and sizes depending on their intended purpose. They serve as mechanical seals that fill the space between two or more surfaces in contact, effectively preventing leaks and spills. The automotive industry’s primary function is to secure oil and gas connectors, stopping leaks.

Gaskets can be made from rubber, lightweight aluminum, and other metals. These washers ensure a tight seal regardless of pressure and temperature, preventing liquids and gases from escaping.