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All You Need to Know About External Tooth Washers

All You Need to Know About External Tooth Washers

External tooth washers, also known as exterior ribbed washers, are used to distribute the load of a fastener evenly over a larger surface area. They are widely used in automotive, construction, and other heavy industries. This blog post will discuss everything you need about external tooth washers, including their uses, applications, and benefits.

What are External Tooth Washers?

External tooth washers are circular metal washers with teeth or ridges on their outer periphery. These ridges or teeth help grip the surface of the material the washer is placed on, preventing it from rotating or moving. They are typically made of high-strength metal alloys for added durability and resistance to wear and tear under heavy loads.

The external tooth washer, also known as an external locking washer or star washer, is specialized fastening hardware used in mechanical assembly. It is typically made of high-quality steel and has small teeth or prongs on the outer edge. These teeth are designed to bite into the mating surface when tightened with a screw or bolt, providing a secure and reliable hold.

One of the key advantages of using an external tooth washer is its ability to distribute pressure evenly over a larger area. This prevents damage to delicate materials such as plastic or thin metal sheets by preventing sharp edges from digging in and causing deformation under pressure. Additionally, the teeth create friction between the surfaces, making it less likely for them to come loose due to vibrations.

In addition to their functional benefits, external tooth washers have been shown to increase the load-bearing capacity of joints by up to 30%. This makes them especially useful for applications involving heavy loads, and reliability is essential.

Uses and Applications of External Tooth Washers

External tooth washers are primarily used to provide a more secure grip on fasteners and prevent them from loosening due to vibration, friction, or other mechanical forces. They also help to distribute the load evenly over a larger surface area, reducing the stress concentration on the material and preventing cracking or deformation.

External tooth washers find applications in various industries, including automotive, aerospace, construction, and heavy machinery. They are commonly used to assemble engines, turbines, generators, and other power machinery subject to high vibrations and stresses. They are also used in building construction, particularly for metal roofing and cladding applications, where they help to prevent leaks and secure the fasteners.

Benefits of using External Tooth Washers

The primary benefit of using external tooth washers is their ability to provide a secure and even load distribution, preventing fasteners from loosening or failing prematurely. This, in turn, improves the safety and reliability of the machinery or building that they are used in, reducing the risk of accidents and costly repairs.

External tooth washers are also relatively easy to install and remove, making them a popular choice for applications where fasteners must be replaced frequently or adjusted to accommodate changes in load or alignment.

In addition, external tooth washers are resistant to corrosion and wear, which means they can withstand harsh environments and extended usage without deteriorating or losing their effectiveness.

Types of External Tooth Washers

External tooth washers come in various sizes and shapes to suit different applications and fastener types. Some of the most common types include a flat washer with external teeth, a curved washer with external teeth, and a conical or Belleville washer with external teeth.

Flat washers with external teeth are the simplest and most widely used type, suitable for most applications requiring a secure grip and even load distribution. Curved washers with external teeth are designed to adapt to angular surfaces and provide a more secure grip on fasteners subject to lateral forces or shifting loads. Conical or Belleville washers with external teeth are used in high-stress applications where a more significant deflection is required to manage the load distribution and prevent fastener failure.


External tooth washers are essential in many industrial applications, providing a secure and reliable means of fastening and load distribution. By understanding their uses, applications, and benefits, you can make informed decisions when selecting the appropriate external tooth washer for your needs. Whether working on a construction project or maintaining heavy machinery, external tooth washers can provide the added safety and reliability your application requires.

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