ThePipingMart Blog Fasteners What is an Internal Tooth Washer? Exploring the Uses and Applications

What is an Internal Tooth Washer? Exploring the Uses and Applications

What is an Internal Tooth Washer? Exploring the Uses and Applications

Have you ever wondered how machinery and other mechanical components stay securely together? One answer is through the use of internal tooth washers. These small but mighty components play a big role in maintaining a machine’s or structure’s integrity. In this blog post, we’ll explore what internal tooth washers are, how they work, and the various applications in which they are used.

What are Internal Tooth Washers?

Internal tooth washers are small metal parts that have teeth on their inside circumference. They create a strong grip between the washer and the fastening object. The teeth help to prevent the washer from turning or slipping, keeping the machine or structure in place. Internal tooth washers are commonly made from materials such as stainless steel, brass, copper, or mild steel and are available in a range of sizes to fit various bolts and screws.

An internal tooth washer, also known as an internal serrated lock washer, is a type of lock washer used in various applications to prevent bolts and screws from loosening under vibration or torque. It comprises a circular metal disc with teeth on one side and a smooth surface on the other. The teeth are designed to dig into the mating surface and create friction when tightened, providing an effective locking mechanism.

This means that even if there is movement or rotation in the joint due to external forces, the internal tooth washer will keep the bolt or screw firmly in place. This makes it an essential component in high-stress assemblies where failure due to loosening can have catastrophic consequences.

What sets internal tooth washers apart from other types of lock washers is their design. The teeth on its inner surface are angled towards the center, resulting in more contact points between the washer and mating surface for improved grip. They also have larger inside diameters compared to external tooth washers, making them suitable for use with larger bolts and screws.

How do Internal Tooth Washers Work?

When a bolt or screw is inserted through a hole in a machine or structure, the internal tooth washer is placed between the head of the bolt or screw and the surface it is being fastened to. As the bolt is tightened, the teeth inside the washer bite into the surface, creating a secure grip. This keeps the bolt or screw from vibrating loose and maintains its tension.

Where are Internal Tooth Washers Used?

Internal tooth washers are used in various applications, from automotive and aerospace to construction and marine industries. They fasten components such as engines, transmissions, and hydraulic systems. Internal tooth washers are also used in electrical assemblies such as circuit breakers and switch gears. In addition, these washers are found in various household items such as plumbing fixtures, appliances, and furniture.

Advantages of Using Internal Tooth Washers

The use of internal tooth washers provides several advantages, such as:

Increased torque and tension – the teeth on the washer distribute the force of the tightening over a wider area, reducing stress on the bolt or screw.

Vibration resistance – the teeth on the washer make contact with the surface, creating friction and reducing the risk of components shaking loose due to vibration.

Prevention of damage – the teeth of the washer bite into the surface rather than digging in. This creates a more even pressure distribution and prevents surface damage.


In summary, internal tooth washers are essential in securing machinery and structures in place. They have teeth on the inside circumference that prevent them from slipping or turning. These washers are used in various applications such as aerospace, construction, household items, etc. An internal tooth washer helps increase torque and tension, provides vibration resistance, and prevents damage to the surface. Understanding the importance and applications of intern tooth washers can be a significant advantage when ensuring the proper functioning of machinery and components.

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