We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is a Lock Washer?

By Dorothy Distefano
Updated May 17, 2024
Our promise to you
About Mechanics is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At About Mechanics, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Threaded fasteners are commonly used to attach and secure two or more objects together. While very effective, a threaded connection can loosen over time due to reasons such as vibration, temperature cycling, and wear. A lock washer is a type of fastener that is used to prevent a joint which is secured using threaded fasteners from coming loose and separating. Lock washers are available in several different types and sizes, such as split lock washers, star lock washers, and tab lock washers. These are used extensively in the manufacture of airplanes, and in numerous structural applications where loosening of connections could have significant safety implications.

Threaded connections between two or more objects typically involve the use of a screw, or bolt and a nut. Lock washers are used for threaded connections using a screw and nut combination. The screw has a large head on one end and a shaft with an external thread, which is a helical structure that allows the screw to be advanced when rotated. The nut, which is usually hexagonal in shape, has a hole with an internal thread that matches the thread of the screw.

When a screw is inserted and rotated into a nut, the screw advances. A significant force can be generated when the screw and nut are tightened against two or more objects located between the screw head and nut surfaces. A lock washer is placed between the nut and surface being secured or joined. It resists the force being applied by the nut and prevents the nut from loosening.

A split lock washer has a donut shape — a circle with a hole in the center — and has a single cut which extends from the outside diameter to the inside hole. The cut is the reason this type of washer is called a split lock washer. The two sections adjacent to the cut are misaligned in the direction perpendicular to the washer surface. This misalignment allows the lock washer to resist force by creating friction through resulting spring action that prevents the nut from loosening.

In addition to resisting force through friction, the shape of certain types of lock washers can cause them to bite into the mating surface and create a mechanical grabbing force. Star lock washers have internal and external teeth, and each adjacent tooth is bent in alternating directions perpendicular to the washer surface. The teeth bent to one side embed themselves into the nut, while the teeth bent in the opposite direction embed themselves into the work surface being fastened. Similarly, tab lock washers have bent tabs at the edges that mate with the surface of the nut, and lock the nut in place.

About Mechanics is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
About Mechanics, in your inbox

Our latest articles, guides, and more, delivered daily.

About Mechanics, in your inbox

Our latest articles, guides, and more, delivered daily.