Locknuts

Understanding Different Types of Locknuts and Their Functions

Locknuts are critical fastening components designed to prevent loosening caused by vibration, torque, and dynamic loads. Used across automotive, industrial, construction, and mechanical applications, locknuts add reliability and safety where standard nuts may fail. Understanding the different types of locknuts helps ensure you select the right solution for strength, durability, and long-term performance.

What Is a Locknut?

A locknut is a specially designed nut that resists rotation after installation. Unlike standard hex nuts, locknuts use mechanical locking features—such as thread deformation, serrations, or inserts—to maintain clamp load and prevent back-off.

Common Types of Locknuts

Flexlock Locknuts

Flexlock locknuts use an all-metal locking mechanism, typically a deformed or flexing metal section that grips the bolt threads. These locknuts perform exceptionally well in high-vibration environments and are commonly used in automotive assemblies, heavy machinery, and industrial equipment where durability is critical.

External Tooth Locknuts

External tooth locknuts feature teeth on the bearing surface that bite into the mating material. This design provides strong resistance to loosening and eliminates the need for washers. They are frequently used in sheet metal assemblies and electrical enclosures.

Serrated Locknuts

Serrated locknuts include serrations on the flange or underside of the nut, creating enhanced grip and vibration resistance. These are ideal for automotive, aerospace, and heavy machinery applications where joint security is essential.

Nylon Insert Locknuts

Also known as nyloc nuts, nylon insert locknuts use a nylon collar to create prevailing torque on the bolt threads. They are reusable and effective in low- to moderate-temperature environments, making them popular in electronics, appliances, and general machinery.

Flange Serrated Locknuts

Flange serrated locknuts combine a built-in washer flange with serrations for superior load distribution and locking strength. They are widely used in automotive and construction applications.

Locknut Grades Explained

Grade A Locknuts

Grade A locknuts are typically made from low carbon steel and are suited for general-purpose, light-duty applications.

Grade C Locknuts

Grade C locknuts are manufactured from higher-strength steel, offering increased durability for heavy-duty and structural applications.

Choosing the Right Locknut

Selecting the proper locknut depends on vibration levels, load requirements, temperature exposure, and reusability needs. From Flexlock to nylon insert and Grade A to Grade C, each locknut type plays a vital role in creating secure, long-lasting fastener assemblies across countless industries.