ThePipingMart Blog Fasteners 5 Types of Tab Lock Washer and Their Uses

5 Types of Tab Lock Washer and Their Uses

Tab Lock Washer

Tab lock washers are essential components in many applications. Whether in the automotive industry, aerospace engineering, or industrial manufacturing, their role in fastening bolts and screws is critical. However, not all tab lock washers are designed equal. This comprehensive guide will explore different types of tab lock washers and their features.

Types of Tab Lock Washer

External Tooth Tab Lock Washer

The external tooth tab lock washer is the most common tab lock washer type. As its name implies, it features teeth on its outer circumference to grip the mating surface and prevent loosening. The external tooth design applies more tension to the bolt or screw, making it suitable for high-torque applications. This type of tab lock washer is known for its effectiveness in providing torsional resistance, vibration resistance, and shock absorption.

Internal Tooth Tab Lock Washer

Unlike the external tooth tab lock washer, the internal tooth tab lock washer has teeth on the inner circumference. The washer is placed between the screwhead and the assembly surface. The teeth on this washer bite into the underside of the screw head, holding it firm. The internal tooth tab lock washer is suitable for applications that damage the surface surrounding the screw holes. Additionally, they are helpful in small spaces due to their compact size.

Countersunk Tab Lock Washer

Countersunk tab lock washers, also called cupped lock washers, are designed to fit the countersunk recess of the screw head. They feature a rounded surface and flat bottom that support the screwhead. Countersunk tab lock washers are typically used in applications where the top surface should remain flat, flush, and free of obstruction. They are perfect for decorative applications and are commonly used in guitar and woodworking projects.

Square Tab Lock Washer

The square tab lock washer is similar to the external tooth tab washer but has four tabs instead of teeth. The square tabs grip the surface surrounding the hole and can be used to fasten bolts directly to the surface. They are ideal for applications requiring significant load distribution and increased grip torque. The square tab lock washer holds up well in harsh environments and is commonly used in construction, mining, and agricultural equipment.

Wave Tab Lock Washer

The wave lock washer, or spring washer, features a unique shape with a curved wave-like design that flattens when under load. The wave tab lock washer is ideal for applications requiring movement or flexibility under vibration or thermal cycles.


In conclusion, each type of tab lock washer serves a specific purpose and application. External tooth, internal tooth, countersunk, square, and wave tab lock washers can provide additional holding power, reduce vibration, and protect surfaces under high loads. Careful consideration should be taken when selecting the appropriate tab lock washer for your project or application. Choosing the suitable tab lock washer is essential to ensure the safety and reliability of your assembly.

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