11 Types of Washers: Fewer Than 1% of People Have Used Them All

In engineering applications such as mechanical assembly, automotive components, and steel structure construction, washers may seem insignificant, yet they are an indispensable part of the fastener system. Many failures—including bolt loosening, workpiece indentation, and joint failure—often stem from incorrect washer selection.

**11 Types of Washers: A Comprehensive Guide to Their Structures and Applications**

In engineering applications such as mechanical assembly, automotive components, and steel structure construction, washers may seem insignificant, yet they are an indispensable part of the fastener system. Many failures—including bolt loosening, workpiece indentation, and joint failure—often stem from incorrect washer selection.

Today, let's take a closer look at these 11 types of washers and develop a systematic understanding of their structural features and application scenarios.

## I. Introduction to 11 Types of Washers

### 1. Flat Washer
**Structure:** A flat annular metal sheet with regular inner and outer circles and uniform thickness—the simplest structure among washers.

**Application:** The first choice for basic fastening. It enlarges the bearing area of the bolt, distributes tightening pressure, prevents the bolt head from damaging the workpiece surface, and compensates for clearance in mounting holes. It can be used in routine fixing scenarios for general equipment, sheet metal, and steel structures.

### 2. Wave Washer
**Structure:** An annular body with a continuous wave profile that generates elastic force through its own deformation.

**Application:** An elastic cushioning washer capable of shock absorption and clearance compensation, and can offset dimensional expansion and contraction caused by temperature changes. Suitable for locations with limited axial space. Commonly used in motor bearings, small valves, and home appliance assemblies to eliminate assembly clearance and achieve light anti-loosening.

### 3. Disc Spring Washer (Belleville Washer)
**Structure:** Conical dish shape. A single piece can be used independently, or multiple pieces can be stacked in combination. It can withstand large loads over a short travel.

**Application:** Provides elastic tension, shock absorption, and anti-loosening. Suitable for high-strength connections in compact spaces that require high preload. Widely used in heavy equipment, hydraulic fixtures, automotive chassis, and high-pressure valves. It can compensate for bolt creep and maintain long-term stable preload.

### 4. External Tab Lock Washer
**Structure:** The outer ring has a bendable protruding tab, and the inner hole fits over the bolt shank.

**Application:** Mechanical positive locking for anti-loosening. After tightening the nut, the external tab is bent into the keyway or side wall of the workpiece to physically lock the nut and prevent rotation. Mostly used in heavy equipment, construction machinery, and lathe spindles subject to severe vibration, and suitable for connections that are not frequently disassembled.

### 5. Wave Spring Washer
**Structure:** An open wave-shaped annular washer. The open design makes it easier to compress and provides a more sensitive elastic response.

**Application:** Elastic cushioning, continuously maintaining a small preload, and absorbing vibration. Mostly used in light-load assemblies such as bearing preloading and electronic assemblies to eliminate assembly clearance and suppress slight vibration.

### 6. Internal-Tooth Conical Lock Washer
**Structure:** Conical slope with a ring of fine teeth on the inner side. When tightened, the slope tightens and the teeth bite into the contact surface.

**Application:** Achieves anti-loosening through tooth engagement. Tightening generates radial clamping force, and the teeth firmly bite into the workpiece surface. Suitable for conical mounting structures. Commonly used in automobiles and powertrain components under medium vibration conditions.

### 7. Embossed Disc Spring Washer
**Structure:** Disc spring base with a radial embossed pattern covering the surface.

**Application:** The disc spring structure provides elasticity, while the surface embossing increases friction—providing dual anti-loosening. Suitable for thin sheet parts, aluminum alloy, and plastic parts to prevent bolts from loosening under vibration. Commonly used in automotive interiors and sheet metal assemblies.

### 8. Internal Tooth Lock Washer
**Structure:** An annular washer with a ring of sharp teeth on the inner ring. When the nut is pressed down, the tooth tips embed into the workpiece surface.

**Application:** The internal teeth grip the bolt or nut, and tooth-surface engagement prevents the nut from rotating. Suitable for locations with limited contact surface space. It can be used in motors, pump bodies, and general mechanical components; note that soft aluminum materials are easily dented by the teeth.

### 9. Concave-Convex Washer (Spherical Washer Pair)
**Structure:** Consists of a convex surface and a concave surface used as a pair, forming a spherical pair when fitted together.

**Application:** Works with conical surfaces for anti-loosening while compensating for angular deviation of the assembly surface. When the connecting surfaces are not parallel and have tilt errors, the concave-convex washers automatically self-align to prevent the bolt from bearing bending stress. Mostly used in connections with angular errors such as flanges and frames.

### 10. Conical External-Tooth Lock Washer
**Structure:** A ring of radial sharp teeth on the outer ring, resembling a gear in shape.

**Application:** Serrated engagement for high-strength anti-loosening. After tightening, the sharp teeth press into the workpiece, providing extremely strong frictional resistance and outstanding vibration resistance. Mostly used in high-strength vibration scenarios such as mining equipment, construction machinery, and vehicle chassis. Not suitable for soft base materials.

### 11. Square Taper Washer
**Structure:** A square washer with gradually changing thickness on one side and an inclined surface.

**Application:** Adapts to the inclined surface of channel steel. The surfaces of I-beams and channel steel profiles have a built-in inclination angle. Direct fastening would subject the bolt to bending load. Square taper washers are used to level the bearing surface. Often used in steel structure workshops and section steel support connections.

## II. Experience and Summary

### 2.1 Core Classification

**Basic fastening:** Flat washers enlarge the force-bearing area and protect the workpiece; concave-convex washers achieve anti-loosening through conical surface matching; square taper washers are specially designed for inclined surface assembly of channel steel.

**Elastic cushioning:** Wave washers and disc spring washers rely on their own elastic tension to provide shock absorption and anti-loosening.

**Anti-loosening and locking:** External tab lock washers prevent rotation by engaging into the keyway; internal-tooth conical lock washers achieve anti-loosening through tooth engagement; embossed disc spring washers increase friction through surface embossing; internal tooth lock washers grip the bolt or nut with internal teeth; conical external-tooth lock washers achieve high-strength anti-loosening through serrated engagement.

### 2.2 Selection Guidelines

For general assembly, flat washers are preferred due to their high cost-effectiveness and practicality.

For vibration conditions, choose disc spring or wave spring washers for cushioning and shock absorption.

For applications with high anti-loosening requirements, choose tooth lock washers or tab lock washers, which lock the nut through tooth-surface engagement or mechanical locking.

That's all for today's topic. If you have any questions or suggestions, would like to submit an article, or need to join our group for discussion, please leave a comment below or contact the editor.

 

 

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