Double stack self-locking washers in different sizes for anti-loosening fastening

Double stack self-locking washer with radial serrations for anti-loosening fastening

Wedge Lock Washer (Two-Piece Self-Locking Type)

Double Stack Self-Locking Washer

The Double Stack Self-Locking Washer is an advanced fastening solution designed to prevent loosening under vibration, shock, or dynamic loads. With a unique serrated surface and paired design, this washer ensures secure locking without additional adhesives or re-tightening. It is widely applied in automotive, aerospace, heavy machinery, wind power, and bridge construction projects, where safety and reliability are critical.

What Is a Double Stack Self-Locking Washer?

A double stack self-locking washer consists of two matched washers with interlocking serrations on the contact surfaces. When tightened, the serrations generate a wedge-locking effect that resists loosening caused by vibration or load variation.

Compared with conventional spring washers, this anti-loosening washer maintains preload more effectively and supports repeated installation without loss of locking performance, making it suitable for high-vibration fastening environments.

Production Process of Double Stack Self-Locking Washer

At Weforging, every Double Stack Self-Locking Washer is produced through a precise, multi-step process that ensures performance, strength, and durability.

Material Preparation – Premium alloy steel wire or billet is selected for its strength, ductility, and wear resistance. The material undergoes strict inspection before processing.
Cold Forging – Using high-pressure cold forging, each washer is shaped with accurate geometry and uniform grain flow, improving mechanical integrity and dimensional precision.
CNC Machining – The serrated contact surfaces are precisely machined and matched to guarantee perfect interlocking between the upper and lower washers.
Heat Treatment – Controlled quenching and tempering enhance hardness and resilience, ensuring stable locking performance even under vibration or repeated loading.
Surface Treatment – Protective coatings such as phosphating or Dacromet are applied to increase corrosion resistance and smooth assembly operation.
Inspection and Testing – Every washer pair is verified through torque, dimensional, and anti-loosening tests to confirm consistent quality and reliable performance.

Advantages of Double Stack Self-Locking Washer

Weforging’s self-locking washers combine cold forging precision and CNC machining accuracy to deliver reliable fastening performance:

Effective anti-loosening performance under vibration and dynamic loads
Stable preload retention without adhesives or secondary locking components
High dimensional accuracy for consistent assembly fit
Enhanced corrosion resistance for harsh environments
Suitable for repeated installation and long service life

Technical Specifications & Custom Options

Below are the typical specifications of double stack self-locking washers. Custom dimensions and performance requirements are available upon request.

Serrated Washer Specifications

Parameter	Range / Option
Outer Diameter (OD)	10 mm – 200 mm
Inner Diameter (ID)	Custom
Thickness	1 mm – 10 mm
Serration Type	Single-sided / Double-sided
Material	Carbon Steel / Alloy Steel / Stainless Steel
Heat Treatment	Quenched & Tempered / Carburized
Surface Treatment	Zinc Plating / Black Oxide / Phosphate
Hardness	HRC 25–45 (Customizable)
Standard	DIN / ISO / Custom Drawing

Manufacturing Process Comparison

Process	Forged (Weforging)	Stamped
Strength	High (optimized grain flow)	Medium
Fatigue Resistance	Excellent	Moderate
Surface Quality	Superior	May have burrs
Dimensional Accuracy	High	Medium
Customization	Flexible	Limited
Application	Heavy-duty / vibration	General fastening

OEM & Custom Options

Size Range: Customized according to bolt size and assembly requirements
Materials: Alloy steel, carbon steel, stainless steel, or specified grades
Surface Treatments: Phosphated, Dacromet, zinc plating, or customer-specified coatings
Standards: DIN, ISO, or drawing-based production
OEM / ODM: Supported for custom dimensions, performance targets, and batch production

Applications of Double Stack Self-Locking Washer

Designed for high-vibration and safety-critical environments:

Automotive Industry – Engine mounts, suspension joints, braking systems
Heavy Machinery & Construction Equipment – Excavators, loaders, hydraulic systems
Wind Energy & Power Systems – Turbine hubs, generator assemblies
Marine & Offshore Engineering – Pumps, gearboxes, deck structures
Industrial Equipment & Automation – Robotic systems, precision assemblies

Why Choose Weforging?

As a professional self-locking washer manufacturer, Weforging integrates forging, CNC machining, heat treatment, and inspection within one quality-controlled production system. Each washer set is verified through mechanical and dimensional testing to ensure stable locking performance.

With extensive experience serving global OEM customers in automotive, energy, and heavy equipment industries, Weforging delivers fastening components designed for reliability, consistency, and long-term service.

Contact

Not sure which washer design fits your application?

Send us your drawing, bolt size, or working conditions — we’ll review and suggest a suitable solution based on load, vibration level, and environment.

👉 Typical response time: within 24 hours
👉 Engineering support available for custom designs

No pressure — just a practical recommendation to help you evaluate options.

What is the difference between a self-locking washer and a spring washer?

A self-locking washer uses precision serrated surfaces to create a mechanical locking effect that resists loosening under vibration and dynamic loads. This design helps maintain stable preload through repeated service cycles. Spring washers rely on elastic deformation to provide tension, which is commonly used in general fastening applications. For assemblies exposed to continuous vibration or load variation, self-locking washers are often selected for their consistent locking performance.

Are double stack self-locking washers suitable for high-vibration applications?

Yes. Double stack self-locking washers are designed for high-vibration and dynamic load environments. The paired washer structure and interlocking serrations create a wedge-locking effect that helps prevent loosening caused by shock or repeated movement. They are commonly used in automotive systems, heavy machinery, wind energy equipment, and other applications where fastening stability is critical.

Can self-locking washers be reused?

Self-locking washers are designed to support repeated installation under controlled conditions. When the serrated surfaces and overall geometry remain within specification, they can maintain effective locking performance. For critical assemblies, inspection after disassembly is recommended to confirm surface condition and dimensional integrity before reuse.