Custom Locking Tab Washers DIN 432 High Strength Superior External Tab Washer

What are Locking Tab Washers?

Locking tab washers are specialized fastener security components designed to prevent nuts, bolts, and other fasteners from loosening under vibration or rotational forces. These washers feature protruding tabs that can be bent upward against the flat sides of a nut or against a fixed surface, creating a positive mechanical lock that maintains clamping force and prevents unintended rotation. Unlike chemical threadlockers, locking tab washers provide a visible, reusable, and vibration-resistant locking solution that doesn’t require precise torque measurement for effectiveness.

Materials

Locking tab washers are manufactured from various materials to meet different environmental and mechanical requirements:

• Carbon Steel: The most common material, offering high strength and durability for general industrial applications

• Stainless Steel (typically 304 or 316 grade): Provides excellent corrosion resistance for marine, food processing, and chemical environments

• Brass: Used in applications requiring non-magnetic properties or compatibility with plumbing systems

• Phosphor Bronze: Offers superior spring properties and fatigue resistance for high-vibration applications

• Aluminum: Selected for lightweight applications in aerospace and transportation industries

Surface Finishes

Surface treatments enhance corrosion resistance and sometimes provide aesthetic benefits:

• Zinc Plating: Most common finish, often with yellow, blue, or clear chromate conversion coating for added protection

• Hot-Dip Galvanizing: Provides thick, durable coating for harsh outdoor environments

• Nickel Plating: Offers good corrosion resistance and an attractive silver appearance

• Black Oxide: Provides mild corrosion resistance and reduces light reflection

• Cadmium Plating: Excellent corrosion protection though less common due to environmental concerns

• Passivation: Chemical treatment for stainless steel that enhances the natural protective oxide layer

• Plain/Unfinished: Raw material without coating, typically used in non-corrosive environments

Specifications

Locking tab washers are characterized by several key dimensional and design attributes:

• Inner Diameter: Must match the bolt or stud diameter precisely

• Outer Diameter: Determines the bearing surface and tab placement

• Thickness: Affects strength and bending characteristics of the tabs

• Number of Tabs: Typically 2-4 tabs, though single-tab designs exist for specific applications

• Tab Configuration: Can feature symmetrical or asymmetrical tab placement

• Material Thickness: Ranges from light-duty (0.8mm) to heavy-duty (3mm+) versions

• Standards Compliance: Often manufactured to DIN 463, ANSI B18.21.1, or other industry standards

• Temperature Rating: Varies by material, with stainless steel offering the highest temperature tolerance

Application Fields

Locking tab washers serve critical roles across numerous industries:

• Automotive and Transportation: Securing wheel bearings, axle nuts, and drivetrain components

• Aerospace: Fastening critical components in aircraft control systems and engines

• Industrial Machinery: Locking bearings, gears, and pulleys on shafts in manufacturing equipment

• Marine and Offshore: Preventing corrosion-related failure in saltwater environments

• Rail Industry: Maintaining fastener integrity in track systems and rolling stock

• Energy Sector: Securing components in wind turbines, generators, and oil field equipment

• Construction: Ensuring structural connections remain secure in buildings and infrastructure

An Excellent Case: Wind Turbine Blade Pitch System

A wind turbine manufacturer was experiencing premature failures in their blade pitch control systems. These critical systems adjust blade angle to optimize energy capture and protect the turbine during high winds. The constant vibration and reversing loads were causing the main retention nuts to loosen, leading to inaccurate blade positioning and potential safety hazards.

The engineering team implemented a solution using high-grade stainless steel locking tab washers with a passivation finish to withstand the harsh outdoor environment. The washers were specially designed with four asymmetrical tabs to provide maximum locking force in both rotational directions.

During assembly, technicians torqued the main pitch bearing nuts to specification, then bent two opposing tabs firmly against the nut’s flats and the remaining two against mounting holes in the bearing housing. This created a positive mechanical lock that prevented any rotational movement.

The results were exceptional. The locking tab washers completely eliminated nut loosening issues, extending maintenance intervals from every 6 months to over 3 years. The visible inspection feature allowed maintenance crews to quickly verify proper locking during routine checks. This solution significantly reduced downtime, improved safety, and increased energy production by maintaining optimal blade positioning, demonstrating the remarkable effectiveness of properly specified locking tab washers in demanding applications.