DIN6796

Characteristics and Advantages of Using Stainless Flat Washers

Stainless Flat Washers is often discussed alongside flat washers due to its frequent use in high-strength bolted joints, but it is important to clarify its role. DIN 6796 defines a conical spring washer , not a flat washer. Unlike flat washers, DIN 6796 washers are designed to provide elastic preload and resistance against loosening under dynamic loads.

Key characteristics of DIN 6796 include:

A conical shape that generates axial spring force when compressed

High load capacity suitable for structural and heavy-duty applications

Typically manufactured from hardened carbon steel with controlled heat treatment

The main advantage of using DIN 6796 washers is their ability to maintain bolt tension under vibration, thermal expansion, or cyclic loading. In contrast, flat washers are primarily load-distribution components and do not offer active locking or spring behavior. In many fastening systems, flat washers and DIN 6796 washers are used together: the flat washer protects the surface and spreads the load, while the DIN 6796 washer provides elastic compensation and preload retention.

Understanding this distinction helps prevent incorrect washer selection and ensures the fastening system performs as intended.

Key Dimensional Parameters of a Flat Washer

The performance of a Stainless Flat Washer is directly influenced by its geometry. Three primary dimensional parameters define its function:

Inner Diameter (ID)

The inner diameter must match the bolt or screw size with appropriate clearance. An excessively large ID reduces load transfer efficiency, while an overly tight ID can cause installation issues or misalignment. Proper ID tolerance ensures smooth assembly and concentric load distribution.

Outer Diameter (OD)

The outer diameter determines the effective contact area between the washer and the clamped surface. A larger OD spreads the load over a wider area, reducing surface pressure and preventing material deformation, especially on softer substrates such as aluminum, wood, or plastics. 

Thickness

Washer thickness affects stiffness and bearing capacity. Thicker flat washers offer higher resistance to bending and surface embedding under load. In high-load or structural applications, increased thickness improves joint stability and reduces long-term settlement.

In addition to these dimensions, flatness, parallelism, and edge quality are critical for ensuring even load transfer and consistent fastening performance.

FAQ

Q1: What are flat washers NOT designed to do?

A1: Flat washers are not locking devices . They do not prevent loosening caused by vibration, impact, or cyclic loads. Without additional locking elements—such as spring washers, lock washers, or thread-locking methods—a flat washer alone cannot maintain preload in dynamic conditions.

Q2: What are the limitations of flat washers in dynamic loads?

A2: Under vibration or repeated load cycles, flat washers offer no elastic compensation. As bolt tension relaxes due to material creep or joint movement, flat washers cannot recover or maintain clamping force. This limitation makes them unsuitable as the sole washer in applications involving machinery, vehicles, or structural assemblies exposed to continuous motion.

Q3: When should flat washers be replaced by special washers?

A3: Flat washers should be replaced or supplemented when:

The joint is subject to vibration or shock loads

Preload retention is critical

Thermal expansion or contraction is expected

Surface hardness mismatch could lead to embedding or loosening

In such cases, spring washers, conical washers (such as DIN 6796), or other specialized locking washers provide better long-term fastening reliability.