A Plain Washer, also commonly known as a flat washer, is one of the most widely used fastening components in industrial and construction applications. Designed with a simple circular shape and a smooth flat surface, a flat washer is installed between the fastener (bolt or nut) and the contact surface. Because of its versatility, durability, and cost-effectiveness, the flat washer is an essential component in mechanical systems, building structures, automotive assembly, electrical equipment, and general manufacturing.

Functions and Applications of Flat Washer

The primary function of a flat washer is to evenly distribute the load applied by a bolt, screw, or other fastener across a broader surface area. By spreading the pressure, a flat washer helps protect the underlying material—especially softer substrates like wood, plastic, or softer metals—from deformation or damage. In addition to load distribution, flat washers can serve as spacers to adjust height or alignment, provide a stable bearing surface, and minimize friction between the fastener and the connected parts. These combined functions help improve joint stability and extend the service life of the fastening assembly.

Thanks to these functional advantages, the flat washer is widely used in:

• Construction and steel structures

• Automotive and transportation equipment

• Industrial machinery and heavy equipment

• Electrical and electronic installations

• Energy, railway, and infrastructure projects

Whether used in light-duty or heavy-duty environments, a high-quality flat washer significantly improves fastening performance and connection safety.

Differences Between DIN 6796, DIN 125A, and F436

1. DIN 6796 — High-Load Disc Spring Washer

Type: Disc spring washer (also called conical washer or Belleville washer)

Function: Provides high spring force and excellent anti-loosening capability under dynamic loads.

Typical Applications:

Heavy machinery, hydraulic systems, railway equipment, electrical connections, and bolted joints requiring reliable preload retention.

2. DIN 125A — Standard Flat Washer

Type: Flat washer

Function: Distributes load and protects surfaces.

Typical Applications:

General machinery, construction, furniture, automotive assembly, and standard bolted joints.

3. F436 — Hardened Structural Flat Washer

Standard: ASTM F436 (U.S. structural standard)

Type: Hardened structural flat washer

Function: Supports high-strength bolts in structural applications.

Typical Applications:

Steel structures, bridges, buildings, towers, heavy construction, and railway structural assemblies.