Plain flat round washers are the most common type of washer.
They are thin, flat discs with a central hole, used primarily to distribute the load of a threaded fastener (like a bolt or screw) across a wider surface area.
Key Functions
- Load Distribution: They prevent the bolt head or nut from digging into and damaging the material being fastened.
- Surface Protection: Washers provide a smooth bearing surface, which is crucial when working with soft materials like wood, plastic, or thin sheet metal.
- Clearance Bridging: They can bridge holes that are slightly larger than the fastener head or nut.
- Spacing: They can act as simple spacers in industrial or domestic assemblies.
Common Standards and Variations
Flat washers are typically manufactured according to specific international standards that define their exact dimensions:
Material Choices
- Steel (Zinc-Plated): The most common choice for indoor applications, offering basic corrosion resistance.
- Stainless Steel (A2/304 or A4/316): Essential for outdoor, marine, or chemical environments where rust prevention is critical.
- Nylon/Plastic: Used for electrical insulation or when a non-conductive, lightweight spacer is needed.
