Choosing the Right Washer

Flat washers spread clamping load over a wider area and protect the surface under the bolt head or nut. Use them on softer materials (aluminum, wood, plastic) to prevent crushing.

Fender washers are oversized flat washers — useful when the through-hole is larger than the bolt diameter, common in sheet metal work.

Split-lock washers create a friction connection by digging into the nut and the joint surface. They're cheap and common but largely ineffective above Grade 5.

Belleville (conical spring) washers maintain bolt tension through thermal cycling and vibration. Use them where joint clamp load matters more than absolute torque.