Cup Washer

A cup washer is a dished washer with a raised rim that spreads load and can centre a fastener. It is used with bolts or screws in furniture, panels and general assembly.

A cup washer is used to spread load and protect the surface under a fastener. It often sits under a nut or bolt head in general assembly work. It can be matched with a bolt or screw of the same thread and a nut where required.

Cup washers are often made in stainless steel 304, which gives good resistance to rust in indoor and mild outdoor conditions. This grade is not intended for salt water or strong chemicals.

This is a general guide to checking this kind of part. It says nothing about any supplier's parts.

Ask for a certificate of conformance for the material grade. On receipt, check the cup shape is even and the surface is free from burrs or cracks.