In the MS20 455 AD 4-8 rivet, what does 455 indicate?

In the designation of the MS20 455 AD 4-8 rivet, the "455" specifically refers to the shape of the head of the rivet. This number indicates that the rivet has a brazier head. A brazier head design features a low dome shape, which provides a larger bearing surface compared to other head styles and is useful for applications requiring a strong connection without significant protrusion above the surface.

Understanding the different rivet head shapes is crucial as they influence the rivet's application in aircraft construction and maintenance. For example, flat heads and countersunk rivets are designed for flush applications, while round heads are typically used where a more conventional fastening method is acceptable. The use of a brazier head, as represented by "455," indicates a particular usage scenario where the dome shape improves the structural integrity of the joint, especially in circumstances where surface smoothness is not as critical.