shop head

A shop head is the larger end of a rivet as it leaves the manufacturing process, formed by upsetting (compressing and enlarging) the end of a wire rod or bar stock. It contrasts with the point or tail end, which remains relatively thin and sharp. In rivet terminology, the shop head is the formed end, made intentionally larger to provide bearing surface and grip, while the field end is what gets installed and formed further at the assembly site.

Most solid rivets come from the factory with one shop head already formed and one end ready to be driven. The shop head is typically hemispherical, conical, or countersunk in profile, depending on the rivet type and application. The diameter of the shop head is always larger than the shank diameter; this difference allows the rivet to grip two or more overlapping metal sheets when the field end is driven and deformed around it.

Why the name matters

The term "shop head" originated to distinguish the factory-made end from the head formed during assembly by the rivet gun or hammer. A worker would receive rivets with one shop head ready to go and would drive the other end, creating a field head or installation head. This naming convention survives because a single rivet can only have one pre-formed head; describing which end is which prevents mistakes in assembly.

Rivet specifications always cite shop head diameter, shank diameter, and length. A typical aircraft rivet might have a shop head of 0.375 inches (9.5 mm) with a 0.125 inch (3.2 mm) shank. The shop head must be strong enough to resist deformation during handling and installation, yet the upset material itself must remain ductile enough that the shank deforms cleanly without the head cracking.

Defects in the shop head, such as incomplete upsetting, surface cracks, or off-center formation, are caught during manufacturing inspection because they affect how the rivet will perform. A malformed shop head may slip through overlapping materials or fail to transfer force correctly to the field end as it is driven, resulting in poor clamping or joint separation over time.