Definition
The original, factory-formed heads on a solid rivet, as opposed to the shop head that is formed by the mechanic when the rivet is driven during installation.
Plain English
The pre-shaped end of a rivet that came already formed from the factory. The other end gets squashed into shape during installation by the person doing the riveting.
Context Anchor
Seen in aircraft sheet-metal repair, rivet inspection, and maintenance instructions.
Derivation
From 'manufacture,' Latin manu (by hand) + factus (made) -- literally 'made by hand,' now meaning made in a factory. The 'head' is simply the formed end of the fastener. The name distinguishes the factory-made end from the one formed later in the shop during installation.
Why Pilots Care
Pilots performing preflight or owner-permitted maintenance inspections need to recognize which end of a rivet is the manufactured head, because inspection criteria, allowable damage, and replacement decisions often depend on the condition of that specific end.
Analogy
Think of a rivet like a small metal nail with one finished end. The finished end is the manufactured head; the other end is formed after it is put through the parts.
Intuition Check
Do not read “heads” as people or sections of an engine here. In this context, heads are the enlarged ends of rivets, and “manufactured” means preformed before installation.
Example Sentence 1
Before driving the rivet, the mechanic seated the manufactured head flush against the skin so the bucking bar could form a clean shop head on the other side.
Example Sentence 2
Mechanics prefer manufactured heads when the overhaul limits have been exceeded on the existing set.