How door hinges are made

A top-grade butt hinge must pass 2.5 million open-and-close cycles to earn its rating.

stations: 7
things upstream: 42
raw sources: 18
steps from the ground: 6

The short version

Most butt hinges begin in a stamping press, where sheet metal feeds through dies that cut the leaves, punch the screw holes and countersinks, and shape the edges. Machining can tighten the pin fit. Each leaf's edge is rolled into knuckles, a pin joins the pair, and a finish such as plating goes on before samples face cycle testing.

Blank the sheet

Sheet or profile in stainless steel, brass or aluminum alloy is cut or blanked into flat pieces. Stamping comes first because it suits high volumes.

Goes in
Sheet steel Brass
Punch the screw holes

Dies form the leaf shape, screw holes, countersinks and edges. A stable die keeps batches matching, which matters when every hinge on a door has to line up.
Machine the tight spots

Where stamping is not accurate enough, cutters finish holes and slots and true up the surfaces that meet the pin or bearings.
Roll the knuckles

The edge of each leaf is rolled or formed into knuckles that interlock with those on the opposite leaf.
Join with the pin

The knuckles are matched up with a pin, and some models add bearings or bushings. This fit sets how the hinge feels and sounds, how fast it wears, and how well it resists sag.

Goes in
Steel wire
Finish the surface

The assembled body is polished, brushed, plated, passivated or powder coated. For hinges facing humidity or coastal air, this layer is what holds off corrosion.
Cycle-test samples

The ANSI and BHMA A156.1 standard covers cycle, wear, friction, strength, finish and dimensional checks on hinges.

2.5 million cycles for Grade 1

End of the lineDoor hinge

Worth repeating

Hinges of stone, marble, wood and bronze survive from antiquity, some going back to ancient Egypt.
One patent makes a self-closing hinge's pin from the leaf itself, curling the metal past 425° so no separate pin has to be fitted.
Ancient Egyptian doors swung on pivots that stuck out from the door's edge, either carved from the door or added as dowels.