How safety pins are made

The safety pin was invented to pay off a $15 debt, and the inventor sold the patent for $400.

stations: 9
things upstream: 48
raw sources: 21
steps from the ground: 6

The short version

Automated lines make the whole pin. Spring-steel wire is straightened, cut and ground to a point, then a fourslide machine coils it around a spindle and bends a hook at the blunt end. A cap stamped from sheet steel meets the wire inside that same machine and is crimped on. Pins are usually plated in a rotating tank and finished with wax.

Straighten and cut wire

Coils of high-carbon spring-steel wire feed from spools into a roll straightener, which also chops it to length. Brass and stainless steel are the other common metals.

Goes in
Steel wire
Grind the point

Cut pieces drop from a hopper and press against grinding wheels, which taper one end to a point and take off nicks and burrs.
Coil around a spindle

A custom-tooled fourslide machine, able to move in four directions, picks the wires up on a chain and winds each around a spindle. That coil becomes the spring. A 1902 patent coiled the pin and slipped on a guard in one continuous operation.
Bend the hook

The same machine curls the dull end around into a hook, ready to take the cap.
Stamp the cap

Sheet steel feeds in from the other side. A die first cuts odd flat shapes, then a second stamping raises them into three-dimensional caps.

Goes in
Sheet steel
Crimp the pair

Sharpened wire and cap meet inside the machine, and the cap is crimped around the hook. The pin comes out formed with its clasp closed. Pins sold open cost more, since they nest and tangle in small batches.
Plate in a tank

Pins are loaded into perforated baskets. Steel is usually chromed and brass nickel-plated, in an electrically charged tank that rotates to shake the pins for an even coat.

Goes in
Nickel Chromium
Polish and wax

After a water rinse, a chemical bath gives the final polish. A detergent wash and a wax finish follow.
Box the pins

Industrial buyers usually get bulk boxes of 10 gross. Stores take polybags or blister packs.

End of the lineSafety pin

Worth repeating

Walter Hunt made his first safety pin from a piece of brass wire about 8 inches long.
An early ancestor, the fibula brooch, was used by the Mycenaeans between the 14th and 13th centuries BC.
A single factory can turn out over 3 million safety pins in a day.