How nails are made

In 1913, nine out of ten nails made were wire nails, and a machine still shapes each one in a blink.

stations: 6
things upstream: 48
raw sources: 14
steps from the ground: 8

The short version

A modern nail starts as a coil of steel wire. A machine straightens the wire, grips it, squeezes one end flat into a head and shears the other end to a point, all within a fraction of a second. The nails are then tumbled clean, often dipped in zinc or glue, and weighed into boxes.

Straighten and feed it in

The coil unwinds through a set of offset rollers that take out the curl. A feeder pushes exactly the right length of straight wire into the heading machine.

Goes in
Steel wire
Squeeze the head flat

Clamps hold the wire while a punch hits the protruding end under high pressure and spreads it into a head. The metal is simply pushed sideways, so nothing is cut away.
Shear the tip

A blade cuts the free end at an angle to leave a point. Other dies can press grooves or ridges into the shank for extra grip in wood.
Tumble them clean

Fresh nails spill into a rotating drum where they rub against each other and shed oil and burrs.
Dip against rust or slippage

Nails for outdoor use are galvanized with a skin of zinc. Others get a coat of glue-like cement that melts from friction as the nail is driven and then grips as it cools.

Goes in
Zinc Adhesive
Weigh and box

Nails are sold by weight and by length. Scales fill the boxes, or the nails are strung into collated strips for nail guns.

End of the lineNail

Worth repeating

By 1913, about 90 percent of manufactured nails were wire nails.
The word penny in nail sizes probably began in medieval England as the price of a hundred nails.
The Roman army left behind seven tons of nails when it abandoned the fortress of Inchtuthil in Scotland.