HOW NAILS ARE MADE

1. HOW NAILS ARE MADE

2. A nail consists of a metal rod or shank, pointed at one end and usually having a formed
head at the other, that can be hammered into pieces of wood or other materials to
fasten them together. A nail is usually made of steel, although it can be made of
aluminum, brass, or many other metals. The surface can be coated or plated to improve
its corrosion resistance, gripping strength, or decorative appearance. The head, shank,
and point may have several shapes based on the intended function of the nail.
Nails are divided into three broad categories based on their length. In general nails
under 1 inch (2.5 cm) in length are called tacks or brads. Nails 1-4 inches (2.5-10.2 cm)
in length are called nails, while those over 4 inches (10.2 cm) are some-times called
spikes. These categories are roughly defined, and there is considerable crossover
between them. The length of a nail is measured in a unit called the penny
Design
Most nails have a broad, circular head. Finishing nails have a narrow, tapered head
which allows them to be countersunk below the surface of the material and covered
over to produce a smooth finish. Upholstery nails have decorative heads. Double-
headed nails are used to fasten wood forms used in concrete pouring. The nail is driven
in up to the first head, leaving the second head protruding. The protruding head allows
the nails to be easily removed and the forms quickly dismantled once the concrete has
hardened.
Most nails, called common nails, have a relatively large diameter. Box nails, originally
used to make thin-walled boxes, have a smaller diameter shank than common nails.
Finishing nails have a very small diameter shank in order to make the smallest hole
possiblity
Raw Materials
Most nails are made of steel. Aluminum, copper, brass, bronze, stainless steel, nickel
silver, monel, zinc, and iron are also used. Galvanized nails are coated with zinc to give
them added corrosion resistance. Blued steel nails are subjected to a flame to give
them a bluish oxide finish that provides a certain amount of corrosion resistance. So-
called cement-coated nails are actually coated with a plastic resin to improve their grip.
Some brads are given a colored enamel coating to blend in with the color of the material
they are fastening.

3. The Manufacturing Process
Most nails are made from coils of metal wire. The wire is fed into a nail-making machine
which can produce up to 700 nails per minute. The nails may then be further twisted or
formed, cleaned, finished, and packaged.
Forming
 1 Wire is drawn from a coil and fed into the nail-making machine where it is
gripped by a pair of gripper dies. The shape of the head of the nail has been
machined into the end of the dies.
 2 While the dies clamp the wire in place, the free end of the wire is struck by a
mechanical hammer. This deforms the end of the wire into the die cavity to form
the head of the nail.
 3 With the wire still clamped in the dies, a set of shaped cutters strike the
opposite end of the nail, forming the point and cutting the nail free from the rest
of the wire coming off the coil.
 4 The dies open and an expelling mechanism knocks the nail into a collection
pan below the machine. The free end of the wire is drawn from the coil and fed
into the machine. The cycle then begins again.
Additional forming
 5 Nails with helical twists, serrations, or other surface configurations are fed into
other machines that roll, twist, stamp, or cut the required forms. This may be a
purely mechanical process or may require heating the material before forming.

4. Finishing
 6 The nails are cleaned in a rotating barrel filled with hot caustic soda.
This removes any oil from the forming machine and cleans up any small metal
scraps, or nippings, that might be clinging to the nails.
 7 Many nails are given a final bright finish before being packaged. This is
accomplished by placing the nails in a rotating drum of hot sawdust to lightly
polish the surface of the nails. Other nails may be passed through an open flame
in an oven to give them a blued finish. Galvanized nails are dipped into a tank of
molten zinc in a process called hot-dip galvanizing. A zinc coating may also be
applied by heating the nails to about 570°F (300°C) in a closed container filed
with a powder composed of zinc dust and zinc oxide. Other coated nails are
either dipped or sprayed to obtain their final finish.
 8 Depending on the tolerances desired, some specialty nails may also require an
additional heat treating step.
Packaging
 9 Magnetic elevators convey the finished nails to weighing machines which drop
them into open cardboard boxes. As they are dropped in, a magnetic field aligns
them so they stack in neat rows. After they are packaged, the nails are
demagnetized. Nails are usually sold in boxes of 1, 5, 10, 25, and 50 pounds.
Smaller nails, such as brads, are sold in 2-ounce or 4-ounce boxes and are
packaged without being magnetically aligned.

5. Quality Control
Raw materials must meet certain standards for chemical composition, yield strength,
hardness, corrosion resistance and other properties. These are usually certified by the
company supplying the wire, and may be independently checked by the nail
manufacturer.
During manufacture, nails must also meet certain specifications regarding dimensions
and properties. These are achieved using a method known as statistical process
control, which periodically samples the dimensions and properties of the nails being
produced and evaluates any changes through statistical analysis techniques.

6. An original 7" (180mm) long Roman nail found in Scotland
A replica of the hand made nails found on board the 'Mary Rose'
A Décor nail used mainly for studding on doors
The bronze nail specially made for the 'Matthew'