In engineering, woodworking and construction, a nail is a pin-shaped, sharp object of hard metal or alloy used as a fastener. Formerly wrought iron, today's nails are typically made of steel, often dipped or coated to prevent corrosion in harsh conditions or improve adhesion. Ordinary nails for wood are usually of a soft, low-carbon or "mild" steel (about 0.1% carbon, the rest iron and perhaps a trace of silicon or manganese). Nails for concrete are harder, with 0.5-0.75% carbon.
Nails are typically driven into the workpiece by a hammer, a pneumatic nail gun, or a small explosive charge or primer. A nail holds materials together by friction in the axial direction and shear strength laterally. The point of the nail is also sometimes bent over or clinched after driving to prevent falling out.
Nails are made in a great variety of forms for specialized purposes. The most common is a wire nail. Other types of nails include pins, tacks, brads, and spikes.
Nails go back at least to the Ancient Roman period. The provision of iron for nails by King David for Solomon's Temple is mentioned in the Bible. Until the end of the 18th century, they were made by hand, an artisan known as a Nailer providing them with a head and point. Until the early 17th century there were workmen called Slitters who cut up iron bars to a suitable size for Nailers to work on, but in 1590 the slitting mill was introduced to England, providing a mechanical means of producing rods of uniform cross-section. In the 19th century, after the invention of machines to make "cut nails", some nails continued to be made by hand, but the handmade nail industry gradually declined and was largely extinct by the end of that century.
Manufactured cut nails were first introduced in America at the end of the 18th century. Cut nails are machine-cut from flat sheets of steel (originally iron). They are also called square nails because of their roughly rectangular cross section. Though still used for historical renovations, and for heavy-duty applications, such as attaching boards to masonry walls, cut nails are much less common today than wire nails.
Full article ▸