A rivet is a fastening device that consists of a shaft with a head at one end. The shaft is put through holes that have been pierced in the material to be joined, and a second head is formed on the rivet, usually by squeezing or hammering. Rivets of various sizes and forms are used in making seams or joints in materials that range from cardboard and cloth to steel girders and plates.
Small rivets of steel, copper, or aluminum are widely used in sheet-metal work and in leathercraft. For each rivet a hole is punched or drilled through the layers of material to be joined. The rivets are then put through the holes, and the work is placed with the heads of the rivets bearing down on a firm surface. A tool called a rivet set or a setting punch is placed over each rivet in turn. Tapping the rivet set with a hammer brings the rivet head and the layers of material close together to ensure a firm joint. The end of the rivet is then upset, or slightly flattened, by the hammer. Finally, a heading die, usually part of the rivet set, is placed over the rivet and is hammered to form the second head.
Large steel rivets are used in shipbuilding, building construction, and the manufacture of boilers. These rivets are heated immediately before use to make them malleable. The second head is formed by a powered riveting hammer. However, in some assemblies the end of the rivet is inaccessible, requiring the use of so-called blind rivets. One type of blind rivet contains a small explosive charge in its end. After the rivet is in place, the charge is set off by a hot wire inserted through a hole in the rivet. The explosion causes the end of the rivet to expand, thereby forming the second head.