RIVET

headed pin or bolt used as a permanent fastening in metalwork; for several decades it was indispensable in steel construction. A head is formed on the plain end of the pin by hammering or by direct pressure. Cold riveting is practicable for small rivets of copper, brass, aluminum, iron, or steel, but the larger iron and steel rivets have to be heated to secure rapid and easy closing. The various shapes of rivet heads or tails include the countersunk head, which is beaten flush into a conical recess in the plate; the cup, or round, head; the pan head, which has sloping sides and a flat top; the conical head, with sloped sides ending in a point; and the thin flat head. Bifurcated rivets for belts and harnesses have thin heads, but the tails are split and opened like a paper fastener. Often gas or electric welding has been substituted for riveting in the case of hollow ware and other sheet-metal products. Electric welding has increasingly displaced riveting as a method for connection of structural members such as columns and beams in building construction. Rivets in which an explosive charge is used to set the tail are sometimes employed where the tail is not easily accessible, as in riveting the aluminum skin onto airplane wings.