![]() ![]() The countersunk rivet is primarily intended for use when aerodynamics smoothness is critical, such as on the external surface of a high-speed aircraft. This rivet is used where flushness is required because the rivet is flat-topped and undercut to allow the head to fit into a countersunk or dimpled hole. The countersunk head angle can vary from 60° to 120°, but the 100° has been adopted as standard because this head style provides the best possible compromise between tension/shear strength and flushness requirements. This action causes the rivet to expand about 11⁄2 times the original shaft diameter, forming a second head that firmly holds the material in place. ![]() Once placed in this predrilled hole, the bucktail is upset or deformed by any of several methods from hand-held hammers to pneumatically driven squeezing tools. To secure two or more pieces of sheet metal together, the rivet is placed into a hole cut just a bit larger in diameter than the rivet itself. Since rivets are permanently installed, they must be removed by drilling them out, a laborious task.īefore installation, the rivet consists of a smooth cylindrical shaft with a factory head on one end. Riveted joints are neither airtight nor watertight unless special seals or coatings are used. The longer the total grip length (the total thickness of sheets being joined), the more difficult it becomes to lock the rivet. Rivets should not be used in thick materials or in tensile applications, as their tensile strengths are quite low relative to their shear strength. They are faster to install than bolts and nuts since they adapt well to automatic, high-speed installation tools. Widely used in the aircraft manufacturing industry, solid shank rivets are relatively low-cost, permanently installed fasteners. Used to join aircraft structures, solid shank rivets are one of the oldest and most reliable types of fastener. The solid shank rivet is the most common type of rivet used in aircraft construction. For the purposes of this discussion, fasteners are divided into two main groups: solid shank rivets and special purpose fasteners that include blind rivets. Since some structural fasteners are common to all aircraft, this post focuses on the more frequently used fasteners. Structural fasteners, used to join sheet metal structures securely, come in thousands of shapes and sizes with many of them specialized and specific to certain aircraft. ![]()
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