However, some types, such as the Cherry SPR® 3⁄32-inch Self-Plugging Rivet, are ideal for securing nutplates located in inaccessible and hard-to-reach areas where bucking or squeezing of solid rivets is unacceptable. To combat that problem, most friction-lock blind rivets are replaced by the mechanical-lock, or stem-lock, type of blind fasteners. Many friction-locked blind rivet center stems fall out due to vibration, which greatly reduces its shear strength. Metals used for these rivets are 2117-T-F aluminum alloy.

The excess portion of the stem breaks off at a groove due to the continued pulling action of the rivet gun. As the stem is drawn up into the rivet shank, the stem portion upsets the shank on the blind side, forming a plug in the hollow center of the rivet. Friction-locked blind rivets have a multiple-piece construction and rely on friction to lock the stem to the sleeve. The blind head is formed as the stem is pulled into the sleeve. For clarity, the word “stem” is used in this site and refers to the piece that is inserted into the hollow sleeve.įriction-Locked Blind RivetsStandard self-plugging blind rivets consist of a hollow sleeve and a stem with increased diameter in the plug section. The terms “mandrel,” “spindle,” and “stem” are often used interchangeably. NOTE: Fastener manufacturers use different terminology to describe the parts of the blind rivet. Since the exposed head of the rivet is held tightly against the outer sheet by the rivet gun, the sheets of metal are clamped, or clinched, together. This presses the inner sheet upward and closes any space that might have existed between it and the outer sheet.

When the pulling force of the rivet gun forces the blind head upward into the sleeve, its stem upsets or expands the lower end of the sleeve into a tail. This portion contains a tapered joining portion and a blind head that has a larger diameter than the stem or the sleeve of the tubular rivet. The lower end of the stem extends beyond the inner sheet of metal. Inserted within the rivet’s core is a stem that is enlarged or serrated on its exposed end when activated by a pulling-type rivet gun. The past decades have seen a proliferation of blind fastening systems based on the original concept, which consists of a tubular rivet with a fixed head and a hollow sleeve. NOTE: For metal repairs to the airframe, the use of blind rivets must be specifically authorized by the airframe manufacturer or approved by a representative of the Federal Aviation Administration (FAA).īlind RivetsThe first blind fasteners were introduced in 1940 by the Cherry Rivet Company (now Cherry® Aerospace), and the aviation industry quickly adopted them.

On aircraft control surfaces, hinges, hinge brackets, flight control actuating systems, wing attachment fittings, landing gear fittings, on floats or amphibian hulls below the water level, or other heavily stressed locations on the aircraft.

On aircraft in air intake areas where rivet parts may be ingested by the engine.

Therefore, blind rivets are usually not used when driven rivets can be installed. Typically, the locking characteristics of a blind rivet are not as good as a driven rivet. Although the shear loads of riveted joints are very good, the tension, or clamp-up, loads are less than ideal. There are also areas of high loads, high fatigue, and bending on aircraft.

In these instances, it is not possible to use solid shank rivets, and special fasteners have been designed that can be bucked from the front. There are many places on an aircraft where this access is impossible or where limited space does not permit the use of a bucking bar. To install solid shank rivets, the aircraft technician must have access to both sides of a riveted structure or structural part. For example, the attachment of many nonstructural parts (aircraft interior furnishings, flooring, deicing boots, etc.) do not need the full strength of solid shank rivets. Solid shank rivets have been the preferred construction method for metal aircraft for many years because they fill up the hole, which results in good load transfer, but they are not always ideal. Special purpose fasteners are designed for applications in which fastener strength, ease of installation, or temperature properties of the fastener require consideration.

Lockbolts industrial rivet