Blind Fasteners & Rivets Flashcards

A 'Rivnut' (threaded insert or nutsert) is classified as a blind fastener because:

Answer: It is installed by pulling a threaded mandrel that deforms the insert body from one side, creating a nut thread

A threaded insert (Rivnut/nutsert) is set by rotating and pulling a mandrel that collapses the insert body to grip the back of the panel, creating a reusable threaded hole from one side.

According to IFI and industry standards, a blind rivet's nominal diameter is measured:

Answer: By the body (shank) outer diameter before installation

The nominal diameter of a blind rivet refers to the outer diameter of the unset rivet body (shank), which corresponds to the drill size used for hole preparation.

What failure mode is most likely when a blind rivet is installed in a joint that exceeds the rivet's maximum grip range?

Answer: The rivet body will not fully collapse, leaving the joint under-clamped with a loose mandrel stub

When the material stack exceeds the maximum grip, the rivet body does not deform enough to clamp the joint properly, resulting in a loose connection and a protruding or improperly broken mandrel.

Which military or aerospace specification is commonly referenced for solid (non-blind) aluminum aircraft rivets, providing a baseline to which blind rivet specifications are often compared?

Answer: MS 20470 (AN470)

MS 20470 (also known as AN470) covers the universal head solid aluminum aircraft rivet that is a foundational standard in aerospace fastening, distinguishing it from blind rivet specs.

A 'drive rivet' (or hammer-set rivet) differs from a pull-type blind rivet in that it is set by:

Answer: Driving a pin into the rivet body with a hammer or press, expanding the blind end

Drive rivets are set by hammering or pressing a pre-installed pin into the rivet body, causing the blind end to splay and clamp the joint without needing a pull-type tool.

For a tri-fold (3-leg) blind rivet design, what is the main engineering advantage over a standard single-bulge design?

Answer: The three-petal blind-side flange distributes the clamp load over a larger area, improving performance in soft or thin materials

The three folding petals of a tri-fold rivet create a wider bearing footprint on the blind side, reducing stress concentration and preventing pull-through in soft substrates like plastics or thin sheet metal.

When inspecting a completed blind rivet installation, which visual indicator suggests the rivet has been properly set?

Answer: The mandrel head is flush with or slightly below the rivet head face, with a fully formed blind-side bulge

A properly set blind rivet will have the mandrel fractured at or just below the rivet head surface and a fully formed upset bulge on the blind side indicating correct clamp-up.