A rivet is a mechanical fastener composed of a head on one end and a cylindrical stem on another (called the tail) which has the appearance of a metal pin.
When installed the rivet is either drilled, placed or punched into a hole, afterwards the tail is then deformed, holding the rivet in place.
The rivet is deformed by pounding or smashing of the tail, which makes the material flatter and usually causes the tail to be expanded by about one and a half times the size of the stem's original diameter.
When finished the tail has the appearance of a dumbbell shape completing the riveted joint.
Riveting can create either lap or butt joints with a variety of different rivet configurations, including single, double and zig-zag formations.
There are eight widely used types of rivets, which include:
- Blind rivets (also known as hollow or pop rivets) – These are used when it isn't possible to see the other side of a join. This type of riveting is very fast to apply and is used in a variety of sectors including aerospace, shipbuilding and electronics.
- Drive rivets – This type of blind rivet has a short mandrel which protrudes from the head and is driven in with a hammer causing the end inserted into the hole to flare.
- Flush rivet – Used for external surfaces to provide a good appearance and eliminate aerodynamic drag, this type of rivet uses countersunk heads and a countersunk hole and are also called countersunk rivets.
- Friction-lock rivet – Available as countersunk or dome shaped, these early forms of blind rivet where the first to be widely used in aerospace applications these rivets resemble an expanding bolt.
- Oscar rivets – Similar to blind rivets, Oscar rivets have splits along the hollow shaft. These splits, which usually come in sets of three cause the shaft to bend and flare outwards as the mandrel is drawn into the rivet. The flare creates a wide surface which reduces the chance of the rivet being pulled out.
- Self-piercing rivets – These rivets do not need a drill or punched hole as the end includes a chamfered poke to pierce materials to be joined. Self-piercing rivets go through the top sheet of material but do not fully pierce the bottom sheet, creating a water or gas-tight joint.
- Solid rivets (also known as round head rivets) – A technique that goes back to the Bronze Age, making this one of the oldest and also one of the most reliable types of fasteners.
- Structural steel rivets – This type of rivet was widely used to join structural steels, but has been largely replaced by the use of high-strength bolts as they do not require skilled workers to install and tighten these bolts.
A pop rivet is also known as a blind or hollow rivet and is used where you are only able to work with one side of the rivet. A special pop rivet gun or tool pulls the mandrel head into the body of the rivet, which then expands against the blind side of the join. Once it meets the face of the join’s blind side the mandrel snaps, causing the stem to eject to create a tight joint. A pop rivet can be used as a replacement for nuts and bolts, screws, welds and adhesives.