Rivets are mechanical fasteners made up of a cylindrical shaft with a head at one end. They are installed into pre-drilled holes in metal, plastic, leather or other materials. Then, the end of the rivet is deformed so that it holds the rivet in place. Rivets come in a number of different types, which are suitable for specific uses.
Also called blind rivets, pop rivets are tubular, and have a mandrel in the middle. A specially designed tool is used to set these rivets. It expands one end of the rivet, popping off the mandrel. These rivets are easy to install, especially when it's only possible to access the joint from one side of the material. Unfortunately, they are also less strong and more prone to corrosion than other types of rivet. Pop rivets are more likely to fail than solid or speciality rivets. Pop rivets are suitable for joining thin pieces of metal and plastic.
Cold rivets are generally used to join steel or other metal plates. At one time, they were common in heavy industry, but they have largely been replaced by welding and brazing. Unlike pop rivets, these are solid throughout, which allows for greater strength. Cold rivets come in a number of different shapes, depending on whether it's appropriate for the rivet head to be visible. They work well to join small metal plates. Cold rivets must be installed using a rivet set, a special metal tool that flattens the end of the rivet.
Hot rivets are the most difficult to install, but provide the strongest joint. They are similar to cold rivets, but must be heated before setting them into place. The end of the hot rivet is flattened with a hammer or rivet set. As the metal in the rivet cools, it also contracts, pulling the joined materials together. This makes the joint stronger than that provided by a cold rivet. Hot rivets were once popular for use on large buildings and other steel structures, but have fallen out of favour. They are still used in making steel cars, tanks and in some structural steel projects. Modern hot rivets are usually set with an automatic machine called a rivet buster.