Self-piercing rivets (SPR) join two or more pieces of material using a rivet without a pre-drilled hole. They are a semi-tubular rivet driven at high force through the material layers to be joined, into a die which causes the tail of the rivet to flare out and form a joint.
The process requires no hole preparation and delivers high static strength similar to, or better than, spot welding. This process produces a fatigue resistant joint that is stronger than spot welding and less susceptible to corrosion.
The use of coated, lightweight and high-strength materials, such as galvanized or pre-painted steel, and aluminum makes welding these materials difficult and often not possible.
Self-Piercing rivets use a special tool that presses the rivet into place and requires access to both sides of mating panels.