Common rivet nuts generally include compression nuts and pull nuts. Compression nuts are commonly used in automobiles because of their high resistance to twisting and unbending.
1) Structural Elements and Forms of Compression Nuts
Compression nuts are available in various connection styles: embedded serrations, rivet-pressed and rolled-up serrations, and holeless serrations. Embedded serrations are round in shape, with embossed serrations and guide grooves on one end. The serrations are pressed into a prefabricated hole in the sheet metal. The diameter of the prefabricated hole is smaller than the outer diameter of the nut's embossed serrations. The nut's serrations are pressed into the sheet metal, causing plastic deformation around the prefabricated hole. The deformed material is then forced into the guide groove, creating a locking effect. These nuts are generally used for connecting thinner sheet metal.
Rolled-up nuts deform along with the sheet metal during riveting, creating a secure connection and can be used for thicker sheet metal.
Non-hole serrations, also known as self-piercing serrations, penetrate the sheet metal directly at the desired location and securely rivet. They are generally used for connecting thinner sheet metal.
2) Structural Elements and Forms of Pull Rivet Nuts
Pull rivet nuts come in a variety of structural forms, suitable for different applications. The following are commonly used types: ① Spline Body
Compared to standard rivet nuts, they offer improved torsional resistance in softer material applications.
Used on substrates such as aluminum, magnesium, plastics, composites, and wood.
② Hexagonal Body
Compared to round and splined rivet nuts, the hexagonal cross-section and hole improve component torque through form-locking.
Automotive chassis components require high resistance to cornering under vibration loads.
③ Large Flange
Provides a large bearing surface for use in thin plates and soft materials, and is installed in locations requiring high push-out forces.
④ Square Body
Compared to round and splined rivet nuts, the square cross-section and hole improve component torque through form-locking due to the larger contact surface.