Both the rivet nut and the materials to be fastened will affect the ultimate joint strength. The rivet nut body material selection would generally be the same as the material(s) being assembled i.e. an aluminium body into an aluminium section. A marked dissimilarity of materials may cause joint failure due either to material fatigue or galvanic corrosion.
The flat head rivet nut is appropriate for most applications including when soft or brittle materials are fastened to a rigid backing member. This will spread the load over a greater surface area. Where a flush surface is required, the countersunk head rivet style should be selected if there is enough material thickness to form a countersunk hole, slightly deeper than the head thickness of the rivet nut. If not, or the material is very thin material, then a reduced head version would be more suitable.
Hole size can be important in blind riveting. Too small a hole will, of course, make rivet nut insertion difficult and conversely too big a hole will cause a rivet nut to fail. Best practice is to follow the hole size recommendations provided in the technical data.
Joint Thickness (Grip Range)
Firstly, measure the total thickness of the materials to be joined. This determines the required “grip” of the rivet nut you select. Refer to the “Grip Range” column and select a rivet nut with a grip range that includes the thickness required. Please note, that insufficient rivet nut length will not allow proper deformation at the back of the work and could result in rivet nut failure.
Rivet Joint Strength
The single-joint tensile and shear values vary from application to application. The functions of total joint strength, fastener spacing, rivet nut body material and rivet nut diameter are all factors that result in the final shear and tensile strengths required. Refer to the technical data supplied for typical strength values.