Rivet Selection: Factors to Consider

This illustration provides a graphic representation of the selection factors described in greater detail in the accompanying text.

1. Joint strength
First determine the single-joint tensile and shear values required for the application. These are functions of total joint strength, fastener spacing, rivet body material and rivet diameter. Then refer to the "Shear" and "Tensile" columns on the product, and select a POP brand rivet that provides the values required. "POP" brand rivets are not certified for structural aerospace applications and such use is not recommended.

2. Joint thickness
Measure the total thickness of the materials to be joined. This determines the required "grip" of the rivet you select. Refer to the "Grip Range" column and select a rivet with a grip range that includes the work thickness required. Remember that insufficient rivet length will not allow proper formation of the secondary head at the back of the work.

3. Nature of materials
Both the rivet and the materials to be fastened will affect the ultimate joint strength. As a general rule, the rivet materials should have the same physical and mechanical properties as the materials to be fastened, because a marked dissimilarity may cause joint failure due either to material fatigue or galvanic corrosion.

4. Hole size
Hole size can be important in blind riveting. Too small a hole will, of course, make rivet insertion difficult. Too large a hole will reduce the shear and tensile strengths and it may even cause bulging or separation of the members by allowing the rivet to expand between them instead of on the blind side. Best practice is to follow the hole size recommendations provided. Also, avoid burrs in and around the holes.

5. Head Style
The low-profile dome head is appropriate for most applications. However, when soft or brittle materials are fastened to a rigid backing member, the large flange head should be considered, because it offers twice the bearing. surface. Where a flush surface is required, the countersunk head style should be selected.