Detailed inspection is likely to include examination of a cross-sectioned joint as this will allow assessment of the joint's interior features.
Prior to cross-sectioning, the exterior of the joint should be carefully examined: the way this can be carried out is explained in 'What should be checked during simple visual inspection of self-piercing riveted joints?'
The following points should be checked on the sectioned joint (see illustration):
- the joint should be symmetrical, indicating that there was no misalignment between the punch, die and sheets (1)
- there should be no gaps underneath the rivet head (2) and, ideally, none between the rivet and the sheets (3)
- the rivet tail should have flared properly so that it provides good mechanical interlock and there should be sufficient material around the foot of the rivet to give the button strength (4)
Specific quality requirements will depend on the particular application, as well as additional criteria such as allowable damage to any coating(s) used. Minimum rivet compression may also be defined.
In addition to examining the exterior and a cross-section, it may be considered necessary to obtain further information on joint quality by performing peel and shear tests.