Self-piercing riveting is a high-speed mechanical fastening process for point joining sheet material, typically steels and aluminium alloys. It is a single-step technique, generally using a semi-tubular rivet to clinch the sheets in a mechanical joint. There is also a process variant which utilises solid rivets.
As the name suggests, pre-drilled holes are not required, allowing the joint to be made rapidly in one operation. The process cycle is shown in cross-section below.
The process starts by clamping the sheets between the die and the blankholder. The semi-tubular rivet is driven into the materials to be joined between a punch and die in a press tool. The rivet pierces the top sheet and the die shape causes the rivet to flare within the lower sheet to form a mechanical interlock. The rivet may be set flush with the top sheet when using a countersunk rivet head. The die shape also causes a button to form on the underside of the lower sheet; ideally, the rivet tail should not pierce this.
Advantages of self-piercing riveting include -
- Fast, single operation joining process
- Can be used on unweldable materials and dissimilar material combinations
- Little or no damage to pre-coated materials
- No fume or heat, low noise emission, low energy consumption
Self-piercing riveting is, essentially, a proprietary process. Although the principles of operation are basically the same, there are variations from one system to another in, for example, rivet and die shape.
Self-piercing riveting - a guide to best practice
Self-piercing riveting - knowledge summary