What is Flush Self-Pierce Riveting?

An Alternative Permanent Assembly Method

Posted on 05/22/2017 | by The Orbitform Blog Team


Flush self-pierce riveting is a metal assembly process used to join two or more metals together. The flush self-pierce riveting process is used when there is a need to join dissimilar metals, when the metals being fastened have varying thicknesses, if pre-painted metal materials are to be joined, and/or if pre-coated materials are required to be fastened together.

The flush self-pierce riveting process is often an alternative to spot welding or clinching when those permanent assembly processes are not possible / not optimal for the fastening characteristics required.

Flush self-pierce rivet machines built by Orbitform perform the fastening operation via a punch and die method which automatically feeds, punches, inserts and locks the self-piercing rivet in place to produce a solid joint in a single cycle operation.


The process steps involved include:

Punch:  after the metals are compressed together a special self-piercing punch tool drives a self-piercing rivet into the top piece of metal and begins to push the self-piercing rivet through

Set:  the upper tooling pushes and shears the metals through the lower die

Coin:  the metal slugs pass through the lower die tooling and the self-piercing rivet is positioned (the head on the top and the coining ring on the lower die tooling are forced around the self-piercing rivet to permit the sides of the pierced hole to flow into and form around the concave section of the rivet)

Rivet:  the metal sheets now are permanently fastened together with the flush self-pierce rivet in place (the rivet, being the same length as the total thickness of the materials being joined, takes the place of the pierced section)

Flush the joint is locked tight and the rivet is flush with both surfaces of the assembly

Secure:  a strong joint is secured based on the application of the appropriate tooling and proper machine force being utilized…all based on the characteristics of the combined materials and the proper selection of the self-pierce rivet


Flush self-pierce rivet machines range from standard Orbitform single-hit machines to completely automated turn-key metal fastening machines used in production lines.


To learn more about Flush Self-Pierce Rivet machines built by Orbitform, please click here.