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Wobble, radial and press riveting

Wobble, radial, and press riveting is a non-machining, non-detachable joining technology (cold forming) During wobble riveting, the forming force is only applied to a partial surface of the workpiece, e.g. a relatively low force is used to execute large forming operations.

The required tools can have a simple design, which results in low tool costs. Wobble, radial and press riveting technology is used to fabricate high quality rivet joints in fixed and mobile configurations. A force-distance control facility can be integrated for quality control purposes.
DUNKES supplies wobble, radial, and press riveting machines for manual operation, and also for integration into custom machinery.
Furthermore, we can also supply end-to-end automated automation solutions in indexed round table configurations, as well as workpiece pallet configurations.
Flat dimensioned operations are executed with a user programmable cross table. Different rivet heights are possible with a user programmable height positioning feature.
Multi-spindle rivet heads can be used when several riveting operations are performed within a short period in a fixed, planar rivet pattern.
Riveting forces up to 40 kN are implemented pneumatically, riveting forces up to 100 kN are implemented hydraulically.


During the wobble riveting process, the tool (anvil) rotates at a constant angle of attack around the centre axis of the rivet. The rivet material is formed axially and tangentially by a linear contact at concurrent axial feed. 


Process advantages:

  • short riveting cycle times
  • relatively simple structure of the total system
  • convenient service
  • worn bearings can be replaced relatively easily and quickly



During the radial riveting process, the tool (anvil) rotates at a variable angle between 0° and the maximum angle of attack around the centre axis of the rivet. The rivet material is formed axially and tangentially.



Process advantages:

  • The process exerts low lateral forces on the rivet to be formed
  • Higher strength rivets are in part more easily formed.
  • Depending on the surface coating, surface treated rivets are not destroyed.


Process disadvantages:

Longer rivet cycle time, e.g. cycle times are longer compared to the wobble riveting process.


Operational examples for rivet head shapes
Wobble and radial riveting can achieve a variety of rivet head shapes, even in poorly accessible locations.
An anvil axis bent at a 5° angle is available and supplied as standard equipment.
An anvil axis bent at a 3° angle is optionally available for poorly accessible locations. This permits riveting operations, e.g. in a deep pocket that is located closely to an interfering contour.
Extended service life rivet anvils are available in a "Ferro-Tic ® Alloy".



The following image shows several examples of rivet head shapes: