The clinch joint is formed thanks to the interaction of a die and a punch
In the SPOT CLINCH® joining process, the materials to be joined are firstly forced into the die with the punch.
As soon as the lowest material is resting on the die anvil, it starts flowing sideways under the pressure being exerted by the punch. The movable die sections are pushed outwards. The flow of material forms the button-like joint.
The punch is then returned to its starting position by the operator or by a pneumatic timer which removes the force. The joined part can now be removed and the side sections of the die are pulled back together by a spring.
4 essentials parameters characterize the clinch joint
- Material ductility: the required ductility values are 20% for a rectangular (partial cut) joint and 30% for a round joint.
- Access from both sides: needed for pressing the material between the punch and the anvil.
- Better joint feasibility and strength: with the punch on the tick side, when joining sheet metal with different thicknesses.
- Residual bottom thickness, “St”: is directly related to the interlocking effect and consequently the joint strength once the joint is formed