Clinching (Aluminum)

In clamping step, a holder and a die tightly clamp two overlapped sheets. Then, in punching step, a round punch indents the overlapping sheets into the die. The inner and outer buttons of a FSC joint are made of the upper and lower sheets, respectively. In interlocking step, as the downward force continuously increases, the material at the bottom of the inner button is forced to move downward and outward, and the material of the outer button is then squeezed into the groove of the die. Note that the expanded part of the inner button is denoted as undercut, which could provide strong mechanical interlock between the two buttons. In final step, the punch is drawn out from the sheets and a round clinch joint is made.