What tool or machinery is used to hem a circle made of any type of light weight sheet metal?

Any tool of the type that would produce an open or closed hem on the edge of sheet metal is called a hemming die.





Due to the constraints of geometrical physics, I would presume the only way to produce one upon a circular piece of metal would require a three step process instead of the normal two steps.





First, the laser or punch press would have to create reliefs around the edge of the metal, to eliminate the hem closing in upon itself, as it cuts out the circle.





Second, a press would have to push the circle into a die, to do the pre-bend on the outer edge, hopefully past 90 degrees, into an acute angle.





Third, a press would have to press the hem closed, or to an open hem, with the appropriate spacer for an open hem.





Upon further reflection, it could be done in two steps by the punch cut/stamping the circle out into the die, then closing the hem in the second step.





It would still be called a hemming die.