In bottom pressing, or bottoming, the punch presses the workpiece versus the bottom floor of the V or U-formed die, which defines the ultimate bend angle. This technique provides specific bends and minimizes the tendency for springback within the workpiece as a consequence of the applying of greater bending force. https://martin0uw12.wikienlightenment.com/7364625/details_fiction_and_stamping_golf_irons