3 Fundamentals of press design

20 Basic principles of metal forming
shear cutting
parting
dividing
wedge-actioncutting
tearing
breaking
Fig. 2.1.28 Parting techniques classified under forming
Shear cutting – known in practice as shearing for short – is the separation
of workpieces between two cutting edges moving past each other
(Fig. 2.1.29 and cf. Sect. 4.5).
During single-stroke shearing, the material separation is performed
along the shearing line in a single stroke, in much the same way as using
a compound cutting tool. Nibbling, in contrast, is a progressive, multiple-stroke
cutting process using a cutting punch during which small
waste pieces are separated from the workpiece along the cutting line.
Fine blanking is a single-stroke shearing method that uses an annular
serrated blank holder and a counterpressure pad. Thus the generated
blanked surface is free of any incipient burrs or flaws, which is frequently
used as a functional surface (Fig.2.1.30 and cf. Sect. 4.7).
punch
die
openshearing blankingcontour
Fig. 2.1.29 Shearing
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998