Determine the shear (rake) angle needed on a punch or die to reduce peak tonnage and quiet the press.
Grinding a shear (rake) angle onto the punch or die staggers the moment of cut so the whole perimeter is not sheared at once. This spreads the force over more of the stroke, lowering peak tonnage and softening snap-through.
A shear height of roughly one stock thickness is common. More shear lowers tonnage further but distorts the part, so it is balanced against part flatness.
Formula: Peak force ≈ Full force × Thickness / (Thickness + Shear height)
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