If you punch round holes or square holes, or some other forms of holes through a given thickness of metal, you just want to know the force required to punch a hole in steel. You can calculate the punching tonnage been required with the help of the following punching force calculation formula (blanking force formula):
Standard Perforated Sheet Specifications – Untreated/Galvanised Steel Product Code Hole size (mm) Pitch (mm) Open Area % Thickness (mm) Sheet Size (mm) Weight (kg/m2) P0163212 1.60 3.20 23.0 1.2 2440 x 1220 7.2 P0243710 2.41 3.66 40.0 1.0 2440 x 1220 4.7 P0335616 3.25 5.59 30.0 1.6 2440 x 1220 8.7 P0486416 4.76 6.35 51.0 1.6 2440 x 1220 6.1 Notching is a piercing operation that removes material from the edge of the workpiece. Nibbling. The nibbling process cuts a contour by producing a series of overlapping slits or notches. This allows for complex shapes to be formed in sheet metal up to 6 mm (0.25 in) thick using simple tools.