The Tonnage Formula is the pressure required in tons to cut a blank or contour using a flat faced punch with no shear. Tonnages can be calculated for forming, bending, cutting, drawing, and blanking operations. Having the ability to calculate the tonnages for a sheet metal project is vital for the completion and success of your project.
FORMULA
T = P x Th x C
T = Pressure required in tons
P = Perimeter of blank in inches
Th = Thickness of material
C = Constant (see common ones below)
Constant = The material shear strength/2000 pounds
EXAMPLE
.050 CR Steel, 1/2 Hd; Cutting edge of 12 linear inches T
= 12 x .050 x 32
T = 20 tons required
CONSTANTS
Aluminum- Soft-11
T4/T6-15
Steel- HR/Cold Rolled-27
1/2 Hard-32
Stainless Steel- Annealed-37
1/2 Hard-50
4130 AQ - 40
Brass- 1/2 Hard-22
Hard-25