Tonnage: Use the following formula to calculate the tonnage required to punch a round hole in mild steel:
Punch diameter x Material Thickness x 80 = Tons of pressure required
Example: to punch a 1/2" hole through 1/4" thick mild steel
0.500 x 0.250 x 80 = 10 tons required
Use the following formula to calculate the approximate tonnage required to punch a shaped hole in mild steel:
1/3 Perimeter of punch x Material Thickness x 80 = Tons of pressure required
Example: to punch a 9/16" x 1" hole through 1/2" thick mild steel
- Find perimeter: 0.5625 + 0.5625 + 1.000 + 1.000 = 3.125
- Find 1/3 perimeter: 0.33 x 3.125 = 1.031
- 1.031 x 0.500 x 80 = 41 tons of pressure required
NOTE: The thickness of the material should not exceed the punch diameter.