Material hardness, punching force and the relative calculations
Punching is usually performed on mild or low alloy steels. Highly resistant materials are more difficult to punch or require special punches which are, however, subject to greater wear. Force calculation is necessary for defining the performance of the punching action.
In any case, the maximum force needed to make the punching must be considerably lower than the maximum compression resistance of the punch. The force can easily be calculated by multiplying the thickness of the material by its shear strength and by the development of the cutting perimeter.
When calculating the force, the maximum compressive load that the punch can withstand will depend on the type and hardness of the steel. For example, hardened and impact-resistant tool steel can withstand a compressive load of 2000 N/mm2 before breaking and can be used with specific working pressures up to 1500 N/mm2, thus still providing good results in terms of durability. When ordering a punching tool, we recommend that you specify the type and thickness of the material to be punched.
Force calculation: generic tonnage calculation formula
|(P x S x K) / 28,3|
P = shape perimeter
S = material thickness
K = material coefficent
|Example: 40 (square perimeter with edge of 10 mm) x 2 (material thickness in mm) x 1,5 (K stainless steel) / 28,3 = 4,24 (tonnage)|