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How to Calculate Punching Force (Formula & Tonnage Calculator)

Punching Force Calculation Formula

Punching Force Calculation Formula

punching force calculation formula

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):

Punching Force (KN) = Perimeter (mm) * Plate Thickness (mm) * Shear Strength (kn / mm2)

Converted into metric tons: dividing the result of KN by 9.81

  • Perimeter: add up the continuous line forming the boundary of a closed geometric figure.


  • Thickness: the thickness which will be piecing through by the punching mold.
  • Shear Strength: The physical properties of the plate, determined by the material of the sheet and can be found in the material manual.

Common materials’ shear strength are as follows: unit: KN/mm2

Aluminum Brass Low Carbon Steel Stainless Steel
0.1724 0.2413 0.3447 0.5171

For various shear strength table, you can check out the following post:

e.g: If punching one square hole in the 3mm thickness low-carbon steel plate, side length 20mm, you will get:

  • Perimeter = 20×4 = 80mm
  • Thickness = 3mm
  • Shear Strength = 0.3447kn/mm2

Punch Force (KN) = 80 x 3 x 0.3447 = 82.728 KN Convert into tonnage: 82.728 KN ÷ 9.81 = 8.43 Ton

For more details about the shearing strength including how to calculate it, you can refer to the answer from Wikipedia.

Punching Force Calculator

P.S: If you want to calculate hydraulic press tonnage, you can use our hydraulic press tonnage calculator.

Punch And Die Clearance

Punch and Die Clearance

The clearance between punch and dies is represented by the total difference, which is one of the critical factors in the punching process.

For example, when using ø12 upper die and ø 12.25 lower die, the optimal clearance is 0.25mm.

Improper clearance will reduce the die service life, or burrs and lead to secondary cutting, the irregular opening will increase the demounting force, etc.

Besides, the die clearance is subject to the material and thickness, generally, for carbon steel plate, 12%-18% of the thickness is best.
See also:

If no special requirements in CNC punch, you can refer to the following table for selecting the die clearance:

Punch Machine’s Die Clearance Table

Plate Thickness Material
Mild Steel Aluminum Stainless Steel
0.8-1.6 0.15-0.2 0.15-0.2 0.15-0.3
1.6-2.3 0.2-0.3 0.2-0.3 0.3-0.4
2.3-3.2 0.3-0.4 0.3-0.4 0.4-0.6
3.2-4.5 0.4-0.6 0.4-0.5 0.6-1.0
4.5-6.0 0.6-0.9 0.5-0.7

77 thoughts on “How to Calculate Punching Force (Formula & Tonnage Calculator)”

  1. Sehab chaudhari

    I might purchase punching machine to perform riveting operation. for that I needs to calculate the force require to rivet of mild steel material having following specifications,
    diameter of mild steel material is 5mm
    for further details isn’t able to share here make contact us on below Email
    [email protected]

  2. I would like to punch 24k gold and silver discs from extruded bars. The thickness is 2.8mm and a 30mm dia. I do not need it to be automated, We can perform foot pedal control as we are punching 50 a day.

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