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Punching Force Calculator & Formula (Online & Free)

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Key takeaways:

1. The fundamental concept of the article lies in providing a practical methodology for calculating the force required by a punch press machine to create holes in metal sheets, emphasizing that this force is contingent upon the material's shear strength, the perimeter of the shape being punched, and the thickness of the metal sheet, with the formula serving as a universal tool for different types of materials and hole shapes.

2. The article underscores the importance of die clearance in the punching process, detailing that improper clearance can lead to a range of issues such as reduced die life, burrs, and secondary cutting, while also offering guidance on selecting the appropriate clearance based on material thickness and type, thereby highlighting the nuanced balance between precision tooling and material characteristics for optimal punching performance.

3. The article suggests a holistic approach to punching by not only providing a calculation formula but also by integrating material properties data and practical recommendations for die clearance, thereby illustrating that successful punching operations require both accurate force calculations and an understanding of the physical interactions between the tool and material.

Punching Force Calculator

How to calculate the force (tonnage) of a punch press machine for power press machine?

I believe the following press tonnage calculator can be used to calculate the required punch force (blanking force) for your workpiece.

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

Related calculator: V & U-shaped Bend Force Calculator

Press Tonnage Calculation Formula

If you need to punch round, square, or any other type of hole through a given metal thickness, you’ll need to determine the punching force required to accomplish this task.

To calculate the required press tonnage, you can use the following punching force calculation formula, which is also applicable for blanking force calculation.

Press Tonnage (KN) = Perimeter (mm) * Plate Thickness (mm) * Shear Strength (kn / mm2)

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

punching force calculation formula
  • Perimeter: The total length of the continuous line forming the boundary of a closed geometric figure.
Perimeter
  • Thickness: The thickness that will be penetrated by the punching mold.
  • Shear Strength: The physical properties of the plate, which are determined by the material of the sheet, can be found in the material manual.

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

AluminumBrassLow Carbon SteelStainless Steel
0.17240.24130.34470.5171

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 further information about shearing strength, including how to calculate it, you can refer to the Wikipedia article.

The formula mentioned can also be applied as the cutting force formula in press tooling or as the formula for determining the force required to punch a hole.

Punch and Die Clearance

Punch and Die Clearance

The clearance between the punch and dies is a critical factor in the punching process, and it is represented by the total difference.

For instance, suppose you are using an ø12 upper die and an ø12.25 lower die. In that case, the optimal clearance should be 0.25mm.

If the clearance is not proper, it can reduce the die’s service life, cause burrs, and lead to secondary cutting. An irregular opening can also increase the demounting force.

Moreover, the die clearance depends on the material and thickness, and for carbon steel plates, it is recommended to use a value between 12-18% of the thickness.

See also:

If there are no special requirements for the CNC punch, you can refer to the following table for selecting the die clearance.

Punch Press Die Clearance Table

 ThicknessMild SteelAluminumStainless Steel
0.8-1.60.15-0.20.15-0.20.15-0.3
1.6-2.30.2-0.30.2-0.30.3-0.4
2.3-3.20.3-0.40.3-0.40.4-0.6
3.2-4.50.4-0.60.4-0.50.6-1.0
4.5-6.00.6-0.90.5-0.7

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79 thoughts on “Punching Force Calculator & Formula (Online & Free)”

  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.

  3. omdutt sharna

    Dear Sir
    We need punching m/c for spring steel hole dia18 mm Max Thikness 18 mm .So we want know how much ton pres required for this operation much

    Omdutt Sharma
    Jamna Auto industress

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