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# How to Calculate Punching Force (Formula & Tonnage Calculator)

## 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

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

## 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

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.

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

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

1. Walid Gabr-Rayan

How would this apply to punching ribs into sheetmetal, instead of holes. Would you change the shear strength to yield strength?

2. this is a good site!
i was looking for information about the force when cutting with a guilotineshear

it is for schoolassignment

so just 1 straight line
i need the cutting/shear force of this. (with calculation)
then i need to convert to bar for a hydraulic press (with calculation)

this is for cutting low carbon steel
with specification of 1000mm with and 8mm thick.

when use the calculator i came to 281.10 metric tons
and when converted it i get 27 bar pressure is this correct?

also the blade of a guilltineshear is in this case straight on the steel but for pressure reduction the cutting blade have an angle. if the 27 bars is correct how do i calculate the force that is on the blade with a angled cutting blade along the 1 m steel plate

sorry for the long text (english is not my first language)

thank you in advance al help is welcome since this is not my daily job knowlege

[email protected] is my email

3. KATTAMURI VENKATA SIVA SAI KUMAR

I need to know punching calculations for plastics
How to calculate the force and the required cylinder for that punching operation.
How clearence need to be given for the punch and die.

1. The formula mentioned in this article is can also be applied to plastic punching, what you need to know is to find out the shear strength of the plastics.

4. hello sir, i required a force calculation for punching sheet of paper on a punching machine please provide me a solution.

5. Sean R Hartsough

Would anyone on here happen to know the shear strength for extruded vinyl like in windows?