How to Calculate the Shear Force for a Punching Tool for Thin Materials

I will now show you a very simple formula to calculate the shear force for a high turret punching tool. From my experience, the accuracy of this formula is sufficient for ninety percent of applications.

First, given the shape of the figure to be cut (hole, square, slot, or special shape), we calculate its perimeter in millimeters. For example, if we have a square hole with a 20mm side, the perimeter will be 80mm.

Then, we multiply the perimeter by the thickness of the sheet. If the thickness is 0.8mm, the value we obtain is 64mm².

Third step: multiply the obtained value by the material’s shear strength, in N/mm².

For the most common materials, I use:

• 250 N/mm² for aluminum
• 400 N/mm² for sheet metal (non-high strength)
• 700 N/mm² for stainless steel

Note: Some special steels today can have values even higher than 1200 N/mm²!

So, if in the example above we wanted to cut normal sheet metal, the calculation would be:

(Force) = 80mm x 0.8mm x 400 N/mm² = 25600 N

Which I prefer to indicate as 25.6 kN. To be conservative, we should add another 10% for the extraction force, which in high turret tools is provided by the springs applied to the punch body.

To discover more about our punching lines, contact us.

Andrea Dallan
CEO – Dallan Spa