Punching Force Calculator (Sheet Metal)
Force a press needs to punch round holes in sheet metal, from the hole diameter, sheet thickness and the material's shear strength.
Results
Punching force
28.3
kN
In tonnes-force
2.88
tf
Force per hole
28.27
kN
What this tool does
Punching shears the sheet around the edge of the hole, so the force is the cut area — perimeter times thickness — times the shear strength. For steels the shear strength is commonly taken as roughly 80 % of the tensile strength; mild steel is often around 300 MPa, stainless considerably more. Leave a margin on the press, because worn punches, tight clearances and harder material all raise the force, and punching several holes at once adds them together unless the punches are staggered in height.
Formula
F = π × d × t × τ (perimeter × thickness × shear strength)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
dh | Hole diameter | mm |
st | Sheet thickness | mm |
ss | Shear strength of the material | MPa |
nh | Holes punched at once | — |
F | Punching force | kN |
TF | In tonnes-force | tf |
FH | Force per hole | kN |
Worked example
- Hole diameter10 mm
- Sheet thickness3 mm
- Shear strength of the material300 MPa
- Holes punched at once1
- Punching force28.3 kN
- In tonnes-force2.88 tf
- Force per hole28.27 kN
Limitations
- Coverage and consumption figures vary between products. Take the values from the manufacturer's datasheet for the product you are actually using.
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.