BIZOMAT MAKEOS · Fabrication
Punching Force Estimate
What ideal force follows from the total cut perimeter?
Estimate nominal flat-punch cutting force from total simultaneous perimeter, thickness and material shear strength.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Total cut perimeter | mm | Sum of all edges cut at the same instant, including every punch in a cluster. |
| Material thickness | mm | Actual sheet thickness. |
| Shear strength | MPa | Verified shear strength for the material and condition; do not assume tensile strength is identical. |
| Additional force multiplier | Task-specific allowance supported by tooling/process evidence; 1.2 is only illustrative. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Total cut perimeter
- What it is
- The total length of all edges being cut at the same instant: the perimeter of the punch shape, added up for every punch that cuts together.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.001 mm to 1000000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 100 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Punching force is directly proportional to cut perimeter.
- Get it right
- For a cluster tool, add every punch that cuts in the same stroke; for a round punch the perimeter is π times diameter.
What this means: Material thickness
- What it is
- The actual thickness of the sheet being punched.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.001 mm to 1000000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Punching force is directly proportional to thickness.
- Get it right
- Measure the sheet; coated or rolled sheet can be thicker than nominal.
What this means: Shear strength
- What it is
- The shear strength of the sheet material in its delivered condition: the stress at which it shears through, from verified material data.
- Units and format
- Enter a number in MPa: megapascals (1 MPa = 1 N/mm²). The form accepts 0.001 MPa to 100000 MPa. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 300 MPa as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Punching force is directly proportional to shear strength.
- Get it right
- Shear strength is not the same as tensile strength; do not substitute one for the other.
What this means: Additional force multiplier
- What it is
- An extra multiplier on the nominal cutting force to allow for tool wear, clearance and other process effects, supported by tooling or process evidence.
- Units and format
- Enter a plain number with no unit. The form accepts 1 to 10. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1.2 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The adjusted force is directly proportional to this factor.
- Get it right
- Base it on your tooling records or press supplier guidance; 1 means no allowance.
Method and formulas
- Nominal force (N) = perimeter (mm) × thickness (mm) × shear strength (N/mm²).
- Adjusted estimate = nominal force × supplied multiplier.
- Metric tonne-force = force (N) / 9806.65. Example: 100 mm × 2 mm × 300 MPa gives 60 kN; with 1.2 multiplier the estimate is 72 kN.
Limitations
- Flat-punch cutting estimate; shaped shear faces alter the force history.
- Does not approve press capacity, energy, stripping, eccentric loading, tool stress or punch-to-thickness ratio.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- press tonnage
- blanking
- punch force
Who it is for
- Toolmakers
- Manufacturing engineers
What you get
- Nominal cutting force
- Adjusted estimate
- Adjusted metric tonne-force
Interpreting the result
- Check the press force-versus-stroke curve, tooling limits and actual material before selecting equipment.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1339–1343. Topic reference; no source tables or recommended settings are reproduced.
- Mate Precision Technologies: Calculating Punching Force — https://www.mate.com/wp-content/uploads/2015/10/SalvIII_LIT00828PN_2020_MPTECH_LR.pdf
Learn the Concepts Behind This Tool
These BIZOMAT Library readings explain the method this tool uses, with worked examples.
Method explained here · BIZOMAT original book
Cutting force from the perimeter
In Blanking and Piercing Dies by the Numbers
What it covers: Estimating a die's cutting force from cut length, thickness and shear strength, the MP-40 die's 192.8 kN, three estimates compared, stepped punches, shear angles and a slot left out.
Method explained here · BIZOMAT original book
Press brake force and punching force
In Sheet Metal Parts by the Numbers
What it covers: Estimate air bending force from a manufacturer's formula converted to SI, see how bottoming multiplies it, estimate punching force from cut perimeter, and why small holes break punches.
BIZOMAT tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.