Press Brake Bending Force Calculator & Tonnage Chart
Estimate air-bending force and required press brake tonnage using material tensile strength, sheet thickness, bend length, and V-die opening. Compare die widths and check machine capacity and tooling limits before production.
Press Brake Bending Force Calculator: Enter Job Details
This press brake tonnage calculator estimates force for one conventional air bend. Enter the actual sheet thickness, bend length, V-die opening and material tensile strength. Bottoming, coining and special tools are not calculated with this model.
Material values are editable examples, not certified grade properties. Use the relevant mill test report or supplier specification.
Press Brake Force Calculator: Capacity Check
The planning allowance is a user-adjustable buffer, not a manufacturer-prescribed safety factor. Machine ratings alone do not establish local bed loading, tooling limits, deflection or permissible part geometry.
Bending Force Calculator: Estimated Tonnage
*The 0.77 × V minimum flange estimate is a general mild-steel air-bending rule of thumb, not a guarantee for all materials, dies or geometries.
Press Brake Tonnage Chart by V-Die Opening
A practical press brake tonnage chart helps compare the effect of die opening without pretending all V widths are usable. The following live table holds your entered thickness and tensile strength constant, and recalculates theoretical force for a 1,000 mm bend. All rows are model estimates, not measured manufacturer tooling limits.
| V / thickness | V opening | Force for 1 m bend | Force with allowance | Review |
|---|---|---|---|---|
| Complete the inputs to calculate the comparison. | ||||
A wider die generally reduces force but can increase inside radius and minimum flange length. An 8× thickness die opening is a common starting rule for mild-steel air bending, subject to tooling and design constraints.
Sheet Metal Bending Tonnage Calculator: Method and Limits
The sheet metal bending tonnage calculator uses the publicly described Bystronic air-bending relationship for conventional tooling and a 60,000 psi reference tensile strength. It scales the result using the actual material UTS. It assumes a single straight bend, with no force concentration from special forming tools. It does not predict bottoming, coining, offset forming, hemming or multi-bend dies.
| Quantity | Calculation |
|---|---|
| Baseline air-bending force (US short ton-force) | (575 × tin² ÷ Vin ÷ 12) × Lin × (UTSpsi ÷ 60,000) |
| Convert to kilonewtons | kN = US short ton-force × 8.896443 |
| Metric tonne-force | tf = kN ÷ 9.80665 |
| Force per meter | kN/m = calculated kN ÷ bend length (m) |
| Planning load | Estimated kN × (1 + user allowance ÷ 100) |
Input lengths are converted internally to inches and UTS from MPa to psi for the source equation. Published press-force tables can differ materially due to tooling and process assumptions. The baseline relationship is attributed to Bystronic; manufacturer-specific press force tables, including those from TRUMPF, may use different assumptions. Verify the actual machine and tooling data before approving a bend.
Press Brake Tonnage: Practical Engineering Questions
What information does a press brake force calculator need?
For a preliminary single air bend: sheet thickness, bend line length, V-die opening and material ultimate tensile strength. Die/punch geometry and the forming method affect actual forces. Use the grade-specific UTS rather than relying on a generic material name.
How does V-die opening affect the bending force?
In the chosen air-bending baseline, force varies inversely with the V opening. Doubling the opening approximately halves the model force at a fixed thickness and material, but the new radius, flange support and accuracy still require review.
Can I use the air-bending force for bottoming or coining?
No. Bottoming and coining can require substantially more force and different tooling factors. This first-version calculator deliberately does not give a falsely precise converted tonnage for those operations.
Does enough machine tonnage mean the bend is safe?
No. Confirm manufacturer-approved machine capacity, load distribution, tooling kN/m rating, minimum flange, available stroke, bend angle, punch clearance and material forming limits. Nominal machine capacity alone cannot approve a setup.
How do I read the press brake tonnage chart?
Choose a candidate V-die ratio, compare the force per 1 m with your own bend length, then review the tooling manufacturer’s die/radius/flange limits. The table is a calculation matrix, not a certified manufacturer chart.
For quotations and process feasibility, see sheet metal fabrication services.
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