Press Brake Force per Line Calculator

Sheet & Bend Inputs

Bending Method

Press Brake Force Result

Force Summary

Detailed Bend Takeoff

Press Brake Bending Preview

Air-Bending Force Formula

A commonly used preliminary air-bending relationship can be expressed in SI units as:

where F is force, Rm is material tensile strength, L is bend length, t is sheet thickness and V is die opening. The coefficient K depends on the selected empirical formula and unit system.

This calculator uses a simplified empirical coefficient for preliminary estimating and then applies the selected bending-method and machine factors.

Force per Bend Length

The total calculated force can be normalized to a selected bend length so different bends can be compared.

For example, a long bend may require substantially more total tonnage even when the material thickness and die opening remain unchanged.

Effect of Thickness and Die Opening

In the simplified air-bending relationship, bending force increases approximately with the square of sheet thickness.

The estimated force also decreases as the die opening increases, all else being equal.

This is why sheet thickness and selected V-die opening are important inputs when screening press-brake capacity.

Material Strength Effect

Higher tensile-strength materials generally require greater bending force for the same thickness, bend length and tooling conditions.

The tensile strength entered here is used as an estimating input rather than a substitute for the actual material specification.

Important Limitations

• This is a preliminary press-brake force estimator.
• It does not determine the exact force required by a specific machine.
• Actual force depends on tooling geometry and condition.
• Actual force depends on material grade, temper, grain direction and condition.
• The selected V-die opening has a major effect on air-bending force.
• Bottoming and coining can require substantially different forces from air bending.
• It does not check punch or die capacity.
• It does not check machine frame or hydraulic capacity.
• It does not calculate bend allowance or flat-pattern dimensions.
• It does not determine minimum flange length.
• It does not account for complex tooling, multi-axis bending or special forming operations.
• Actual machine tonnage should include the manufacturer's recommended safety margin.

Frequently Asked Questions

What does the Press Brake Force per Line Calculator calculate?
It estimates the preliminary bending force required for a sheet-metal bend and converts that force into tonnage and force per unit bend length.

Why is die opening required?
The V-die opening strongly affects the force required for air bending. A wider opening generally reduces the estimated force.

Does sheet thickness have a large effect?
Yes. In the simplified relationship used here, force varies approximately with the square of sheet thickness.

Can I use different material strengths?
Yes. Enter the approximate tensile strength of the material being formed.

Does the calculator work for bottoming and coining?
It can apply user-selected method factors, but those are only estimating adjustments. Actual bottoming and coining requirements should be taken from reliable machine and tooling data.

Can I compare different bend lengths?
Yes. The calculator provides force per selected unit of bend length as well as total force.

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