Press Brake Tonnage Calculator

Air-bending force estimate for capacity planning

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Sheet metal & brake setup tools

Cutting, measuring, and layout gear for press brake and flat-pattern work.

Shear
Malco TS1 turbo shear

Malco TS1 Turbo Shear

  • Clean cuts before brake bends
  • Reduces burrs that affect tonnage
  • 18-gauge capacity in mild steel
  • Essential for blank prep
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Snips
Malco left-cut aviation snips

Malco M2006 Max2000 Left Snips

  • Offset cuts on bracket blanks
  • Long-life forged blades
  • Trim to bend length accurately
  • Pairs with flat-pattern layout
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Gauge
Stainless steel radius gauge set

Stainless Steel Radius Gauge Set

  • Verify inside radius after air bend
  • Match punch nose to target radius
  • Check springback on test coupons
  • Layout reference for V-die setup
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Measure
Starrett digital caliper

Starrett Digital Caliper

  • Confirm material thickness for tonnage
  • Verify actual gauge vs nominal
  • Measure die opening on setup
  • Decimal thickness for formulas
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Right
Malco right-cut aviation snips

Malco AV73 Right-Cut Snips

  • Complete left/right snip pair
  • Clean edges reduce crack risk
  • Field trimming on duct work
  • Shop standard for sheet metal
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Force vs flat-pattern math

Press brake tonnage is how much bending force the machine must apply — a capacity-planning question. The Bend Allowance Calculator and Bend Radius Calculator solve different problems: how much material to allow in the flat pattern and how tight you can bend without cracking. Use all three on a new part — tonnage first to know the brake can handle it, then radius and allowance for the blank.

Air-bending formula used here

This calculator uses the standard air-forming estimate: T ≈ k × 575 × t² × L / V (US tons), where t = thickness (in), L = bend length (in), V = V-die opening (in), and k = material factor (1.0 mild steel, 1.7 stainless, 0.5 aluminum). The 575 constant assumes ~60 ksi mild steel; factors adjust for other materials. Bottom bending or coining needs substantially higher force — see the Press Brake Tonnage Guide.

V-die opening default (8× thickness)

For mild steel air bending, a common starting V-die width is 8× material thickness. Thicker material needs wider dies — too narrow a V for the thickness spikes tonnage and can mark the part. The calculator pre-fills V at 8× when you change thickness; override with your actual die if it is already mounted in the brake.

Sheet metal cluster

Bend Allowance Calculator Flat pattern length and K-factor. Bend Radius Calculator Minimum radius and springback. Sheet Metal Gauge Chart Gauge to decimal thickness. Sheet Metal Bending Guide Full brake setup workflow. Press Brake Tonnage Guide Air vs bottom bend and die selection.

When Tonnage Looked Safe — Diagnose Beyond the Estimate

Calculator air-bend math was under capacity but the brake still overloaded, stalled, or tripped: Press Brake Tonnage Troubleshooting. Setup rules: Press Brake Tonnage Guide. Flat-pattern forks: Sheet Metal Bending Troubleshooting.

Tonnage gets the bend to move — blank method and diagnosis live next door: BA vs BD Decision and Sheet Metal Bending Troubleshooting.

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