KEVOS® MAKEOS · Fabrication
Sheet-Metal Flat Pattern (Up to Four Bends)
What flat blank length gives this formed part with up to four bends, and are the flanges and bend radius workable on the press brake?
Flat pattern of a formed sheet-metal part with up to four bends of the same inside radius: bend allowance, outside setback and bend deduction for each bend angle from the K-factor (as the bend allowance tool), the flat length from the outside flange dimensions less the deductions, and checks that every flange is longer than its setbacks and your shortest flange for the die, and that the inside radius is at least your minimum ratio to thickness.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Thickness | mm | Sheet thickness. |
| Inside bend radius | mm | Inside radius of every bend. |
| K-factor | Position of the neutral axis as a share of thickness (about 0.33–0.45 for air bending). | |
| Flanges (outside dimensions) and bends | ||
| Flange 1 | mm | Outside length of the first flange. |
| Bend 1 angle (0 = no bend) | ° | Angle of the first bend (the change in direction; 90° for a right-angle bend; 0 if there are no bends). |
| Flange 2 | mm | Outside length of the second flange (between bends 1 and 2, outside to outside). |
| Bend 2 angle | ° | Angle of the second bend (0 to stop here). |
| Flange 3 | mm | Outside length of the third flange. |
| Bend 3 angle | ° | Angle of the third bend. |
| Flange 4 | mm | Outside length of the fourth flange. |
| Bend 4 angle | ° | Angle of the fourth bend. |
| Flange 5 | mm | Outside length of the fifth flange. |
| Your limits | ||
| Shortest flange for the die | mm | Shortest flange the press-brake die can form (see the press brake set-up tool). |
| Smallest inside radius ÷ thickness | Smallest inside radius as a multiple of thickness for the material (your value). | |
Method and formulas
- Bend allowance = θ (R + K t); outside setback = (R + t) tan(θ ÷ 2); bend deduction = 2 × setback − allowance (as the bend allowance tool).
- Flat length = Σ outside flanges − Σ bend deductions.
- Each flange must exceed the setbacks of the bends at its ends, and the end flanges your die minimum.
- Example: 2 bends of 3 mm radius in 2 mm sheet give a flat length of 101.94 mm.
Limitations
- All bends share one radius and K-factor; mixed radii need separate deductions.
- Outside dimensions to the virtual sharps; dimension to the drawing’s convention.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Cut blanks for a channel, hat or Z section
- Check a drawing’s flanges against the press brake die
- Compare K-factors for a material
Who it is for
- Sheet-metal designers
- Press brake operators
- Fabrication supervisors
What you get
- Allowance, setback and deduction for each bend
- Flat length
- Flange and radius checks
Interpreting the result
- Confirm the K-factor with a test bend: a 0.05 error changes each 90° deduction by about 0.08 t.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1346–1353. Topic reference; no source tables or recommended settings are reproduced.
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Open the Sheet-Metal Flat Pattern (Up to Four Bends) calculator
