Sheet Metal Bend Allowance Calculator
K-factor, BA, BD — flat pattern length
📚 Learn more — how it works, FAQ & guide Click to expand
Learn more — how it works, FAQ & guide
Click to expand
Sheet Metal Bend Allowance Calculator
Calculate bend allowance, bend deduction, K-factor adjusted neutral axis, flat pattern length. Essential for sheet metal CAD layouts and laser-cut prep.
How to use this tool
- 1
Material + thickness
Determines K-factor.
- 2
Bend angle + radius
Inner radius + bend angle.
- 3
See BA + flat pattern
Bend allowance + flat layout length.
Frequently Asked Questions
What is K-factor?
Ratio of distance from inner surface to neutral axis vs material thickness. Material- and process-dependent. Aluminum soft: 0.33-0.40. Steel: 0.40-0.45. Stainless: 0.45-0.50.
Bend allowance vs bend deduction?
BA = arc length along neutral axis. BD = how much material to subtract from leg-sum to get flat pattern. Both methods give the same flat length, just different formulas.
Inner radius minimum?
Rule: minimum inner radius = thickness for soft materials, 1.5-2× thickness for hard. Below minimum = cracking. Stainless 304: typically 1.5×T minimum.
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