Bend Allowance Calculator
Calculate bend allowance and deduction for sheet metal forming operations
Calculate Bend Allowance
Angle of the bend from flat position
Radius at the inside of the bend
Thickness of the sheet metal
Neutral axis position factor (0.3 - 0.5 typical)
Calculation Results
Formula used: BA = θ × (r + K × T)
Neutral axis position: 0.000 mm from inside surface
Outside radius: 0.000 mm
Engineering Guidelines
Example Calculation
Aluminum Bracket Example
Material: Aluminum 5052-H32 (K = 0.32)
Bend angle: 90°
Inside radius: 2 mm
Material thickness: 1.5 mm
Calculation Steps
1. Convert angle: θ = 90° = π/2 rad = 1.571 rad
2. Calculate BA: BA = 1.571 × (2 + 0.32 × 1.5) = 1.571 × 2.48 = 3.896 mm
3. Calculate BD: BD = 2 × (2 + 1.5) × tan(45°) - 3.896 = 7 - 3.896 = 3.104 mm
Common K-Factors
Key Formulas
Bend Allowance
BA = θ × (r + K × T)
Bend Deduction
BD = 2(r+T)tan(θ/2) - BA
K-Factor
K = t / T
Neutral Axis
t = K × T
Understanding Bend Allowance
What is Bend Allowance?
Bend allowance is the length of the neutral axis in a bend. It represents the actual material length needed to form a bend, accounting for the stretching and compression that occurs during the bending process.
Key Concepts
- •Neutral Axis: The layer that neither stretches nor compresses
- •K-Factor: Position of neutral axis relative to material thickness
- •Inside Radius: Radius at the inner surface of the bend
- •Bend Deduction: Amount to subtract from flat pattern length
Mathematical Foundation
BA = θ × (r + K × T)
Bend allowance formula
BD = 2(r+T)tan(θ/2) - BA
Bend deduction formula
Variables:
- θ: Bend angle (radians)
- r: Inside radius
- K: K-factor (0.3-0.5 typical)
- T: Material thickness
- t: Distance to neutral axis
Manufacturing Applications
Aerospace
- • Aircraft skin panels
- • Structural brackets
- • Engine components
- • Interior panels
Automotive
- • Body panels
- • Chassis components
- • Exhaust systems
- • Interior trim
Construction
- • HVAC ductwork
- • Roofing panels
- • Structural angles
- • Architectural elements