Sheet Metal K-Factor and Bend Deduction Mathematics in Automated Design

Neutral Axis & Plastic Deformation

When sheet metal is bent on a press brake, the material on the inner radius undergoes compression, while the material on the outer radius experiences tension. The Neutral Axis represents the theoretical plane where the material length remains unchanged.

Key Equations

• Bend Allowance (BA):
  $$BA = \frac{\pi}{180} \times A \times (R + K \times T)$$
• Bend Deduction (BD):
  $$BD = 2 \times (R + T) \times \tan\left(\frac{A}{2}\right) - BA$$

Where:

• $A$ = Bend Angle (degrees)
• $R$ = Inside Bend Radius (mm)
• $T$ = Sheet Thickness (mm)
• $K$ = K-Factor (empirical ratio $t/T$)