Bend Deduction (BD) represents the amount subtracted from the total flat length of a sheet to account for the bend region. It is the difference between the sum of the two leg lengths and the flat length of the part.

BD=2×(Outside Setback)−BA

• Outside Setback (OSSB): The distance from the bend apex to the material edge. It accounts for the bend radius and material thickness.

OSSB=tan⁡(θ/2)×(R+T)

• BA: Bend Allowance, the length of the arc along the neutral axis of the bend.

BA=π×(R+K×T)×θ/180

• Flat Length (L): The total length of the flat sheet before it is bent

L=A+B-BD

• R= Promień gięcia
• T= Grubość
• K= Współczynnik K
• θ= Kąt zgięcia
• A= Długość A
• B= Length B​