Bend Allowance
The arc length of the neutral axis through a bend, added to the flange lengths to find the flat blank length.
What it means on the floor
Bend allowance (BA) is the amount of material consumed by a bend, measured along the neutral axis — the layer inside the material that is neither stretched nor compressed. When you develop a flat pattern, you add the bend allowance to the flat lengths of the flanges to get the total blank length.
BA depends on the bend angle, the inside bend radius, the material thickness, and the K-factor (which locates the neutral axis). For a 90° bend: BA = (π / 2) × (R + K × T), where R is the inside radius, T is thickness, and K is the K-factor.
Category: Forming
Applying the term
Interpret Bend Allowance in the context of the drawing, governing standard, and customer requirement in front of you — the same word can carry different limits in design, quality, and production documents. Check whether a stated value is nominal, minimum, maximum, or reference-only, and whether it applies before forming, after forming, or after heat treatment.