About Bend Allowance and Developed Length

Bend allowance calculations are used to determine the developed length of flat sheet metal required to make a bend with a specific radius and angle. These calculations are important to create an accurate flattened model for manufacture. Bend allowance calculations take into account the sheet metal thickness, bend radii, and bend angles of a part or wall feature. Bend allowance compensates for stretching in the area of a bend, where the material on the outside of the neutral bend axis stretches while the material on the inside of the neutral bend axis compresses.

You can set default values for bend allowance for the part or override these values using a feature-specific bend allowance calculation method during wall creation. Depending on the type of developable geometry, you can use one of the following methods to calculate the developed length for a sheet metal part or feature:

• System-defined equation that uses either Y factor or K factor to calculate the developed length for all developable geometry

• Bend table that uses a standard or customized bend table to calculate the developed length only for geometry containing arcs

You can override an incorrect value for developed length by modifying the value or by using a customized bend table.

You can use the following system-defined equation to calculate developed length for a part or wall feature:

L = (Π/2 x R + Y factor x T) Θ/90
Where: L =	Developed length
Π =	3.142
R =	Inside radius
Y factor =	The default Y factor = 0.50
T =	Material thickness
Θ =	Bend angle in degrees (°)