The bend allowance formula takes into account the geometries of bending and the properties of your metal to determine the bend allowance.
Bend allowance formula in sheet metal.
The material thickness will be measured in decimal form not by the gauge number.
Where ba is bending allowance.
The following illustration shows the equation calculation for determining the bend allowance when forming sheet metal.
Lf l1 l2 ba.
Most sheet metal materials will conform to the calculations.
Ba bend allowance.
The bend allowance region is shown in green in my diagram this is a region wherein theory all deformation occurs during the bending process.
The total length of the flatten sheet is equal to the sum of l1 that s the first length and l2 plus the bend allowance.
You will need to know your material thickness mt the bend angle b the inside radius ir and the k factor k.