We also know the developed length of the sample ( P).Since, all the items of right hand sides of the Eqn.3 and Eqn.4 are known so we can get the values of X and Y of the sample. Now by referring Fig.1 and Fig.2 we can write:.But the most accurate way to find out K factor is reverse engineering of a small but same sheet metal sample piece. There are standard charts available with sheet metal design handbook for calculating K factor (ideally it should be 0.5). So, if you got K factor value now, you can easily calculate bending allowance. The formula for calculating sheet metal bending allowance is (Please refer to the above picture):īA= Bend Angle * (Π/180)* (R+ K factor* T)……Eqn.1īend Angle represents the angle to which sheet metal has bend (here it is 90 degree). If you have a sheet metal bending product (as shown in above picture) with two legs of length “X” and “ Y” and you unbend it, you will see that total length of the unbend sheet will NOT X + Y rather, the length will be X + Y + BA.
Bending Allowance Calculationīending allowance is the input for calculating developed sheet metal size. Bending brake is used to bend the sheet metal piece to the required shape and angle.Developed sized sheet metal is cut out from large sheet by punching operation.Developed sheet metal size is obtained from drawing.Sheet metal bending process can be briefly jotted down as:
