Bend deduction in Sheet metal design
Mufaddal Rasheed 
What is the meaning of Bend deduction in sheet metal design
Bend Deduction is how much shorter to make the flat length in order to end up with the right length after bending.
Consider a sheet metal part as shown after bending
The straightened sheet or unbent sheet looks like this
The length which will taken by the bend in Flat sheet is called as bend allowance.
For a Bent part these are the important dimensions
OSSB – Outside Set Back
Arc length is the Bend allowance on the neutral axis
How bend allowance is calculated have a look here : Bend allowance
Bend deduction is the deduction from the length of bend on the Outside to achieve the arc length.
Which is 2 x OSSB – Bend Allowance = Bend deduction .
IF we have OSSB , Bend allowance then Den deduction can be calculated for a given bend with known bend angle , bend radius and k factor.
Both Bend deduction and Bend allowance are important for accurate manufacturing of the Bent parts from Flat patterns.
If the Bend allowance is not known , then it can be calculated from the Bend deduction measured physically.
For more content on sheet metal design have a look at the list of articles here :
How to Stiffen Sheet metal design
Categories: : Sheet metal