Manufacturing question: Is there a difference in sheet metal bend allowances between v-forms and wipe forms?

Are there seperate formulas for calculating the two different bending types?Manufacturing question: Is there a difference in sheet metal bend allowances between v-forms and wipe forms?
I wish I could say for sure. But I am only familiar with the V forms. My experience is that there are only two main factors. Number 1 is the material itself. The material bends around its neutral axis which is not necessarily the center of the material. For Stainless steels it is about 45% of the thickness measured from the inside of the bend. For Carbon steel about 33% and for Aluminum 25%.





The other factor is the inside radius of the bend. For Sheet metal the inside radius is usually about 1 metal thickness for plates thicker than 3/16'; the inside radius is usually increased to 1 1/2 x the thickness or more.





We use the wipe type forms for the thinnest materials. The thinner the material the less errors in estimating the bend allowance will effect the final dimensions.Manufacturing question: Is there a difference in sheet metal bend allowances between v-forms and wipe forms?
In mild steel if you are still ';air'; bending it, no. The width of the bottom die can have a significant effect on the amount of material stretch in forming, so conversely, the gap between the wiper and the die block also needs to be considered. It's not unusual in mild steel fabrication to actually coin the material while forming if a bottom die opening is less than 6T. Even with the variance in thickness, tensile strength and grain direction in mild steel fabrication, as long as your measurements are being done with a tape measure, bend allowance calculations will generally be close enough.,