bend allowances and k-factor

huangyhg

bend allowances and k-factor
is the k-factor purely a geometric coefficient for sheet metal bending, or does it change depending on the material?  take for instance, form-bending with a male and female die..will the k-factor be different for different metals give the same geometry, ie .125 thick metal of different varieties?  and, if so please explain why.
i believe that the k-factor is different because the modulus of elasticity and poissons ratio.  different metals will exhibit different values of deformation.   
published values, for ex. in the machinery handbook are different for copper, aluminum, stainless, etc.  the bottom line is, is the neutral axis different, and will different "flat" lengths for different metals be required to produce the same formed/finished product.  good luck and please keep posting with all of your comments.  thanks in advance, 13