It is also notable that the forming tools can easily make geometry that is impossible to attain.
Most apparent are lances (or any form) that are as long as their opening - they always shorten in real life - and form tools will not automatically adjust for developed length. Foresight in the form-tool design process can account for correct development, but this becomes problematical as the form tool must be adapted for the "as used" conditions.
Another one comes to mind is on the periphery of a form tool, the material backside can be dead sharp as if the inner & outer radius were zero. I have seen this on louvers for example. One can get different levels of realism depending on the form tool design.
Another big problem is that the form tool cannot (usually) in any way have a disparity between the punch & die side of a feature - i.e. cannot account for size differences in shear/break. Generally this is not a huge problem if one dimensions the die or punch size exclusively (not using both sides to define definitions). Related to this is the inability for a form tool to model things with different punch / die sizes. Take a simple semi-perf for example. Anyone worth their salt (my opinion - dissenters received) would not size a punch for a semi-perf _smaller_ than the die opening as it creates a shear (weak semi-perf). Common practice is to size the punch _bigger_ than the the die to create more of an extrusion and create less of a shear line (remember it does not enter and does not need to be smaller). Form tools cannot deal with this very well.
Form tool detail all depends on what one needs (part designer or tool designer), so there is usually a way to create the geometry needed in either case. What a part designer and a tool designer deem passable is often different.