Inventor has its own bend tables located in C:\Program Files\Autodesk\Inventor 9\Samples\Bend Tables. Copy and modify that chart to suit your needs. Does your company make your parts in house? If not, then the K-factor will most likely do for you. My company uses a bend deduction chart we made almost 20 years ago and it works perfect, but that chart is based on our tooling from the brake. For 14 gauge (0.075) hrs material, we use 0.141 for a bend deduction, for 12 gauge hrs (0.105), we use 0.169 for a bend deduction etc....
Later, Steve Harrity
Universal Dynamics