A novel method is described to estimate the material characteristics of a sheet being bent in a pressbrake from punch force-displacement data. The method is simple enough to be used for real time identification of uncertain sheet characteristics. This procedure can be combined with a model of pressbrake bending to provide real time control of the pressbrake. The setup procedure can be eliminated, and the final angle of the bends can be made insensitive to material property variations. A machine controlled in this manner can be integrated into an unmanned flexible sheet metal manufacturing cell.